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17 pages, 657 KiB  
Article
Hayekian Hurdles: Challenges to Cryptocurrency as a Viable Basis for a New Monetary Order
by Luís Pedro Freitas, Jorge Cerdeira and Diogo Lourenço
Economies 2025, 13(1), 12; https://doi.org/10.3390/economies13010012 - 7 Jan 2025
Viewed by 387
Abstract
The rise of cryptocurrencies over the past decade has promised to challenge the dominance of fiat money systems and reshape monetary policy. However, recent developments, including market volatility and the collapse of key exchanges like FTX, have eroded public trust, raising skepticism of [...] Read more.
The rise of cryptocurrencies over the past decade has promised to challenge the dominance of fiat money systems and reshape monetary policy. However, recent developments, including market volatility and the collapse of key exchanges like FTX, have eroded public trust, raising skepticism of a feasible transition to a crypto-based monetary system. This paper explores why cryptocurrencies have not met the expectations of their proponents, particularly those who saw them as a step towards Friedrich Hayek’s vision for competitive currency issuance. While cryptocurrencies reflect some aspects of Hayek’s model, their instability—especially in Bitcoin-like assets—undermines their role as a reliable alternative to fiat money. The paper also considers how central bank independence and regulatory gaps further hinder the development of a robust cryptocurrency framework. Despite the continued relevance of Hayek’s ideas in today’s monetary landscape, the entrenched structures of modern central banks and the rise of Central Bank Digital Currencies suggest that a decentralised currency order remains unlikely in the near future. Full article
(This article belongs to the Special Issue The Political Economy of Money)
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<p>Daily returns (%) of assets.</p>
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<p>Daily returns (%) of assets (2021).</p>
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16 pages, 4006 KiB  
Article
Stablecoin: A Story of (In)Stabilities and Co-Movements Written Through Wavelet
by Rubens Moura de Carvalho, Helena Coelho Inácio and Rui Pedro Marques
J. Risk Financial Manag. 2025, 18(1), 20; https://doi.org/10.3390/jrfm18010020 - 6 Jan 2025
Viewed by 438
Abstract
Stablecoins are crypto assets designed to maintain stable value by bridging fiat currencies and volatile crypto assets. Our study extends previous research by analyzing the instability and co-movement of major stablecoins (USDT, USDC, DAI, and TUSD) during significant economic events such as the [...] Read more.
Stablecoins are crypto assets designed to maintain stable value by bridging fiat currencies and volatile crypto assets. Our study extends previous research by analyzing the instability and co-movement of major stablecoins (USDT, USDC, DAI, and TUSD) during significant economic events such as the COVID-19 pandemic and the collapses of Iron Finance, Terra-Luna, FTX, and Silicon Valley Bank (SVB). We investigated the temporal volatility and dynamic connections between stablecoins using wavelet techniques. Our results showed that the announcement of USDT’s listing on Coinbase in April 2021 significantly impacted the stability of stablecoins, evidenced by a decline in the power spectrum. This phenomenon has not been explored in the literature. Furthermore, the collapse of SVB was highly relevant to the stablecoin market. We observed high coherence between pairs during the pandemic, the Coinbase listing, and the collapse of SVB. After the collapse of Terra-Luna, USDT, USDC, and DAI became more connected in the medium term, with USDC and DAI extending in the long term despite a negative co-movement between USDT and the others. This study highlights the impact of exchange listings on the volatility of stablecoins, with implications for investors, regulators, and the cryptocurrency community, especially regarding the stability and safe integration of these assets into the financial system. Full article
(This article belongs to the Special Issue Financial Technologies (Fintech) in Finance and Economics)
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<p>Wavelet power spectrum analysis of the USDT, USDC, DAI, and TUSD.</p>
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<p>Wavelet coherence between stablecoins.</p>
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<p>Wavelet coherence between stablecoins.</p>
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15 pages, 2240 KiB  
Article
First Look at the Venoms of Two Sinomicrurus Snakes: Differences in Yield, Proteomic Profiles, and Immunorecognition by Commercial Antivenoms
by Xiang-Yu Li, Ya-Qi Zhang, Xin-Ru Qian, Hong-Yan Zhao, Hong-Liang Lu and Jian-Fang Gao
Toxins 2025, 17(1), 19; https://doi.org/10.3390/toxins17010019 - 2 Jan 2025
Viewed by 409
Abstract
Chinese coral snakes (Sinomicrurus) are highly neglected regarding their venom profiles and harm to humans, which impedes our ability to deeply understand their biological properties and explore their medicinal potential. In this study, we performed a comparative analysis to reveal the [...] Read more.
Chinese coral snakes (Sinomicrurus) are highly neglected regarding their venom profiles and harm to humans, which impedes our ability to deeply understand their biological properties and explore their medicinal potential. In this study, we performed a comparative analysis to reveal the venom profiles of two Chinese coral snakes in terms of their venom yields, proteomic profiles, and immunorecognition by commercial antivenoms. The results showed that Sinomicrurus kelloggi expels more venom (lyophilized venom mass) than Sinomicrurus maccelellandi but possesses a similar solid venom content. These interspecific differences in venom yield were influenced by the snout–vent length. The venoms of these two species varied in their electrophoretic profiles, as well as in the presence or absence and relative abundance of protein families. They exhibited a 3-FTx-predominant phenotype, where the S. maccelellandi venom was dominated by 3-FTx (32.43%), SVMP (23.63%), PLA2 (19.88%), and SVSP (12.61%), while the S. kelloggi venom was dominated by 3-FTx (65.81%), LAAO (11.35%), and AMP (10.09%). While both the commercial Naja atra and Bungarus multicinctus antivenoms could immunorecognize these two Chinese coral snake venoms, the N. atra antivenom possessed a higher neutralization capability than the B. multicinctus antivenom for both species of coral snakes. Our findings show significant interspecific variations in the venom profiles of these Sinomicrurus snakes for the first time. We suggest screening or preparing specific antivenoms with high efficiency for the clinical treatment of envenomation caused by these snakes. Full article
(This article belongs to the Section Animal Venoms)
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<p>SDS-PAGE profiles of venom proteins from two Chinese coral snakes. Sm, <span class="html-italic">Sinomicrurus macclellandi</span>; Sk, <span class="html-italic">Sinomicrurus kelloggi</span>. The numerically labeled gel regions were excised, tryptic-digested, and analyzed using nESI-MS/MS. The details of the peptides/proteins are listed in <a href="#app1-toxins-17-00019" class="html-app">Supplementary Tables S1 and S2</a>.</p>
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<p>The relative abundances of toxin families in <span class="html-italic">S. macclellandi</span> (<b>A</b>) and <span class="html-italic">S. kelloggi</span> (<b>B</b>) venoms. 3-FTx, three-finger toxin; SVMP, snake venom metalloproteinase; PLA<sub>2</sub>, phospholipase A<sub>2</sub>; SVSP, snake venom serine proteinase; HA, hyaluronidase; NGF, nerve growth factor; AMP, aminopeptidase; 5′NT, 5′ nucleotidase; PDE, phosphodiesterase; CRISP, cysteine-rich secretory protein; VEGF, vascular endothelial growth factor; Kunitz, Kunitz-type serine protease inhibitor; AchE, acetylcholinesterase; LAAO, <span class="html-small-caps">l</span>-amino acid oxidase; PLB, phospholipase B. The details are listed in <a href="#app1-toxins-17-00019" class="html-app">Supplementary Tables S1 and S2</a>.</p>
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<p>Cross-reaction between Chinese coral snake venoms and two commercial monovalent antivenoms assessed with ELISA. (<b>A</b>) <span class="html-italic">N. atra</span> antivenom; (<b>B</b>) <span class="html-italic">B. multicinctus</span> antivenom.</p>
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<p>Cross-reaction between Chinese coral snake venoms and two commercial monovalent antivenoms assessed using Western blotting. Left PVDF membrane: venoms incubated with <span class="html-italic">N. atra</span> antivenom; right PVDF membrane: venoms incubated with <span class="html-italic">B. multicinctus</span> antivenom.</p>
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21 pages, 5193 KiB  
Article
Proteomic Profiling of Venoms from Bungarus suzhenae and B. bungaroides: Enzymatic Activities and Toxicity Assessment
by Chenying Yang, Li Ding, Qiyi He, Xiya Chen, Haiting Zhu, Feng Chen, Wanzhou Yang, Yuexin Pan, Zhiyuan Tai, Wenhao Zhang, Zeyuan Yu, Zening Chen and Xiaodong Yu
Toxins 2024, 16(11), 494; https://doi.org/10.3390/toxins16110494 - 16 Nov 2024
Viewed by 1350
Abstract
Kraits are venomous snakes of the genus Bungarus from the family Elapidae. Their venom typically demonstrates neurotoxicity; however, the toxicity is significantly influenced by the snake’s species and geographical origin. Among the Bungarus species, Bungarus suzhenae and B. bungaroides have been poorly [...] Read more.
Kraits are venomous snakes of the genus Bungarus from the family Elapidae. Their venom typically demonstrates neurotoxicity; however, the toxicity is significantly influenced by the snake’s species and geographical origin. Among the Bungarus species, Bungarus suzhenae and B. bungaroides have been poorly studied, with little to no information available regarding their venom composition. In this study, a proteomic approach was employed using LC-MS/MS to identify proteins from trypsin-digested peptides. The analysis revealed 102 venom-related proteins from 18 distinct functional protein families in the venom of B. suzhenae, with the primary components being three-finger toxins (3-FTx, 25.84%), phospholipase A2 (PLA2, 40.29%), L-amino acid oxidase (LAAO, 10.33%), Kunitz-type serine protease inhibitors (KUN, 9.48%), and snake venom metalloproteinases (SVMPs, 6.13%). In the venom of B. bungaroides, 99 proteins from 17 families were identified, with primary components being 3-FTx (33.87%), PLA2 (37.91%), LAAO (4.21%), and KUN (16.60%). Enzymatic activity assays confirmed the presence of key venom enzymes. Additionally, the LD50 values for B. suzhenae and B. bungaroides were 0.0133 μg/g and 0.752 μg/g, respectively, providing a reference for toxicity studies of these two species. This research elucidates the proteomic differences in the venoms of these two species, offering a foundation for developing antivenoms and clinical treatments for envenomation. Full article
(This article belongs to the Special Issue Transcriptomic and Proteomic Study on Animal Venom: Looking Forward)
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<p>Distribution ranges of <span class="html-italic">B. suzhenae</span> and <span class="html-italic">B. bungaroides</span>. The brown area represents the distribution of <span class="html-italic">B. suzhenae</span>, which is primarily found in Yingjiang County, Dehong Prefecture, Yunnan Province, China, and Kachin State, Myanmar. The yellow area indicates the distribution of <span class="html-italic">B. bungaroides</span>, which is mainly located in Sikkim and Meghalaya in India, Nujiang Lisu Autonomous Prefecture, Yunnan Province, and Medog County in Tibet, China. Blue star and green triangle on the map denote sampling points for <span class="html-italic">B. suzhenae</span> and <span class="html-italic">B. bungaroides</span>, respectively.</p>
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<p>Relative abundance of toxin protein families in the venoms of <span class="html-italic">B. suzhenae</span> and <span class="html-italic">B. bungaroides</span> as determined by LC-MS/MS. (<b>A</b>) Shows the relative abundance of various protein families in <span class="html-italic">B. suzhenae</span> venom; (<b>B</b>) shows the same for <span class="html-italic">B. bungaroides</span> venom. Abbreviations include 3-FTx (three-finger toxin), PLA<sub>2</sub> (phospholipase A<sub>2</sub>), PLB (phospholipase B), CRISP (cysteine-rich secretory protein), SVMP (snake venom metalloproteinase), SVSP (snake venom serine protease), LAAO (L-amino acid oxidase), CTL (C-type lectin), KUN (Kunitz-type serine protease inhibitor), NP (natriuretic peptide), CYS (cystatin), NGF (nerve growth factor), AChE (acetylcholinesterase), PI (PLA<sub>2</sub> inhibitor), PDE (phosphodiesterase), 5′-NT (5′-nucleotidase), VESP (vespryn), and HAase (hyaluronidase).</p>
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<p>Comparison of the content of 3-FTx protein subfamilies in the venoms of nine Bungarus species. * the ones studied in this research: <span class="html-italic">B. suzhenae</span> and <span class="html-italic">B. bungaroides</span>. Other species include <span class="html-italic">B. multicinctus-a</span> (Guangdong, China) [<a href="#B24-toxins-16-00494" class="html-bibr">24</a>], <span class="html-italic">B. multicinctus-b</span> (Taiwan, China) [<a href="#B24-toxins-16-00494" class="html-bibr">24</a>], <span class="html-italic">B. multicinctus-c</span> (Guangxi, China) [<a href="#B25-toxins-16-00494" class="html-bibr">25</a>], <span class="html-italic">B. multicinctus-d</span> (Vietnam) [<a href="#B26-toxins-16-00494" class="html-bibr">26</a>], <span class="html-italic">B. caeruleus</span> (India) [<a href="#B27-toxins-16-00494" class="html-bibr">27</a>], <span class="html-italic">B. sindanus</span> (Pakistan) [<a href="#B28-toxins-16-00494" class="html-bibr">28</a>], and <span class="html-italic">B. flaviceps</span> (Malaysia) [<a href="#B29-toxins-16-00494" class="html-bibr">29</a>]. Subfamilies include LNX (long neurotoxin), SNX (short neurotoxin), WNX (weak neurotoxin), and MTLP (Muscarinic toxin-like proteins).</p>
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<p>Comparison of the content of PLA<sub>2</sub> protein subfamilies in the venoms of nine Bungarus species. * the ones studied in this research: <span class="html-italic">B. suzhenae</span> and <span class="html-italic">B. bungaroides</span>. Other species include <span class="html-italic">B. multicinctus-a</span> (Guangdong, China) [<a href="#B24-toxins-16-00494" class="html-bibr">24</a>], <span class="html-italic">B. multicinctus-b</span> (Taiwan, China) [<a href="#B24-toxins-16-00494" class="html-bibr">24</a>], <span class="html-italic">B. multicinctus-c</span> (Guangxi, China) [<a href="#B25-toxins-16-00494" class="html-bibr">25</a>], <span class="html-italic">B. multicinctus-d</span> (Vietnam) [<a href="#B26-toxins-16-00494" class="html-bibr">26</a>], <span class="html-italic">B. sindanus</span> (Pakistan) [<a href="#B28-toxins-16-00494" class="html-bibr">28</a>], <span class="html-italic">B. fasciatus-a</span> (Vietnam) [<a href="#B26-toxins-16-00494" class="html-bibr">26</a>], and <span class="html-italic">B. flaviceps</span> (Malaysia) [<a href="#B29-toxins-16-00494" class="html-bibr">29</a>]. Subfamilies include β-BGT (beta-bungarotoxin), Acidic PLA<sub>2</sub> (acidic phospholipase A<sub>2</sub>), and Basic PLA<sub>2</sub> (basic phospholipase A<sub>2</sub>).</p>
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<p>Comparison of minor toxin-related protein families in the venoms of various Bungarus species. Abbreviations include Kunitz-type serine protease inhibitors (KUNs), L-amino acid oxidase (LAAO), snake venom metalloproteinases (SVMPs) and acetylcholinesterase (AChE). * the ones studied in this research: <span class="html-italic">B. suzhenae</span> and <span class="html-italic">B. bungaroides</span>. Other species include <span class="html-italic">B. multicinctus-a</span> (Guangdong, China) [<a href="#B24-toxins-16-00494" class="html-bibr">24</a>], <span class="html-italic">B. multicinctus-b</span> (Taiwan, China) [<a href="#B24-toxins-16-00494" class="html-bibr">24</a>], <span class="html-italic">B. multicinctus-c</span> (Guangxi, China) [<a href="#B25-toxins-16-00494" class="html-bibr">25</a>], <span class="html-italic">B. multicinctus-d</span> (Vietnam) [<a href="#B26-toxins-16-00494" class="html-bibr">26</a>], <span class="html-italic">B. candidus</span> (Malaysia) [<a href="#B9-toxins-16-00494" class="html-bibr">9</a>], <span class="html-italic">B. caeruleus</span> (India) [<a href="#B27-toxins-16-00494" class="html-bibr">27</a>], <span class="html-italic">B. sindanus</span> (Pakistan) [<a href="#B28-toxins-16-00494" class="html-bibr">28</a>], <span class="html-italic">B. fasciatus-a</span> (Vietnam) [<a href="#B26-toxins-16-00494" class="html-bibr">26</a>], <span class="html-italic">B. fasciatus-b</span> (Malaysia) [<a href="#B9-toxins-16-00494" class="html-bibr">9</a>], and <span class="html-italic">B. flaviceps</span> (Malaysia) [<a href="#B29-toxins-16-00494" class="html-bibr">29</a>].</p>
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<p>Biochemical activities of venoms from <span class="html-italic">B. suzhenae</span> and <span class="html-italic">B. bungaroides</span>. This figure depicts the (<b>A</b>) PLA<sub>2</sub>, (<b>B</b>) LAAO, (<b>C</b>) SVMP, and (<b>D</b>) Fibrinogen-degrading activities of the venoms. Panel (<b>D</b>) shows the fibrinogen electrophoresis patterns: Lane Fib represents untreated fibrinogen, Lane a and b show fibrinogen hydrolysis by <span class="html-italic">B. suzhenae</span> venom and by <span class="html-italic">B. suzhenae</span> venom with EDTA as an inhibitor, respectively, while Lane c and d show the same for <span class="html-italic">B. bungaroides</span> venom. All experiments were performed in triplicate, with error bars representing standard deviation. Statistical significance was assessed with multiple comparison tests: <span class="html-italic">p</span> &gt; 0.05 (ns), <span class="html-italic">p</span> &lt; 0.0002 (***), <span class="html-italic">p</span> &lt; 0.0001 (****).</p>
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<p>Hemolytic activities of venoms from <span class="html-italic">B. suzhenae</span> and <span class="html-italic">B. bungaroides</span>. (<b>A</b>) Illustrates the direct hemolytic activity of PLA2 on red blood cells, expressed as a percentage in relation to the positive control (1% Triton X). (<b>B</b>) Shows the hemolytic effect of phospholipids generated by PLA<sub>2</sub> hydrolysis on red blood cells. All tests were carried out in triplicate, with error bars denoting standard deviation. Statistical significance was assessed with multiple comparison tests: <span class="html-italic">p</span> &lt; 0.05 (*), <span class="html-italic">p</span> &lt; 0.002 (**), <span class="html-italic">p</span> &lt; 0.0001 (****).</p>
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18 pages, 2041 KiB  
Article
The Toxin Diversity, Cytotoxicity, and Enzymatic Activity of Cape Cobra (Naja nivea) Venom
by Tim Lüddecke, Ignazio Avella, Maik Damm, Lennart Schulte, Johanna Eichberg, Kornelia Hardes, Susanne Schiffmann, Marina Henke, Thomas Timm, Günter Lochnit and Andreas Vilcinskas
Toxins 2024, 16(10), 438; https://doi.org/10.3390/toxins16100438 - 11 Oct 2024
Viewed by 1290
Abstract
“True” cobras (genus Naja) are among the venomous snakes most frequently involved in snakebite accidents in Africa and Asia. The Cape cobra (Naja nivea) is one of the African cobras of highest medical importance, but much remains to be learned [...] Read more.
“True” cobras (genus Naja) are among the venomous snakes most frequently involved in snakebite accidents in Africa and Asia. The Cape cobra (Naja nivea) is one of the African cobras of highest medical importance, but much remains to be learned about its venom. Here, we used a shotgun proteomics approach to better understand the qualitative composition of N. nivea venom and tested its cytotoxicity and protease activity as well as its effect on intracellular Ca2+ release and NO synthesis. We identified 156 venom components representing 17 protein families, with the dominant ones being three-finger toxins, mostly of the short-chain type. Two-thirds of the three-finger toxin entries identified were assigned as cytotoxins, while the remainder were categorized as neurotoxins, including short-chain, long-chain, and ancestral three-finger toxins. We also identified snake venom metalloproteinases and members of CRISP, l-amino acid oxidase, and other families. Protease activity and its effect on intracellular Ca2+ release and NO synthesis were low. Phospholipase A2 activity was surprisingly high, despite this toxin family being marginally recovered in the analyzed venom. Cytotoxicity was relevant only at higher venom concentrations, with macrophage and neuroblastoma cell lines showing the lowest viability. These results are in line with the predominantly neurotoxic envenomation symptoms caused by Cape cobra bites. The present overview of the qualitatively complex and functionally intriguing venom of N. nivea may provide insights into the pathobiochemistry of this species’ venom. Full article
(This article belongs to the Section Animal Venoms)
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<p>Phenotypic variation and hooding behavior in the Cape cobra (<span class="html-italic">Naja nivea</span>). The top row shows juveniles (<b>A</b>,<b>B</b>); adults are shown in middle and bottom rows (<b>C</b>–<b>F</b>). Specimens in (<b>C</b>,<b>D</b>) display the widespread yellowish to brown coloration, (<b>E</b>) shows a speckled specimen, and a dark brown variety is shown in (<b>F</b>). Images by Andries Cilliers.</p>
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<p>One-dimensional SDS-PAGE of <span class="html-italic">Naja nivea</span> venom under (<b>A</b>) reduced and (<b>B</b>) non-reduced conditions. Shown are stained protein bands of 5 µg and 2 µg venom. Putative toxin classes matching the molecular weight of the retrieved bands are assigned based on their known sizes. Abbreviations: svMP P-III = snake venom metalloproteinases of class P-III; LAAO = <span class="html-small-caps">l</span>-amino acid oxidase; PLA<sub>2</sub> = phospholipase A<sub>2</sub>; PLB = phospholipase B; CE = carboxylesterase; 5N = 5′-nucleotidase; CRISP = cysteine-rich secretory proteins; 3FTx = three-finger toxins.</p>
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<p>Bar chart depicting toxin diversity in <span class="html-italic">Naja nivea</span> venom. The numbers refer to the variety of venom proteins detected within each protein family, thus providing a snapshot of the toxin diversity within <span class="html-italic">N. nivea</span> venom. The most diverse component family was three-finger toxins (3FTxs), with cytotoxins (CTx, 26 entries), neurotoxins (NTx, 10 entries) including 1 muscarinic toxin, and non-conventional neurotoxins (NC, 6 entries). The second most diverse family was snake venom metalloproteinases (svMP), followed by venom complement C3 proteins, cysteine-rich secretory proteins (CRISP), <span class="html-small-caps">l</span>-amino acid oxidases (LAAO), 5′ nucleotidases (5N), carboxylesterases (CE), phosphodiesterases, and phospholipase B proteins (PLB). The less diverse families (&lt;5 components) are grouped as “Other”.</p>
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<p>In vitro effects of <span class="html-italic">N. nivea</span> venom. (<b>A</b>) The heatmap shows the cytotoxic effect of the analyzed <span class="html-italic">N. nivea</span> venom on the viability of the five tested cell lines (A549, HEK 293T, SH-SY5Y, RAW 264.7, PBMC). (<b>B</b>) Protease and (<b>C</b>) phospholipase A<sub>2</sub> activity. The bar charts illustrate the photometrically determined protease and PLA<sub>2</sub> activity of <span class="html-italic">N. nivea</span> venom at three concentrations relative to the trypsin control, and at five concentrations relative to the PLA<sub>2</sub> stock solution provided with the assay kit, respectively.</p>
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21 pages, 680 KiB  
Article
Decrypting Cryptocurrencies: An Exploration of the Impact on Financial Stability
by Mohamed Nihal Saleem, Yianni Doumenis, Epameinondas Katsikas, Javad Izadi and Dimitrios Koufopoulos
J. Risk Financial Manag. 2024, 17(5), 186; https://doi.org/10.3390/jrfm17050186 - 30 Apr 2024
Cited by 2 | Viewed by 4379
Abstract
This study aims to empirically examine the relationship between cryptocurrency and various facets of the financial system. It seeks to provide a comprehensive understanding of how cryptocurrencies interact with, and influence, the stock market, the U.S. dollar’s strength, inflation rates, and traditional banking [...] Read more.
This study aims to empirically examine the relationship between cryptocurrency and various facets of the financial system. It seeks to provide a comprehensive understanding of how cryptocurrencies interact with, and influence, the stock market, the U.S. dollar’s strength, inflation rates, and traditional banking operations. This is carried out using linear regression models, Granger causality tests, case studies, including the collapse of the Futures Exchange (FTX), and the successful integration of Binance. The study unveiled a strong positive correlation between cryptocurrency market capitalization and key financial indicators like the Dow Jones Industrial Average, Consumer Price Index, and traditional banking operations. This indicates the growing significance of cryptocurrencies within the global financial landscape. However, a mild association was found with the U.S. dollar, suggesting a limited influence of cryptocurrencies on traditional fiat currencies currently. Despite certain limitations such as reliance on secondary data, methodological choices, and geographic focus, this research provides valuable insights for policymakers, financial industry stakeholders, and academic researchers, underlining the necessity for continued study into the complex interplay between cryptocurrencies and financial stability. Full article
(This article belongs to the Special Issue Digital Banking and Financial Technology)
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<p>Scatterplots for all variables. Source: Own elaboration.</p>
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25 pages, 6998 KiB  
Article
The Cloning and Characterization of a Three-Finger Toxin Homolog (NXH8) from the Coralsnake Micrurus corallinus That Interacts with Skeletal Muscle Nicotinic Acetylcholine Receptors
by Henrique Roman-Ramos, Álvaro R. B. Prieto-da-Silva, Humberto Dellê, Rafael S. Floriano, Lourdes Dias, Stephen Hyslop, Raphael Schezaro-Ramos, Denis Servent, Gilles Mourier, Jéssica Lopes de Oliveira, Douglas Edgard Lemes, Letícia V. Costa-Lotufo, Jane S. Oliveira, Milene Cristina Menezes, Regina P. Markus and Paulo Lee Ho
Toxins 2024, 16(4), 164; https://doi.org/10.3390/toxins16040164 - 22 Mar 2024
Cited by 1 | Viewed by 1821
Abstract
Coralsnakes (Micrurus spp.) are the only elapids found throughout the Americas. They are recognized for their highly neurotoxic venom, which is comprised of a wide variety of toxins, including the stable, low-mass toxins known as three-finger toxins (3FTx). Due to difficulties in [...] Read more.
Coralsnakes (Micrurus spp.) are the only elapids found throughout the Americas. They are recognized for their highly neurotoxic venom, which is comprised of a wide variety of toxins, including the stable, low-mass toxins known as three-finger toxins (3FTx). Due to difficulties in venom extraction and availability, research on coralsnake venoms is still very limited when compared to that of other Elapidae snakes like cobras, kraits, and mambas. In this study, two previously described 3FTx from the venom of M. corallinus, NXH1 (3SOC1_MICCO), and NXH8 (3NO48_MICCO) were characterized. Using in silico, in vitro, and ex vivo experiments, the biological activities of these toxins were predicted and evaluated. The results showed that only NXH8 was capable of binding to skeletal muscle cells and modulating the activity of nAChRs in nerve–diaphragm preparations. These effects were antagonized by anti-rNXH8 or antielapidic sera. Sequence analysis revealed that the NXH1 toxin possesses eight cysteine residues and four disulfide bonds, while the NXH8 toxin has a primary structure similar to that of non-conventional 3FTx, with an additional disulfide bond on the first loop. These findings add more information related to the structural diversity present within the 3FTx class, while expanding our understanding of the mechanisms of the toxicity of this coralsnake venom and opening new perspectives for developing more effective therapeutic interventions. Full article
(This article belongs to the Section Animal Venoms)
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Figure 1
<p>The nucleotide and deduced protein sequence of the nxh8 cDNA clone. The cDNA clone structure of the nxh8 gene from the venom gland of <span class="html-italic">Micrurus corallinus</span> (EMBL data bank accession number AJ344067) comprises the following regions: a 5′ untranslated region (UTR) (1–5 bp), a signal peptide coding sequence (6–68 bp), a mature peptide coding sequence (69–263 bp, highlighted in a box), and a 3′UTR (264–470 bp). The polyadenylation signal is indicated in bold. The deduced mature peptide sequence (NXH8) starts at the Leu residue and is indicated by an arrow. The sequence utilized for the 5′ primer design for PCR amplification and subcloning into the pRSET C expression vector is emphasized with an underline. The blue numbers on the left indicate amino acid residue positions, while the black numbers on the right indicate nucleotide positions.</p>
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<p>Alignment of NXH8 (3NO48_MICCO) with different Elapidae 3FTx highlighting functionally invariant residues related to skeletal muscle nAChR binding. Functionally invariant residues in three-finger α-neurotoxins that interact with muscular nicotinic acetylcholine receptors (nAChRs) are shaded in gray, based on experimental mutational data for Erabutoxin-a (3S1EA_LATSE) [<a href="#B78-toxins-16-00164" class="html-bibr">78</a>,<a href="#B79-toxins-16-00164" class="html-bibr">79</a>], NMM I (3S11_NAJMO) [<a href="#B80-toxins-16-00164" class="html-bibr">80</a>,<a href="#B81-toxins-16-00164" class="html-bibr">81</a>], and α-Cobratoxin (3L21_NAJKA) [<a href="#B82-toxins-16-00164" class="html-bibr">82</a>,<a href="#B83-toxins-16-00164" class="html-bibr">83</a>], as well as structural data for α-Bungarotoxin (3L21A_BUNMU) [<a href="#B84-toxins-16-00164" class="html-bibr">84</a>,<a href="#B85-toxins-16-00164" class="html-bibr">85</a>]. Residues critical for binding to skeletal muscle (α1)2β1γδ nAChRs, which are shared between short- and long-chain α-neurotoxins, are indicated in bold. Putative functional conserved residues in toxins such as WTX (3NO2_NAJKA), Candoxin (3NO4_BUNCA), and NXH8 (3NO48_MICCO), with analogous binding functions, are also presented. The cysteine residues and structurally invariant residues are enclosed in boxes, and the disulfide bridges are highlighted. Furthermore, the segments contributing to the three loops and the C-terminus are labeled. The fifth disulfide bridge in long-chain α-neurotoxins, between Cys<sup>32</sup> and Cys<sup>36</sup>, is represented by a dotted line, while the corresponding bridge in non-conventional three-finger toxins, between Cys<sup>6</sup> and Cys<sup>11</sup>, is shown as a dashed line.</p>
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<p>Alignment of NXH1 (3SOC1_MICCO) with different Elapidae 3FTx highlighting functionally invariant residues related to skeletal muscle nAChR binding. Functionally invariant residues in three-finger α-neurotoxins that interact with muscular nicotinic acetylcholine receptors (nAChRs) are shaded in gray, based on experimental mutational data for Erabutoxin-a (3S1EA_LATSE). Residues critical for binding to skeletal muscle (α)2βγδ nAChRs, which are shared between short- and long-chain α-neurotoxins, are indicated in bold. Putative functional conserved residues in toxins such as NXH1 from <span class="html-italic">M. corallinus</span> (3SOC1_MICCO), short neurotoxin 1 from <span class="html-italic">Hydrophis cyanocinctus</span> (3S11_HYDCY), short neurotoxins 1 from <span class="html-italic">Hydrophis schitosus</span> (3S11_HYDSC), Toxin 5, from <span class="html-italic">H. schitosus</span> (3S15_HYDSC), short neurotoxin A, from <span class="html-italic">Aipysurus laevis</span> (3S11_AIPLA), short neurotoxin B, from <span class="html-italic">A. laevis</span> (3S12_AIPLA), short neurotoxin c, from <span class="html-italic">A. laevis</span> (3S13_AIPLA), short neurotoxin D, from <span class="html-italic">A. laevis</span> (3S14_AIPLA), Cobrotoxin-b, from <span class="html-italic">Naja atra</span> (3S1CC_NAJAT), short neurotoxin 1, from <span class="html-italic">Hydrophis lapemoides</span> (3S11_HYDLA), short neurotoxins 1, from <span class="html-italic">Naja oxiana</span> (3S11_NAJOX), and three-finger toxin Mnn I, from <span class="html-italic">Micrurus nigrocinctus</span> (3S11_MICNI). The cysteine residues and structurally invariant residues are enclosed in boxes, and the disulfide bridges are highlighted. Furthermore, the segments contributing to the three loops and the C-terminus are labeled.</p>
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<p>Alignment of NXH1 (3SOC1_MICCO) with two fasciculins 3FTx from <span class="html-italic">Dendroaspis</span> spp. Putative functional conserved residues in toxins such as NXH1 from <span class="html-italic">M. corallinus</span> (3SOC1_MICCO), Fasciculin-1, from <span class="html-italic">D. angusticeps</span> (3SE1_DENAN), Acetylcholinesterase toxin C, from <span class="html-italic">D. polylepis polylepis</span> (3SEC_DENPO). The cysteine residues and structurally invariant residues are enclosed in boxes, and the disulfide bridges are highlighted. Furthermore, the segments contributing to the three loops and the C-terminus are labeled.</p>
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<p>Dendrogram of three-finger toxins family. A blue arrow (<span style="color:blue">➔</span>) indicates the NXH8 ally group. 3FTx with a fifth disulfide bridge at loop I are indicated by a star (*). The dendrogram shows that 3FTx with a disulfide bridge at loop I is a non-homogeneous group, probably with distinct functions. The <span class="html-italic">M. corallinus</span> three-finger toxins NXH1 and NXH8 (shaded) are unrelated. Orphan groups’ clades are numbered in agreement with Fry, B.G. et al. [<a href="#B36-toxins-16-00164" class="html-bibr">36</a>]. The parentheses display, respectively, the identity and similarity percentages of each toxin in relation to NXH8. Bootstrap values are shown in red.</p>
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<p>SDS-PAGE analysis of recombinant expression and purification of rNXH8 in <span class="html-italic">Escherichia coli</span> cells transformed with pRSETC-<span class="html-italic">nxh8</span> plasmid, with each lane loaded with a 10 μL sample volume. (<b>a</b>) <span class="html-italic">E. coli</span> BL21 (DE3)-pRSETC-nxh8 cell extracts: 1. Molecular-mass marker; 2. Cell extract before IPTG induction; 3. Cell extract after IPTG induction; (<b>b</b>) Metal ion affinity chromatography, under denaturing conditions (8 M urea/10 mM 2-ME), of rNXH8 from solubilized inclusion bodies: 1. Molecular-mass marker; 2. <span class="html-italic">E. coli</span> BL21 (DE3)-pRSETC-<span class="html-italic">nxh8</span> cell extract after IPTG induction; 3. Supernatant after cell lysate centrifugation; 4. Precipitate after cell lysate centrifugation; 5. Inclusion bodies after solubilization in 8 M urea/10 mM 2-ME buffer; 6. Non-adsorbed material (flow through), after sample loading; 7. Ni<sup>2+</sup>-charged resin after sample loading; 8. Non-adsorbed material after column wash; 9. Adsorbed material after elution; (<b>c</b>) Metal ion affinity chromatography of refolded rNXH8: 1. Molecular-mass marker; 2. Cell lysate extract; 3. Column wash with 5 mM imidazole; 4. Adsorbed material after elution with 1 column volume of 250 mM imidazole elution buffer; 5. Adsorbed material after elution with five column volumes of 250 mM imidazole elution buffer. 6. Adsorbed material after EDTA chelating elution; (<b>d</b>) Reducing SDS-PAGE analysis of rNXH8 aggregate formation during dialysis (2-ME was added to samples): 1. Molecular-mass marker; 2. Inclusion bodies after solubilization in 8 M urea/10 mM 2-ME buffer; 3. Adsorbed material after elution with 2 M urea/10 mM Imidazole buffer; 4. Full dialysis material; 5. Supernatant after dialysis material centrifugation; 6. Precipitate after dialysis material centrifugation. (<b>e</b>) Non-reducing SDS-PAGE analysis of rNXH8-aggregate formation during dialysis (2-ME was not added to sample): 1. Molecular-mass marker; 2. Inclusion bodies after solubilization in 8 M urea/10 mM 2-ME buffer; 3. Adsorbed material after elution with 2 M urea/10 mM Imidazole buffer; 4. Full dialysis material; 5. Supernatant after dialysis material centrifugation; 6. Precipitate after dialysis material centrifugation.</p>
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<p>Cross-reactivity of anti-rNXH8 in diverse snake venoms by Western-blot. (<b>a</b>) SDS-PAGE stained with Coomassie Blue R250 (gradient 10–20%), with each lane loaded with a 10 μL sample volume. (<b>b</b>) Western blot of a replica gel after electroblotting to a nitrocellulose support incubated with anti-NXH8 polyclonal serum. 1. Molecular-mass marker; 2. Venom of <span class="html-italic">M. corallinus</span>; 3. Venom of <span class="html-italic">M. ibiboboca</span>; 4. Venom of <span class="html-italic">M. lemniscatus</span>; 5. Venom of <span class="html-italic">M. spixii</span>; 6. Venom of <span class="html-italic">M. frontalis</span>; 7. Venom of <span class="html-italic">M. altirostris</span>; 8. Venom of <span class="html-italic">M. surinamensis</span>; 9. Venom of <span class="html-italic">M. carinicauda dumerilli</span>; 10. Venom of <span class="html-italic">M. hemprichii</span>; 11. Venom of <span class="html-italic">M. spixii martiusi</span>; 12. Venom of <span class="html-italic">M. decoratus</span>; 13. Molecular-mass marker; 14. Venom of <span class="html-italic">Dendroaspis angusticeps</span>; 15. Venom of <span class="html-italic">Notechis scutatus scutatus</span>; 16. Venom of <span class="html-italic">Bungarus multicinctus</span>; 17. Venom of <span class="html-italic">Crotalus durissus terrificus</span>; 18. Purified cardiotoxin IV <span class="html-italic">Naja naja kaouthia</span>; 19. Venom of <span class="html-italic">Bothrops jararaca</span>. 20. Molecular-mass marker. The polyclonal serum against recombinant NXH8 reacts with homologous <span class="html-italic">M. corallinus</span> venom and with heterologous venoms from <span class="html-italic">M. altirostris</span> (lane 07), <span class="html-italic">Dendroaspis angusticeps</span> (lane 14) and <span class="html-italic">Bungarus multicinctus</span> (lane 16).</p>
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<p>Acetylcholine receptor-binding assay utilizing primary skeletal muscle cell-membrane preparations from newborn rats. The assay employed [<sup>125</sup>I]-labeled α-Bungarotoxin as a tracer. Membrane preparations were incubated for one hour with either nicotine or the <span class="html-italic">M. corallinus</span> crude venom, followed by a wash in binding buffer, and then further incubated for an additional hour at room temperature with [<sup>125</sup>I]-labeled α-Bungarotoxin. Subsequently, the membranes were rewashed, and the resulting pellets, obtained by centrifugation, were analyzed for residual radioactivity. In the neutralizing venom assay, diminishing quantities of crude venom were pre-incubated for 30 min with 10 µL of polyclonal sera (anti-rNXH8, anti-rNXH1, or anti-MIX*) before the addition to the membrane preparation. Assays were performed in quadruplicate. Statistical analysis was conducted using a 2-way ANOVA with multiple comparisons in GraphPad Prism 10 (GraphPad Software, Boston, MA, USA), with a significance threshold of <span class="html-italic">p</span> &lt; 0.05. Different lowercase letters (a–e) above the bars denote statistically distinct groups. Note: * Anti-MIX represents a 1:1 mixture of anti-rNXH8 and anti-rNXH1.</p>
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<p>Representative recordings showing the neuromuscular activities NXH1 and NXH8 three-finger toxins in indirectly stimulated PND preparations at 37 °C. (<b>a</b>) Reversion of synthetic NXH8 (sNXH8) blockade by saline washing (<span class="html-italic">W</span>); (<b>b</b>) Reversion of sNXH8 blockade by neostigmine (29 μM); (<b>c</b>) Reversion of sNXH8 (10 μg/mL) blockade by 3,4-DAP (230 μM); (<b>d</b>) sNXH8 activity after pre-incubation (37 °C, 30 min, 1:1 <span class="html-italic">v</span>/<span class="html-italic">w</span> antivenom–toxin ratio) with antielapidic serum from <span class="html-italic">Instituto Butantan</span>; (<b>e</b>) sNXH8 activity after pre-incubation (37 °C, 30 min, 1:1 <span class="html-italic">v</span>/<span class="html-italic">w</span> antivenom–toxin ratio) with anti-<span class="html-italic">Oxyuranus scutellatus</span> (Coastal Taipan) serum; (<b>f</b>) Synthetic NXH1 (sNXH1) activity; (<b>g</b>) Recombinant NXH8 (rNXH8) activity.</p>
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12 pages, 3698 KiB  
Article
Proteomic Investigation of Cape Cobra (Naja nivea) Venom Reveals First Evidence of Quaternary Protein Structures
by Lewis O. McFarlane and Tara L. Pukala
Toxins 2024, 16(2), 63; https://doi.org/10.3390/toxins16020063 - 23 Jan 2024
Cited by 4 | Viewed by 2124
Abstract
Naja nivea (N. nivea) is classed as a category one snake by the World Health Organization since its envenomation causes high levels of mortality and disability annually. Despite this, there has been little research into the venom composition of N. nivea, [...] Read more.
Naja nivea (N. nivea) is classed as a category one snake by the World Health Organization since its envenomation causes high levels of mortality and disability annually. Despite this, there has been little research into the venom composition of N. nivea, with only one full venom proteome published to date. Our current study separated N. nivea venom using size exclusion chromatography before utilizing a traditional bottom-up proteomics approach to unravel the composition of the venom proteome. As expected by its clinical presentation, N. nivea venom was found to consist mainly of neurotoxins, with three-finger toxins (3FTx), making up 76.01% of the total venom proteome. Additionally, cysteine-rich secretory proteins (CRISPs), vespryns (VESPs), cobra venom factors (CVFs), 5′-nucleotidases (5′NUCs), nerve growth factors (NGFs), phospholipase A2s (PLA2), acetylcholinesterases (AChEs), Kunitz-type serine protease inhibitor (KUN), phosphodiesterases (PDEs), L-amino acid oxidases (LAAOs), hydrolases (HYDs), snake venom metalloproteinases (SVMPs), and snake venom serine protease (SVSP) toxins were also identified in decreasing order of abundance. Interestingly, contrary to previous reports, we find PLA2 toxins in N. nivea venom. This highlights the importance of repeatedly profiling the venom of the same species to account for intra-species variation. Additionally, we report the first evidence of covalent protein complexes in N. nivea venom, which likely contribute to the potency of this venom. Full article
(This article belongs to the Special Issue Animal Venoms: Proteomics, Biochemical Activities and Application)
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Graphical abstract

Graphical abstract
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<p>Size exclusion chromatography elution profile of pooled whole venom from <span class="html-italic">N. nivea</span> eluted in 200 mM ammonium acetate. Peaks are labelled in order of elution.</p>
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<p>Non-reduced (<b>A</b>) and reduced (<b>B</b>) SDS-PAGE analysis of <span class="html-italic">N. nivea</span> venom. Fractions corresponding to pooled size exclusion peaks are indicated for reference.</p>
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<p>Global percentage of each protein family identified in <span class="html-italic">N. nivea</span> venom. Housekeeping proteins abbreviated to ‘House’.</p>
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<p>Percentage of each protein family identified in <span class="html-italic">N. nivea</span> venom grouped by SEC peak. Housekeeping proteins abbreviated to ‘House’. Each pie chart corresponds to labelled fractions from the SEC elution profile in <a href="#toxins-16-00063-f001" class="html-fig">Figure 1</a>.</p>
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<p>LC-MS chromatograph of a sample containing combined proteins from bands 19–22. Deconvoluted masses measured at each retention time are indicated by coloured markers.</p>
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16 pages, 14265 KiB  
Article
Flammutoxin, a Degradation Product of Transepithelial Electrical Resistance-Decreasing Protein, Induces Reactive Oxygen Species and Apoptosis in HepG2 Cells
by Jianguo Wu, Yu Nong, Bingzhi Chen, Yuji Jiang, Yuanhao Chen, Chuanzheng Wei, Yongxin Tao and Baogui Xie
Foods 2024, 13(1), 66; https://doi.org/10.3390/foods13010066 - 23 Dec 2023
Viewed by 1354
Abstract
Proteins from Flammulina filiformis were prepared by sodium chloride extraction and fractionated by ammonium sulfate precipitation with increasing saturation degrees to obtain the protein fractions Ffsp-30, Ffsp-50, Ffsp-70, Ffsp-90, and Ffp-90. Among these protein fractions, Ffsp-50 possessed the [...] Read more.
Proteins from Flammulina filiformis were prepared by sodium chloride extraction and fractionated by ammonium sulfate precipitation with increasing saturation degrees to obtain the protein fractions Ffsp-30, Ffsp-50, Ffsp-70, Ffsp-90, and Ffp-90. Among these protein fractions, Ffsp-50 possessed the most significant cytotoxic effect against three human gastrointestinal cancer cell lines, viz. HT-29, SGC-7901, and HepG2. SDS-PAGE and MALDI-TOF/TOF MS/MS analyses revealed that flammutoxin (FTX) was present as a dominating protein in Ffsp-50, which was further evidenced by HPLC-MS/MS determination. Furthermore, native FTX was purified from Ffsp-50 with a molecular weight of 26.78 kDa, exhibiting notable cytotoxicity against gastrointestinal cancer cell lines. Both Ffsp-50 and FTX exposure could enhance intercellular reactive oxygen species (ROS) generation and induce significant apoptosis in HepG2 cells. FTX was identified to be relatively conserved in basidiomycetes according to phylogenetic analysis, and its expression was highly upregulated in the primordium as well as the pileus of the fruiting body from the elongation and maturation stages, as compared with that in mycelium. Taken together, FTX could remarkably inhibit cell growth and induce ROS and apoptosis in HepG2 cells, potentially participating in the growth and development of the fruiting body. These findings from our investigation provided insight into the antigastrointestinal cancer activity of FTX, which could serve as a biological source of health-promoting and biomedical applications. Full article
(This article belongs to the Section Food Nutrition)
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Figure 1

Figure 1
<p>SDS-PAGE analysis of protein fractions from the fruiting bodies of <span class="html-italic">F. filiformis</span>. Samples were electrophoresed on 12% gel and stained with Coomassie brilliant blue. Column M represents a pre-stained protein marker with <span class="html-italic">M<sub>w</sub></span> range of 15–170 kDa; columns a, b, c, d, and e represent <span class="html-italic">Ffsp-30</span>, <span class="html-italic">Ffsp-50</span>, <span class="html-italic">Ffsp-70</span>, <span class="html-italic">Ffsp-90</span>, and <span class="html-italic">Ffp-90</span>, respectively.</p>
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<p>Purification and analysis of <span class="html-italic">FTX</span> protein. (<b>A</b>) Purification of native <span class="html-italic">FTX</span> from <span class="html-italic">Ffsp-50</span> on a Cellufine Q-500 strong anion-exchange column. <span class="html-italic">FTX</span> was obtained from section (a) of eluents of 0.2 M NaCl in 0.02 M Tris-HCl buffer solution (pH 8.0). (<b>B</b>) SDS-PAGE analysis of purified <span class="html-italic">FTX</span> from the fruiting body of <span class="html-italic">F. filiformis</span>. Column M represents the pre-stained protein marker with <span class="html-italic">M<sub>w</sub></span> range of 10–170 kDa; column F represents purified <span class="html-italic">FTX</span>. (<b>C</b>) Chromatogram of purified <span class="html-italic">FTX</span> determined by HPGPC method.</p>
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<p>AA sequence and molecular weight of <span class="html-italic">FTX</span> determined by MALDI-TOF/TOF MS/MS. (<b>A</b>) The deduced AA sequence of <span class="html-italic">FTX</span> precursor (GenBank accession no. BAA76510.1). The red parts indicate the peptide fragments (sequence coverage: 62%) detected by MALDI-TOF/TOF MS/MS; the region highlighted in luminous yellow denotes the presumed AA sequence of purified <span class="html-italic">FTX</span> lacking the initial Met (M) and C-terminal 30 AA residues (241 AA residues, <span class="html-italic">M<sub>w</sub></span> 26.78 kDa). (<b>B</b>) <span class="html-italic">FTX</span> molecular weight detected by MALDI-TOF/TOF MS/MS.</p>
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<p>Growth-inhibiting effects on three human gastrointestinal cancer cell lines. Using a standard MTT assay, the relative cell viabilities of HT-29, SGC-7901, and HepG2 cells were determined after treatment with indicated concentrations of (<b>A</b>–<b>C</b>) <span class="html-italic">Ffsp-30</span>, <span class="html-italic">Ffsp-50</span>, <span class="html-italic">Ffsp-70</span>, <span class="html-italic">Ffsp-90</span>, and <span class="html-italic">Ffp-90</span> for 24 h or (<b>D</b>–<b>F</b>) <span class="html-italic">FTX</span> for 24, 48, and 72 h. Values are represented as the percentage of viable cells, with vehicle-treated cells regarded as 100% viable. Data are presented as mean ± S.D. of three independent experiments. * <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01 compared with vehicle-treated controls.</p>
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<p>Morphological changes in HepG2 cells examined by DAPI nuclear staining under a fluorescence microscope after challenge with indicated concentrations of (<b>A</b>) <span class="html-italic">Ffsp-50</span> (0, 25, 50, and 100 μg/mL) and (<b>B</b>) <span class="html-italic">FTX</span> (0, 12.5, 25, and 50 μg/mL) for 24 h. Images are representative of three independent experiments (magnification ×200). Apoptosis-inducing effects of <span class="html-italic">Ffsp-50</span> (<b>C</b>,<b>E</b>) and <span class="html-italic">FTX</span> (<b>D</b>,<b>F</b>) in HepG2 cells. HepG2 cells were treated with indicated concentrations of <span class="html-italic">Ffsp-50</span> (0, 25, 50, and 100 μg/mL) and <span class="html-italic">FTX</span> (0, 12.5, 25, and 50 μg/mL) for 24 h and analyzed by flow cytometry with Annexin V/PI double staining. Representative FACS analysis scattergrams of Annexin V/PI show the four different cell populations, which are described as follows: double-negative stained cells (Annexin V<sup>−</sup>/PI<sup>−</sup>, lower left) indicating the live cell population; Annexin V positive/PI negative stained cells (Annexin V<sup>+</sup>/PI<sup>−</sup>, lower right) and double−positive (Annexin V<sup>+</sup>/PI<sup>+</sup>, upper right) stained cells showing early and late apoptotic cells, respectively; Annexin V negative/PI positive stained cells (Annexin V<sup>−</sup>/PI<sup>+</sup>, upper left) denoting dead cells. Data shown are presented as mean ± SD of three independent experiments. ** <span class="html-italic">p</span> &lt; 0.01 compared with vehicle−treated controls.</p>
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<p>Intracellular ROS generation in HepG2 cells detected by DCFH-DA staining using fluorescence microscope after treatment with indicated concentrations of (<b>A</b>) <span class="html-italic">Ffsp-50</span> (0, 25, 50, and 100 μg/mL) and (<b>B</b>) <span class="html-italic">FTX</span> (0, 12.5, 25, and 50 μg/mL) for 24 h. Images are representative of three independent experiments (magnification ×200).</p>
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<p>Phylogenetic tree of <span class="html-italic">FTX</span> protein in <span class="html-italic">F. filiformis</span> and other fungi.</p>
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18 pages, 2114 KiB  
Article
Acetylcholine-Binding Protein Affinity Profiling of Neurotoxins in Snake Venoms with Parallel Toxin Identification
by Giulia Palermo, Wietse M. Schouten, Luis Lago Alonso, Chris Ulens, Jeroen Kool and Julien Slagboom
Int. J. Mol. Sci. 2023, 24(23), 16769; https://doi.org/10.3390/ijms242316769 - 26 Nov 2023
Cited by 2 | Viewed by 2046
Abstract
Snakebite is considered a concerning issue and a neglected tropical disease. Three-finger toxins (3FTxs) in snake venoms primarily cause neurotoxic effects since they have high affinity for nicotinic acetylcholine receptors (nAChRs). Their small molecular size makes 3FTxs weakly immunogenic and therefore not appropriately [...] Read more.
Snakebite is considered a concerning issue and a neglected tropical disease. Three-finger toxins (3FTxs) in snake venoms primarily cause neurotoxic effects since they have high affinity for nicotinic acetylcholine receptors (nAChRs). Their small molecular size makes 3FTxs weakly immunogenic and therefore not appropriately targeted by current antivenoms. This study aims at presenting and applying an analytical method for investigating the therapeutic potential of the acetylcholine-binding protein (AChBP), an efficient nAChR mimic that can capture 3FTxs, for alternative treatment of elapid snakebites. In this analytical methodology, snake venom toxins were separated and characterised using high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) and high-throughput venomics. By subsequent nanofractionation analytics, binding profiling of toxins to the AChBP was achieved with a post-column plate reader-based fluorescence-enhancement ligand displacement bioassay. The integrated method was established and applied to profiling venoms of six elapid snakes (Naja mossambica, Ophiophagus hannah, Dendroaspis polylepis, Naja kaouthia, Naja haje and Bungarus multicinctus). The methodology demonstrated that the AChBP is able to effectively bind long-chain 3FTxs with relatively high affinity, but has low or no binding affinity towards short-chain 3FTxs, and as such provides an efficient analytical platform to investigate binding affinity of 3FTxs to the AChBP and mutants thereof and to rapidly identify bound toxins. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Animal Toxins, Venoms and Antivenoms 2.0)
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Figure 1

Figure 1
<p>Graphical overview of the analytical workflow followed in the current study. Crude snake venoms follow a standardised nanofractionation analytics workflow, which includes HPLC separation of venom toxins followed by a flow split where 10% of the effluent reaches the mass spectrometer (QTOF-MS) for intact toxin analysis and 90% is sent to a high-resolution nanofractionator that collects HPLC fractions onto 384-well plates. Two replicate well plates with separated venom toxins are generated for each snake venom, and after eluent evaporation using a vacuum centrifuge, they are employed for either one of two different purposes. One well plate is used for tryptic digestion and subsequent bottom-up proteomics analysis for protein identification by HT venomics, while the other well plate is used for the fluorescence-enhancement based ligand displacement bioassay with tracer ligand DAHBA for toxin binding profiling to the AChBP. Results from the different analyses (i.e., HPLC-UV, HPLC-MS, so-called bioassay chromatograms, and HT venomics so-called protein score chromatograms) are correlated by superimposing the chromatographic data with the purpose of identifying snake venom toxins binding to the AChBP.</p>
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<p>Fluorescence-based ligand displacement bioassay for neurotoxin-binding profiling of the venoms of (<b>A</b>) <span class="html-italic">Ophiophagus hannah</span>, (<b>B</b>) <span class="html-italic">Dendroaspis polylepis</span>, and (<b>C</b>) <span class="html-italic">Naja mossambica</span>. The bioassay allows investigation of the binding affinity of different snake venom toxins to the target AChBP directly after chromatographic separation of the toxins in the venoms under study. For the bioassay chromatograms in the figure, retention time of fractionation is plotted on the <span class="html-italic">x</span>-axis versus bioassay readout on the <span class="html-italic">y</span>-axis with a connecting line between the measurement points. A decrease in fluorescence is indicative of competition displacement of the tracer ligand DAHBA from the AChBP by eluted toxins.</p>
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<p>Typical protein score chromatograms (PSCs) generated for identification of the toxins in snake venom. In the figure, only several of all toxins retrieved by HT venomics are plotted so asnot to complicate the figure too much with too many PSCs. The PSCs of all toxins retrieved can be found in the <a href="#app1-ijms-24-16769" class="html-app">Supplementary Materials document Prism S3—<span class="html-italic">Ophiophagus hannah</span> proteomics</a>. The <span class="html-italic">x</span>-axis indicates retention time in minutes and the <span class="html-italic">y</span>-axis gives protein scores for each toxin plotted in the figure for each well it was found in by proteomics. Accession numbers (unique protein identifiers) of the toxins for the plotted PSCs are given in the legend on the right panel. Similar results for the venoms of <span class="html-italic">Naja mossambica</span>, <span class="html-italic">Dendroaspis polylepis</span>, <span class="html-italic">Naja kaouthia</span>, <span class="html-italic">Naja haje</span>, <span class="html-italic">and Bungarus multicinctus</span> are given in the <a href="#app1-ijms-24-16769" class="html-app">Prism documents S1–S2, S4–S6, Supplementary Materials</a>.</p>
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<p>Identification of toxins with binding affinity towards the AChBP by correlating the AChBP bioactivity chromatographic peaks in terms of peak shape and retention time with XIC peaks from the MS data and with PSCs from the HT venomics data for the venoms of (<b>A</b>) <span class="html-italic">Ophiophagus hannah</span>, (<b>B</b>) <span class="html-italic">Dendroaspis polylepis</span>, and (<b>C</b>) <span class="html-italic">Naja mossambica</span>. In the figures, the acquired LC-UV data is also given. (<b>i</b>): LC-UV chromatograms measured at 254 nm; (<b>ii</b>): LC-MS total ion chromatograms (TICs); (<b>iii</b>): extracted-ion chromatograms (XICs) from the LC-MS data of <span class="html-italic">m</span>/<span class="html-italic">z</span> values corresponding to some of the bioactive peaks in terms of matching peak shape and retention time (accurate masses calculated from the XICs are also given in the figures; matching XICs could be found only in some cases and are therefore not correlated with all PSCs); (<b>iv</b>): bioactivity chromatograms from the fluorescence enhancement-based AChBP tracer ligand displacement bioassay; (<b>v</b>): protein score chromatograms (PSCs) generated from the UniProt proteomic database. Toxin IDs are indicated next to their relevant PSC trace matching to a bioactive peak.</p>
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22 pages, 4249 KiB  
Article
Unveiling the Venom Composition of the Colombian Coral Snakes Micrurus helleri, M. medemi, and M. sangilensis
by Ariadna Rodríguez-Vargas, Adrián Marcelo Franco-Vásquez, Janeth Alejandra Bolívar-Barbosa, Nohora Vega, Edgar Reyes-Montaño, Roberto Arreguín-Espinosa, Alejandro Carbajal-Saucedo, Teddy Angarita-Sierra and Francisco Ruiz-Gómez
Toxins 2023, 15(11), 622; https://doi.org/10.3390/toxins15110622 - 24 Oct 2023
Cited by 6 | Viewed by 3524
Abstract
Little is known of the biochemical composition and functional features of the venoms of poorly known Colombian coral snakes. Here, we provide a preliminary characterization of the venom of two Colombian endemic coral snake species, Micrurus medemi and M. sangilensis, as well [...] Read more.
Little is known of the biochemical composition and functional features of the venoms of poorly known Colombian coral snakes. Here, we provide a preliminary characterization of the venom of two Colombian endemic coral snake species, Micrurus medemi and M. sangilensis, as well as Colombian populations of M. helleri. Electrophoresis and RP-HPLC techniques were used to identify venom components, and assays were conducted to detect enzyme activities, including phospholipase A2, hyaluronidase, and protease activities. The median lethal dose was determined using murine models. Cytotoxic activities in primary cultures from hippocampal neurons and cancer cell lines were evaluated. The venom profiles revealed similarities in electrophoretic separation among proteins under 20 kDa. The differences in chromatographic profiles were significant, mainly between the fractions containing medium-/large-sized and hydrophobic proteins; this was corroborated by a proteomic analysis which showed the expected composition of neurotoxins from the PLA2 (~38%) and 3FTx (~17%) families; however, a considerable quantity of metalloproteinases (~12%) was detected. PLA2 activity and protease activity were higher in M. helleri venom according to qualitative and quantitative assays. M. medemi venom had the highest lethality. All venoms decreased cell viability when tested on tumoral cell cultures, and M. helleri venom had the highest activity in neuronal primary culture. These preliminary studies shed light on the venoms of understudied coral snakes and broaden the range of sources that could be used for subsequent investigations of components with applications to specific diseases. Our findings also have implications for the clinical manifestations of snake envenoming and improvements in its medical management. Full article
(This article belongs to the Section Animal Venoms)
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Figure 1
<p>Separation of <span class="html-italic">M. helleri, M. medemi,</span> and <span class="html-italic">M. sangilensis</span> venoms obtained using 15% SDS-PAGE under reducing conditions. Each lane was seeded with 20 μg of protein. Std.: molecular weight standard.</p>
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<p>Chromatographic profiles of whole venoms on a C18 column (Discovery<sup>®</sup>, 5 μm particle diameter; 250 × 4.6 mm) highlighting more abundant fractions (bold and underlined) subsequently observed in 12.5% SDS-PAGE under reducing conditions. <span class="html-italic">M. helleri</span> (<b>a</b>,<b>b</b>), <span class="html-italic">M. medemi</span> (<b>c</b>,<b>d</b>), and <span class="html-italic">M. sangilensis</span> (<b>e</b>,<b>f</b>). For analytical purposes, the chromatograms were divided into three sections, the limits of which are indicated by dotted lines. See the text for more detail. Std.: molecular weight standard (kDa).</p>
Full article ">Figure 2 Cont.
<p>Chromatographic profiles of whole venoms on a C18 column (Discovery<sup>®</sup>, 5 μm particle diameter; 250 × 4.6 mm) highlighting more abundant fractions (bold and underlined) subsequently observed in 12.5% SDS-PAGE under reducing conditions. <span class="html-italic">M. helleri</span> (<b>a</b>,<b>b</b>), <span class="html-italic">M. medemi</span> (<b>c</b>,<b>d</b>), and <span class="html-italic">M. sangilensis</span> (<b>e</b>,<b>f</b>). For analytical purposes, the chromatograms were divided into three sections, the limits of which are indicated by dotted lines. See the text for more detail. Std.: molecular weight standard (kDa).</p>
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<p>Percentages of the protein families in the venoms of (<b>a</b>) <span class="html-italic">M. helleri</span>, (<b>b</b>) <span class="html-italic">M. medemi,</span> and (<b>c</b>) <span class="html-italic">M. sangilensis</span>. Snake photos provided by Juan Pablo Hurtado-Gómez.</p>
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<p>Comparison of the number of shared and unique toxin-related proteins among the venoms of <span class="html-italic">M. helleri</span> (red; <span class="html-italic">n</span> = 53), <span class="html-italic">M. medemi</span> (yellow; <span class="html-italic">n</span> = 60), and <span class="html-italic">M. sangilensis</span> (light grey; <span class="html-italic">n</span> = 58). Note the high number of shared proteins between <span class="html-italic">M. medemi</span> and <span class="html-italic">M. sangilensis</span> and the higher number of unique peptides in <span class="html-italic">M. helleri</span> compared with <span class="html-italic">M. medemi</span> and <span class="html-italic">M. sangilensis</span>.</p>
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<p>Relative abundances of identified proteins using the normalized spectral abundance factor (NSAF). The color represents the protein families in this study. PLA<sub>2</sub>: phospholipases A<sub>2</sub>, 3FTx: three-finger toxins, SVMP: snake venom metalloproteinases, PLB: phospholipase B, LAAO: L-amino acid oxidases, SVSP: snake venom serine proteases, CTL: C-type lectin, HYA: hyaluronidases, VNGF: venom nerve growth factor, and MIN: minority compounds.</p>
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<p>Enzymatic activities for <span class="html-italic">M. helleri, M. medemi,</span> and <span class="html-italic">M. sangilensis</span> venoms. (<b>a</b>) Phospholipase A<sub>2</sub> assay in agarose and 10% egg yolk solution using 5 μg of each venom. The translucent halos formed around each well can be observed. Top: phosphate buffered saline (pH 7.4) used as the negative control (C−), and <span class="html-italic">Crotalus durissus cumanensis</span> venom used as the positive control (C+) (5 μg). Bottom: <span class="html-italic">M. helleri</span>, <span class="html-italic">M. medemi,</span> and <span class="html-italic">M. sangilensis</span>. (<b>b</b>) Determination of phospholipase A<sub>2</sub> activity by a colorimetric assay in a medium containing lecithin as the substrate (triplicate). Bars denote ± standard error. Panel (<b>c</b>) shows hyaluronidase activity. Non-stained areas depict positive activity. Std.: molecular weight standard. (<b>d</b>) Protease activity of the venoms obtained using an EnzChek<sup>®</sup> Protease Assay Kit. Trypsin was used as a positive control. Values represent the mean of three replicates. Bars denote standard error.</p>
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<p>Cell viability of three cell lines due to the effect of <span class="html-italic">Micrurus</span> venoms. (<b>a</b>) Hippocampal neuronal assay. Bar plots illustrate the percentage of cell viability in neuronal primary cultures after exposure to varying concentrations (2, 3, 12, 50, and 100 μg/mL) of the venoms. (<b>b</b>) Cell viability in the HTB-132 cell line assay. Bar plots illustrate the percentage of cell viability after exposure to varying concentrations (2, 3, 25, and 100 μg/mL) of the venoms. (<b>c</b>) Cell viability of the PC3 cell line assay. Bar plots illustrate the percentage of cell viability after exposure to varying concentrations (2, 3, 6, 13, 25, 50, and 100 μg/mL) of the venoms. Bars denote ± standard error. Statistical significance compared with the control is indicated by (*) symbols. <span class="html-italic">M. helleri</span> (orange), <span class="html-italic">M. medemi</span> (green), and <span class="html-italic">M. sangilensis</span> (red) venoms.</p>
Full article ">Figure 7 Cont.
<p>Cell viability of three cell lines due to the effect of <span class="html-italic">Micrurus</span> venoms. (<b>a</b>) Hippocampal neuronal assay. Bar plots illustrate the percentage of cell viability in neuronal primary cultures after exposure to varying concentrations (2, 3, 12, 50, and 100 μg/mL) of the venoms. (<b>b</b>) Cell viability in the HTB-132 cell line assay. Bar plots illustrate the percentage of cell viability after exposure to varying concentrations (2, 3, 25, and 100 μg/mL) of the venoms. (<b>c</b>) Cell viability of the PC3 cell line assay. Bar plots illustrate the percentage of cell viability after exposure to varying concentrations (2, 3, 6, 13, 25, 50, and 100 μg/mL) of the venoms. Bars denote ± standard error. Statistical significance compared with the control is indicated by (*) symbols. <span class="html-italic">M. helleri</span> (orange), <span class="html-italic">M. medemi</span> (green), and <span class="html-italic">M. sangilensis</span> (red) venoms.</p>
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16 pages, 2115 KiB  
Article
Evolution of Three-Finger Toxin Genes in Neotropical Colubrine Snakes (Colubridae)
by Kristy Srodawa, Peter A. Cerda, Alison R. Davis Rabosky and Jenna M. Crowe-Riddell
Toxins 2023, 15(9), 523; https://doi.org/10.3390/toxins15090523 - 25 Aug 2023
Cited by 2 | Viewed by 2058
Abstract
Snake venom research has historically focused on front-fanged species (Viperidae and Elapidae), limiting our knowledge of venom evolution in rear-fanged snakes across their ecologically diverse phylogeny. Three-finger toxins (3FTxs) are a known neurotoxic component in the venoms of some rear-fanged snakes (Colubridae: Colubrinae), [...] Read more.
Snake venom research has historically focused on front-fanged species (Viperidae and Elapidae), limiting our knowledge of venom evolution in rear-fanged snakes across their ecologically diverse phylogeny. Three-finger toxins (3FTxs) are a known neurotoxic component in the venoms of some rear-fanged snakes (Colubridae: Colubrinae), but it is unclear how prevalent 3FTxs are both in expression within venom glands and more broadly among colubrine species. Here, we used a transcriptomic approach to characterize the venom expression profiles of four species of colubrine snakes from the Neotropics that were dominated by 3FTx expression (in the genera Chironius, Oxybelis, Rhinobothryum, and Spilotes). By reconstructing the gene trees of 3FTxs, we found evidence of putative novel heterodimers in the sequences of Chironius multiventris and Oxybelis aeneus, revealing an instance of parallel evolution of this structural change in 3FTxs among rear-fanged colubrine snakes. We also found positive selection at sites within structural loops or “fingers” of 3FTxs, indicating these areas may be key binding sites that interact with prey target molecules. Overall, our results highlight the importance of exploring the venoms of understudied species in reconstructing the full evolutionary history of toxins across the tree of life. Full article
(This article belongs to the Special Issue Venom Genes and Genomes of Poisonous Animals: Evolution and Variation)
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<p>Transcript expression from the venom gland transcriptomes of four rear-fanged colubrine snake species. Red transcripts indicate toxin sequences. Transcript abundances estimates are in Fragments Per Kilobase Million (FPKM), and only the top 1000 ranked transcripts are shown. Image credits: José G. Martinez-Fonseca (<span class="html-italic">O. aeneus</span>, <span class="html-italic">S. sulphureus</span>, <span class="html-italic">R. bovallii</span>) and Consuelo Alarcón Rodríguez (<span class="html-italic">C. multiventris</span>).</p>
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<p>Toxin expression from the venom gland transcriptome of four species of rear-fanged colubrine snakes. Bar charts show toxin transcript abundances, measured in Fragments Per Kilobase Million (FPKM), for the top 50 toxin transcripts of each species. Pie charts show proportions of toxin family expression based on Transcripts per Million (TPM). Toxin families are color coded; toxins indicated include three-finger toxins (3FTx), Kunitz-type venom proteins (Kunitz), phospholipase A<sub>2</sub> (PLA<sub>2</sub>), Waprin, snake venom serine proteases (SVSP), snake venom metalloproteinases (SVMPIII), L-amino acid oxidases (LAAO), phospholipases B (PLB), and Cysteine-rich secretory proteins (CRiSP). Venom system morphology is shown on the right for each species; obtained from microCT scans of specimens the University of Michigan Museum of Zoology (UMMZ) and Museo de Historia Natural de la Universidad Nacional Major de San Marcos (MUSM) in Peru. Scans are available from Morphosource (<a href="https://www.morphosource.org/Detail/ProjectDetail/Show/project_id/374" target="_blank">https://www.morphosource.org/Detail/ProjectDetail/Show/project_id/374</a>).</p>
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<p>Bayesian gene tree of 3FTx sequences, including sequences newly generated in this study (gold; pink if putative heterodimer-forming sequence), previously named and functionally characterized sequences (blue), other 3FTx sequences from colubrine species (black), elapid sequences (maroon), and a sequence from a viper species used as an outgroup (orange). All 3FTx sequences not generated in this study were obtained from GenBank (<a href="#app1-toxins-15-00523" class="html-app">Table S1</a>). For the species <span class="html-italic">C. multiventris</span>, “A” and “B” were used to differentiate between the two individuals.</p>
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<p>Amino acid alignment of non-conventional three-finger toxin (3FTx) transcripts generated from this study (gold; pink if putative heterodimer-forming sequence) as well as sequences previously identified and characterized from colubrine snake species (blue). Two elapid (maroon) and one viper (orange) sequence are shown as outgroups. Conserved cysteine residues are colored in green; disulfide bonds between cysteine residues result in formation of five loops in non-conventional 3FTx, which are shown with brackets. Boxes indicate sequence position of additional cysteine residues associated with heterodimer formation. Roman numerals denote the distinctive β-stranded loops of 3FTx; Loops IV and V are unique to non-conventional 3FTxs. N-terminus region indicated with bracket. All 3FTx sequences not generated in this study were obtained from GenBank (<a href="#app1-toxins-15-00523" class="html-app">Table S1</a>). For the species <span class="html-italic">C. multiventris</span>, “A” and “B” were used to differentiate between the two individuals.</p>
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14 pages, 288 KiB  
Article
Developing an Ethical Framework for Responsible Artificial Intelligence (AI) and Machine Learning (ML) Applications in Cryptocurrency Trading: A Consequentialism Ethics Analysis
by Haris Alibašić
FinTech 2023, 2(3), 430-443; https://doi.org/10.3390/fintech2030024 - 3 Jul 2023
Cited by 3 | Viewed by 5783
Abstract
The rise in artificial intelligence (AI) and machine learning (ML) in cryptocurrency trading has precipitated complex ethical considerations, demanding a thorough exploration of responsible regulatory approaches. This research expands upon this need by employing a consequentialist theoretical framework, emphasizing the outcomes of AI [...] Read more.
The rise in artificial intelligence (AI) and machine learning (ML) in cryptocurrency trading has precipitated complex ethical considerations, demanding a thorough exploration of responsible regulatory approaches. This research expands upon this need by employing a consequentialist theoretical framework, emphasizing the outcomes of AI and ML’s deployment within the sector and its effects on stakeholders. Drawing on critical case studies, such as SBF and FTX, and conducting an extensive review of relevant literature, this study explores the ethical implications of AI and ML in the context of cryptocurrency trading. It investigates the necessity for novel regulatory methods that address the unique characteristics of digital assets alongside existing legalities, such as those about fraud and insider trading. The author proposes a typology framework for AI and ML trading by comparing consequentialism to other ethical theories applicable to AI and ML use in cryptocurrency trading. By applying a consequentialist lens, this study underscores the significance of balancing AI and ML’s transformative potential with ethical considerations to ensure market integrity, investor protection, and overall well-being in cryptocurrency trading. Full article
(This article belongs to the Special Issue Advances in Analytics and Intelligent System)
23 pages, 2511 KiB  
Article
The Venom Composition of the Snake Tribe Philodryadini: ‘Omic’ Techniques Reveal Intergeneric Variability among South American Racers
by Emilly Campos Tioyama, Juan David Bayona-Serrano, José A. Portes-Junior, Pedro Gabriel Nachtigall, Vinicius Carius de Souza, Emidio Beraldo-Neto, Felipe Gobbi Grazziotin, Inácio L. M. Junqueira-de-Azevedo, Ana Maria Moura-da-Silva and Luciana Aparecida Freitas-de-Sousa
Toxins 2023, 15(7), 415; https://doi.org/10.3390/toxins15070415 - 27 Jun 2023
Cited by 6 | Viewed by 2260
Abstract
Snakes of the Philodryadini tribe are included in the Dipsadidae family, which is a diverse group of rear-fanged snakes widespread in different ecological conditions, including habitats and diet. However, little is known about the composition and effects of their venoms despite their relevance [...] Read more.
Snakes of the Philodryadini tribe are included in the Dipsadidae family, which is a diverse group of rear-fanged snakes widespread in different ecological conditions, including habitats and diet. However, little is known about the composition and effects of their venoms despite their relevance for understanding the evolution of these snakes or even their impact on the occasional cases of human envenoming. In this study, we integrated venom gland transcriptomics, venom proteomics and functional assays to characterize the venoms from eight species of the Philodryadini tribe, which includes the genus Philodryas, Chlorosoma and Xenoxybelis. The most abundant components identified in the venoms were snake venom metalloproteinases (SVMPs), cysteine-rich secretory proteins (CRISPs), C-type lectins (CTLs), snake endogenous matrix metalloproteinases type 9 (seMMP-9) and snake venom serinoproteinases (SVSPs). These protein families showed a variable expression profile in each genus. SVMPs were the most abundant components in Philodryas, while seMMP-9 and CRISPs were the most expressed in Chlorosoma and Xenoxybelis, respectively. Lineage-specific differences in venom composition were also observed among Philodryas species, whereas P. olfersii presented the highest amount of SVSPs and P. agassizii was the only species to express significant amounts of 3FTx. The variability observed in venom composition was confirmed by the venom functional assays. Philodryas species presented the highest SVMP activity, whereas Chlorosoma species showed higher levels of gelatin activity, which may correlate to the seMMP-9 enzymes. The variability observed in the composition of these venoms may be related to the tribe phylogeny and influenced by their diets. In the presented study, we expanded the set of venomics studies of the Philodryadini tribe, which paves new roads for further studies on the evolution and ecology of Dipsadidae snakes. Full article
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<p>Proportion of toxin families expressed in the venom gland transcriptomes of seven specimens of <span class="html-italic">Philodryas</span>, two specimens of <span class="html-italic">Chlorosoma</span> and one of <span class="html-italic">Xenoxybelis argenteus</span>. Percentages represent the sum of TPM (transcripts per million reads) for each category. 3FTX (three-finger toxin), AChE (acetylcholinesterase), CNP (C-type natriuretic peptide), CRISP (cysteine-rich secretory protein), CTL (C-type lectins), CVF (cobra venom factor), CYS (cystatin), FICOLIN (ficolin), KUNZ (BPTI/KUNITZ inhibitor domain), KUWAP (Ku-wap-fusin), iPLA (phospholipase inhibitor), PLB (phospholipase B), seMMP-9 (snake endogenous matrix metalloproteinase 9), SVMP P-III (snake venom metalloproteinase P-III class), SVSP (snake venom serine proteinase), NUCL (5-nucleotidase), VEGF (vascular endothelial growth factor) and WAP (waprin whey acidic protein-type). SB codes correspond to the identification of individuals.</p>
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<p>Proportion of toxin families in the venom pools of Philodryadini snakes identified from proteomic analysis by mass spectrometry (LC-MS/MS). The normalized total spectra count (TSC) defined the relative expression of each toxin family. 3FTX (three-finger toxin), CNP (C-type natriuretic peptide), CRISP (cysteine-rich secretory protein), CTL (C-type lectins), FICOLIN (ficolin), KUNZ (BPTI/KUNITZ inhibitor domain), KUWAP (Ku-wap-fusin), iPLA (phospholipase inhibitor), PLB (phospholipase B), seMMP-9 (snake endogenous matrix metalloproteinase 9), SVMP P-III (snake venom metalloproteinase P-III class), SVSP (snake venom serine proteinase) and WAP (waprin whey acidic protein-type).</p>
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<p>Gelatinolytic activity of Philodryadini venoms through gel zymography. (<b>A</b>). Samples (0.5 μg of venom) were run in non-reducing conditions on SDS-PAGE 12.5%. The gel was stained with bright blue Coomassie R-250. The dashed red squares correspond to the bands excised from the gels for LC-MS/MS analysis (<a href="#app1-toxins-15-00415" class="html-app">Supplementary Materials</a>). (<b>B</b>). Samples were run as described above but in SDS-PAGE 12.5% containing 20 mg/mL of gelatin. After electrophoresis, the gel was washed with Triton X-100 (2.5%) and incubated overnight in reaction buffer (20 mM Tris, 0.5 mM CaCl<sub>2</sub>, pH 7.4) at 37 °C. The gel was then rinsed with distilled water and stained with bright blue Coomassie R-250. The proteolytic activity produced white/transparent bands on a blue background due to the gelatin hydrolysis. (<b>C</b>). The same procedure as in B was used but 20 mM EDTA was included in the reaction buffer to inhibit the metalloproteinase activity on the gelatin substrate. Black arrows indicate the faint hydrolysis bands. <span class="html-italic">Chlorosoma laticeps</span> (LAT), <span class="html-italic">Chlorosoma viridissimum</span> (VIR), <span class="html-italic">Philodryas patagoniensis</span> (PAT), <span class="html-italic">Philodryas nattereri</span> (NAT), <span class="html-italic">Philodryas olfersii</span> (OLF) and positive control <span class="html-italic">Bothrops jararaca</span> (+C).</p>
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<p>Functional activity of <span class="html-italic">Philodryas</span> and <span class="html-italic">Chlorosoma</span> snake venoms according to enzymatic assays on synthetic substrates for SVMPs and SVSPs. (<b>A</b>). Metalloproteinase (SVMP or MMP) activity was measured by fluorimetry using Abz-AGLA-EDDnp substrate and 10 μg of venom. The results are presented as the ratio of relative fluorescence units (RFU), by time (min) and by the amount of protein used in the assay (μg). (<b>B</b>). Serine proteinase (SVSP) activity was assessed by hydrolysis of benzoyl-arginine-p-nitroanide (L-BAPNA) using 30 μg of venom. The results are presented by the absorbance ratio (Abs), by the time (min) and by the amount of protein used in the assay (μg). (<b>C</b>). The gelatinolytic activity was measured through fluorometric assays using as substrate gelatin from synthetic pig skin conjugated with fluorescein, incubated with 10 μg of Philodryadini venoms or 30 μg of <span class="html-italic">B. jararaca</span> venom as a positive control. The results are presented by the ratio of relative fluorescence units (RFU), by time (min) and by the amount of protein used in the assay (μg). Value *** <span class="html-italic">p</span> &lt; 0.001 corresponds to statistically significant.</p>
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<p>Effects of metalloproteinase and serine proteinase inhibitors in the gelatinolytic activity. The gelatinolytic activity was measured through fluorometric assays using as substrate gelatin from synthetic pig skin conjugated with fluorescein, incubated with 10 μg of Philodryadini venoms or 30 μg of <span class="html-italic">Bothrops jararaca</span> venom pre-incubated with 100mM of 1,10-phenanthroline and PMSF inhibitors. Species-only names correspond to applied venom samples diluted in reaction buffer. Ortho: 1,10-phenanthroline. PMSF: phenylmethylsulfonyl fluoride.</p>
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30 pages, 546 KiB  
Article
Assessing the Credit Risk of Crypto-Assets Using Daily Range Volatility Models
by Dean Fantazzini
Information 2023, 14(5), 254; https://doi.org/10.3390/info14050254 - 23 Apr 2023
Cited by 1 | Viewed by 3264
Abstract
In this paper, we analyzed a dataset of over 2000 crypto-assets to assess their credit risk by computing their probability of death using the daily range. Unlike conventional low-frequency volatility models that only utilize close-to-close prices, the daily range incorporates all the information [...] Read more.
In this paper, we analyzed a dataset of over 2000 crypto-assets to assess their credit risk by computing their probability of death using the daily range. Unlike conventional low-frequency volatility models that only utilize close-to-close prices, the daily range incorporates all the information provided in traditional daily datasets, including the open-high-low-close (OHLC) prices for each asset. We evaluated the accuracy of the probability of death estimated with the daily range against various forecasting models, including credit scoring models, machine learning models, and time-series-based models. Our study considered different definitions of “dead coins” and various forecasting horizons. Our results indicate that credit scoring models and machine learning methods incorporating lagged trading volumes and online searches were the best models for short-term horizons up to 30 days. Conversely, time-series models using the daily range were more appropriate for longer term forecasts, up to one year. Additionally, our analysis revealed that the models using the daily range signaled, far in advance, the weakened credit position of the crypto derivatives trading platform FTX, which filed for Chapter 11 bankruptcy protection in the United States on 11 November 2022. Full article
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<p>Price in USD of the FTX token over the time sample 1 August 2019/11 November 2022.</p>
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<p>One-year-ahead probability of death (PD) estimated over the time sample 30 July 2020/30 October 2022 using an expanding window with the first estimation sample consisting of 365 observations for these ZPP models: CARR model with the Garman—Klass estimator, CARR model with the Yang—Zhang estimator, HAR model with the Garman—Klass estimator, and HAR model with the Yang—Zhang estimator.</p>
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<p>One-year-ahead probability of death (PD) estimated over the time sample 30 July 2020/30 October 2022 using an expanding window with the first estimation sample consisting of 365 observations for these ZPP models: random walk with Garman—Klass estimator), random walk with Yang—Zhang estimator, random walk, and Markov-switching GARCH.</p>
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<p>Young coins: Daily number of total available coins and the daily number of dead coins computed using the previous three criteria. The data are from [<a href="#B11-information-14-00254" class="html-bibr">11</a>]. For convenience, the approach proposed by [<a href="#B7-information-14-00254" class="html-bibr">7</a>] is referred to as “<span class="html-italic">restrictive</span>”, the simplified approach proposed by [<a href="#B9-information-14-00254" class="html-bibr">9</a>] as “<span class="html-italic">simple</span>”, and the professional rule as “<span class="html-italic">1 cent</span>”.</p>
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<p>Old coins: Daily number of total available coins and the daily number of dead coins computed using the previous three criteria. The data are from [<a href="#B11-information-14-00254" class="html-bibr">11</a>]. For convenience, the approach proposed by [<a href="#B7-information-14-00254" class="html-bibr">7</a>] is referred to as “<span class="html-italic">restrictive</span>”, the simplified approach proposed by [<a href="#B9-information-14-00254" class="html-bibr">9</a>] as “<span class="html-italic">simple</span>”, and the professional rule as “<span class="html-italic">1 cent</span>”.</p>
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