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Dobson J, Chowdhury A, Tai-A-Pin J, van der Ploeg H, Gillett A, Fry BG. The Clot Thickens: Differential Coagulotoxic and Cardiotoxic Activities of Anguimorpha Lizard Venoms. Toxins (Basel) 2024; 16:283. [PMID: 38922177 PMCID: PMC11209219 DOI: 10.3390/toxins16060283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Revised: 06/11/2024] [Accepted: 06/17/2024] [Indexed: 06/27/2024] Open
Abstract
Despite their evolutionary novelty, lizard venoms are much less studied in comparison to the intense research on snake venoms. While the venoms of helodermatid lizards have long been assumed to be for defensive purposes, there is increasing evidence of toxic activities more useful for predation than defence (such as paralytic neurotoxicity). This study aimed to ascertain the effects of Heloderma, Lanthanotus, and Varanus lizard venoms on the coagulation and cardiovascular systems. Anticoagulant toxicity was demonstrated for the Varanus species studied, with the venoms prolonging clotting times in human and bird plasma due to the destructive cleavage of fibrinogen. In contrast, thromboelastographic analyses on human and bird plasmas in this study demonstrated a procoagulant bioactivity for Heloderma venoms. A previous study on Heloderma venom using factor-depleted plasmas as a proxy model suggested a procoagulant factor was present that activated either Factor XI or Factor XII, but could not ascertain the precise target. Our activation studies using purified zymogens confirmed FXII activation. Comparisons of neonate and adult H. exasperatum, revealed the neonates to be more potent in the ability to activate FXII, being more similar to the venom of the smaller species H. suspectum than the adult H. exasperatum. This suggests potent FXII activation a basal trait in the genus, present in the small bodied last common ancestor. This also indicates an ontogenetic difference in prey preferences in the larger Heloderma species paralleing the change in venom biochemistry. In addition, as birds lack Factor XII, the ability to clot avian plasma suggested an additional procoagulant site of action, which was revealed to be the activation of Factor VII, with H. horridum being the most potent. This study also examined the effects upon the cardiovascular system, including the liberation of kinins from kininogen, which contributes to hypotension induction. This form of toxicity was previously described for Heloderma venoms, and was revealed in this study was to also be a pathophysiological effect of Lanthanotus and Varanus venoms. This suggests that this toxic activity was present in the venom of the last common ancestor of the anguimorph lizards, which is consistent with kallikrein enzymes being a shared toxin trait. This study therefore uncovered novel actions of anguimorph lizard venoms, not only contributing to the evolutionary biology body of knowledge but also revealing novel activities to mine for drug design lead compounds.
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Affiliation(s)
- James Dobson
- Adaptive Biotoxicology Lab, School of the Environment, University of Queensland, St Lucia, QLD 4072, Australia; (J.D.); (A.C.)
| | - Abhinandan Chowdhury
- Adaptive Biotoxicology Lab, School of the Environment, University of Queensland, St Lucia, QLD 4072, Australia; (J.D.); (A.C.)
| | | | - Harold van der Ploeg
- Working Group Adder Research Netherlands, RAVON, 6525 ED Nijmegen, The Netherlands;
| | - Amber Gillett
- FaunaVet Wildlife Consultancy, Glass House Mountains, QLD 4518, Australia;
| | - Bryan G. Fry
- Adaptive Biotoxicology Lab, School of the Environment, University of Queensland, St Lucia, QLD 4072, Australia; (J.D.); (A.C.)
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Sunagar K, Abraham SV. The Curious Case of the "Neurotoxic Skink": Scientific Literature Points to the Absence of Venom in Scincidae. Toxins (Basel) 2021; 13:toxins13020114. [PMID: 33546362 PMCID: PMC7913497 DOI: 10.3390/toxins13020114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Revised: 01/26/2021] [Accepted: 02/01/2021] [Indexed: 11/16/2022] Open
Abstract
In contrast to the clearly documented evolution of venom in many animal lineages, the origin of reptilian venom is highly debated. Historically, venom has been theorised to have evolved independently in snakes and lizards. However, some of the recent works have argued for the common origin of venom in “Toxicofera” reptiles, which include the order Serpentes (all snakes), and Anguimorpha and Iguania lizards. Nevertheless, in both these contrasting hypotheses, the lizards of the family Scincidae are considered to be harmless and devoid of toxic venoms. Interestingly, an unusual clinical case claiming neurotoxic envenoming by a scincid lizard was recently reported in Southern India. Considering its potentially significant medicolegal, conservation and evolutionary implications, we have summarised the scientific evidence that questions the validity of this clinical report. We argue that the symptoms documented in the patient are likely to have resulted from krait envenomation, which is far too frequent in these regions.
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Affiliation(s)
- Kartik Sunagar
- Evolutionary Venomics Lab, Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, Karnataka, India
- Correspondence:
| | - Siju V Abraham
- Department of Emergency Medicine, Jubilee Mission Medical College and Research Institute, Thrissur 680005, Kerala, India;
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Boyd BS, Colon F, Doty JF, Sanders KC. Beware of the Dragon: A Case Report of a Komodo Dragon Attack. FOOT & ANKLE ORTHOPAEDICS 2021; 6:24730114211015623. [PMID: 35097454 PMCID: PMC8702757 DOI: 10.1177/24730114211015623] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Komodo dragon attacks are rare occurrences, especially in the United States. Attacks are believed to be highly infectious and venomous, leading to demise of its prey. We present a case of a 43-year-old female zookeeper attacked by an adult dragon leading to tendon and neurovascular injuries.
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Affiliation(s)
- Brandon S. Boyd
- Health Science Center College of Medicine, University of Tennessee, Chattanooga, TN, USA
| | - Felipe Colon
- Health Science Center College of Medicine, University of Tennessee, Chattanooga, TN, USA
| | - Jesse F. Doty
- Health Science Center College of Medicine, University of Tennessee, Chattanooga, TN, USA
| | - Kristopher C. Sanders
- Health Science Center College of Medicine, University of Tennessee, Chattanooga, TN, USA
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Koludarov I, Jackson TN, Brouw BOD, Dobson J, Dashevsky D, Arbuckle K, Clemente CJ, Stockdale EJ, Cochran C, Debono J, Stephens C, Panagides N, Li B, Manchadi MLR, Violette A, Fourmy R, Hendrikx I, Nouwens A, Clements J, Martelli P, Kwok HF, Fry BG. Enter the Dragon: The Dynamic and Multifunctional Evolution of Anguimorpha Lizard Venoms. Toxins (Basel) 2017; 9:E242. [PMID: 28783084 PMCID: PMC5577576 DOI: 10.3390/toxins9080242] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 08/04/2017] [Accepted: 08/04/2017] [Indexed: 01/08/2023] Open
Abstract
While snake venoms have been the subject of intense study, comparatively little work has been done on lizard venoms. In this study, we have examined the structural and functional diversification of anguimorph lizard venoms and associated toxins, and related these results to dentition and predatory ecology. Venom composition was shown to be highly variable across the 20 species of Heloderma, Lanthanotus, and Varanus included in our study. While kallikrein enzymes were ubiquitous, they were also a particularly multifunctional toxin type, with differential activities on enzyme substrates and also ability to degrade alpha or beta chains of fibrinogen that reflects structural variability. Examination of other toxin types also revealed similar variability in their presence and activity levels. The high level of venom chemistry variation in varanid lizards compared to that of helodermatid lizards suggests that venom may be subject to different selection pressures in these two families. These results not only contribute to our understanding of venom evolution but also reveal anguimorph lizard venoms to be rich sources of novel bioactive molecules with potential as drug design and development lead compounds.
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Affiliation(s)
- Ivan Koludarov
- Venom Evolution Lab, School of Biological Sciences, University of Queensland, St. Lucia QLD 4072, Australia.
| | - Timothy Nw Jackson
- Venom Evolution Lab, School of Biological Sciences, University of Queensland, St. Lucia QLD 4072, Australia.
- Australian Venom Research Unit, School of Biomedical Sciences, Level 2 Medical Building, University of Melbourne, Victoria 3010, Australia.
| | - Bianca Op den Brouw
- Venom Evolution Lab, School of Biological Sciences, University of Queensland, St. Lucia QLD 4072, Australia.
| | - James Dobson
- Venom Evolution Lab, School of Biological Sciences, University of Queensland, St. Lucia QLD 4072, Australia.
| | - Daniel Dashevsky
- Venom Evolution Lab, School of Biological Sciences, University of Queensland, St. Lucia QLD 4072, Australia.
| | - Kevin Arbuckle
- Department of Biosciences, College of Science, Swansea University, Swansea SA2 8PP, UK.
| | - Christofer J Clemente
- University of the Sunshine Coast, School of Science and Engineering, Sippy Downs, Queensland 4558, Australia.
| | | | - Chip Cochran
- Department of Earth and Biological Sciences, Loma Linda University, Loma Linda, CA 92350, USA.
| | - Jordan Debono
- Venom Evolution Lab, School of Biological Sciences, University of Queensland, St. Lucia QLD 4072, Australia.
| | - Carson Stephens
- School of Biomedical Sciences, Queensland University of Technology, Brisbane QLD 4001, Australia.
| | - Nadya Panagides
- Venom Evolution Lab, School of Biological Sciences, University of Queensland, St. Lucia QLD 4072, Australia.
| | - Bin Li
- Faculty of Health Sciences, University of Macau, Avenida da Universidade, Taipa, Macau.
| | | | - Aude Violette
- Alphabiotoxine Laboratory sprl, Barberie 15, 7911 Montroeul-au-bois, Belgium.
| | - Rudy Fourmy
- Alphabiotoxine Laboratory sprl, Barberie 15, 7911 Montroeul-au-bois, Belgium.
| | - Iwan Hendrikx
- Venom Evolution Lab, School of Biological Sciences, University of Queensland, St. Lucia QLD 4072, Australia.
| | - Amanda Nouwens
- School of Chemistry and Molecular Biology, University of Queenslnd, St. Lucia QLD 4072, Australia.
| | - Judith Clements
- School of Biomedical Sciences, Queensland University of Technology, Brisbane QLD 4001, Australia.
| | | | - Hang Fai Kwok
- Faculty of Health Sciences, University of Macau, Avenida da Universidade, Taipa, Macau.
| | - Bryan G Fry
- Venom Evolution Lab, School of Biological Sciences, University of Queensland, St. Lucia QLD 4072, Australia.
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