North American Coral Snake Envenomation

Anwar, Mehruba; Bernstein, Jeff

doi:10.1007/978-94-017-7438-3_75

Cited by 2 publications

(1 citation statement)

References 24 publications

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“…For instance, the single published account of a Sinomicrurus macclellandi bite indicated that the victim felt nothing until motor issues started developing 6 hours after the bite and culminated in lethal respiratory paralysis after 8 hours [183]. Similarly, bites from snakes of the genus Micrurus often exhibit few symptoms besides paralysis [184][185][186].…”

Section: Introductionmentioning

confidence: 99%

Novelty in three-finger toxin evolution

Dashevsky¹

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Snakes are a striking taxon on many levels and have an indelible place in the collective culture of humanity. This is due to a number of unusual features including their limblessness, ability to ingest large prey, but most importantly their venom. From a biological perspective, snakes are equally fascinating, showing how a simple body plan can be used to great effect in an extremely broad variety of niches. Snakes are globally distributed and ecologically diverse; as a result, since recent research has shown that most snakes are venomous to some degree, their venom is equally diverse. This thesis focuses on one major toxin family: three-finger toxins (3FTx). These toxins can be found in virtually all venomous snake lineages and are often neurotoxic. Since their original recruitment there have been numerous instances of structural and functional innovation within this toxin family. The research in this thesis pertains to several such novel adaptations in snakes of the colubrid and elapid families, many of whose venom is composed primarily of these toxins. Chapter 2 deals with the ancestral version 3FTx and how, in the colubrine genus Boiga, simple mutations in toxins can lead to structural changes, in this case additional cysteines enable the formation of dimeric toxins with increased potency. These novel toxins can, in turn, open up new niches to the snakes which possess those toxins. In B. irregularis they facilitated a destructive invasion event and may have similarly assisted in the spread of an ancestral Boiga since our research shows that several other species possess similar dimeric toxins. This echoes a process that occurred in the ancestor of the elapids where the loss of a pair of cysteines and their disulfide bond was followed by an incredible diversification of these toxins and the snakes that produce them. Chapter 3 explores venom composition and activity of the genus Calliophis, the most basal genus of the elapids. C. bivirgatus and C. intestinalis both possess extremely elongated venom glands and each produce 3FTx with novel sodium channel toxicity. However, the two venoms produce opposite effects from one another. These results suggests some intriguing possibilities about the evolutionary history of these novel traits in Calliophis and the general composition of their venoms inform our understanding of how the venoms of more derived elapids evolved.Chapters 4 and 5 focus on the genus Micrurus. This genus from the Americas is by far the most speciose genus of elapids and belongs to the coral snake clade which is the next branch in the phylogeny of the elapids after Calliophis. The venoms of these snakes all contain a high number of unique 3FTx, though some venoms may be dominated by PLA2 toxins in terms of overall composition. Chapter 4 focuses on the sequence diversity of 3FTx from this genus and the selection regimes under which they operate. This diversity may lay the groundwork for rapid changes in the toxin composition of the venom and accompanying changes in venom activity. Chapter 5 directly ...

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Section: Introductionmentioning

confidence: 99%

Novelty in three-finger toxin evolution

Dashevsky¹

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Electric Blue: Molecular Evolution of Three-Finger Toxins in the Long-Glanded Coral Snake Species Calliophis bivirgatus

Dashevsky

Rokyta

Frank

et al. 2021

Toxins

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The genus Calliophis is the most basal branch of the family Elapidae and several species in it have developed highly elongated venom glands. Recent research has shown that C. bivirgatus has evolved a seemingly unique toxin (calliotoxin) that produces spastic paralysis in their prey by acting on the voltage-gated sodium (NaV) channels. We assembled a transcriptome from C. bivirgatus to investigate the molecular characteristics of these toxins and the venom as a whole. We find strong confirmation that this genus produces the classic elapid eight-cysteine three-finger toxins, that δδ-elapitoxins (toxins that resemble calliotoxin) are responsible for a substantial portion of the venom composition, and that these toxins form a distinct clade within a larger, more diverse clade of C. bivirgatus three-finger toxins. This broader clade of C. bivirgatus toxins also contains the previously named maticotoxins and is somewhat closely related to cytotoxins from other elapids. However, the toxins from this clade that have been characterized are not themselves cytotoxic. No other toxins show clear relationships to toxins of known function from other species.

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North American Coral Snake Envenomation

Cited by 2 publications

References 24 publications

Novelty in three-finger toxin evolution

Novelty in three-finger toxin evolution

Electric Blue: Molecular Evolution of Three-Finger Toxins in the Long-Glanded Coral Snake Species Calliophis bivirgatus

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