Distribution of tetrodotoxin, 6-epitetrodotoxin, and 11-deoxytetrodotoxin in newts

Yotsu, Mari; Iorizzi, Maria; Yasumoto, Takeshi

doi:10.1016/0041-0101(90)90419-8

Cited by 69 publications

(43 citation statements)

References 6 publications

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“…Besides its widespread occurrence in marine animals (Yasumoto and Yotsu-Yamashita 1996) tetrodotoxin (abbreviated TTX) and its analogues 6-epiTTX and 11-oxoTTX have been detected in newts and salamanders of the genera Cynops, Taricha, Triturus and Notophthalmus (Yotsu et al 1990;Hanifin et al 1999Hanifin et al , 2010YotsuYamashita andMebs 2001, 2003;Yotsu-Yamashita et al 2007. TTX specifically blocks voltage-gated sodium channels (Narahashi et al 1964;Kato 1966) and is considered to make theses amphibians unpalatable to potential predators.…”

Section: Introductionmentioning

confidence: 99%

The praying mantis (Mantodea) as predator of the poisonous red-spotted newt Notophthalmus viridescens (Amphibia: Urodela: Salamandridae)

2016

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A Chinese praying mantis, Tenodera sinensis, was observed feeding on a living red-spotted newt, Notophthalmus viridescens. Specimens of that newt's population are known to contain high concentrations of tetrodotoxin (TTX), a specific blocker of voltage-gated sodium channels. After experimental oral administration of a TTX-solution (1 mg/ ml) to adult specimens of four mantis species, all survived high TTX concentrations (up to 30.8 lg/g body mass) as revealed by analysis of their body extracts, but they are rapidly killed by intra-abdominal injection of 1 lg TTX. The toxin was found to be gradually excreted with faeces. As demonstrated by monoclonal antibody-based immunohistochemical technique, TTX does not penetrate the mid-gut membrane, since it was localized only in the gut lumen, but not in the epithelial cells. This prevents the toxin to reach its target, the sodium channels of the insect's nervous system, and enables the mantids to feed on toxic prey without risking poisoning.

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Section: Introductionmentioning

confidence: 99%

The praying mantis (Mantodea) as predator of the poisonous red-spotted newt Notophthalmus viridescens (Amphibia: Urodela: Salamandridae)

2016

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“…This system is ideal because the traits that mediate coevolution are identified, geographically variable, and at least partly controlled by a well-studied gene family. Newts of the genus Taricha possess the neurotoxin tetrodotoxin (TTX; Mosher et al 1964;Wakely et al 1966;Brodie et al 1974;Yotsu et al 1990), which acts as a powerful chemical defence against vertebrate predators (Brodie 1968;Brodie et al 1974). Tetrodotoxin binds selectively to the outer pore of voltage-gated sodium channels in nerves and muscles (Lipkind & Fozzard 2000;Hille 2001), blocking the movement of sodium ions (Na þ ) across the cell membrane and halting the propagation of action potentials (Kao & Levinson 1986;Hille 2001).…”

Section: Introductionmentioning

confidence: 99%

Genetic architecture of a feeding adaptation: garter snake (Thamnophis) resistance to tetrodotoxin bearing prey

2010

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Detailing the genetic basis of adaptive variation in natural populations is a first step towards understanding the process of adaptive evolution, yet few ecologically relevant traits have been characterized at the genetic level in wild populations. Traits that mediate coevolutionary interactions between species are ideal for studying adaptation because of the intensity of selection and the well-characterized ecological context. We have previously described the ecological context, evolutionary history and partial genetic basis of tetrodotoxin (TTX) resistance in garter snakes (Thamnophis). Derived mutations in a voltage-gated sodium channel gene (Na v 1.4) in three garter snake species are associated with resistance to TTX, the lethal neurotoxin found in their newt prey (Taricha). Here we evaluate the contribution of Na v 1.4 alleles to TTX resistance in two of those species from central coastal California. We measured the phenotypes (TTX resistance) and genotypes (Na v 1.4 and microsatellites) in a local sample of Thamnophis atratus and Thamnophis sirtalis. Allelic variation in Na v 1.4 explains 23 per cent of the variation in TTX resistance in T. atratus while variation in a haphazard sample of the genome (neutral microsatellite markers) shows no association with the phenotype. Similarly, allelic variation in Na v 1.4 correlates almost perfectly with TTX resistance in T. sirtalis, but neutral variation does not. These strong correlations suggest that Na v 1.4 is a major effect locus. The simple genetic architecture of TTX resistance in garter snakes may significantly impact the dynamics of phenotypic coevolution. Fixation of a few alleles of major effect in some garter snake populations may have led to the evolution of extreme phenotypes and an 'escape' from the arms race with newts.

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“…In Central and South America, the only known predator of highly poisonous Atelopus toads (23,24) is the Neotropical ground snake, Liophis epinephelus (25,26). In southern Japan, the tetrodotoxic newt Cynops ensicauda (27) is taken by Pryer's keelback, Amphiesma pryeri (28,29), and in East Asia the TTX-bearing tree frog Polypedates cf leucomystax (30) is preyed on by the tiger keelback, Rhabdophis tigrinus (31). Natural selection on these independent lineages of predators is expected to have led to convergent resistance to TTX at the organismal level but not necessarily via the same physiological or genetic mechanisms.…”

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Constraint shapes convergence in tetrodotoxin-resistant sodium channels of snakes

Feldman

Brodie²,

Pfrender³

2012

Proc. Natl. Acad. Sci. U.S.A.

144

220

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Natural selection often produces convergent changes in unrelated lineages, but the degree to which such adaptations occur via predictable genetic paths is unknown. If only a limited subset of possible mutations is fixed in independent lineages, then it is clear that constraint in the production or function of molecular variants is an important determinant of adaptation. We demonstrate remarkably constrained convergence during the evolution of resistance to the lethal poison, tetrodotoxin, in six snake species representing three distinct lineages from around the globe. Resistance-conferring amino acid substitutions in a voltage-gated sodium channel, Na v 1.4, are clustered in only two regions of the protein, and a majority of the replacements are confined to the same three positions. The observed changes represent only a small fraction of the experimentally validated mutations known to increase Na v 1.4 resistance to tetrodotoxin. These results suggest that constraints resulting from functional tradeoffs between ion channel function and toxin resistance led to predictable patterns of evolutionary convergence at the molecular level. Our data are consistent with theoretical predictions and recent microcosm work that suggest a predictable path is followed during an adaptive walk along a mutational landscape, and that natural selection may be frequently constrained to produce similar genetic outcomes even when operating on independent lineages. coevolution | molecular evolution | pleiotropy

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Distribution of tetrodotoxin, 6-epitetrodotoxin, and 11-deoxytetrodotoxin in newts

Cited by 69 publications

References 6 publications

The praying mantis (Mantodea) as predator of the poisonous red-spotted newt Notophthalmus viridescens (Amphibia: Urodela: Salamandridae)

The praying mantis (Mantodea) as predator of the poisonous red-spotted newt Notophthalmus viridescens (Amphibia: Urodela: Salamandridae)

Genetic architecture of a feeding adaptation: garter snake (Thamnophis) resistance to tetrodotoxin bearing prey

Constraint shapes convergence in tetrodotoxin-resistant sodium channels of snakes

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