Tetrodotoxin levels in eggs of the rough-skin newt, Taricha granulosa, are correlated with female toxicity

We quantified the amount of the neurotoxin tetrodotoxin (TTX) present in females and newly deposited eggs of the rough-skin newt, Taricha granulosa, to examine the relationship between the toxicity of an individual female and the toxicity of her eggs. We found high levels of TTX in individual eggs as well as substantial variation among clutches. Variation in the amount of TTX per egg within individual clutches was extremely low. Female skin toxicity was positively correlated with the mean egg toxicity of her clutch. Neither egg volume nor female size was significantly correlated with egg TTX levels. Tetrodotoxin stereoisomer-analog profiles were identical for females and their eggs. The presence of high levels of TTX in individual eggs coupled with the relationship between levels of TTX in female skin and levels of TTX in her eggs suggests that the TTX present in eggs of T. granulosa is maternally derived. The lack of correlation between egg size and TTX levels in individual eggs, as well as the low levels of within clutch variation, may indicate that deposition of TTX in eggs of T. granulosa is not linked to the deposition of other egg resources (e.g., lipids or other yolk components).