Integrated Venomics
and Venom Gland Transcriptome
Analysis of Juvenile and Adult Mexican Rattlesnakes Crotalus
simus, C. tzabcan, and C. culminatus Revealed miRNA-modulated Ontogenetic Shifts
posted on 2017-07-21, 00:00authored byJordi Durban, Libia Sanz, Dilza Trevisan-Silva, Edgar Neri-Castro, Alejandro Alagón, Juan J. Calvete
Adult
rattlesnakes within genus Crotalus express
one of two distinct venom phenotypes, type I (hemorrhagic) and type
II (neurotoxic). In Costa Rican Central American rattlesnake, ontogenetic
changes in the concentration of miRNAs modulate venom type II to type
I transition. Venomics and venom gland transcriptome analyses showed
that adult C. simus and C. tzabcan expressed intermediate patterns between type II and type I venoms,
whereas C. culminatus had a canonical type I venom.
Neonate/juvenile and adult Mexican rattlesnakes showed notable inter-
and intraspecific variability in the number, type, abundance and ontogenetic
shifts of the transcriptional and translational venom gland activities.
These results support a role for miRNAs in the ontogenetic venom compositional
changes in the three congeneric Mexican rattlesnakes. It is worth
noting the finding of dual-action miRNAs, which silence the translation
of neurotoxic heterodimeric PLA2 crotoxin and acidic PLA2 mRNAs while simultaneously up-regulating SVMP-targeting mRNAs.
Dual transcriptional regulation potentially explains the existence
of mutually exclusive crotoxin-rich (type-II) and SVMP-rich (type-I)
venom phenotypic dichotomy among rattlesnakes. Our results support
the hypothesis that alterations of the distribution of miRNAs, modulating
the translational activity of venom gland toxin-encoding mRNAs in
response to an external cue, may contribute to the mechanism generating
adaptive venom variability.