Venom Ontogeny in the Mexican Lance-Headed Rattlesnake (Crotalus polystictus)
Metadatos
Afficher la notice complèteAuteur
Mackessy, Stephen P.; Leroy, Jamie; Mociño-Deloya, Estrella; Setser, Kirk; W. Bryson, Robert; Saviola, Anthony J.Editorial
MDPI
Materia
Bradykinin-inhibitory peptide Enzyme Evolution Phenotypic variation Toxins Venomics
Date
2018-07-03Referencia bibliográfica
Mackessy, S.P. [et al.]. Venom Ontogeny in the Mexican Lance-Headed Rattlesnake (Crotalus polystictus).Toxins 2018, 10, 271; doi:10.3390/toxins10070271.
Patrocinador
Funding for this study was provided in part by the Colorado Office for Economic Development and International Trade (to SPM). Additional funds were provided by the UNC Office of Research.Résumé
As trophic adaptations, rattlesnake venoms can vary in composition depending on several
intrinsic and extrinsic factors. Ontogenetic changes in venom composition have been documented
for numerous species, but little is known of the potential age-related changes in many rattlesnake
species found in México. In the current study, venom samples collected from adult and neonate
Crotalus polystictus from Estado de México were subjected to enzymatic and electrophoretic analyses,
toxicity assays (LD50), and MALDI-TOF mass spectrometry, and a pooled sample of adult venom
was analyzed by shotgun proteomics. Electrophoretic profiles of adult males and females were quite
similar, and only minor sex-based variation was noted. However, distinct differences were observed
between venoms from adult females and their neonate offspring. Several prominent bands, including
P-I and P-III snake venom metalloproteinases (SVMPs) and disintegrins (confirmed by MS/MS) were
present in adult venoms and absent/greatly reduced in neonate venoms. Age-dependent differences
in SVMP, kallikrein-like, phospholipase A2 (PLA2), and L-amino acid oxidase (LAAO) activity levels
were confirmed by enzymatic activity assays, and like many other rattlesnake species, venoms
from adult snakes have higher SVMP activity than neonate venoms. Conversely, PLA2 activity was
approximately 2.5 X greater in venoms from neonates, likely contributing to the increased toxicity
(neonate venom LD50 = 4.5 μg/g) towards non-Swiss albino mice when compared to adult venoms
(LD50 = 5.5 μg/g). Thrombin-like (TLE) and phosphodiesterase activities did not vary significantly
with age. A significant effect of sex (between adult male and adult female venoms) was also observed
for SVMP, TLE, and LAAO activities. Analysis of pooled adult venom by LC-MS/MS identified 14
toxin protein families, dominated by bradykinin-inhibitory peptides, SVMPs (P-I, P-II and P-III),
disintegrins, PLA2s, C-type-lectins, CRiSPs, serine proteinases, and LAAOs (96% of total venom
proteins). Neonate and adult C. polystictus in this population consume almost exclusively mammals,
suggesting that age-based differences in composition are related to physical differences in prey (e.g.,
surface-to-volume ratio differences) rather than taxonomic differences between prey. Venoms from
adult C. polystictus fit a Type I pattern (high SVMP activity, lower toxicity), which is characteristic of
many larger-bodied rattlesnakes of North America.