Ontogenetic Variation in Venom Composition and Diet of Crotalus oreganus concolor: A Case of Venom Paedomorphosis?

Abstract

Ontogenetic shifts in diet are common for snakes, and such shifts in diet for venomous snakes may be associated with changes in venom composition. The present study investigated whether an ontogenetic shift in diet and venom composition, as observed for Crotalus oreganus helleri and Crotalus oreganus oreganus, occurs in Crotalus oreganus concolor. Like C. o. helleri and C. o. oreganus, and at similar body sizes, C. o. concolor show an ontogenetic shift in diet. Juvenile snakes primarily feed on small lizards, whereas adults typically consume small rodents. However, C. o. concolor do not show the same pattern of venom ontogeny as do C. o. helleri and C. o. oreganus.Because of the presence of a phospholipase A 2 -based ␤-neurotoxin (concolor toxin) and several myotoxins, C. o. concolor venom is particularly toxic, but mouse LD 50 assays demonstrated no significant difference in toxicity between adult (0.38 g/g) and juvenile (0.45 g/g) venoms. Metalloprotease activity (correlated with extensive tissue damage and prey predigestion) was extremely low in both juvenile and adult venoms. Levels of peptide myotoxins and several serine proteases that interfere with hemostasis (specifically thrombin-like and plasmin-like activities) showed a positive correlation with size. Human envenomations recorded during this study showed symptoms consistent with biochemical analyses, with numbness associated with the bite, coagulation abnormalities and essentially no tissue damage. Results suggest that the occurrence of potent neurotoxic component(s) in a venom minimizes predigestive components (metalloproteases). Further, concurrence of these functional components in the venom of an individual may be selected against, and highly toxic venom in both juvenile and adult C. o. concolor may represent a form of venom paedomorphosis.

Age-dependent variations in the venom proteins of Vipera kaznakovi Nikolsky, 1909 and Vipera ammodytes (Linnaeus, 1758) (Ophidia: Viperidae)

“…As a result of the increased head size and so venom gland size, venom yields and total dry weight of adult snakes are generally greater than those of neonate or juvenile individuals and this can be regarded as a general trend for all venomous reptiles (Klauber, 1956;Meier and Freyvogel, 1980;Mackessy, 1985Mackessy, , 1988Furtado et al, 1991;Mackessy et al, 2003Mackessy et al, , 2006Mackessy et al, , 2010. The total protein content of venom may also vary (generally increase) with age (Bonilla et al, 1973;Mackessy et al, 2006).…”

“…Age-dependent variations in biological and biochemical features of venom extracts have been frequently reported by various researchers and significant differences in toxicity, antigenic make-up, and biochemical composition, including enzyme activities, have been reported (Minton, 1967(Minton, , 1975Fiero et al, 1972;Theakston and Reid, 1978;Meier and Freyvogel, 1980;Meier, 1986;Mackessy, 1988;Furtado et al, 1991;Tun-Pe et al, 1995;Mackessy et al, 2003;Mackessy et al, 2006;Arıkan et al, 2006;Guércio et al, 2006).…”

Intraspecific variation of venom injected by fish-hunting Conussnails

“…Significantly less dramatic variations in the peptide complement of injected venoms have been reported for several other organisms, including snakes (Chippaux et al, 1991;Creer et al, 2003;Daltry et al, 1996a,b;Francischetti et al, 2000;MacKessy et al, 2003;Monteiro et al, 1998a,b), spiders (Binford, 2001;Cristina de Oliveira et al, 1999;Escoubas et al, 2002) The α-, ω-conotoxins and s4a have all been previously isolated from the DV and characterized. Underlined peptides are those that are putatively identified in this work by mass matching to published cDNA sequences with predicted modifications.…”

Influência da paisagem na dieta de Bothrops atrox na Amazônia oriental

“…A escolha do tecido e da dieta dependerá então da questão de interesse, de acordo com . Alguns estudos com esta serpente mostraram ser uma espécie generalista, consumidoras principalmente de centopéias, peixes, anuros, lagartos, outras serpentes, aves e pequenos mamíferos (MARTINS; TRAVAGLIA-CARDOSO; FURTADO, 2008;MACKESSY et al, 2003). A variabilidade na composição dos venenos pode ser verificada entre as diferentes espécies, e de forma intra-especifica representada por variações ontogenéticas (SALDARRIAGA et al, 2003, GUÉRCIO et al, 2006, ligadas ao sexo , ou conforme a distribuição geográfica (ALAPE-GIRÓN et al, 2008).…”

“…Acredita-se que venenos de serpentes são influenciados pelo tipo de presa consumida, o que interfere na composição das proteínas formadas no organismo do animal, e conseqüentemente, na toxicidade deste veneno (MACKESSY, 1988;ZELANIS;TRVAGLIA-CARDOSO;FURTADO, 2008;WILLIANS;ASHTON, 2003). A variabilidade na composição dos venenos pode ser verificada entre as diferentes espécies, e de forma intra-especifica representada por variações ontogenéticas (SALDARRIAGA et al, 2003, GUÈRCIO et al, 2006, ligadas ao sexo , ou conforme a distribuição geográfica (ALAPE-GIRÓN et al, 2008).…”