Browsing Biology by Subject "Biology"
Now showing 1 - 4 of 4
Results Per Page
- ItemEcology of the Eastern Ribbonsnake (Thamnophis sauritus) in southern Alabama with evidence of seasonal multiple broods(Herpetological Conservation and Biology, 2011-12) Langford, Gabriel J.; Borden, Joel A.; Nelson, David H.Studies are lacking on the ecology of the Eastern Ribbonsnake (Thamnophis sauritus), especially in the southern United States. We describe some aspects of the sexual dimorphism, sex ratio, feeding habits, reproductive biology, and seasonal activity of the Eastern Ribbonsnake in a southern Alabama Tupelo-Gum swamp from 2003-2005. We captured 339 Eastern Ribbonsnakes 379 times; females were significantly longer than males, but males had longer tails. Snakes were active year-round, and the longest straight-line distance travelled by any snake was 1,050 m. Snakes consumed only frogs (Hyla spp. and Lithobates spp.); a shift occurred when juveniles switched from feeding on tadpoles to adult frogs. We found females had an extended reproductive season, producing broods April-October. Two females double brooded during the 2004 reproductive season, with 99 and 118 days between broods. The average brood size for Eastern Ribbonsnakes from six females that produced eight broods was 14 ± 3.18 (range 9-19). A reduction in brood size occurred in both females that produced multiple broods, but no decrease in neonate snout-vent length was detected between broods. Overall, our study provides needed natural history data from a southern location and the first evidence for multiple broods in a wild, temperate snake.
- ItemSome like it hot: population-specific adaptations in venom production to abiotic stressors in a widely distributed cnidarian(BMC Biology, 2020) Sachkova, Maria Y.; Macrander, Jason; Surm, Joachim M.; Aharoni, Reuven; Menard-Harvey, Shelcie S.; Klock, Amy; Leach, Whitney B.; Reitzel, Adam M.; Moran, YehuAbstract Background In cnidarians, antagonistic interactions with predators and prey are mediated by their venom, whose synthesis may be metabolically expensive. The potentially high cost of venom production has been hypothesized to drive population-specific variation in venom expression due to differences in abiotic conditions. However, the effects of environmental factors on venom production have been rarely demonstrated in animals. Here, we explore the impact of specific abiotic stresses on venom production of distinct populations of the sea anemone Nematostella vectensis (Actiniaria, Cnidaria) inhabiting estuaries over a broad geographic range where environmental conditions such as temperatures and salinity vary widely. Results We challenged Nematostella polyps with heat, salinity, UV light stressors, and a combination of all three factors to determine how abiotic stressors impact toxin expression for individuals collected across this species’ range. Transcriptomics and proteomics revealed that the highly abundant toxin Nv1 was the most downregulated gene under heat stress conditions in multiple populations. Physiological measurements demonstrated that venom is metabolically costly to produce. Strikingly, under a range of abiotic stressors, individuals from different geographic locations along this latitudinal cline modulate differently their venom production levels. Conclusions We demonstrate that abiotic stress results in venom regulation in Nematostella. Together with anecdotal observations from other cnidarian species, our results suggest this might be a universal phenomenon in Cnidaria. The decrease in venom production under stress conditions across species coupled with the evidence for its high metabolic cost in Nematostella suggests downregulation of venom production under certain conditions may be highly advantageous and adaptive. Furthermore, our results point towards local adaptation of this mechanism in Nematostella populations along a latitudinal cline, possibly resulting from distinct genetics and significant environmental differences between their habitats.
- ItemToxin-like neuropeptides in the sea anemone Nematostella unravel recruitment from the nervous system to venom(National Academy of Sciences, 2020-10) Sachkova, Maria Y.; Landau, Morani; Surm, Joachim M.; Macrander, Jason; Singer, Shir A.; Reitzel, Adam M.; Moran, YehuThe sea anemone (Anthozoa, Cnidaria) is a powerful model for characterizing the evolution of genes functioning in venom and nervous systems. Although venom has evolved independently numerous times in animals, the evolutionary origin of many toxins remains unknown. In this work, we pinpoint an ancestral gene giving rise to a new toxin and functionally characterize both genes in the same species. Thus, we report a case of protein recruitment from the cnidarian nervous to venom system. The ShK-like1 peptide has a ShKT cysteine motif, is lethal for fish larvae and packaged into nematocysts, the cnidarian venom-producing stinging capsules. Thus, ShK-like1 is a toxic venom component. Its paralog, ShK-like2, is a neuropeptide localized to neurons and is involved in development. Both peptides exhibit similarities in their functional activities: They provoke contraction in polyps and are toxic to fish. Because ShK-like2 but not ShK-like1 is conserved throughout sea anemone phylogeny, we conclude that the two paralogs originated due to a -specific duplication of a ShK-like2 ancestor, a neuropeptide-encoding gene, followed by diversification and partial functional specialization. ShK-like2 is represented by two gene isoforms controlled by alternative promoters conferring regulatory flexibility throughout development. Additionally, we characterized the expression patterns of four other peptides with structural similarities to studied venom components and revealed their unexpected neuronal localization. Thus, we employed genomics, transcriptomics, and functional approaches to reveal one venom component, five neuropeptides with two different cysteine motifs, and an evolutionary pathway from nervous to venom system in Cnidaria.
- ItemTranscriptomic Analysis of Four Cerianthid (Cnidaria, Ceriantharia) Venoms(MDPI AG, 2020) Klompen, Anna M. L.; Macrander, Jason; Reitzel, Adam M.; Stampar, Sérgio N.Tube anemones, or cerianthids, are a phylogenetically informative group of cnidarians with complex life histories, including a pelagic larval stage and tube-dwelling adult stage, both known to utilize venom in stinging-cell rich tentacles. Cnidarians are an entirely venomous group that utilize their proteinaceous-dominated toxins to capture prey and defend against predators, in addition to several other ecological functions, including intraspecific interactions. At present there are no studies describing the venom for any species within cerianthids. Given their unique development, ecology, and distinct phylogenetic-placement within Cnidaria, our objective is to evaluate the venom-like gene diversity of four species of cerianthids from newly collected transcriptomic data. We identified 525 venom-like genes between all four species. The venom-gene profile for each species was dominated by enzymatic protein and peptide families, which is consistent with previous findings in other cnidarian venoms. However, we found few toxins that are typical of sea anemones and corals, and furthermore, three of the four species express toxin-like genes closely related to potent pore-forming toxins in box jellyfish. Our study is the first to provide a survey of the putative venom composition of cerianthids and contributes to our general understanding of the diversity of cnidarian toxins.