Biology subjects

Sachkova, M. Y.

Publications and source records attributed to Sachkova, M. Y..

4 recordsLinked to original sources

bioRxiv2022

Dominant toxin hypothesis: unravelling the venom phenotype across micro and macroevolution

Venom is a complex trait with substantial inter- and intraspecific variability resulting from strong selective pressures acting on the expression of many toxic proteins. However, understanding the processes underlying the toxin expression dynamics that determine the venom phenotype remains unresolved. Here, we use comparative genomics and transcriptomics to reveal that toxin expression in sea anemones evolves rapidly with little constraint and that a single toxin family dictates the venom phenotype in each species. This dominant toxin family is characterized by massive gene duplication events. In-depth analysis of the sea anemone, Nematostella vectensis, revealed significant variation in the number of copies of the dominant toxin (Nv1) across populations, corresponding to significant differences in Nv1 expression at both the transcript and protein levels. These differences in Nv1 copies are driven by independent expansion events, resulting in distinct haplotypes that have a restricted geographical distribution. Strikingly, one population has undergone a severe contraction event, causing a near-complete loss of Nv1 production. Our findings across micro- and macroevolutionary scales in sea anemones complement observations of single dominant toxin family present in other venomous organisms and establishes the dominant toxin hypothesis whereby venomous animals have convergently evolved a similar strategy in shaping the venom phenotype.

evolutionary biology↗

bioRxiv2020

Toxin-like neuropeptides in the sea anemone Nematostella unravel recruitment from the nervous system to venom

The sea anemone Nematostella vectensis (Anthozoa, Cnidaria) is a powerful model system for characterizing the evolution of genes functioning in venom and nervous systems. Despite being an example for evolutionary novelty, the evolutionary origin of most toxins remains unknown. Here we report the first bona fide case of protein recruitment from the cnidarian nervous to venom system. The ShK-like1 peptide has 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. Interestingly, both peptides exhibit similarities in their functional activities: both of them provoke contraction in Nematostella 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 Nematostella-specific duplication of a ShK-like2 ancestor, a neuropeptide-encoding gene, followed by diversification and partial functional specialization. Strikingly, 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 new venom component, five neuropeptides with two different cysteine motifs and an evolutionary pathway from nervous to venom system in Cnidaria.

evolutionary biology↗

bioRxiv2020

Population Specific Adaptations in Venom Production to Abiotic Stressors in a Widely Distributed Cnidarian

Nematostella vectensis is a sea anemone (Actiniaria, Cnidaria) inhabiting estuaries over a broad geographic range where environmental conditions such as temperatures and salinity vary widely. In cnidarians, antagonistic interactions with predators and prey are mediated by their venom, which may be metabolically expensive. In this study, we challenged Nematostella polyps with heat, salinity, UV light stressors and a combination of all three 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 suggesting that downregulating venom expression under stressful conditions may be advantageous. Strikingly, under a range of abiotic stressors, individuals from different geographic locations along this latitudinal cline modulate venom production levels differently in a pattern reflecting local adaptation.

evolutionary biology↗

bioRxiv2017

Dynamics of venom composition across a complex life cycle

Little is known about venom in young developmental stages of animals. The appearance of stinging cells in very early life stages of the sea anemone Nematostella vectensis suggests that toxins and venom are synthesized already in eggs, embryos and larvae of this species. Here we harness transcriptomic and biochemical tools as well as transgenesis to study venom production dynamics in Nematostella. We find that the venom composition and arsenal of toxin-producing cells change dramatically between developmental stages of this species. These findings might be explained by the vastly different ecology of the larva and adult polyp as sea anemones develop from a miniature non-feeding mobile planula to a much larger sessile polyp that predates on other animals. Further, the results suggest a much wider and dynamic venom landscape than initially appreciated in animals with a complex life cycle.

evolutionary biology↗