Biology subjects

Mesrop, L. Y.

Publications and source records attributed to Mesrop, L. Y..

3 recordsLinked to original sources

bioRxiv2024

Ancient secretory pathways contributed to the evolutionary origin of an ecologically impactful bioluminescence system

Evolutionary innovations in chemical secretion - such as the production of secondary metabolites, pheromones, and toxins - profoundly impact ecological interactions across a broad diversity of life. These secretory innovations may involve a "legacy-plus-innovation" mode of evolution, whereby new biochemical pathways are integrated with conserved secretory processes to create novel products. Among secretory innovations, bioluminescence is important because it evolved convergently many times to influence predator-prey interactions, while often producing courtship signals linked to increased rates of speciation. However, whether or not deeply conserved secretory genes are used in secretory bioluminescence remains unexplored. Here, we show that in the ostracod Vargula tsujii, the evolutionary novel c-luciferase gene is co-expressed with many conserved genes, including those related to toxin production and high-output protein secretion. Our results demonstrate that the legacy-plus-innovation mode of secretory evolution, previously applied to sensory modalities of olfaction, gustation, and nociception, also encompasses light-producing signals generated by bioluminescent secretions. This extension broadens the paradigm of secretory diversification to include not only chemical signals but also bioluminescent light as an important medium of ecological interaction and evolutionary innovation. Significance StatementAnimals produce an enormous diversity of secreted chemical products, like toxins and pheromones, with wide-ranging impacts on ecological interactions. Although a deeply conserved toolkit of secretory genes may often underlie chemical interactions mediated through smell, taste, and sensing pain, whether or not this evolutionary mode generalizes to sensing light is unknown. Here we show that a bioluminescence secretion system, which creates light for anti-predator and courtship interactions, also uses genes of a deeply conserved secretory toolkit. Therefore, secretory innovations may act through all sensory modalities by integrating conserved genes with novel biosynthesis pathways, to serve as crucibles of evolutionary and ecological diversity.

evolutionary biology↗

bioRxiv2022

Single cell analysis reveals the molecular signaling and cellular composition of the regenerating Hydra head

The extent to which animals can regenerate cells, tissues, or body parts varies largely. Hydra has a remarkable ability to undergo full body regeneration. Bisected polyps can regenerate the head and foot, and whole polyps can form from aggregates of cells. This capability is made possible by a cluster of cells known as the head organizer. Previous studies have found Wnt3 and other developmental genes associated with head organizer function. Yet, the genetic and molecular mechanisms of regenerating Hydra heads remain unresolved. In this study, we used bulk RNA-seq, bulk ATAC-seq, and single-cell RNA-seq from a regeneration time course to characterize the gene expression, gene regulation, molecular, and cellular features of Hydra head regeneration. WGCNA modules and cis-regulation of candidate head organizer genes identified genes co-expressed with Wnt3 and transcription factors important for regeneration. At the single-cell level, we identified at least six distinct cell types in the regenerating head tissue and characterized the expression of candidate genes. With these combined data sets, we identify and clarify some of the interactions between JNK, Wnt3, and EGRF signaling during Hydra head regeneration. Our study reveals coordination of early wound response, developmental transcription factors, and transposable elements during Hydra tissue regeneration and provides insight into the evolution of regeneration programs.

developmental biology↗

bioRxiv2018

Intra-host symbiont diversity and extended symbiont maintenance in photosymbiotic Acantharea (clade F)

Photosymbiotic protists contribute to surface primary production in low-nutrient, open-ocean ecosystems and constitute model systems for studying plastid acquisition via endosymbiosis. Little is known, however, about host-symbiont dynamics in these important relationships, and whether these symbioses constitute mutualisms is debated. In this study, we applied single-cell sequencing methods and advanced fluorescent microscopy to investigate host-symbiont dynamics in clade F acantharians, a major group of photosymbiotic protists in oligotrophic subtropical gyres. We amplified the 18S rRNA gene from single acantharian hosts and environmental samples to assess intra-host symbiont diversity and to determine whether intra-host symbiont community composition directly reflects the available symbiont community in the surrounding environment. Our results demonstrate that clade F acantharians simultaneously host multiple species from the haptophyte genera Phaeocystis and Chrysochromulina. The intra-host symbiont community composition was distinct from the external free-living symbiont community, suggesting that these acantharians maintain symbionts for extended periods of time. After selective staining of digestive organelles, fluorescent confocal microscopy showed that symbionts were not being systematically digested, which is consistent with extended symbiont maintenance within hosts. Extended maintenance within hosts may benefit symbionts through protection from grazing or viral lysis, and therefore dispersal, provided that symbionts retain reproductive capacity.

ecology↗