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キーワード:
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要旨:
Genomics has revolutionised biology and together with functional tests, such as gene knockout by CRISPR/Cas9, allows novel insight into non-model organisms including nematodes. One unexpected finding in genomics was that essentially all organisms harbour a large number of genes that are not conserved over larger evolutionary distances. Three mechanisms can be responsible for the evolution of taxonomically restricted genes. First, genes might evolve rapidly, for example, under the influence of positive selection; second, genes might also evolve de novo. Indeed, recent studies provide evidence for both mechanisms. Finally, genome-sequencing projects revealed widespread horizontal gene transfer between eubacteria and eukaryotes. However, little is known about the function of taxonomically restricted and horizontally acquired genes. I will provide insight into genomics and transcriptomics of Pristionchus pacificus, a species that we have established as model system in evolutionary biology to integrate development with ecology and population genetics. P. pacificus lives in association with scarab beetles. One key feature of its life style is a mouth dimorphism that enables predatory feeding. The development of teeth-like denticles of two discrete forms represents an example of developmental plasticity and we test if plasticity is a facilitator of phenotypic diversification. Using forward and reverse genetics and genome-wide association studies in P. pacificus, we made the surprising finding that taxonomically restricted genes seem to be functionally overrepresented in regulating plasticity and I will provide case studies to highlight this finding. Similarly, we found that a horizontally acquired gene was developmentally integrated into P. pacificus by co-option of genetic regulators of plasticity. I argue that a full understanding of biological processes in any organism requires a balanced view of conserved, taxonomically restricted and horizontally acquired genes.
