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キーワード:
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要旨:
Horizontal gene transfer is the passage of genetic material between phylogenetically distant lineages. Using whole-genome sequencing platforms, horizontally-acquired genes have been identified in numerous organisms including eukaryotes. However, to become functional, new genes must be integrated into gene regulatory networks, and little is known about how this is achieved. We studied developmental integration of a horizontally-acquired cellulase cel-2 in the nematode Pristionchus pacificus. We show that cel-2 is expressed in pharyngeal gland cells and the secretory-excretory system, consistent with the presumptive extracorporeal hydrolytic function of the encoded enzyme. Strikingly, cel-2 expression is tightly linked to the regulation of a dimorphism of feeding structures. We observe that cel-2 is more highly expressed in the ‘stenostomatous’ microbivorous morph than in the ‘eurystomatous’ morph that can kill other nematodes. Using mutants in the developmental switch genes eud-1 and nhr-40, which regulate the mouth-form decision, we could elucidate that these genes also regulate the level and pattern of cel-2 expression. In addition, cel-2 expression is influenced by bacteria provided to the worm as food and is increased upon starvation. We conclude that a horizontally-acquired cellulase gene in P. pacificus was integrated into development by co-option of existing regulators of feeding plasticity.
