TY - JOUR T1 - Bacterial contribution to genesis of the novel germ line determinant <em>oskar</em> JF - bioRxiv DO - 10.1101/453514 SP - 453514 AU - Leo Blondel AU - Tamsin E. M. Jones AU - Cassandra G. Extavour Y1 - 2018/01/01 UR - http://biorxiv.org/content/early/2018/10/25/453514.abstract N2 - New cellular functions and developmental processes can evolve by modifying the functions or regulation of preexisting genes, but the creation of new genes and their contributions to novel processes is less well understood. New genes can arise not only from mutations or rearrangements of existing sequences, but also via acquisition of foreign DNA, also called horizontal gene transfer (HGT). Here we present evidence that HGT contributed to the creation of a novel gene indispensable for reproduction in some insects. The oskar gene evolved to fulfil a crucial role in insect germ cell formation, but was long considered a novel gene with unknown evolutionary origins. Our analysis of over 100 Oskar sequences suggests that Oskar arose through a novel gene formation history involving fusion of eukaryotic and prokaryotic sequences. One of its two conserved domains (LOTUS), was likely present in the genome of a last common insect ancestor, while the second (OSK) domain appears to have been acquired through horizontal transfer of a bacterial GDSL-like lipase domain. Our evidence suggests that the bacterial contributor of the OSK domain may have been a germ line endosymbiont. This shows that gene origin processes often considered highly unusual, including HGT and de novo coding region evolution, can give rise to novel genes that can both participate in pre-existing gene regulatory networks, and also facilitate the evolution of novel developmental mechanisms. ER -