Expansion and Evolution of the X-Linked Testis Specific Multigene Families in the melanogaster Species Subgroup

Abstract

The testis specific X-linked genes whose evolution is traced here in the melanogaster species subgroup are thought to undergo fast rate of diversification. The CK2ßtes and NACβtes gene families encode the diverged regulatory β-subunits of protein kinase CK2 and the homologs of β-subunit of nascent peptide associated complex, respectively. We annotated the CK2βtes-like genes related to CK2ßtes family in the D. simulans and D. sechellia genomes. The ancestor CK2βtes-like genes preserved in D. simulans and D. sechellia are considered to be intermediates in the emergence of the D. melanogaster specific Stellate genes related to the CK2ßtes family. The CK2ßtes-like genes are more similar to the unique autosomal CK2ßtes gene than to Stellates, taking into account their peculiarities of polymorphism. The formation of a variant the CK2ßtes gene Stellate in D. melanogaster as a result of illegitimate recombination between a NACßtes promoter and a distinct polymorphic variant of CK2ßtes-like ancestor copy was traced. We found a close nonrandom proximity between the dispersed defective copies of DINE-1 transposons, the members of Helitron family, and the CK2βtes and NACβtes genes, suggesting an involvement of DINE-1 elements in duplication and amplification of these genes.

Heterochromatin-enriched assemblies reveal the sequence and organization of theDrosophila melanogasterY chromosome

“…All sex-linked 395 members of this gene family exist in multiple copies. The X-linked copies and Y-396 linked copies amplified independently, perhaps driven by sex chromosome conflict 397 (KOGAN et al 2012). We used our assembly to study the evolution of this interesting 398 gene family and patterns of gene conversion on the Y chromosome.…”

Helitrons , the Eukaryotic Rolling-circle Transposable Elements

“…Texim genes containing the SGNH hydrolase domain are also found to associate with some Helentrons in the platyfish genome; however, it is not clear whether they are mobilized by Helentrons or duplicated as part of segmental duplications (152). In Drosophila, HINEs are reported to have nonrandom associations with several gene duplicates, which are functional (144,(153)(154)(155). However it is not clear whether or not the duplications occur as a result of capture or by ectopic recombination (144,(153)(154)(155) because of the rapid sequence turnover and high deletion rates in the drosophilids (11,156).…”

“…In Drosophila, HINEs are reported to have nonrandom associations with several gene duplicates, which are functional (144,(153)(154)(155). However it is not clear whether or not the duplications occur as a result of capture or by ectopic recombination (144,(153)(154)(155) because of the rapid sequence turnover and high deletion rates in the drosophilids (11,156). HINE insertions were described near 11 gene duplicates from different Drosophila species (144,153,154,157).…”

“…However it is not clear whether or not the duplications occur as a result of capture or by ectopic recombination (144,(153)(154)(155) because of the rapid sequence turnover and high deletion rates in the drosophilids (11,156). HINE insertions were described near 11 gene duplicates from different Drosophila species (144,153,154,157). To date, no genomes boast a frequency of protogene formation by Helentrons that rivals that observed with maize or bat Helitrons (e.g., 51,81), but this may result from an ascertainment bias because the relationship of these elements to Helitrons was only recently unequivocally demonstrated (11).…”

Transcription factors, chromatin proteins and the diversification of Hemiptera

“…The LSE of developmental genes is not unprecedented in insects – members of the MADF/SAZ-BESS family of TFs, initially studied in dipteran wing development (Lander et al, 2001; Shukla et al, 2014), and the methuselah/methuselah-like gene family involved in organ morphogenesis (Patel et al, 2012), were found to be expanded in Drosophila . While many of these expansions happen via tandem gene duplication, transposable elements (TEs) such as the DINE-1 of D. melanogaster may trigger gene amplification and even allow for dispersal of the duplicated genes (Kogan et al, 2012). …”