Biology subjects

Kuhn, G. C. S.

Publications and source records attributed to Kuhn, G. C. S..

3 recordsLinked to original sources

bioRxiv2017

An eutherian intronic sequence gave rise to a major satellite DNA in Platyrrhini

Satellite DNAs (satDNAs) are major components of eukaryote genomes. However, because of their quick divergence, the evolutionary origin of a given satDNA family can rarely be determined. Herein we took advantage of available primate sequenced genomes to determine the origin of the CapA satDNA (~1,500 bp long monomers), first described in Sapajus apella. We show that CapA is an abundant satDNA in Platyrrhini, whereas in the genomes of most eutherian mammals, including humans, this sequence is present only as a single copy located within a large intron of the NOS1AP (nitric oxid synthase 1 adaptor protein) Gene. Our data suggest that this intronic CapA-like sequence gave rise to the CapA satDNA and we discuss possible mechanisms implicated in this event. This is the first report of a single copy intronic sequence giving origin to a satDNA that reaches up to 100,000 copies in some genomes.

genomics↗

bioRxiv2017

Concomitant Duplication Of The Cid And Cenp-C Genes In Drosophila

The constitutive centromeric proteins CenH3 and Cenp-C are interdependent in their role of establishing centromere identity and function. In a recent paper, Kursel and Malik (February 2017; doi: 10.1093/molbev/msx091) reported that the Drosophila CenH3 homologue Cid underwent four independent duplication events during evolution. Particularly interesting is the duplication that took place in the common ancestor of the Drosophila subgenus and led to the subfunctionalization and high divergence of the Cid1 and Cid5 paralogs. Here, we describe another independent Cid duplication (Cid1 leading to Cid6) in the buzzatii cluster (repleta group) of the Drosophila subgenus. Moreover, we found that, in addition to the Cid1/Cid5 duplication, Cenp-C was also duplicated (Cenp-C1, Cenp-C2) in the common ancestor of the Drosophila subgenus. Analyses of expression and tests for positive selection indicate that both Cid5 and Cenp-C2 are male germline-biased and evolved adaptively, indicating subfunctionalization of the Cid and Cenp-C paralogs. Our findings further highlight the strong interdependence between CenH3 and Cenp-C, paving the way to new perspectives by which centromere function and evolution can be addressed.

genetics↗

bioRxiv2017

A horizontally transferred autonomous Helitron became a full polydnavirus segment in Cotesia vestalis

Bracoviruses associate symbiotically with thousands of parasitoid wasp species in the family Braconidae, working as virulence gene vectors, and allowing the development of wasp larvae within hosts. These viruses are composed by multiple DNA circles that are packaged into infective particles and injected together with wasp's eggs during parasitization. One of the viral segments of Cotesia vestalis bracovirus contains a gene that has been previously described as a helicase of unknown origin. Here we demonstrate that this gene is a Rep/Helicase from an intact Helitron transposable element that covers the viral segment almost entirely. We also provide evidence that this element underwent at least two horizontal transfers, which appear to have occurred consecutively: first from a Drosophila host ancestor to the genome of the parasitoid wasp Cotesia vestalis and its bracovirus, and then from C. vestalis to a lepidopteran host (Bombyx mori). Our results reinforce the idea of parasitoid wasps as frequent agents of horizontal transfers in eukaryotes. Additionally, this Helitron-bracovirus segment is the first example of a transposable element that effectively became a whole viral circle.

genomics↗