Accepted_test

Deciphering the structural organization of sex chromosomes in Siberian silk moth, Dendrolimus sibiricus

by Shipova A.A. | Ershov N.I. | Yakimova M.E. | Martemyanov, V.V. | Institute of Cytology and Genetics SB RAS, Novosibirsk, Russia | Institute of Cytology and Genetics SB RAS, Novosibirsk, Russia | Laboratory of Ecological Physiology, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia | Laboratory of Ecological Physiology, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia

Abstract ID: 737

Event: BGRS-abstracts

Sections: [Sym 1] Section “Structural-functional organization of genomes and transcriptomics”

The W chromosome of Lepidoptera is typically saturated by genomic repeats, gene-poor and completely heterochromatinized, which significantly hamper the accurate assembly of W chromosome from heterogametic individuals. We explored the possibility to circumvent these problems at low cost using an approach of contig classification and targeted reassembly of available long-read genomic data obtained from female D. sibiricus. The chromosome assembly retained some fragmentation and included 10 contigs. The unresolved fragmentation is explained by an exceptional saturation of the W chromosome with genomic repeats as well as by the fact that the W chromosome contained several large and extremely homologous duplications. The W chromosome sequences are also distinguished by a clear expansion of LTR transposons. Taken together, we revealed the abundance of young repeats and young insertions of foreign genetic material which indicates the recent formation of the W chromosome during the speciation of D. sibiricus and echoes the theory of multiple non-canonical emergence of W chromosomes in the evolution of Lepidoptera, including its formation from B chromosomes. At the same time, the W exhibits significant sequence similarity to the Z, which confirms its evolutionary origin from the Z chromosome.