Accepted_test

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

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