Chromosome-level Genome Assembly, Annotation And Evolutionary Analysis Of Mustela Stolonifer

Siberian weasel(Mustela sibirica),a small carnivore of the genus Mustela in the family Mustelidae(Carnivora),has a wide distribution and complex habitat types,including woodlands,thickets,grasslands,mountains,and even man-made environments such as fields and villages.The siberian weasel is not only an important species for preventing rodent infestation and maintaining the stability of the ecosystem,but also an important furbearer.However,up to now,the research on the adaptive evolution of the siberian weasel is still in its initial stage.Based on the above,this study was conducted for the first time to sequence the genome of the siberian weasel through second-and third-generation sequencing techniques and Hi-C technology to assemble high-quality siberian weasel chromosomal-level genome sequences.The evolutionary analysis was carried out using bioinformatics techniques to identify gene families of expansion and contraction and positively selected genes,and to investigate the adaptive evolutionary mechanisms of the siberian weasel at the molecular level.The main study contents and results are as follows.The size of the siberian weasel genome constructed in this study was 2,459.99 Mb,and the contig N50 reached 70.53 Mb.The assembly was then elevated to the chromosome level using HiC technology,and finally 98.73% of the siberian weasel genome sequence was anchored to 19 chromosomes.The assembled siberian weasel genome was annotated with repetitive sequences,and a total of 1.09 Gb of repetitive sequences were annotated,accounting for 44.5% of the entire siberian weasel genome size.Gene structure annotation of the siberian weasel genome resulted in the annotation of 18,766 protein-coding genes from the siberian weasel genome.The coding sequences obtained from the genome annotation were compared with multiple databases for functional annotation,and 99.53%(n=18,678)of the coding genes were annotated in at least one database.This indicates that the quality of the assembled genomes is good.Gene family clustering analyses were performed on siberian weasel,ermine,eurasian river otter,ferrets,eurasian badger,dogs,cats,giant pandas,and humans to obtain single-copy gene families,multi-copy gene families,and species-specific gene families for each species.A total of18,784 gene families were clustered in the nine species,of which 13,514 gene families were common to all species.A total of 12,571 single-copy gene families and 2,607 multicopy gene families were identified in the siberian weasel genome,and 42 gene families(containing 122 genes)were unique to the weasel.Phylogenetic analysis using single-copy orthologous genes revealed that the whole skunk family clustered into a monophyletic group,and the ferret and the siberian weasel clustered into one group,which was consistent with the phylogenetic relationships constructed by previous work based on morphology and mitochondrial genomes.In the present study,the differentiation time between the siberian weasel and the nearest related ferret was about3.08 MYA,which was slightly earlier than previous studies.Gene family expansion and contraction analysis showed that 332 gene families expanded,2,272 gene families contracted,and 767 rapidly evolving gene families(containing 2,832 genes)occurred in the siberian genome.Selection pressure analysis identified 827 positively selected genes from the siberian weasel genome.Subsequently,GO and KEGG functional enrichment was performed on the weasel-specific gene families,the expansion gene families,and the positively selected genes.The enriched signaling pathways were mainly related to lipid metabolism,olfactory receptors,signal transduction,immune response and heat stress response.Genes associated with dental development,sugar and lipid metabolism,circadian rhythms,and immune responses were also found to be positively selected in the siberian weasel genome.These genes may reveal the molecular mechanisms of adaptation in the siberian weasel.In summary,this study completed the sequencing,assembly,and annotation of the siberian weasel genome,and conducted an evolutionary analysis using the siberian weasel genome to conduct a preliminary exploration of functional genes for its environmental adaptations.Genomic resources and annotation information are provided for subsequent population genetic and other comparative genomics studies of the Mustelidae.