Study On The Genetic Basis Of Semi-aquatic Adaptation And Fur Domestication In American Min

Neogale vison,also known as the American mink,is the only existing species in the genus of the Neogale of Mustelidae,which is native to North America.Due to its strong adaptability to the environment and the irregular confinement of aquaculture industry,wild populations are now distributed on all continents.The back and abdomen of wild individuals are dark brown,with white spots on the lower lip,and semi-webbed and undercoated feet.It not only has excellent tree climbing ability,but also has superb swimming skills,so its habitat is often distributed along the waterways in the forest.In previous studies,it was pointed out that the fur characteristics,eye structure and foot shape of the American mink evolved to adapt to the semi-aquatic ability,but the molecular basis of the external characteristics and the genomic characteristics of the internal physiological changes have not been reported.At the same time,the American mink is one of the main fur-breeding animals in the world,with its long and dense wool,thick needle hair and diversified fur color variation.Adaptation and domestication of species are a hot topic in the study of life evolution,and the American mink is an excellent animal model for the study of adaptation and domestication of species.Therefore,this paper discusses the semi-aquatic adaptation traits,the domestication traits of fur development and the domestication traits of coat color formation in American mink from the genome level,transcriptome level and population resequencing level,in order to reveal molecular mechanism of semi-aquatic adaptation and fur development and coat color of American mink.The main results obtained in this study are as follows:1.The genomic basis of semi-aquatic adaptation of American mink was preliminarily revealed by comparative genomics.Based on the comparative genomic analysis of 14 species,the number of single-copy genes in the American mink genome was 13,389.Compared with the four Mustelidae genomes selected in this paper,the American mink has 133 specific gene families,including 397 genes.Functional enrichment analysis showed that these specific genes were related to coagulation,nitrogen metabolism and immunity.Gene family expansion and contraction analysis showed that the expansion gene family was related to nitrogen metabolism,energy metabolism,immunity,coagulation and neuropeptide activity,while the contraction gene family was related to olfaction and bone development,which may help the American mink with high energy consumption in water and sensitive predation.A total of 2315 positive selection genes were selected by using Canidaes and Mustelidaes as background branches and semi-aquatic American mink as foreground branches.Functional analysis showed that positive selection genes were related to nitrogen metabolism,lipid metabolism,muscle development and individual activity.The findings of this chapter may be related to the specialized physical characteristics and physiology of the American mink adapted to semi-aquatic life.2.Based on comparative transcriptomic analysis,the genetic basis of fur development in American mink was investigated.A comparative analysis of the skin transcriptome during fur development and maturation in American minks revealed a total of 80.71Gb of clean bases obtained from 12 transcriptome samples.The ratio of sample comparisons to reference genomes was greater than 94.69%,and 1,943 new genes were identified.The results of inter-sample correlation analysis demonstrated the rationality of grouping.The gene expression distribution and principal component analysis showed that the skin gene expression levels of American minks of the same age were similar.Analysis of gene differential expression between groups showed that 2794 up-regulated genes and 2895 down-regulated genes were obtained in the black comparison group.The white comparison group obtained 2,979 up-regulated genes and 3,474 down-regulated genes.By combining the functional enrichment results of the two groups of differentially expressed genes,13 keratin associated protein genes were enriched in the keratin fiber items related to fur development.And five developmental metabolic pathways(sticky spot signaling pathway,Ras signaling pathway,regulating stem cell pluripotency signaling pathway,ECM-receptor interaction signaling pathway and JAK-STAT signaling pathway)are significantly enriched.Further screening of differentially expressed genes between adult and juvenile groups revealed that the number of keratin and keratin associated protein genes related to fur development was 34 and 22,and both were up-regulated genes in the skin of juvenile American minks.The high expression of these key genes may play an important role in the composition of the hair characteristics of American minks,and five enriched metabolic pathways may play a role in the regulation of hair follicle cycle in American minks.Finally,the transcriptome analysis results were verified by qPCR experiment,and the results were in line with expectations.The results of this study not only elucidate the changes in the expression of key genes during the development of American mink fur,but also discover the related metabolic pathways.3.In this paper,comparative transcriptomics and genome resequencing were used to reveal the genetic basis of hair color formation in American mink.Firstly,skin transcriptome data of adult and juvenile black and white minks were used to analyze the differences in gene expression levels in the skin of different hair color minks of the same age.It was found that there were 257 differentially expressed genes in the juvenile comparison group,116 differentially expressed genes in the adult comparison group,and 4 differentially expressed genes shared by the two age comparison groups.Functional enrichment analysis of differentially expressed genes revealed that significantly enriched tyrosine metabolic pathways were associated with hair melanin synthesis,including TYR and TYRP2 genes,which were up-regulated in juvenile black minks.Further analysis of the genes related to hair color revealed that the expression of ASIP gene,which plays an antagonistic role in melanin synthesis,was up-regulated in juvenile white minks.In conclusion,the difference in hair color between black and white minks may be caused by the different expression levels of tyrosinase gene family and ASIP gene.In order to clearly understand the formation mechanism of the two kinds of hair color,591 and 388 strongly selected genes were found in the black and white mink populations by using the genome resequencing data and the selection elimination analysis method,and 8 and 15 hair color genes were obtained after screening,respectively.According to the interaction between ASIP and MITF gene and the phenotypic characteristics of MITF gene mutation,the hair color forming gene of short-haired black mink was identified as MITF gene by comparing the gene expression levels in transcriptome analysis.According to the distribution characteristics of Fst value in the genomic region and the expression levels of TYRP1 gene in different populations,the hair color forming genes of red-eyed mink were identified as TYR and TYRP1 genes.In conclusion,the genetic characteristics of semi-aquatic adaptation and fur development domestication of American mink were revealed by using the multi-omics method in this paper,and the molecular evidence of semi-aquatic adaptation evolution was found.The genetic basis of fur development and color formation of American mink was determined,which provided scientific basis for its protection and utilization.