Study On The Mitochondrial Genome And Genetic Diversity Of Leuciscus Baicalensis From Irtysh River In Sinkiang, China

Leuciscus baicalensis belongs to Cyprinidae Cypriniformes Leuciscus Subclass, Neopterygii, Osteichthyes. In this study, we sequenced the whole mitochondrial genomes of L. baicalensis. We also analyzed genetic variation and relationship of L. baicalensis in different location using mitochondrial DNA D-Loop. The main results were summarized as follows:1. The genome which had a mostly conserved structural organization in comparison with that of other teleost fish was16,606bp in size. It consisted of37genes (13protein-coding genes,22transfer RNA genes, and two ribosomal RNA genes), and two main non-coding regions (the control region and the origin of the light strand replication). All protein-coding genes started with ATG except for COX1, which began with GTG. However, the termination codons of13protein-coding genes varied with TAA, TA, T or TAG. The complete mitochondrial genome sequence provided useful information for phybgenetic analysis and studies of population genetics of L. baicalensis. In addition, we used11protein-coding genes in L. baicalensis to reconstruct the phybgenetic relationship of20species in subfamily of Leuciscinae.2. Mitochondrial DNA control region sequences were used to investigate the genetic diversity and population structure of L. baicalensis from four locations of Sinkiang, China;29polymorphic sites were defined from53distinct hapbtypes. The diversity indices of haplotype (0.973-0.910) and nucleotide (0.00349-0.00434) verified low genetic diversity of the L. baicalensis populations in the four lakes. The analysis of molecular variance and the fixation index (Fst=—0.00858) showed that there were insignificant differences in population genetic structure in different lakes. In addition, neutral tests and analysis of mismatch distribution suggested that L. baicalensis might have undergone a population expansion Neighbor-joining tree indicated that these population genetic differences had a relation with geographic distance. Analysis of molecular variance (AMOVA) revealed that100.86%of the genetic variability occurred within annual temporary samples, and negative value of0.86%came from among temporary samples. This study revealed the extant population genetic diversity and structure of the L. baicalensis and it was conducive to the settlement of fishery management issues involving fishery stock identification, conservation, and artificial breeding.