Otolith Morphological Study And Analysis Of The Mitochondrial Genome Of Chinese And Japanese Dotted Gizzard Shad (Konosirus Punctatus)

In this study, the otolith morphological comparison and analysis of mtDNAgenome of dotted gizzard shad (Konosirus punctatus) from China and Japan wereconducted, the phylogenetic relationship among seven species of Dorosomatinae andtheir relatives was also discussed, meanwhile, genetic differentiation of eightpopulations of K. punctatus was analyzed. This study will provide primarily scientificevidence for marine fishes otolith research, and will enrich the mt genome database ofworld fishes, finally will provide useful information on the fisheries management andgenetics diversity protection of K. punctatus.Otolith morphological parameters obtained by Shape index method and Fouriermethod were analysed respectively among eight populations of K. punctatus. Ourstudy showed the geographical variances between Chinese populations were small,whereas there was a certain difference between Chinese and Japanese populations,which was an evidence of divergence between dotted gizzard shads from Chinese andJapanese coastal areas.Using37pairs of primers, we dermined the mitochondrial genome of dottedgizzard shad from China and Japan, in which process long PCR and regular PCRtechnologies were employed. The mitogenome lengths of dotted gizzard shad fromChina and Japan are16697bp and16698bp, respectively. The two completesequences share the similar strcture with the published mt genomes of vertebrate, bothcontain22transfer RNAs, two ribosomal RNAs,13protein coding genes andnoncoding region, whose arrangements follow the universial pattern in most fishes.The nucleotide composition shows a nucleotide bias against GC and especially in thesecond site of codons in protein coding genes in both sequences. Only two kinds ofrestriction enzymes exists different effects on fragments in the two mt-genomes. As inother fishes, all the mitochondrial protein coding genes take ATG as start codons except COâ…  which starts with GTG. The usage of teiminal codons showed the samepattern between Chinese and Japanese individuals. The Chinese individual exists thesame lengths in the two rRNA with Japanese individual. The origin of light strandreplication can form the steady secondary structure in the two sequences. Thetermination associated sequences (TAS), central conserved domains (CDs, namely,CSB-F, CSB-E, CSB-D, CSB-C, CSB-B), and conserved sequence blocks (CSBs,such as CSB-2, CSB-3) are identified in both genomes.Concatenated protein-coding genes, concatenated tRNAs genes, concatenatedrRNAs genes and control region were used respectively to construct phylogenetictrees of seven species of Dorosomatinae and their relatives. The results showed dottedgizzard shad has a relatively closer relationship with genus Dorosoma compared withNematalosa using concatenated protein-coding genes, concatenated rRNAs genes andconcatenated whole mt-genomes, whereas, using the other two genes we got theopposite relationship.Through analyzing the complete sequences of control region (1055bp) andcytochrome b (Cyt b) without tenimate codon thymine (1140bp) of eight populationsof dotted gizzard shads, high haplotype diversity (h) and low nucleotide diversity (Ï€)pattern were found. Genetic structure analysis showed larger genetic distance betweenChinese populations and Japanese populations, the source of variation were mainlyamong groups as demonstrated by AMOVA results, those results suggested a certaindifferentiation may exsit between Chinese populations and Japanese populationswhich were congruent with the results of otolith morphological analysis. Chinesepopulations may undergo potential dispersal revealed by neutrality test and mismatchdistribution analysis.