Preliminary Study On Germplasm Resource And Inherited Character Of Yellowtail Kingfish(Seriola Aureovittata)

Yellowtail kingfish,Seriola aureovittata,is a globally distributed marine pelagic fish species,and is of great economic importance all over the world.Many countries including China has launched the artificial culture of this species due to its fast growth,nutritional value and market value.The biological characteristics are basic knowledge for aquaculture biology and especially for taxonomy and evolutionary ecology.To understand the biological characteristics of S.aureovittata,both external morphological traits and internal anatomy were investigated by using traditional,morphometric,anatomical and statistical measurement methods.The truss network of S.aureovittata was constructed by computer simulation.The morphology of otolith and scale was described.Calculating the ratios between morphological traits,suggested the ratios of total length?TL?/soma length?SL?,lower jaw length?LJL?/upper jaw length?UJL?,peduncle length?PL?/peduncle distance?PD?were closely correlated.The mathematical correlation models between TL,body height?BH?and body weight?BW?were calculated with the formulas:BW=BW=4.133TL^0.345,R²=0.9735 and BW=1.2504BH^0.3155,R²=0.9824.The correlation analysis showed that 11 morphological traits were significantly correlated except for the eye diameter?ED?.The internal structure was also described,and the vertebra number was 24.Furthermore,total meat yield could achieve 75%of BW.Our results provided the morphometric tools for species identification,systematic taxonomy,breeding and aquaculture production of S.aureovittata.Karyological study is a useful tool in exploring evolutionary mechanisms of fish because it provided basic information on the number,size and morphology of chromosomes.In this study we characterized the karyotype and chromosomal characteristics of the yellowtail kingfish Seriola aureovittata by examining metaphase spreads from head kidney cells of one-year-old fish artificially bred from wild broodstock in the Dalian coast of China.Chromosome samples were prepared through in vivo injection of phytohemagglutinin?PHA?,olchicine-air drying technique,and Giemsa staining.A total of 80 mitotic metaphases from 21 individuals were analyzed,and 65 spreads showed 2n=48 chromosomes,which represented 78%of the observed metaphases.The size of the chromosomes in this subspecies varied from 2.50±0.23 to5.16±0.56?m.The long arm,short arm,and total length of the first submetacentric chromosomes were 1.81±0.090,0.87±0.028,and 2.68±0.089?m respectively.Two pairs of subtelocentric chromosomes were found in this subspecies.The length of their short arms was 0.55±0.042 and 0.39±0.057?m,and that of the long arms was 2.10±0.057 and1.87±0.074?m.The diploid consisted of 4 submetacentric,6 subtelocentric,and 38telocentric chromosomes,and the fundamental number of chromosome arms was 54.The first pair of chromosomes had secondary constriction and satellite.The karyotype formula for this species was determined to be 2n=48=6sm+4st+38t.The total haploid chromosome length was approximately 51.97?m.The fact that S.aureovittata has 3pairs of submetacentric and 2 pairs of subtelocentric chromosomes distinguishes this species from other previously reported Seriola species.The comparison of karyotypes suggested that S.aureovittata might belong to an advanced and specific evolutionary group.Our study promoted the understanding of the specific karyotype evolution of the genus Seriola,and provided information on the polyploidy manipulation,hybridization,and sex control.In this study,we injected phytohemagglutinin?PHA?and colchicine and collected all the head kidney cells of Seriola aureovittata.The characteristics of the C-banding,G-banding and Ag-NORs bands were analyzed by hypotonic treating,dripping on cold slides in air-drying and Giemsa staining.Results show that?1?The C-bands of S.aureovittata were located mainly in the centromere regions of chromosomes.The 2nd,4th,5th,16th,18th and 19th pairs of chromosomes show positive C-banding in the terminal region.However,chromosome doer not show entire positive C-band.?2?The Ag-NORs polymorphisms were specific in this fish.The silver staining pots were 1-2.The number of Ag-NORs was mainly 1.A pair of nucleolar organizer regions was found on the 5th pair of chromosomes in the terminal region.?3?The G-banding has different amounts of darkly stained band and lightly stained band in each chromosome.Moreover,the G-banding contains 118 bands including 70 darkly stained bands and 48 lightly stained bands.These results would provide basic data for the biodiversity conservation of S.aureovittata.