Species Identification Analysis On Channidae And Genetic Structure Of Channa Maculata

The Channidae belongs to Perciformes fish,is called snakeheads because of its snake like heads.It is mainly distributed in Asia and Africa.The flesh has no intermuscular bone and contains calcium,phosphorus,iron,zinc and other nutrients that required by human to keep healthy.It also has the functions of removing stasis and regenerating blood,promoting wound healing.It is an important aquatic product,with total output around 500 000 tons per year.Now,the breeding faces some problems such as seed quality,inbreeding,and germplasm parasitism.It is necessary to make a sustainable project to promote the quality of breeding stocks.And the first step is to clear the genetic background of parents resorces.In this study,the DNA barcoding sequence gene COⅠ was used to analyze the diversity among Channidae,and attempt to identifying taxonomy;the wild Channa maculata population was collected,and high-throughput sequencing was used for the development of microsatellite markers,in which the polymorphic loci were used for genetic analysis;fluorescence in situ hybridization was used to localize the 18S rDNA of the Channa maculata,and to distinguish the different chromosomes of the Channa maculata.It will provide the basis for the conservation management and rational utilization of germplasm resources of th.1. Phylogenetic and species identification analysis on the snakeheads(Channidae)based on the DNA barcoding sequenceIn this study,the mitochondrial COⅠ(cytochrome oxidase subunit I)gene fragments of 576bp were used to analyze the phylogenetic and diversity of snakeheads in and out of China,to probe the properbility of COⅠ gene as barcoding sequence for speices identification.149 specimens of different geographic populations of C.argus,C.maculata,C.asiatica and C.gachua native to China and 122 sequences downloaded from Gen Bank of others species,totally 271 snakehead individuals of 25 species,were analyzed.Of all the sequences,no Insert-Deletion site exixts.The average base content of A+T(51.4%)was higher than G+C(48.6%).The average intraspecies genetic distance was 0.028,but reached 0.137 in C.barca which was higher than some interspecies distances.The interspecies distances ranged from 0.030 to 0.302,with average of 0.217.The largest distance exists between the C.ornatipinnis and C.melasoma,exceeding some distances to outgroup.Phylogenetic trees based on Neighbour-Joining and Maximum Likelihood method were calculated.Most individuals from the same species formed a monophyly and obtained high bootstrapvalue,except in several species.But,the relationships of species have low bootstrapvalues,indicating inproper for phylogenetic analysis of COⅠ gene for snakeheads.Furtherly,a C.barca compound and a C.gachua compound formed according to phylogenetic trees.The results of this research indicating that the COⅠ gene is proper for the species identification of native species of snakeheads in China,but more information is needed for the imported ornamental snakeheads.2. Characterization of micorsatellites and genetic structure of wild Channa maculataIn this study,the patterns of microsatellite markers in the genome of C.maculata,developed twenty polymorphic loci to analyze the genetic diversity and genetic structure of six wild populations named Guangzhou,Huazhou,Jianghua,Nanning,Yangjiang and Shaowu population were analyzed.The results showed that the number of alleles(N_a) of the six wild populations is 3-28,the number of effective alleles(N_e)is1.28-14.88,and the observed heterozygosity(H_o)is 0.10-1.00,the expected heterozygosity(H_e)is 0.14-0.95 and the polymorphic information content(PIC) is 0.13-0.95.The UPGAM dendrogram indicated that the genetic relationship between Huazhou and Fujian populations is the closest,but there is the farthest genetic relationship between Huazhou and Jianghua populations.The results of this study would provide basis for the conservation and management of germplasm resources for C.maculata.3. The amplification and FISH analysis of 18S rDNA in Channa maculataIn this present,18S rDNA was amplified by 18S rDNA primers in Genomic of Channa maculata.Phylogenetic tree of 18S rDNA in C.maculata and 19 vertebrates else was constructed by MEGA5.1,so evolution positioa of C.maculata in vertebrates was preliminarily.At the same time,using the methon of Fluorescence in situ hybridization(FISH),18S rDNA were located in C.maculata.The results showed that the amplified 18S rDNA sequence of this study was 945 bp,and the sequence similarity to Oreochromis niloticus was 99.24%,followed by Maylandia zebra,99.13%.The phylogenetic tree showed that the species of the same order and the same class first gathered into one branch,and the grouper was closely related to the O.niloticus and M.zebra.FISH results showed that the karyotype formula of the cantharidophora was 2n=4m+2 sm+18 st+18 t,and the 18S rDNA was located on the 4th chromosome.This study provides reference materials for clarifying the phylogenetic positional relationship of C.maculata in vertebrates,enriches the cytogenetics of C.maculata,and the resulte would be useful to assist identifying the chromosome of C.maculata.