Exploration Evolution Of Vertebrates System And Species Identification For Fish Products Based On Mitochondrial DNA Polymorphisms

China is rich in fish resources,and there are many kinds of fish.Fish are at a lower order in the system evolution of vertebrate,it is difficult to distinguish from their appearance characteristics.In order to effectively carry out the development and utilization of marine fish resources,maximize the economic value and increase the protection of fish sources,it is particularly important to identify the species of fish correctly.Traditionally,morphological methods can hardly distinguish the species for deep processed fish products.There has not yet established an authoritative technical standard for fish products in China so far.The problems of food quality and safety caused by the phenomenon of low-value fish posing as high-value fish and food label confusion in the market have occurred from time to time.This study draws on our research results in molecular biology and bioinformatics to establish a provenance identification system for common fish products in Yantai,and to provide technical support for the quality assurance of fish products.A phylogenetic tree was constructed based on the mitochondrial COI gene and Cytb gene of 46 species vertebrates published on the NCBI,which is used to discuss the status of fish in the process of vertebrate evolution,in order to study the taxonomy and species relationship of fish systems after later.The DNA sequence between the 12 SrRNA and 16 SrRNA genes of fish mitochondria is selected as the target fragment,and the universal amplification primers is designed.10 fish species samples are amplificated with PCR,and the PCR products are sequenced after purification.Then,the sequencing results are enter into NCBI database for similarity search.By comparative analysis of the sequence obtained.The molecular systematic relationships among fish species are explored,and specific primers of each fish species is designed for species-specific PCR amplification.Finally,multiplex PCR amplification is carried out by combining some species-specific primers,and the constructed multiplex PCR amplification system is used to verify the provenance of some common fish products in the market.The results show that,basically,the phylogenetic tree meets the traditional classification criteria,and the fish is in the lower order of evolution of the vertebrate system,which prove that the mitochondrial genome can be used for the study of animal molecular evolution.The method is simple and has important significance in understanding on animal classification and system evolution.At present,there is no relevant research report with the selected target segment.The target fragment has the characteristics of great interspecific variation and relatively conservative within species,and can be used as a molecular marker to identify fish species.According to the sequencing results,the specific primers of each fish species designed is highly specific.At the appropriate annealing temperature,only the target fish species had specific amplification bands.In addition,combined PCR amplification system constructed with specific primers for each species of fish can be used to detect multiple species of fish in one multiplex PCR system,which has simpler and more accurate advantage in species identification.Using the compound PCR amplification system constructed to detect the deep-processed fish meat products,which are commonly found on the Yantai market,reveals some cases that the fish meat products on the market are inconsistent with the labels,it provides technical support for the quality assurance of fish meat products.