Study On Mitochondrial Dna Gene Diversity Of Lucilia Srticata And Its Prediction In Forensic Death Site

Objective:The aim of this study was to sequence the mitochondrial genes of Lucilia sericata in China and to fill in the information gaps in this area,and to explore the effect of geographical isolation on the genetic diversity of the mitochondrial genes of Lucilia sericata,and explore its application in the speculation of forensic death sites.Methods:Using PCR amplification and first-generation sequencing,mitochondrial DNA extraction and partial gene sequencing were performed on populations of Lucilia sericata collected from different parts of China.Trying to find the genetic information related to the regional differences,the genetic diversity of the mitochondrial DNA and the genetic structure of the population were analyzed and then applied to forensic medicine.Nucleotide composition analysis,phylogenetic analysis,genetic distance analysis and SNP locus statistics with regional characteristics were performed using MEGA 6.0,cluster analysis was performed using Primer5,and genetic differentiation was performed using WinArl35 software.DNAsp 5.0 was used to analyze the genetic diversity of each gene and region and the haplotypes with regional characteristics,Network was used for haplotype structure analysis,and SPSS was used for data rearrangement.Results:This experiment sequenced the mitochondrial DNA of 55 L.sericata samples from 11 regions in 9 provinces of China,The sequencing length is 6889 bp.The sequencing part includes 7 genes and 14 tRNA.The average content of samples in the 11 regions was 36.49(A),38.11(T),14.17(C),and 11.21(G),with higher AT bias.The initiation,codon of protein coding region is ATG except that COX1 is TCG,and the stop codon of COX1,COX2,ND5 coding region is 3'A residue,and the others are TAA.The overall nucleotide polymorphism(Pi)was 0.191%.The number of polymorphic sites(S)was 150,the haplotype diversity(Hd)was 0.995,and the two genes with the largest average genetic distance were COX3 and ND5,and the ATP8 gene is the most conserved.In terms of regions,the nucleotide diversity of Yancheng and Haikou are the highest,being 0.00351 and 0.00270,respectively,and the lowest in Pingliang,Tajima's D test and Fu's Fs test show that mutations in most areas are greatly affected by environmental factors.The cluster analysis results showed that 55 samples were divided into 2 categories,representing 2 subspecies.Phylogenetic analysis showed that the 11 regions were in a parallel evolutionary relationship,and there was no evolution in the sequence.The population genetic differentiation coefficient(Fst)was 0.13500 in 11 populations,of which 22 groups were statistically significant.Haplotype analysis revealed a total of 50 haplotypes,10 private haplotypes with regional characteristics were found in the COX3 gene,which can be used as the identification of 8 regions.A total of 14 parsimony-informative sites with regional characteristics were found in multiple sequence alignments,which can be used for the identification of 6 regions.Conclusion:Geographical segregation has an influence on the genetic diversity of the mitochondrial genes of L.sericata in China,and this effect may be helpful to the prediction of the location of death in forensic medicine.