Huanglian Oil Gourd And Cloud Spot Gold Cricket Mitochondrial Genome Sequence Determination And Analysis

The Mitochondrial DNA with the properties of high polymorphism,rapid evolutionary rate,maternal inheritance and almost lack of intermolecular genetic recombination,makes it as a good model for research in genome structure,function,transcription and gene expression.Upto now,there were 1212 metazoan species which the mitochondrial genomes had been sequenced,including 870 vertebrates,81 Hexapods,among them five Orthoptera species,Locusta migratoria,Gryllotalpa orientalis,Oxya chinensis,Anabrus simplex,and Ruspolia dubia.In order to study the genome structures and evolutional characters of mitochondrial genome in Orthoptera in-depth and enrich the sequncence database used to reconstruct the phylogenomic relationship Orthoptera or Polyneoptera.In this study,the complete sequences of Teleogryllus emma and Xenorryllus marmoratus mitochonddal genomes were determined using long PCR and conserved primer walking approaches,and annotated according information of Locusta migratoria and Gryllotalpa orientalis mitochondrial genomes.We made comprehensive anlysis by combined two new mtDNA sequences with orther Orthoptera species.The conclusions drawn from the study as follows:1.The complete mitochondrial genomes of Teleogryllus emma and Xenorryllus marmoratus are 15660bp and 15583bp respectively,including 13 protein genes,22 tRNA genes,2 rRNA genes,and an A+T-rich regions which is located between the SrRNA and tRNAIle.The base dispairty in the two mitochondrial genomes arr seriously,as the contents of A+T are 73.1%and 71.8%respectively.2.There are two unusual intergenic regions in the mitochondrial genome of Xenorryllus marmoratus.One is located between tRNA^Gln andtRNA^Met(IR-1),with the length of 94 bp;and the other is located between tRNA^Ser(UCN) and ND1(IR-2),with the length of 99 bp.Among these sequences two tRNA-like structures were found:tRNA^Val-like in IR-1 and tRNA^Leu(cun) in IR-2.These tRNA-like sequences have proper folding structures and regular anticodon sequences,but their functionality in their respective amino acid transfers remained uncertain.3.The most distinct feature of two mtDNA is the tRNA^Glu,tRNA^Ser(AGN) and tRNA^Asn,are located in minor strand,and thus constitutes the third type of mitochondrial gene order in Orthoptera.The gene order of tRNA^Lys and tRNA^Asp is consistent with other Ensifera species.4.The COI gene has an unusual start codon TTA in the mtDNA of Teleogryllus emma and Xenorryllus marmoratus,instead of ATN or NTG.And The TAA and TAG codons are used as stop codons in all the protein coding genes(PCGs) excepting COII and ND5,T as the uncomplete stop codons in the latter genes,which will be completed by the addition of A residues to the mRNAs.5.Most of the tRNAs,except tRNA-Ser(AGN),could form typical second structures,and the anti-codons are consistent with the other Hexapoda.There are more or less dispair,The G-U as an usual dispair is present in the tRNAs of two mtDNAs.6.Properties of genetic code evolution was briefly discussed according the statistic analysis the of codon usage and the A+T contents of tRNAs.7.We determined the replication origins of N-strand in the A+T region of Teleogryllus emma and Xenorryllus marmoratus by Zplotter programme.There is a ubiquitous secondary structure found in the A+T regions of Orthoptera and other orders of Insecta,such as Diptera,Lepidoptera, Hymenoptera,but not in Collembola which is considered as the basal group of Insecta.8.The phylogenotic relationships among 28 Orthoptera species based combined datasets of NADH dehydrogenase subunit genes(ND5,ND4,ND4L,ND1) were reconstructed by Maximum Likelihood method,and the phylogenetic utility of these genes also tested.Acording the phylogenotic analysis,As a basal group,Grylloidea is monophyletic,which is consistent with the conclusion drawed by gene order.