The Sequencing And Polymorphism Analysis Of Complete Mitochondrial Genome Of Romanomermis Wuchangensis And Ovomermis Sinensis

The entomogenous nematode is a kind of valuable resource in biological control, and has very important value in the research of insect comprehensive management, environmental protection,and the realization of diversified farmland creature.The mitochondria is a main cellular organelle for oxidative phosphorylation of the most eukaryote.The mitochondrial genome is a double stranded extranuclear genetic element,and has the same genetic characteristics,such as abundant content,smaller molecular weight,rapid evolution velocity,conservative structural genes,et cetera.So, it is widely used as a molecular marker in the fields of systematic evolution, categorization,developmental biology,mutation and disases reaserch.Currently,the study of this field basically focuses on the mitochondrial complete genome of six species of Mermithidae(Hexamermis agrotis,Agamermis sp.BH-2006, Romanomermis culicivorax,R.iyengari,R.nielseni and Thaumamermis cosgrovei) abroad,whereas the domestic research is still at the beginning.In order to unveil the study of Mermithidae mitochondrial complete genome in all directions,our laboratory firstly carried out the research on the mitochondrial genome of Mermithidae in domestic.A developed method on the study of mitochondrial complete genome is established by combining the rolling circle amplification and Long-PCR.And we identified the sequences of mitochondrial genomes of Romanomermis wuchangensis and Ovomermis sinensis.What's more,we studied the polymorphism of O.sinensis. By contrasted with 6 other species of Mermithidae,we summarized the characteristics of the mitochondrial genome in Mermithidae.All the details are displayed in the following.1,The figure of agarose gel electrophoresis shows that the mitochondrial genome of R.wuchangensis is permanent in length.Then,we identified the sequence of mitochondrial genome of R.wuchangensis by two-step Long-PCR amplification and sequencing.The result shows that the mitochondrial genome of R.wuchangensis is 14832 base pairs.It contains 37 genes(12 protein-coding genes,2 ribosomal RNA and 23 transfer RNA) and a putative control region,a sequence of AT-rich. 2,The figure of agarose gel electrophoresis shows that the mitochondrial genome of O.sinensis exists the phenomenon of polymorphism,ranging from16.5 to 24.5kb in length.Then,we identified the sequence of mitochondrial genome of O.sinensis by four-step Long-PCR amplification and sequericing.The result shows that the mitochondrial genome of O.sinensis is 16777 base pairs.It contains 35 genes(13 protein-coding genes,2 ribosomal RNA and 20 transfer RNA) and a putative control region,a sequence of AT-rich.3,Contrasted with 2 mitochondrial genomes of O.sinensis,we studied the cause of polymorphism in O.sinensis.The variable part which has the different gene order and phenomenon of gene duplication is the main origin.We explained the phenomenon with the duplication-random loss model and mitochondrial DNA recombination. Duplication,coupled with intra-or intermolecular recombination,would be a plausible and parsimonious explanation for the complicated structure of the bypervariable region in O.sinensis mtDNA.4,Contrasted with 6 other species of Mermithidae,we summarized the characteristics of the mitochondrial genome in Mermithidae.The first,gene orders of mitochondrial genome in Mermithidae are different;the second,it exists the phenomenon of gene duplicastion and the frequency varies between species;the third, the sizes of complete mitochondrial genome are different.By adopting the improved combination method of rolling circle amplification and Long-PCR,we obtained the complete sequences of mitochondrial genomes of R. wuchangensis and O.sinensis.This research can provide resources for study of mitochondrial genomes and systematic reseach of Mermithidae nematodes.