Clone And Sequence Analysis Of Important Genes In Sitobium Avenae Under The Ultraviolet Induction

As a result of environmental pollution, the gradual thinning of the ozone layer, resulting in a large number of ultraviolet radiation to the surface, tested and proven to reduce ozone in the atmosphere for every 1%, exposure to UV on the Earth's surface increased by 2%, an excessive amount of ultraviolet light to enter the biosphere, it is bound to the biological heredity and variation of the choice of strong pressure.Aphids are a class of important agricultural pests,small,quick reproduction and parthenogenesis. For survival and reproduction,aphids must have a corresponding mechanism for the genetic evolution and resistance to cope with environmental change.In this study, we make S.avenae's as experimental materials .In order to confirming the results of early study and show the theory of ecological genetics under the ultraviolet induction.According to the conserved regions of other known insects, a pair of specific primers were designed and the RT-PCR method was used to amplify the partial sequences of some important genes from S.avenae .Analyze the sequences and derive the amino acid residues. The purpose of this research is to making clear the mutation style and specific mutant sites on some important genes, revealing genetic and evolutional mechanism of which were under ultraviolet induction in the essence of life. The results are as follows.1. The mutation frequency of genes is related to the intensity of UV radiation The results show than in aphids which were under the UV induction for 12h has no significant difference. But the electrophoresis patterns of cDNA fragment of SOD genes and cytochrome b gene have significant difference between the aphids which were inducted by UV for 24h,48h and the contrast ones. The results display that the nucleotide sequence of cytochrome b gene in ones which were under ultraviolet induction for 48h have three mutant sites different from contrast ones. So we can say the aphids'genes could have mutations until the UV radiation reaching specific strength.2. Cytochrome b gene has made mutations under the UV induction Sequencing results show that the cDNA fragment of cytochrome b gene was 420bp in size. The results display that the nucleotide sequence of cytochrome b gene in ones which were under ultraviolet induction 30w-48h have three mutant sites different from contrast ones. The mode of mutation is gene conversion or transversion, and has no base insertion and base deletion. The mutation frequency is about 1%. The sequence analysis of DNA shows that the content of A+T is 79%. It is obviously superior to that of G+C, and it's also obviously superior to that of usual insects. This result shows that the stability of DNA of cytochrome b is lower, that is to say the DNA easily makes mutations. The base substitutions mainly occurred at the second site of codon, 66.7% of the total mutations. This result accords with the evolution regulation of mtDNA.3. Sequencing results show that the cDNA fragment of cytochrome b gene encoded 140 amino acid residues, and make 2 mutant sites on acid residues. The mutation frequency is about 1.4%, and it's lagged far higher than that in nature.4. SOD gene has made no mutations under the UV inductionThe electrophoresis pattern of cDNA fragment of SOD genes has significant difference between the aphids which were inducted by UV for 48h and the contrast ones. The results display the cDNA fragment of SOD gene was 357bp in size and it encoded 119 amino acid residues. The nucleotide sequences of SOD gene are the same between UV- induction ones and contrast ones. The sequence analysis of DNA shows that the content of A+T is 48%. The stability is obviously higher than that of cytochrome b. Therefore, it is very hard to have mutations.5. HSP70 gene and CarE gene have made no mutations under the UV inductionThe results show that the electrophoresis detections of HSP70 gene and CarE gene in aphids which were under the UV induction for 12h,24h,48h all have no significant difference. There was no specific electrophoresis strips. That is to say, the strength of the UV radiation which was designed in this research can't induce mutation in these two genes. The sequence analysis of DNA shows that the content of A+T is 55%. The stability is obviously higher than that of cytochrome b. Therefore, it is very hard to have mutations.In conclusion, some specific mutant sites on some important genes which participate in intimidation and metabolism of S. avenae which were under ultraviolet induction have been found. We have found out the mode of mutation, providing theoretical basis for deep research on genetics and evolutionary mechanism of aphids which were under the UV induction...