Research On Disease Gene Preference Based On Quasi-amino Acid Coding Method

Disease genes play an important role in the development of drugs and in the structure,function of living organisms.Scientists recognize the important role of codon bias in the study of gene expression.By studying the codon preference of different species,it was found that the codon usage of different species is not the same and there is a clear preference.In the same species,there are significant differences in the codon usage bias of genes with different functions.Prof.Zhu Ping proposed quasi amino acid coding method to study 78 human genes using amino acid coding methods,and it would be of great significance to use the quasi amino acid coding method to study disease gene preference.This thesis takes the disease gene as the research object,applies the quasi-amino acid coding method to study the disease gene’s preference,and analyzes the codons according to the Euclidean distance to get the preference result.The main work of this dissertation is as follows:(1)In Chapter 2,the Codon Adaptation Index(CAI)is an important indicator reflecting codon bias.Due to the diversity of species,indicators of study codon preferences have emerged.Therefore,this chapter proposes the quasi-codon adaptation index(Q-CAI)according to the quasi-amino acid coding method.First,through the CAI model method,the experimental results show that the codons have a preference.Second,using the Q-CAI method proposed in this chapter,the experimental data is higher than the CAI calculation value,and more effectively to evaluate codon preferences.It shows that the Q-CAI method is more superior than the CAI method,and it is an effective method for measuring the bias of codons.It has important reference significance for the study of gene mutation in species.(2)The third chapter studies hemagglutinin genes under the quasi amino acid coding method.Hemagglutinin is the main cause of avian influenza virus mutation.The analysis of codon bias and genetic relationship of hemagglutinin gene provides a theoyl for the prevention of influenza virus and vaccine development.The hemagglutinin sequence of 70 influenza viruses was selected and the base composition was analyzed.Using spss software and neutral plot analysis,it was found that the virus sequence was greatly affected by natural selection.According to the RSCU(relative synonymous codon usage)and QRSCU(quasi relative synonymous codon usage)values,the hemagglutinin sequences of 70 influenza viruses were systematically clustered.From the two clustering results,it was analyzed that H7N2 and H7N3 clustered together,H2N2 and H2N9 clustered,and H7N1 and H7N9.The clustering shows that these hemagglutinin genes are closely related.This plays an important role in studying the evolution of influenza hemagglutinin and provides important reference data for studying influenza vaccines.(3)The fourth chapter applies the theory of codon preference theory to further study the preference of p53 family.We mainly use the p53 family gene coding sequence and amino acids as the research object,using the Markov model’s transition probability matrix to analyze the preference of p53 family bases,and then use the concept of state space merger mapping to classify the amino acid linkages,the p53 family amino acid linkage preference was studied.Finally,we analyzed the preference of the third base linkage.