Codon Preliminary Study Of The Point Feature And Histone Gene Evolution Dynamics

By using the method of bioinformatics, we analyzed the distributing of 187511 CDS' codon bases from 20 species and different organisms' histone genes H2A and H2B. These data are all from GenBank, KEGG and DW DateBase.The results are as follows:1. Within the 20 species, one codon content in each codon position has the obvious positive correlation with the codon's whole content. The effect of codon content in 3rd codon position shows much grater than the other positions. This phenomenon plays a part in the stabilization of protein evolution.2. In usage of codons, the frequency of T in 2nd codon position is much higher than in 1st codon position; on the contrary, the frequency of C in 2nd codon position is much lower than in 1st codon position. The character of amino acid coding by the base in this position plays an important part in this conclusion.3. The discrepancy between T2/T1 values of the same gene and those of the genomes are different in different species. The reason maybe is that: with the evolution of the organism from the lower species to the higher species, the content of non-keeping genes is much more than before.4. Within the animals' H2A and H2B, the GC% and GC3% has the obvious positive correlation with thire expression efficiency. On the contrary, fungi show the negative correlation and plants show no correlation. Fungi, plants and animals' H2A, H2B genes have gone through different selection pression in of synonymous codons' usage; fungi H2A, H2B genes' positive selection is translation efficiency while animals' positive selection is translation stability. Otherwise plants choose the balance between translation efficiency and translation stability.5. Fungi, plants and animals H2A, H2B genes' p_S and p_N behaviors both within and between species are quite different, with plants and animals H2A, H2B genes' showing p_S>>p_N, fungi H2A and H2B genes' showing p_S≈p_N, yeasts H2A and H2B showing p_N>>p_S. So they may follow different evolution models, with plants and animals' H2A, H2B genes following the birth-and-death model, fungi's H2A, H2B genes following the between birth-and-death model and concerted evolution model, and yeasts' H2A and H2B genes following the concerted evolution model.