外显子与内含子序列分维的双碱基研究

RESEARCH OF TWO-BASE FRACTAL DIMENSION OF EXON AND INTRON SEQUENCES

引入碱基间的关联,研究了外显子和内含子序列以双碱基为单位的分维.我们发现在这种情况下,外显子和内含子序列在短程和中程(称Geometrical range及Main range)存在自相似性并分别定义了这两个区域的分维(D_g和D_m).结果表明,短程的分维值D_g一般比中程的D_m大.外显子的两个分维值比内含子大.我们改变双联体的位相而分维却不变,这反映出在双联体基础上,外显子的不规则性大于内含子,短程的不规则性大于中程,外显子和内含子序列对以2为周期的结构没有位相的特异性.

The fractal dimension of exon and intron sequences based on two - base were studied. taking into consideration the correlation between bases. Self-similarity was found to exist in the geometrical range and main range of a nucleotide sequence. Fractal dimensions of these two ranges ( Dg and Dm) were obtainned for different phases of the two-base units and found to be unaffected by this difference. Further investigation of Dg and Dm reveals that the nucleotide sequences are more uneven in short range and exons are more irregular than introns.