3号染色体短臂末端两个大片段基因组区域的基因分布与GC含量分析

运用鸟枪法测序技术，得到了位于3p25．1和3p26．1区域、大小分别为328kb和753kb的2个基因组片段，分析各片段的GC含量及重复顺序的分布特征，并研究不同区域内的基因分布密度。结果表明：位于3025．1区域的328kb片段具有较高的GC含量，在此区域内蛋白编码基因分布密度较高，而位于3p26．1区域的753kb片段平均GC含量较低，并且是基因贫乏区域。同时发现：GC—rich的SINE类重复顺序在GC含量较高的区域有较高的覆盖率，相反AT-rich的LINE类重复顺序在GC较低的区域分布较多，基因分布与基因组这一关系的形成是基因与基因组长期共进化的结果。

Comparing Gene Density and GC Content Between Two Large Genomic Blocks at Short Arm of Chromosome 3

The present paper is to investigate gene distribution at different genomic region with different local GC content.With shout-gun technology,we sequencing two sequences at 3p25.1 and 3p26.1,at genome size 328 kb and 753 kb respectively.The 328 kb sequence,with an average GC content as high as 47.57%,has high gene density (13.7 gene/100 kb).However,another sequence at 3p26.1 only includes one exon and one intron of large gene GRM7 and the coding sequence size is 11 520 bp only taking a small part(1.31%) of the whole genome region.High percentage distribution of GC-rich repeats of SINEs explain high GC genomic region at 3p25.1 and high concentration of AT-rich repeats of LINEs at 3p26.1 lead to low GC content of the region.Our results suggest isochore structure is the result of coevolution between gene and genome.