Research Of Exon-Intron Structures In The DNA Sequences

In the history of genes?evolution, a huge change has taken place in the evolution of exon-intron structures. And the problem of origin and evolution of intron and the role of exon-shuffling have been the subject of debate in the biological circle. Two alternative theories, the introns-early theory(IE) and the introns-late theory(IL), dabate the presence or absence of intron, and both have focused on the positions of introns with respect to protein and gene structures. At the same time, there are some results in the exon-intron structures of gene. Since the human genome project was begun in Oct.1990, up to now, research into new methods to identify genes in anonymous g~iomic sequences has been going on for more than ten years. Over this period of time, the field has evolved from finding individual exons to predicting complete gene structures and from the designing of programs to identify protein coding region in compact mitochondrial or bacterial to the challenge of predicting the detailed organization of multi-exon vertebrate genes. The best program currently available perfectly locates more than 80% of the internal coding exons, and only 5% of the predictions do not overlap a real exon. The filly automamted annotation of megabase-long anonymous genomic sequences is the next big challenge in bioinformatics. This review presents a comprehensive study of problems about gene抯 concept, origin and evolution and so on, of methods, and programs of gene identification in details and their recent development, and of introduction some methods in details. And the performances that some program have exacuted in the genbank have been listed and talked. Finally, hene present open problems and future directions of development. And the AT- contents of exon will be presented in the experiments.