Application Of Ribosomal RNA Gene ITS And IGS Regions In The Molecular Identification And Classification Fungi

Application of ribosomal RNA gene ITS and IGS regions in the molecular identification and classification of fungi With the wide ues of the anti-malignant tumor drug , immuno- suppressive drugs and the development of broad-spectrum antibiotic, organ transplanting and other intervenal treatment, and with the spread of the AIDS, fungal infection has become the hidden killer to people health. In the recent years , there has appeared many new behavior of fungal infection, that is the increasing of incidence rate, death rate and to be disalbed. It has become very important that early diagnosis and specifical treatment for fungal infection to save the patient and rise the relive quality. The classification for fungi is a huge system entineering. The traditional fungi taxology depends on the morphological and physio- biochemistry and antigen construct feature. However, since there are so many species of fungi and obvious individual polymorphisms, it will get false results to reflect the entity characteristics of fungi. And it will cause massiness workload, consume long and promiscuous conclusion. In the recent thirty years , with the rapid development of molecular biology , fiingal taxonomy has entered the new era from phenotype to genetype. There are many molecular technology ,such as ftmgi genome DNA GH-C moL%, nucleic acid hybridization , chromosome electrophoresis (EK), ribose type, genome DNA restrict fragment length polymorphism (RFLP), solobilital protein electrophoresis, multi-enzyme elesctrphoresis(MEE) and ribosomal RNA genes sequential analysis. 7 These techonology differences in the resolving power and typing . At present , many fungi classification research workers are turn to find a high grouping , better discrimination, good reproducibility and cheap fungus genetyping instrument. Ribosomal RNA genes analysis is believed to be one of the indicators that could reflect the genetic affinity among species. That is , first ribosomal is the most popular organelle among organism, which has collective inheritance and evolution origin. Therefore ,it can afford a inheritance atlas for all the fungi with a high comparability. Second , the sequences which encode ribosomal RNA is relatively conservational in the evolution. There are large homology between difference fungi, which can be used as the identification target for the distant fungi , such as species ,genus and those above genus . however, many fragment could be used as the basis to the species , variety and strains. In the past ,the emphasis in the ribosomal RNA genes focus on the conservative sequence. By now, there are more and more investigater found that the spacer region has more worth in the fungal taxology. There are two kinds of spacer regions,as ITS and IGS. The main means is to probe hybridzation, PCR, RFLP and sequence analysis. And sequence analysis is believed to be one of the most directness and clear target. The aim of our study is to resolve following problems: (1) the identification of the most ordinary pathogenicitical fungi in the class of genus;(2) identification of important fungi in the species level (e.g. Candida genus);(3) identify Cryptococcus genus in the species variety ,and strains level. (4) the identification of clinical specimen in the species level not culturing.