| 英文摘要 |
Simple sequence repeat (SSR) DNA and single nucleotide polymorphisms(SNPs) plays an important role in animal environmental adaptation by directly or indirectly affecting the gene regulation. These DNA markers have been suggested in marker assist breeding and strain identification schemes. This project included two parts. The first part was to clone IGFⅠ 5’ untranslated regions from different species of tilapia. We found the fast growing nilotica tilapia only had a 230 bp length 5’UTR. Oreochromis aureus had two types of 5’ UTR. One had the same length as that of the fast growing tilapia. The other had a length of about 190 bp. In contrast, Oreochromis spilurus had five types of 5’ UTR with a length ranging from 110 to 230 bp. Whether the length of 5’ UTR will affect the stability of mRNA or transcription of IGFⅠwill be investigated in the future. In the second part of the project, magnetic separation was used to establish SSR DNA database of tilapia to search the DNA polymorphism and possible location in coding region. Twenty-one clones with amino acid repeat motif and an expect value smaller than E-05 were checked in coding region identification by polymerase chain reaction. No direct SSR was found in this region, which might be due to the few sample size, differential tissue distribution and/or strong DNA secondary structure of SSR in nature. |