The P. Haitanensis Filamentous Sporophyte Access To Est, Bioinformatics Analysis And Functional Gene Was Cloned And Sequenced

RNA of filamentous sporophyte of Porphyra haitanensis was extracted by improved one step method and cDNA library of filamentous sporophyte of P. haitanensis was constructed. 2.5×105 primitive clones were gained. 1280 ESTs were sequenced and jointed into 490 sequences after removing the low quality sequences and vector sequences. Each sequence from the 490 non-redundant EST species was subjected to similarity search against the NCBI-provided non-redundant protein database, nr, using the blastx program. 275(56.1%) of the 490 clustered ESTs showed sequence similarity to genes registered in the public databases. Similarity search against over 20,000 ESTs of P. yezoensis showed that 260 (53%) of the 490 clustered ESTs showed sequence similarity to ESTs registered in the GeneBank.The average GC content of 490 sequences of P. haitanensis is 58.9%. 28 ESTs showed sequence similarity with the ESTs of P. yezoensis were selected. 3221 codons were contained in these ESTs and the average GC content of the third letter in the codons (73.1%) is much higher than the second and the first letter's. Frequency of usage of 3221codons was analyzed.Research results shows that the characters　of ESTs of P. haitanensis and P. yezoensis are quite similar though they live in different environment and they are not in the same genus.According to the conserved region of the phosphoglycerate dehydrogenase of other species in GenBank, positive and negative primers were designed by Primer 5 software, and partial DNA sequences of phosphoglycerate dehydrogenase in P. haitanensis were amplified via PCR. The DNA sequence was compared with other congeneric sequences in GenBank. The sequence from Trichodesmium erythraeum (ACCESSION　number: ZP₀0073958) shows the highest indentity with that from P. haitanensis. E-value is 4e-25, Homologic identity is 30%, Score is 117.