Transcriptome Sequencing And Analysis Of Galaxea Astreata Under Different Temperature Stress

The phenomenon of coral bleaching and death caused by the changing of global climate, has become one of the most widely concerned problems in the world. It seriously affected the balance of Marine ecosystems. If this situation continues to deteriorate, it will bring immeasurable loss and disaster to human beings. Coral reef ecosystem plays an important role in Marine ecosystem, but so far, people know the mechanism and the mechanism of coral bleaching is so less. In order to better understand the coral in the regulation law and molecular mechanism under temperature stress, In this study, we choose the Galaxea astreata as the research object, which is the much more common corals in GalaxeaOken genus at xuwen in guang dong coral reefs of national nature reserve; we using high-throughput sequencing technologies of Illumina HiSeqTM2000 to obtain the transcriptome information for Galaxea astreata coral under different temperature stress, and then analyzing, using bioinformatics knowledge.The results are as follows:1 when the Galaxea astreata was temperature stressed 12 hours, we found that the corals still extend their tentacles and their life was in good condition.On the contrary, the corals’ tentacles all has completely retracted in high temperature(35 ℃) group and low temperature(14 ℃) group, and some of the corals appear obvious white phenomenon, some even died.2 After sequencing through Illumina HiSeqTM2000,135,781,662 reads were got, then the reads were assembled into 94,002 Unigenes. Through the function of the gene annotation, 42,240 annotated genes were received.There were 41124 Unigenes annoted on Nr(Non-redundant), 17,284 Unigenes annoted on KEGG(Kyoto encyclopedia of genes and genomes), 17,119 Unigenes annoted on COG(Cluster of Orthologous Groups of proteins), 31,810 Unigenes annoted on Swissprot.3 With the threshold of FDR≤0.001 and |log2Ratio|≥1, there were 4,891 up-regulated Unigenes and 14,949 down-regulated genes between high temperature group and normal temperature group; 4201 up-regulated Unigenes and 8,956 down-regulated genes between normal temperature group and low temperature group and5,896 up-regulated Unigenes and 11,450 down-regulated genes between high temperature group and low temperature group.4 By screening, two annotated functional genes Hsp40, Hsp70 were got, then through gene cloning method to validate two genes, the results prove that cloning Hsp40, Hsp70 gene sequence are similar to the transcription sequencing. At the same time, we get the Galaxea astreata’s several gene sequence From NCBI, and then,through local blast, we find the corresponding sequence of the transcriptome. At last, we compared the sequence and find the sequences are almost the same, suggesting that the result of transcriptome Sequencing is accurate, it can be used in subsequent research.5 Furthermore, through quantitative real-time PCR validation, 5 of these Unigenes(Hsp40, Hsp70, Hsp90,Fe,and CuZnSOD genes) were successfully confirmed with the result of Illumina HiSeq TM2000 sequencing between high temperature group and normal temperature group; However,there were two Unigenes(Hsp90,Fe) didn’t successfully confirme with the result of Illumina HiSeq TM2000 sequencing between low temperature group and normal temperature group. The others gene’s expression are same with the Illumina HiSeq TM2000 sequencing. The whole, the transcriptome sequencing is accurate, it can be used for further research.