Physiological Effects Of High Temperature Stress On And Cloning And Expression Of Hsp70 Gene From Conchocelis Of Porphyra Yezoensis

Porphyra is not only one of seaweed that has the most economic value, but also has high scientific research value. At present, greenhouse effect and coastal industrial pollution are serious. The normal growth and development of P. yezoensis are intimidated. Heat shock proteins can be synthesized especially under temperature stress. They are highly conservative. They participated in various cellular processes under normal and stress conditions. They are also playing key role in the defence processes of environment stress to plants such as heat, cold. Some physiological index including the contents of chlorophyll a, soluble protein, MDA and soluble sugar and POD activity of conchocelis of P. yezoensis under different temperature were measured. In addition, we cloned an Hsp70 gene of P. yezoensis and analyzed its function. The results showed that:All of the measured contents and activity of conchocelis of P. yezoensis have little change under 24℃. When the conchocelis were cultured 12 hours at 28℃or 30℃, the content of chlorophyll a sharply descend. The color of conchocelis changed from dark green to brown. Some cells were dead. The contents of soluble protein, MDA and soluble sugar increased in initial stage and then declined. POD activity was lower than the control.By the methods of RT-PCR, we successfully isolated an Hsp70 gene. We studied its expression levels by using a semiquantitative analysis method after induced by high temperature. At 24℃,the expression of Hsp70 was almost same; At 28℃, the expression of Hsp70 was more than that of 24℃.Its expression reached the most when the time is 24h.But its expression decreased after 24h.At 30℃,the expression of 24h was two times than that of 12h.In certain time frame, Hsp70 can protect P. yezoensis against harm of high temperature. We constructed the prokaryotic expression vector and eukaryote expression vector of Hsp70 gene.We found these recombinants did not have effect to E.coli and yeast in normal temperature. But in high temperature, the growth of E.coli and yeast with recombinants were better than those without recombinants. The results showed that Hsp70 could improve the capacity of E.coli and yeast to against high temperature.The results provide some references to the mechanism study of P. yezoensis high temperature resistance and resistant cultivar breeding.