Effects Of High Temperature Stress On Sinonovacula Constricta "Shen-zhe No.1" And Early Screening Of New High Temperature Resistant Strains

Sinonovacula constricta is widely distributed in coastal areas of china.S.constricta has a variety of edible methods and a certain medical value.It is easy to be managed in the breeding process.It is popular among people because of its high yield and short breeding cycle.At present,the breeding area of S.constricta in China is decreasing and the breeding yield is increasing steadily.In 2018,our research team successfully bred the first S.constricta new variety‘Shen-zhe No.1'in China,which improved the body weight.This experiment was carried out in order to further cultivate new strain of S.constricta resistant and ensure the healthy and sustainable development of S.constricta industry.The experiment mainly included the determination and analysis of SOD,CAT and T-AOC enzyme activities of S.constricta under high temperature stress environment,the gene cloning,sequence analysis and expression of heat stress related gene HSF1,and the early breeding and screening of heat-resistant new lines of S.constricta.The specific research results were as follows:1?This experiment investigated the changes of catalase,superoxide dismutase and total antioxidant capacity of S.constricta‘Shen-zhe No.1'in three immune indexes under the sudden temperature rise stress for 48h,and measured the changes of three enzyme activities in the hepatic and pancreatic tissues of S.constricta at different time nodes under different temperature stress conditions.The results showed that the three immune indexes in hepatopancreas of each experimental group increased significantly with time.In the first 12 hours,CAT,SOD and T-AOC increased significantly,and then gradually decreased to the initial level.These results suggest that high temperature stress may cause significant changes in the antioxidant immunity of S.constricta,which may affect the growth and survival of S.constricta.It will provide theoretical basis for evaluating the thermal resistance of S.constricta‘Shen-zhe No.1',the effect of reactive oxygen metabolism after heat stress and the cultivation of the new heat-resistant strain of S.constricta.2?The results showed that the full-length c DNA of Sinonovacula constricta HSF1 gene was 2026 bp,the open reading frame was 1707 bp in length,encoding 568 amino acids,the 5'non-coding region was 196 bp long,and the 3'non-coding region was 123 bp long.Amino acid sequence alignment and phylogenetic tree results showed that the HSF1 gene was closest to the Crassostrea virginica,and its phylogenetic analysis was consistent with the traditional morphological classification.The results of real-time PCR showed that HSF1 gene was expressed in all tissues,and the relative expression of mantle membrane was the highest,followed by sputum,hepatopancreas and water tube,and the relative expression in axillary and gonadal tissues was low.It's speculated that HSF1 gene is involved in the process of S.constricta heat stress and plays a role.3?Three high temperature resistant families of S.constricta were screened from 10 whole sibling families of S.constricta by growth,survival and high temperature resistan,and median-ethal temperatures(UILT₅₀)were compared in different days old larval stages of the 2?4?6?10?muddy period?,and 20 and 30 water temperature of 30?32?34?36?and 38°C to select the resistant high temperature varieties of S.constricta.The results showed that the family C had significantly better growth compared with the other two families?P<0.05?,and that there was significant difference in the UILT₅₀ temperature among the families?P<0.05?.The S.constricta in family C had significantly higher survival rate than that in other families did.The findings indicate that UILT₅₀temperature is ued as a measure to carry out the breeding of the high temperature-oriented family on the basis of the new variety‘Shen-zhe No.1',which can achieve high temperature resistance screening in the larval stage of the family.