Artificial Breeding Of Thermaltolerant Strain Of Sea Cucumber Apostichopus Japonicus (Selenka)

Sea cucumber Apostichopus japonicus (Selenka) aquaculture is a big industry and contributes enormously to the economic development of coastal provinces in north China. However, there are many problems in this industry, such as deteriorations of germ plasm, environment and product quality. especially lacking of good artificial seed.In this paper, comparative study on growth and mRNA expression level of HSP70 between different populations collected from different coastal area of China. Temperature stimulation was carried out in order to obtain a population which can tolerate higher temperature. The main results are as follows:1. Studies on difference expression level of HSP70 mRNA in sea cucumber collected from different coastal area and their F1 were carried out. In addition, comparative study on growth of F1 at different temperature was executed. Results showed that the mRNA expression level of HSP70 of sea cucumber collected from Qingdao, Rizhao and Fujian were higher than those of Dalian and Changdao.2. Fluorescent real-time quantitative RT-PCR was used to examine the mRNA expression level of HSP70 in different tissues of sea cucumber challenged by different temperature. When the temperature was above 12 (temperature of natural sea water is 12 ), the mRNA expression level of HSP70 was higher than those of the natural temperature in the respiratory tree. In the respiratory tree of adult and juvenile sea cucumber, HSP70 mRNA level increased and reached maximal level at 9h after heat stimulation.3. The temperature stimulation was initially started at fertilized eggs and early auricularia stage. The viability rate of larvae varied with different temperature. Both the initial stimulation stage and temperature had significant effect on the larval viability rate. However, there was no the correlation between maximal body length and temperature or initial stimulation time. Moreover, temperature influenced larval metamorphosis and settlement significantly. In conclusion, the larvae, stimulated by the temperature above 26 , which viability rate and metamorphosis rate were significantly lower than those stimulated by lower temperature.4. From the results that have been shown, the sea cucumber collected from Rizhao was selected as broodstock. Juvenile sea cucumbers were obtained by the stimulation at the temperature of 26 . Comparative studies on the growth and different expression of HSP70 of these populations and the natural population were also carried out. The larval viability rate, specific growth rate and the mRNA expression level of HSP70 of artificial seeding group were significantly higher than the control group. 5. Similar results also had been obtained from the comparative growth experiment in Cangnan, Zhejiang province. These results showed that the tolerance temperature of artificial breeding sea cucumbers enhanced 0.7 and the time to begin aestivation delayed 15d.