| Cold tolerance of Pseudosciaena crocea is paid close attention to. In recent years, the loss of cage cultured Pseudosciaena crocea in Zhejiang coast was disastrous during overwintering, owing to the cold wave and genetical characterization decline, etc. In january 2007, low temperature breeding of Pseudosciaena crocea was carried out in the base of Zhoushan fisheries research institute, and 225 Daiqu race Pseudosciaena crocea which could tolerate 5.5℃were breeded from 920 fishes, using the method of cooling with ice in indoor concrete tank; accept F1 by self cross breeding, then accept F2 by the same way. Evaluation of Pseudosciaena crocea of low temperature breeding group was conducted by analyzing SSR and changes of physiology and biochemistry index (Antioxidant system, serum biochemical index and fatty acid) during winter, hoping to provide important reference for low temperature breeding of the offspring from breeded group and cold tolerance mechanism study.Nine microsatellite markers were applied to detect genetic differences between F1 offsprings, F2 offsprings of low temperature breeding group and normal control group of Pseudosciaena crocea by SSR-PCR, 46 alleles were received .the value of polymorphism information content (PIC) of F1 and F2 was 0.5303 and 0.5165, both of them bigger than 0.5, so the high genetic diversity of the two group is available, which prove possible to further breed research. But protect must be paid to avoid variety degeneration. The presence frequency of three group are disparity(LYC0015112:F1 28.6%,F2 10%, control 80%;LYC0015102:F1 57.1%,F2 35%,none of control)which indicated that this allele is probably sensitive to temperature and associated with gene for cold tolerance.Results of changes of physiology and biochemistry during winter prove that some ways are used to defense cold when temperature descent. The activity of SOD increased gradually with decrease of temperature, the activity of SOD at 20℃is 53.32U/mgprot, however it is 61.76 U/mgprot at 8℃.The activity of POD and CAT change with irregularity or no notable. the activities of each enzyme in muscles is lower than them in liver. For example, the activity of SOD in liver is five times as high as it is in muscle and the activity of CAT in liver is ten times as high as it in muscle. The activity of each enzyme in muscle descent gradually or increase behind with decrease of temperature. The system of antioxidant keep balance during the winter, the content MDA and the activity of antioxidant enzyme keep the same trend with the descent of temperature. The capability of Pseudosciaena crocea to eliminate reactive oxygen species caused by cold temperature is available.Effect of temperature descent serum biochemical indexes of Pseudosciaena crocea during winter was studied .The results showed that the activity of most enzyme decreased. Such as ALT(from 22.4U/L at 20℃to 14.77U/L at 8℃),AST(form 84.4U/L at 20℃to 53.27U/L at 8℃),ALP(from 12.78U/L at 20℃to 6.31U/L at 8℃).These indexes reflect injuries of organ with the temperature decreasing. The change of NEFA, TG and BUN reflect the changes of fat and protein metabolism during winter.During the winter, the content of unsaturated fatty acid increased, especially the content of EPA(C20:5(n-3)), the content of it in muscle from 5.71% at 20℃to 8.06% at 8℃and it in liver from 6.76% at 20℃to 8.44% at 8℃. Transformation and metabolism by organism itself, saturated fatty acid decreased and unsaturated fatty acid increased to keep cell membranes fluidity. That's important for cold tolerance. |
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