温度和盐度对虹鳟(Oncorhynchus mykiss)“水科1号”生长、消化酶活性和相关基因表达的影响

EFFECTS OF TEMPERATURE AND SALINITY ON GROWTH,INTESTINAL DIGESTIVE ENZYME ACTIVITY,AND GENE EXPRESSION IN TISSUES OF RAINBOW TROUT(ONCORHYNCHUS MYKISS)

温度和盐度变化的影响是虹鳟(Oncorhynchus mykiss)海水驯化和养殖生产中需要解决的重要问题。为探究温度和盐度对虹鳟生长发育的影响,通过在3种温度(10、16和22℃)条件下均设置5种盐度梯度处理(盐度分别为0、8、16、24、32),分别以A_(1)~A_(5)表示10℃各盐度组,以B_(1)~B_(5)表示16℃各盐度组,以C_(1)~C_(5)表示22℃各盐度组,将温度16℃且盐度为0组(B_(1))作为淡水对照组,开展为期21 d的养殖实验。养殖实验结束后分析不同温度和盐度对虹鳟生长、肠道消化酶活性、鳃和肠组织中生长相关基因(gh和igf-1)、应激相关基因(hsp70)和渗透压调节相关基因(aqp3和nka)表达的影响。结果显示,除B_(2)(16℃下盐度为8)盐度组的饵料转化率(FCE)、增重率(WGR)和特定生长率(SGR)较B_(1)(淡水对照组)显著升高,肠道中淀粉酶和脂肪酶活性分别较B1(淡水对照组)显著升高约23%和8%外(P<0.05),其余实验组以上指标均较淡水对照组降低。此外,鳃和肠组织中,B_(2)和B_(3)组gh和igf-1的表达量较对照组显著上调(P<0.05),而其余实验组gh和igf-1的表达量较对照组均显著下调(P<0.05)。鳃组织中B_(2)和B_(3)组以及肠组织中B_(2)组的hsp70表达量较对照组无显著差异(P>0.05),其余实验组hsp70的表达量较对照组显著上调(P<0.05)。不同温度条件下,鳃组织中aqp3表达量随实验组盐度增大呈下调趋势,而肠组织中则呈上调趋势;两组织中nka表达量随实验组盐度增大均呈上调趋势。研究结果表明,16℃下8盐度组的虹鳟较淡水组生长更好。因此,在虹鳟适宜的温度下,适当地提升养殖水体的盐度有利于促进虹鳟的生长发育,这为完善海水条件下虹鳟的驯化和养殖提供了基础资料。

Temperature and salinity are key factors on the growth and development of rainbow trout Oncorhynchus mykiss.To understand the effects of temperature,salinity,and their interaction,we conducted a 21-day experimental study in which combinations of temperatures(10,16 and 22℃)and salinities(0,8,16,24,32)were tested.The salinity groups at 10℃ are denoted as A_(1)~A_(5)(1~5 represent the five salinity levels,respectively),16℃ as B_(1)~B_(5),and 22℃ as C_(1)~C_(5).The 16℃ and 0 salinity group(B_(1))was used as the freshwater control group.At the end of the experiments,effects of different temperatures and salinities on rainbow trout growth,intestinal digestive enzyme activity,expression of growth-related genes(growth hormone,gh and insulin-like growth factor-1,igf-1),stress-related genes(heat shock protein,hsp70),and osmolarity-regulated genes(Aquaporin3,aqp3 and Na^(+)/K^(+)-ATPase,nka)were recorded and analyzed statistically.Results show that the feed conversion rate(FCE),weight gain rate(WGR),and specific growth rate(SGR)were significantly higher in B_(2)(16℃,salinity 8)group compared to B_(1)(freshwater control).Amylase and lipase activities in the intestine were significantly higher in B_(2)group than B1’s by 23%and 8%,respectively(P<0.05).The other groups showed a decrease in the abovementioned indices compared to the control group.In addition,the expressions of gh and igf-1 in gill and intestinal tissues were significantly up-regulated(P<0.05)in the B_(2)and B_(3) groups.In contrast,compared to the control,the expressions of gh and igf-1 in the rest of the groups were significantly down-regulated(P<0.05);those of hsp70 in B_(2)and B3 groups in gill tissues and B_(2)group in intestinal tissues showed no significant difference(P>0.05);and those of hsp70 in the other groups was significantly up-regulated(P<0.05).Under different temperature conditions,the expression of aqp3 in gill tissues was down-regulated with increasing salinity,while it was up-regulated in intestinal tissues;the expression of nka in both tissues was up-regulated with increasing salinity.Rainbow trout of B_(2)group(16℃,salinity 8)grew the best.Therefore,under a suitable temperature,a certain increase of salinity shall be beneficial to the growth and development of rainbow trout.This study provided basic information for improvement in the domestication and culture of rainbow trout in seawater.