Low Temperature Resistant Performance And Six Body Color Relevant Genes Expression Analysis In Three Red Tilapia Strain

Body color is a special phenotypic trait in fish,which provides important values of biodiversity and genetics research.Body color variation of fish is a complex process,including water temperature,light,pH value,dissolved oxygen and so many other external environment that will lead to body color variation of fish.During the overwintering of RedTilapia,wefind that Red Tilapia which undergoes low temperature usually result in body color variation,and red or black stripe appears.These variation will decrease the value of Red Tilapia.Red Tilapia is a warm water fish that has the character of low temperature resistant.So we indicate that low temperature can influence the body color variation of Red Tilapia.This research analyzes and compares the differences of the low temperature resistant of IsraelRed Tilapia,TaiwaneseRed Tilapia and Malaysian Red Tilapia from the view of physiological and biochemical indexes,antioxidant enzyme and two cold resistance candidategenes.In order to further discuss the body color variation mechanism of Red Tilapia,we can discuss from the view of Melanin synthesis pathway's molecular.Furthermore we use Real-time quantitative PCR technology to compare the differencesexpression of the six body color relevant genes(MC1R,TYRP1,ASIP,DCT,SOX10 and S1C7A11)in three Red Tilapia strains.The main research result is as follows:1.The comparison of low temperature resistant of three strains of Red TilapiaSelecting an average weight of 500g of Israel,Taiwanese and Malaysian red tilapia strains as experimental subjects.The control group was 19? and the experimental group decrease 1? everyday from 19? to 8?.Every group had 2 parallel groups,and there are 6 fishes in every parallel group.The control group sampled in 19? and the experimental group sampled when the fishes begin to die.Several indices were determined,such as ALT,AST,LDH,GLU,TP,K+,Na+,Cl-,SOD,MDA,Na+-K+-ATP.Three strains Red Tilapia all died in 8.3 ?.Tilapia can exist shortly in low temperature of 6 to 10?,but they can not exist over 24hs.The death temperature of Israel and Taiwanese Red Tilapia strain is one degree higher than Malaysia Red Tilapia strain.With the reduction of temperature,in the Israeli Red Tilapia,ALT,AST,GLU,K+ were significantly increased(P<0.05).Na+ and Cl-were significantly reduced(P<0.05).In the Taiwanese Red Tilapia,ALT,AST,LDH,GLU and Na+ were significantly increased(P<0.05).In the Malaysian Red Tilapia,ALT,AST,LDH,GLU and K+ were significantly increased(P<0.05).TP;ALB were significantly reduced(P<0.05).In the Israeli Red Tilapia,the activity of SOD was significantly increased(/P<0.05),MDA level was significantly increased(P<0.05),the activity of Na+-K+-ATP was significantly reduced(P<0.05).In the Taiwanese Red Tilapia,the activity of SOD.was significantly reduced(P<0.05),MDA level was significantly reduced(P<0.05),the activity of Na+-K+-ATP was significantly reduced(P<0.05).In the Malaysian Red Tilapia,the activity of SOD was significantly reduced.(P<0.05),MDA level was significantly increased(P<0.05)the activity of Na+-K+-ATP was slightly increased.When under the low temperature stress,in the Israeli Red Tilapia and the Taiwanese Red Tilapia,the expression of SCD gene was significantly increased(P<0.05),but in the Malaysian Red Tilapia,the expression of SCD gene was significantly reduced(P<0.05).In the Israeli Red Tilapia,the Taiwanese Red Tilapia and the Malaysian Red Tilapia,the expression of HSP70 gene was significantly increased(P<0.05).So we can primary indicate that Malaysia Red Tilapia strain had higher low temperature resistant than Israel red Tilapia and Taiwanese Red Tilapia strain.2.Expression analysis of red tilapia color related genes in Israeli,Taiwanese and Malaysian Red Tilapia strains(1)Expression analysis of 6 genes from Malaysian Red TilapiaSelecting three types of Malaysian red tilapia with good health,every fish sampled dorsal skin,venter skin,muscle,intestine,heart and brain.qRT-PCR analysis revealed that,MC1R,ASIP,TYRP1,DCT and SLC7A11 gene was highly expressed in skin,weakly expressed in heart and liver,and had the lowest level expression in muscle and brain;SOX 10 gene was highly expressed in brain,weakly expressed in skin and muscle,and lowest expression in liver and heart.MC1R,ASIP,TYRP1,SOX 10 and SLC7A11 gene expression in red spots was significant higher than other color patterns(P<0.05).DCT gene expresses in pink and white stripe was significant higher than red stripe(P<0.05).The results primarily indicated that the type of skin is not controlled by one gene.It was controlled by a complex gene networks.Finally,the type of Red Tilapia skin was decided by the interaction of 6 genes.(2)Expression analysis of 6 genes in three strain Red Tilapiaskin tissuesSelect 3 strains red tilapia from Israel,Taiwanese and Malaysian with good health as experimental subjects.Every fish sample the dorsal skin,venter skin.These three strains compare the differential expression in dorsal skin and venter skin.qRT-PCR analysis revealed that,in the back skin tissue from three strains,MCIR,ASIP,TYRP1,DCT,SOX10 and SLC7A11 gene expression quantity in Malaysian Red Tilapia was significant higher than other two strains(P<0.05).ASIP and TYRP1 gene in Israeli Red Tilapia was significant higher than Taiwanese Red Tilapia.MC1R,DCT,SOX10 and SLC7A11 gene was no significant expression difference between Israeli Red Tilapia and Taiwanese Red Tilapia(P<0.05).In the ventral skin tissue of three strains,MC1R,ASIP,DCT and SOX10 gene expression was on the highest level in Malaysian Red Tilapia.TYRP1 and SLC7A11 gene expression was on the highest level in Taiwanese Red Tilapia.TYRP1 and SLC7A11 had significant expression difference between Israeli,Taiwaneseand Malaysian Red Tilapia(P<0.05).MC1R,ASIP and SOX10 gene all had significant expression difference between Israeli Red Tilapia,and Taiwanese Red Tilapia(P<0.05).We can indicate that body gene expression quantity had some relevant with the strain of fish.(3)Expression analysis of 6 genes in the back and ventral skin tissues of three strain.Select 3 fish each Israel,Taiwanese and Malaysian strain of red tilapia strains with good health as experimental subjects.Every fish sample the dorsal skin,venter skin.Each of these three strains compares the difference expression in dorsal skin,venter skin.qRT-PCR analysis revealed that,in the Israeli Red Tilapia,of MC1R,TYRP1,DCT,SOX10 and SLC7A11 gene expression quantity in back skin was significant higher than in ventral skin(P<0.05).In the Taiwanese Red Tilapia,ASIP gene expression quantity in ventral skin was higher than in back skin(P<0.05).MC1R,DCT,SOX10 and SLC7A11 gene expression quantity in back skin was significant higher than in ventral skin expression(P<0.05).In the Malaysian Red Tilapia,MC1R,ASIP,DCT,SOX10 and SLC7A11 gene expression quantity in back skin was significant higher than in ventral skin(P<0.05).ASIP gene can participate in the skin pigmentationpattern between the back and ventral skin tissues and influence colour difference among the three Red Tilapia strains.