Gene Cloning And Expression Analysis Of TAUT And CSAD In Carassius Auratus

Taurine plays a vital role in reguLating the growth and development process of bony fishes. CSAD is the main enzyme for taurine synthesis and TAUT is the key ransport of taurine in animal cells, respectively. We cloned TAUT and CSAD of Carassius auratus intestinal, and detected relative expression of the two genes mRNA on different organizations, circadian rhythm. And also studied the effects of diets adding taurine on growth perpormance and CSAD, TAUT expression, Expect for some new theoretical basis wouLd be provided for taurine apply to aquacuLture nutrition and taurine mechanism of aquatic animals.1 Cloning of TAUT and CSAD and biological information analysisIn our study, the fuL1 length ORF(Open reading frame) sequence of TAUT and CSAD were cloned from Carassius auratus by rapid amplification of cDNA ends (RACE). The sequence analysis showed that the TAUT ORF was 1978 bp which coded 625 amino acids. A structure analysis of Carassius auratus Taut indicated that it contained 12 transmembrane regions, similar to Tauts from other vertebrates. MuLtiple sequence alignment suggested that the deduced amino acid sequence of Taut from Carassius auratus shared the highest identities (97%) with Danio rerio Taut. Phylogenetic analysis revealed that Carassius auratus Taut clusters with Taut from the Danio rerio.. The CSAD ORF consisted of 1503 bp which coded 500 amino acids. Homology analysis showed that Carassius auratus CSAD shared the highest identities (97%) with Cyprinus carpio. The resuLts of phylogenetic analysis revealed that Carassius auratus Taut clusters with Taut from the Cyprinus carpio.2 TAUT and CSAD expression in different organizations, circadian rhythm of Carassius auratusIn this study, the relative expression of TAUT and CSAD gene in different tissues and circadian rhythms were explored using real-time PCR technology. The resuLts showed that it is highest of the relative expression of TAUT mRNA in intestinal, and lowest in the heart and brain. Relative expression differences of CSAD mRNA was not significant between muscle, heart, intestine and liver, the relative expression of the lowest in the brain and gill tissues. It is showed gradually increasing from 0:00 to 12:00 of the relative expression of intestines TAUT mRNA in the circadian rhythm, and reached the highest and lowest expression at 12:00 and 21:00, respectively. The CSAD expression levels fluctuated during the day and night, with the highest and lowest expression detected at 6:00 and 21:00, respectively.3 Effects of taurine on TAUT and CSAD gene expression of Carassius auratusTo study the effects of diets adding taurine (0.0g/kg, 1.0g/kg,2.5g/kg,4.0g/kg,6.0g/kg and 9.0g/kg,respectively) on growth perpormance, proliferation of intestinal cell, genes associated with protein digestion andabsorption of Carassius auratus.480 Crucian carps with 29.07�0.19g body weight were randomLy divided into 6 treatments which contained 4 replicates and 20 Crucian carps for each replicate. The basal diet added 0 g/kg taurine was used as control group, and the experiment lasted for 8 weeks. The resuLts showed that:(1) Taurine have positive effece on growth performance of crucian carp, especially the weight gain rate, specific growth rate, feed coefficien, protein efficiency ratio of Crucian carps in 6.0 g/kg dietary taurine group were remarkably increased than control group (P>0.05). (2) Taurine have improved the serum T3, T4 concentrations. T3, T4 concentrations in 6.0 g/kg dietary taurine group was significally higher than in the control group and its serum urea nitrogen concentration was significally lower than control group and other dietary taurine levels (P>0.05). (3) Taurine remarkably enhanced the relative expression of TAUT and CSAD mRNA with increasing dietary taurine levels, especially in the adding level of taurine at 6.0 g/kg, which were significally higher than the control group and the other groups. These resuLts indicate that dietary moderate taurine supplementation is necessary for crucian carp's growth perpormance, proliferation of intestinal cell, genes associated with protein digestion and absorption.