Cloning And Sequence Analysis Of Tyrosinase Gene In Oujiang Color Common Carp And Genetic Structure Study On Eurasian Perch

1 Cloning and Sequence Analysis of Tyrosinase Gene in Oujiang Color Common carpOujiang color common carp (Cyprinus carpio var. color) is a regional freshwater species distributing in the Oujiang River drainage in China. Due to its rich color patterns and graceful body shape, Oujiang color common carp is very popular fish to local inhabitants of the Oujiang River drainage. The fish has five kind of basical body color patterns, namely"Whole red","Whole red with big black patch","Whole red with scattered black spots","Whole white"and"Whole white with big black patch". So, this fish can be a very good model and material for studying body color inheritance in fish. Furthermore, it can provide theoretical foundation for genetic improvement or breeding of the orimental traits in this fish, and referenced information for body color inheritance studies in other organisms via investigating the molecular mechanism of body color inheritance in the Oujiang color common carp. Tyrosinase is a key enzyme involved in the formation of melanin compounds. The melanin can not be synthesized if premature transcription termination occur in this gene. In the present study, we cloned the cDNA sequence of tyrosinase gene from the skin tissue of five body color patterns of Oujiang color common carp using the technique of rapid amplification of cDNA ends (RACE).The study showed that the lengths of tyrosinase gene cDNA sequence are different from different color patterns of Oujiang color common carp. For instance, the length of"Whole red"is 2100 bp,"Whole red with scattered spots"is 2107 bp,"Whole red with big black patch"is 2073 bp,"Whole white"is 1976 bp and"Whole white with big black patch"is 2111 bp. There are two types mRNA transcripts in each kind of body color patterns. Analyzing the amino acid sequence from two types mRNA, the first and second structures of predicted protein are different, whereas the third structure and typical structural domian are same in tyrosinase gene. The result of this study implied that the sequence difference of tyrosinase gene do not determine different color patterns of Oujiang color Common carp, and the black patch or scattered spots are not directly controlled by the tyrosinase gene. 2. Genetic structure Study on Eurasian perchThe Eurasian perch (Perca fluviatilis L.) is a very important freshwater species in the Eurasian and Asian Continent. In Eurasian, the natural distribution of this species is widespread. But in China, the natural distribution of this species is restricted to drainage area of the Irtse River, Xinjiang Province. Thus, China is the Asian edge of the natural range for the Eurasian perch. Due to genetic, ecological and other reasons, the populations distributed in the edge are more risk of extinction than the populations distributed in other areas. In recent years, more and more studies have focused on the genetic structure of edge populations.In this paper, twelve noval microsatellite markers in this specie were first developed and were found useful for assessment of genetic variation in Perca fluviatilus. Then, the population structure was analyzed for eight natural populations and one colonized population using 8 microsatellite markers. The results indicated that the Eurasian perch in China was found to possess high allelic richness (7.097–8.662) and heterozygosities (HO = 0.734–0.856, HE = 0.798–0.876), but significant bottleneck signal for six populations were found. Meanwhile significant genetic differentiation among populations were revealed from pairwise FST values, as well as analysis of molecular variance, Bayesian clustering analysis in STRUCTURE, and Principal coordinate analysis. The hierarchical analysis for selection sweep suggested local adaptation to habitat conditions. As the results, it was specultaed that the habitat fragmentation would have been occurred in the Eurasian perch in China. The results provide theoretical evidence for effective management and conservation of this fish in China.