Analysis On Color Polymorphism And Comparison Of MC1R Gene Of Lanius Schach

The Rufous-backed Shrike(Lanius schach)belong to Laniidae Passeriformes. It is one of the species which have color polymorphism.They are widely distributed in china,and there are different morphs coexist in some regions,such as brown morph, black morph,the color morph between brown and black and so on.Color polymorphism is meaningful in understanding the heredity,variation and evolution of species,but there is rare reports about Color polymorphism in china.In order to study the Color polymorphism of Lanius schach,field ecology and molecular biology were used for the study in this paper.The main contents and results were summarized as following:1.The population investigation of Lanius schach in Guangdong Province and morphology analysisHere,we analyzed the deviation of the distribution of different color morphs of Lanius schach by the field data in Guangdong Province from Apr 2005 to Jan 2007. The results were:①A new color morph,which is different from black morph by having white flight feather,was identified and only recorded in Haifeng,Guangdong.①Brown morph are widely distributed and have larger population than black morph and the later mostly distributed near seaside area but never found in mountainous area. Hence we supposed that the new color morph suggested seashore regions be important for the differentiation of black morph and the differentiation is undergoing now.The body measurements including stem length,tail length,culmen length,wing length and tarsus length were measured in South China Institute of Endangered Animals,body weight was the label mark of the specimen.The software SPSS11.5 was used for data analysis.The results show there was no obviously deviation in the body measurements(p＞0.05)for brown morph and black morph.The main difference among Lanius schachs is just in plumage color,brown morph is obviously different from black morph,and the difference between black morph and white-remiged black morph is the later has several white remiges.2.The study on the difference of melanocortin-1 receptor(MC1R)gene between brown morph and black morph of Lanius schachA candidate gene for the color difference is the melanocortin-1 receptor(MC1R), a key regulator of melanin synthesis in feather melanocytes.Point mutations, deletions and insertions of the melanocortin-1 receptor(MC1R)locus,are responsible for melanic polymorphisms in many different kind of animals.MC1R gene of 25 individuals from six populations in Guangdong province had been sequenced by TA cloning.The results show:12 haplotypes were discovered in the total individuals.16 heterozygotes were detected,the others 9 individuals were maybe homozygotes or heterozygotes which the other haplotype hadn't been detected.There were 15 variable sites discovered during the 899 bp of the MC1R gene from codons 34 to 931 among all Lanius schach sampled,and there were some deletions detected in some haplotypes from codons 268 to 303.Point mutations didn't show certain relationship to the phenotypes,but the haplotypes with deletions from codons 268 to 303 were detected in all black morphs.The length of the deletions is 36bp,it leads to an 12 amino acid deletions but nonframeshift.When the nucleotide were transformated to amino acid,all the substitutions occurred in the open reading frame,of which 1 was synonymous and 14 were replacement substitutions,but the nonsynonymous site showed no correlation with phenotype.The haplotypes with amino acid deletion of LVKMLFMLLLEH from amino acids 90 to 101 were appeared in all black morphs of Lanius schach,the independent nonframeshift deletions in the MC1R gene are associated with black morph of Lanius schach,36bp deletions within this region of the gene are responsible for the black morph of Lanius schach.Presume the deletions are gain of function mutations,the activation of MC1R through binding ofα-MSH and ACTH leads to an increase in intracellular cAMP.Treatment of melanocytes with agents that increase cAMP such as forskolin leads to induction of tyrosinase and increased melanin production.Finally,the black morph of Lanius schach is induced after a-MSH stimulation.We concluded that the deletions of the melanocortin-1 receptor(MCIR)locus,is responsible for melanin synthesis in Lanius schach,MC1R was initially determined as one of a candidate gene for melanin synthesis in Lanius schach.