It has been shown that duplicate genes on the X chromosome evolve much faster than duplicate genes on autosomes in Drosophila melanogaster. However, whether this phenomenon is general and can be applied to other speci...It has been shown that duplicate genes on the X chromosome evolve much faster than duplicate genes on autosomes in Drosophila melanogaster. However, whether this phenomenon is general and can be applied to other species is not known. Here we examined this issue in chicken that have heterogametic females （females have ZW sex chromosome）. We compared sequence divergence of duplicate genes on the Z chromosome with those on autosomes. We found that duplications on the Z chromosome indeed evolved faster than those on autosomes and show distinct patterns of molecular evolution from autosomal duplications. Examination of the expression of duplicate genes revealed an enrichment of duplications on the Z chromosome having male-biased expression and an enrichment of duplications on the autosomes having female-biased expression. These results suggest an evolutionary trend of the recruitment of duplicate genes towards reproduction-specific function. The faster evolution of duplications on Z than on the autosomes is most likely contributed by the selective forces driving the fixation of adaptive mutations on Z. Therefore, the common phenomena observed in both flies and chicken suggest that duplicate genes on sex chromosomes have distinct dynamics and are more influenced by natural selection than autosomal duplications, regardless of the kind of sex determination systems.展开更多
A unique characteristic of the Silkie chicken is its fibromelanosis phenotype.The dermal layer of its skin,its connective tissue and shank dermis are hyperpigmented.This dermal hyperpigmentation phenotype is controlle...A unique characteristic of the Silkie chicken is its fibromelanosis phenotype.The dermal layer of its skin,its connective tissue and shank dermis are hyperpigmented.This dermal hyperpigmentation phenotype is controlled by the sex-linked inhibitor of dermal melanin gene(ID)and the dominant fibromelanosis allele.This study attempted to confirm the genomic region associated with ID.By genotyping,ID was found to be closely linked to the region between GGA_rs16127903 and GGA_rs14685542(8406919 bp)on chromosome Z,which contains ten functional genes.The expression of these genes was characterized in the embryo and 4 days after hatching and it was concluded that MTAP,encoding methylthioadenosinephosphorylase,would be the most likely candidate gene.Finally,target DNA capture and sequence analysis was performed,but no specific SNP(s)was found in the targeted region of the Silkie genome.Further work is necessary to identify the causal ID mutation located on chromosome Z.展开更多
基金supported by the National Science Foundation of China (No. 30600064)the National Basic Research Program of China (973 Program) (No. 2007CB815702) to X.Lu
文摘It has been shown that duplicate genes on the X chromosome evolve much faster than duplicate genes on autosomes in Drosophila melanogaster. However, whether this phenomenon is general and can be applied to other species is not known. Here we examined this issue in chicken that have heterogametic females （females have ZW sex chromosome）. We compared sequence divergence of duplicate genes on the Z chromosome with those on autosomes. We found that duplications on the Z chromosome indeed evolved faster than those on autosomes and show distinct patterns of molecular evolution from autosomal duplications. Examination of the expression of duplicate genes revealed an enrichment of duplications on the Z chromosome having male-biased expression and an enrichment of duplications on the autosomes having female-biased expression. These results suggest an evolutionary trend of the recruitment of duplicate genes towards reproduction-specific function. The faster evolution of duplications on Z than on the autosomes is most likely contributed by the selective forces driving the fixation of adaptive mutations on Z. Therefore, the common phenomena observed in both flies and chicken suggest that duplicate genes on sex chromosomes have distinct dynamics and are more influenced by natural selection than autosomal duplications, regardless of the kind of sex determination systems.
基金This work was funded by the National Natural Science Foundation of China(U0831003)the National Advanced Technology Research and Development Program of China(2011AA100301).
文摘A unique characteristic of the Silkie chicken is its fibromelanosis phenotype.The dermal layer of its skin,its connective tissue and shank dermis are hyperpigmented.This dermal hyperpigmentation phenotype is controlled by the sex-linked inhibitor of dermal melanin gene(ID)and the dominant fibromelanosis allele.This study attempted to confirm the genomic region associated with ID.By genotyping,ID was found to be closely linked to the region between GGA_rs16127903 and GGA_rs14685542(8406919 bp)on chromosome Z,which contains ten functional genes.The expression of these genes was characterized in the embryo and 4 days after hatching and it was concluded that MTAP,encoding methylthioadenosinephosphorylase,would be the most likely candidate gene.Finally,target DNA capture and sequence analysis was performed,but no specific SNP(s)was found in the targeted region of the Silkie genome.Further work is necessary to identify the causal ID mutation located on chromosome Z.
