摘要
Sarcopterygians is an important vertebrate clade that includes crossopterygians and tetrapods.Crossopterygians are lobe-finned fish that include lungfish and coelacanths.Tetrapods include amphibians,reptiles,avians and mammals.To compare the interferon regulatory factor 1 (irf-1) gene structure and to explore phylogenetic relationships among sarcopterygians,we cloned the cDNA sequence of irf-1 from lungfish and compared it with irf-1 orthologs in other sarcopterygian species.The lungfish is a primitive sarcopterygian that occupies a very important position in vertebrate phylogeny.Interferon regulatory factors (IRFs) are a family of proteins involved in innate immunity.To date,11 IRF family members have been reported.All IRFs share homology in the first 115 amino acids,which encompasses a DNA binding domain containing a characteristic repeat of 5 tryptophan residues separated by 10-18 amino acids.IRF-1 and IRF-2 were the first members of this family to be reported and they have a very important role in innate immunity.However,studies of the irf-1 and irf-2 genes are mostly confined to mammals;very few non-mammalian irf-1 genes have been reported.Consistent with the irf-1 gene sequences already published,the first 345 nucleotides of lungfish irf-1 are highly conserved.At the carboxyl terminal a C-terminal transactivating region motif and an interferon associated domain (IAD2) were identified.417 million years separate the present from the closest common ancestor of lungfish and tetrapods;however,the irf-1 genes among sarcopterygians are highly conserved and have very obvious phylogenetic relationships.Also the interrelationship tree of sarcopterygians,based on IRF-1 amino acid sequences,is identical with trees produced using other data,such as morphological characteristics or mitochondrial gene sequences.
Sarcopterygians is an important vertebrate clade that includes crossopterygians and tetrapods. Crossopterygians are lobe-finned fish that include lungfish and coelacanths. Tetrapods include amphibians, reptiles, avians and mammals. To compare the inter- feron regulatory factor 1 （irf-1） gene structure and to explore phylogenetic relationships among sarcopterygians, we cloned the cDNA sequence of irf-1 from lungfish and compared it with irf-1 orthologs in other sarcopterygian species. The lungfish is a primitive sarcopterygian that occupies a very important position in vertebrate phylogeny. Interferon regulatory factors （IRFs） are a family of proteins involved in innate immunity. To date, 11 IRF family members have been reported. All IRFs share homology in the first 115 amino acids, which encompasses a DNA binding domain containing a characteristic repeat of 5 tryptophan residues separated by 10-18 amino acids. IRF-1 and IRF-2 were the first members of this family to be reported and they have a very im- portant role in innate immunity. However, studies of the irf-1 and irf-2 genes are mostly confined to mammals; very few non-mammalian irf-1 genes have been reported. Consistent with the irf-1 gene sequences already published, the first 345 nucleo- tides of lungfish irf-1 are highly conserved. At the carboxyl terminal a C-terminal transactivating region motif and an interferon associated domain （IAD2） were identified. 417 million years separate the present from the closest common ancestor of lungfish and tetrapods; however, the irf-1 genes among sarcopterygians are highly conserved and have very obvious phylogenetic rela- tionships. Also the interrelationship tree of sarcopterygians, based on IRF-1 amino acid sequences, is identical with trees produced using other data, such as morphological characteristics or mitochondrial gene sequences.
基金
supported by the National Key Basic Research Program of China (HCV2009CB522500)
