Origin and evolution of vertebrate ABCA genes: A story from Amphioxus

Key Laboratory of the Ministry of Education for Cell Biology and Tumor Cell Engineering, School of Life Sciences, Xiamen University, Xiamen, 361005, China.
Gene (Impact Factor: 2.14). 01/2008; 405(1-2):88-95. DOI: 10.1016/j.gene.2007.09.018
Source: PubMed


Previous studies showed that the vertebrate ABCA subfamily, one subgroup of the ATP-binding-cassette superfamily, has evolved rapidly in terms of gene duplication and loss. To further uncover the evolutionary history of the ABCA subfamily, we characterized ABCA members of two amphioxus species (Branchiostoma floridae and B. belcheri), the closest living invertebrate relative to vertebrates. Phylogenetic analysis indicated that these two species have the same set of ABCA genes (both containing six members). Five of these genes have clear orthologs in vertebrate, including one cephalochordate-specific duplication and one vertebrate-specific duplication. In addition, it is found that human orthologs of amphioxus ABCA1/4/7 and its neighboring genes mainly localize on chromosome 1, 9, 19 and 5. Considering that most of analyzed amphioxus genes have clear orthologs in zebrafish, we conclude these four human paralogous regions might derive from a common ancestral region by genome duplication occurred prior to teleost/tetrapod split. Therefore, the present results provide new evidence for 2R hypothesis.

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    • "The 3 genes on scaffold 149 show close homology to the one on scaffold 152 and the two genes on scaffold 89 respectively, both in sequence and gene structure (Supplemental Table1). Since the B. floridae genome database contains sequences of two haplotypes (Li et al., 2007), we suggest that the 6 genes might represent different alleles of three independent genes. "
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