Cloning and Molecular Characterization of Grouper Immunoglobulin M (IgM) Genes
Date Issued
2007
Date
2007
Author(s)
Tseng, Shih-Jou
DOI
zh-TW
Abstract
Groupers, coral fish species that inhabit in tropical and subtropical regions, are critical to Taiwanese aquaculture as well as to the rest of Southeast Asia. Due to the culinary value and the ever-growing demand, the yields of groupers progressively increase year after year. However, the highly populated breeding methods within confined or limited habitation space are prone to induction and prevalence of diseases. In order to strengthen the groundwork of disease control and preventative research via a better understanding of grouper's immune system, we initiated this study concerning immunoglobulin M (IgM) of groupers. Immunoglobulin M is a tetramer that consists of two heavy chains and two light chains. Our previous findings identified and cloned 4 CH families from Epinephelus coioides (Cheng et al., 2006). Based on that result, we further analyzed the light chain genes in this proposed study. Utilizing a 1006 bp light chain gene that developed by our laboratory as a probe, we cloned 20 full-length light chains from grouper's head kidney cDNA library. The length of this light chain gene is between 708 to 747 bp, with a non-translated region at 5' and 3' end. In addition, its ORF can be translated into a light chain with molecular weight of 24.6-26.5 kDa. The variable and constant regions are located behind the leader. The variable region is composed of FRs and CDRs; while the constant region consists of 3 highly constant cysteines. It has been suggested that these cysteines formed intradomain and interchain disulfide bonds. According to the amino acid sequences of the constant region, these genes can be classified into 4 isotypes; while the variable region can be distinguished into 5 families. Based on the difference in N- and C-terminal in J segment, J segment can bridge variable and constant region with varieties of VJC combinations, which make it diversity. Overall, we've found 10 different sequences of C-terminal. According to the phylogenetic analysis of grouper's IgM light chains constant region to that of other fish species, we've found that groupers possess 4 isotypes of IgM light chains, relatively higher than other teleost fish. Furthermore, the result of RT-PCR analysis indicated that there are 4 isotypes of IgM light chains expressed in grouper's head kidney tissue.
Subjects
點帶石斑
石斑魚
免疫球蛋白
輕鏈
Epinephelus coioides
Grouper
Immunoglobulin
IgM
Light chain
Type
other
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