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Published on: February 7, 2014
Extraordinary intraspecific diversity in oyster sperm bindin
G W Moy1, S A Springer, S L Adams
1Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093-0202, USA.
Summary
Pacific oysters generate thousands of bindin protein variants through positive selection, alternative splicing, and recombination. This diversity in gamete recognition proteins may drive reproductive isolation and speciation.
Area of Science:
- Evolutionary Biology
- Reproductive Biology
- Marine Biology
Background:
- Sperm-egg incompatibility in free-spawning invertebrates, driven by gamete recognition protein (GRP) divergence, causes reproductive isolation.
- Intraspecific GRP variants are crucial for mate choice and early speciation.
- Pacific oysters (Crassostrea gigas) utilize bindin protein in sperm acrosomes for fertilization.
Purpose of the Study:
- To investigate the mechanisms generating diversity in oyster bindin protein within the species.
- To understand the role of intraspecific GRP variation in reproductive isolation and sexual conflict.
Main Methods:
- Analysis of bindin gene structure and protein domains.
- Identification of evolutionary processes like positive selection and recombination.
- Examination of alternative splicing in bindin gene expression.
Main Results:
- Oyster bindin genes possess a conserved N-terminal region and variable tandem fucose-binding lectin (F-lectin) domains.
- Positive selection has diversified eight sites on the F-lectin's fucose-binding face.
- Recombination within introns and alternative splicing of cDNA contribute to thousands of potential bindin variants.
Conclusions:
- Multiple evolutionary mechanisms, including positive selection, recombination, and alternative splicing, generate extensive bindin diversity in Crassostrea gigas.
- High intraspecific polymorphism in male GRPs may be influenced by sexual conflict and the efficiency of polyspermy blocks during fertilization.
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