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The analysis of genes expressed in the sperm storage organs of Drosophila melanogaster: Patterns of evolution and expression
The molecular evolutionary rate of genes associated with sexual traits and reproduction is (on average) faster than that of genes coding for non-sex-related traits. In Drosophila, this trend has been observed in genes expressing male accessory gland products, as well as in genes expressed in the entire reproductive tract of the females. Though a general trend of rapid evolution has been observed in the Drosophila female reproductive tract, relatively little is known about the evolutionary patterns of the genes expressed in specific organs within the female reproductive system. Sperm storage organs are important to the reproductive success of both males and females, as sperm in storage must remain viable and be properly released for successful fertilization. Further more, sperm storage organs provide an arena for important evolutionary processes such as sperm competition and female sperm choice. This study investigated the evolutionary and expression patterns of genes found in the sperm storage organs of Drosophila. A high percentage of genes found in sperm storage organs were found to be evolving at rapid rates. Polymorphism data confirmed that for five of the genes discovered, the rapid evolution can be attributed to positive selection acting on a subset of the codons of these genes. The function of many of the genes identified suggests that these genes could interact with seminal products, and this interaction could be a factor in the elevation of evolutionary rates. Regions upstream of genes typically contain a number of non-coding regulatory regions; changes in these regions could result in changes in gene expression. Regions upstream of five of the sperm storage genes were found to be over twice as polymorphic as neutral regions of non-coding DNA. Using microarrays to investigate expression patterns, it was found that the expression of genes associated with sperm storage showed time and organ dependent patterns, presumably associated with different sperm storage events. The identification of genes involved in sperm storage and the characterization of their expression and evolutionary patterns is a new and important development in the understanding of the mechanics and timing of fertilization. This understanding has broader impacts such as insight into important processes (entrance, maintenance and release) of sperm storage for a wide range of species. This study is one of the first to describe important female proteins that may be interacting (possibly co-evolving), either in concert or antagonistically with male seminal products. ^
Biology, Genetics|Biology, Bioinformatics
Prokupek-Pickett, Adrianne Marie, "The analysis of genes expressed in the sperm storage organs of Drosophila melanogaster: Patterns of evolution and expression" (2008). ETD collection for University of Nebraska - Lincoln. AAI3297753.