Browsing by Subject "Generative organs, Male"
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Item Comparative genomics and molecular population genetics of Drosophila male reproductive genes(2004) Wagstaff, Bradley Jon; Mueller, Ulrich G.; Begun, David J.DNA sequence data from male reproductive genes in numerous taxa have shown that these genes typically evolve more rapidly than other genes, often as a result of directional selection. In the genus Drosophila, the rapidly evolving male accessory gland protein genes (Acps) of melanogaster subgroup flies have contributed to this observation. Acps are small proteins that are transferred to females during mating as a major component of the seminal fluid and are considered agents of chemical communication between the sexes. Acps are known to contribute to normal ovulation and sperm storage, as well as increase oviposition rates and reduce female receptivity. Thus, Acps are considered likely targets of directional selection because of their potential roles in postcopulatory sexual selection and antagonistic coevolution between the sexes. Outside of melanogaster subgroup Acps, little is known about the evolutionary biology of male reproductive genes in Drosophila. For example, the male testis contains a richly diverse transcriptome but no studies have explored the evolutionary dynamics of a large set of testis-expressed genes. If clear differences in the evolutionary dynamics of different classes of male reproductive genes exist, empirical documentation of these differences will help identify the specific evolutionary forces at work. Additionally, mating systems differ between Drosophila species, potentially affecting the evolutionary dynamics of Acps across lineages. Comparative analyses of Acps from species with different mating systems are needed to address this issue. Finally, if Acps are generally rapidly evolving in Drosophila species, comparative analyses of orthology and Acp gene loss/gain are needed to determine how Acps respond to persistent directional selection across lineages. The data presented here aim to address these questions. Included are polymorphism and divergence data from 56 genes of Drosophila arizonae and D. mojavensis, repleta group species with mating systems that differ dramatically from melanogaster subgroup flies. The sample includes 19 Acps, 31 testis-expressed genes, and six more evenly expressed genes. Comparative genomics analyses of D. melanogaster-D. mojavensis male reproductive genes and D. melanogaster-D. pseudoobscura Acps are also presented to address questions of functional conservation across lineages.Item Function and regulation of CCAAT/enhancer binding protein beta in Leydig cell development and steroidogenesis(Texas Tech University, 2002-08) Nalbant, DemetPituitary luteinizing hormone (LH) is required for the development of multiple cell types in both the male and female reproductive systems. In particular, LH promotes differentiation of testicular Leydig cells and stimulates steroid production by Leydig cells in the testis, theca, granulosa and luteal cells in the ovary. We have been interested in identifying nuclear transcription factors that are targets of LH signaling pathways in Leydig cells and concentrated on CCAAT/enhancer binding protein beta (C/EBPp). Our initial studies showed that C/EBPp is expressed in a differentiation specific pattern whose expression is stimulated by LH/human chorionic gonadotropin (hCG) and cyclic AMP (cAMP) in Leydig cells. We hypothesized that C/EBPp plays an important role in LH regulated Leydig cell development and steroidogenic function. To assess the specific roles of C/EBPp in Leydig cell function we have analyzed the steroidogenic capacity of Leydig cells from C/EBPp-deficient mice generated by gene targeting. This study revealed that testosterone production in male C/EBPp deficient mice is severally compromised suggesting that C/EBPp is essential for complete functional differentiation of Leydig cells. In order to understand how LH effects on Leydig cell differentiation and/or function may be mediated through C/EBPp, we attempted to identify genetic control elements that control C/EBPp transcription in steroidogenic and non-steroidogenic cells. We identified an evolutionarily conserved, steroidogenic cell-specific, distal enhancer element located in the C/EBPp 5'-flanking region. Our studies suggest that the activity of the enhancer may be, at least in part, controlled by as yet uncharacterized nuclear factors specifically detected in nuclear extracts of steroidogenic cells. These studies set the stage for elucidation of the molecular mechanisms controlling C/EBPp expression in steroidogenic cells in general, and may aid in uncovering alternative LH-dependent signaling pathways critical for functional maturation of Leydig cells