Prior research has focused on studying female fertility, but male fertility remains overlooked. Using data from the 2001 Demographic Yearbook, the 1964 to 2002 Taiwan-Fukien Demographic Yearbooks, the 2004 National Statistics Reports and the 2002 National Survey of Family Growth (NSFG) Cycle 6, this dissertation examines male and female fertility at the aggregate and individual levels by studying men’s and women’s fertility differentials in rates and in determinants. Based on examining the age-specific fertility rates (ASFRs) and the total fertility rates (TFRs) for men and women during the 1990 to 1998 period in 43 countries and places, results show that male and female age-specific fertility mainly differs in the older age groups. In those age groups, male fertility largely outnumbers female fertility. And this pattern is especially apparent in low fertility countries (TFR<2,200). With regard to total fertility, male and female TFRs tend to be similar in countries with TFR values lower than 2,200 where female fertility tends to be higher than male fertility. The opposite pattern is true for countries with male and female TFRs higher than 2,200. In the analysis of Taiwan fertility, results reveal that male and female TFRs for most years during 1975 to 2004 are far from identical. The ASFRs for men and women also differed over time and varied by educational attainment. Although fertility determinants at the aggregate level impact men’s and women’s fertility similarly, models combining these factors are more powerful when explaining female than male fertility. The individual level analyses of the U.S. samples also show significant fertility differentials by gender. Age, marriage, and Hispanic origin increase men’s fertility to a greater extent compared to women’s fertility. Family income increases men’s fertility but decreases women’s fertility. Participating in the labor force shows a much stronger positive effect on male than on female childbearing. Cohabitation experience, however, has a significantly stronger impact increasing women’s than men’s fertility. And an increased number of sexual partners is more likely to reduce men’s children compared to women. These findings reported draw research attention to male fertility and contribute to understanding the dynamics of male fertility.

A number of genes have been associated with variation in human spermatogenesis related to fertility. One of these, the Deleted in Azoospermia (DAZ) gene, exists as copies on two chromosomes, 3 and Y. The autosomal copy, DAZ-like (DAZL), has one RNA recognition motif (RRM) and is homologous to the DAZL gene found throughout the vertebrate lineage. There are four copies of DAZ on the Y chromosome with a pair at each of two sites. One pair contains a single RRM and the other has three RRMs. Human DAZ is homologous to genes in old world primates and ape Y chromosomes. Both DAZ and DAZL bind messenger RNAs at U-rich sequences near the poly-A tail in a manner that facilitates translation. Both are expressed in spermatogonia during the transition from mitotic cellular expansion through meiotic chromosomal reduction and during spermiogenesis. This study examined genomic variation in DAZ and DAZL, including deletion of DAZ from individuals with various levels of sperm cell production and mutations of DAZL in male partners of infertile couples. Deletions in DAZ are not as common in azoospermic men from central Texas as compared to other reports. Single nucleotide polymorphisms (SNPs) were identified in anonymous infertility patients, but were not located in the exons of the RRM. Proteins produced from transcripts encoded by genes from human DAZL, DAZL with SNPs within and outside the RRM, and a DAZ with single RRM were identified. Binding activity of DAZL to mRNA was confirmed using a microarray method, and mRNA from human testes was screened to identify at least 1,313 mRNA potential targets for DAZL. These targets were involved in ribosome construction, pyruvate metabolism, cell cycle control, and proteasome function. Variations in binding of protein to a high and a low bound target mRNA were demonstrated between protein constructs of DAZL, DAZL with mutations, and DAZ. Binding of DAZL to mRNA was also confirmed using electrophoretic mobility shift assays. With materials and procedures developed during this study, comparisons of genetic variants of DAZ and DAZL can be performed to identify mechanisms responsible for structural and functional differences in control of spermatogenesis.

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Environmental pollution and its effect on the living organisms has attracted lots of attention recently. There is a growing body of evidence that we are exposed to environmental pollutants at low concentrations in everyday life. The cells and organisms have tools to identify, neutralize and excrete the majority of the toxic compounds. The most dangerous are those that can escape this process or act at low trace concentrations. Endocrine disruptors (EDs) belong to the latter group. Endocrine disruptors can be of natural and anthropogenic origin. EDs target corresponding hormonal receptors and can act at low concentrations. A wide family of nuclear receptors recognize steroid hormones. The majority of EDs can pass through the cytoplasmic membrane, use the hydrophobic nature of the receptor-ligand binding, trigger hormone response and change the expression of the sensitive genes. By interfering with estrogen and androgen signaling, EDs can have effect on the whole organism, but the reproductive system is influenced most. In the present work, our aim was to develop the methods for ED detection and monitoring, analyze the estrogenic potency of EDs, and evaluate the effects of natural estrogens and EDs on male reproductive functions, including sperm and testicular physiology and endocrine functions. First, we...

NMES1 is a gene of unknown function first characterized in 2002. Reduction of the expression of this gene has been implicated in skin tumorigenesis in mice. Expression of NMES1 is observed in epithelial tissue but expression in the testis is significantly higher than in epidermis. Because stallion fertility is an economically important trait, we decided to characterize the NMES1 gene in stallions. We screened the CHORI241 library and obtained the full length equine NMES1 genomic sequence by direct sequencing off of clone CH241-11J8. In order to experimentally determine the 5’ and 3’ untranslated regions (UTRs) we conducted RLM-RACE experiments using stallion testis RNA. The equine NMES1 mRNA is 534 nt long and contains 5 exons. Fluorescence in situ hybridization mapped NMES1 to chromosome Eca1q23. In situ experiments to testis tissue sections were inconclusive and yielded no data confirming the physical expression pattern of NMES1 in stallion testis tissue. In order to determine the expression pattern of NMES1 mRNA we conducted qRT-PCR assays on a panel of stallion testis samples from horses with normal and abnormal fertility. We found that expression was variable among both groups, with significantly less expression in some individuals. We also conducted the qRT-PCR assay on a panel of five equine tissues and found that the expression of NMES1 was more than 100-fold greater in testis than in other tissues examined. miR-147b is a miRNA of unknown target found within the 3’ UTR of NMES1. We conducted a miRNA qRT-PCR assay to determine the expression levels in stallion testis samples from fertile and sub-fertile stallions. We observed similar expression among both groups and the ratio of mRNA to miRNA did not appear constant. We also investigated miR-147b expression in a panel of five equine tissues and found that equine spleen had more than 8-fold greater expression than testis.

In this dissertation I investigate whether or not a series of social, demographic, and cultural factors affect fertility differently, in either direction or magnitude, for men and women. This work situates the study of male fertility within the existing demographic literature, models and compares male and female fertility through the use of a variety of dependent and independent variables, discovers which of those variables reveal a difference between the determinants of male and female fertility, and extends understanding of how male fertility should be studied in addition to and alongside female fertility. Although there is a significant literature on the biological and anatomic components of male fertility, there is little work published on the social and cultural factors that affect male fertility. Comparisons of male and female fertility are also lacking within the discipline of demography. The National Survey of Family Growth (Cycle 7) provides survey data on both men and women on a number of social, cultural, and demographic variables used either on their own, or as components in the construction of indicator variables. I present the results of models utilizing both direct and indirect measures of fertility. Three models are direct measures of fertility, and three other indirect models examine behaviors as a measure of exposure to the risk of fertility. Only four of these models were significant under the initial analysis. Within each of the models, the respondent’s age, poverty level, age at first intercourse, and whether the respondent ever married or cohabited presented the most frequent differences, in either direction, magnitude, or both, between males and females. I discuss the implications of the findings presented in the dissertation, as well as the potential for future research using other data or methods.

Apyrases (NTP-diphosphohydrolases, EC 3.6.1.5) are a family of enzymes that catalyze the hydrolysis of phosphoanhydride bonds of nucleoside tri- and di- phosphates in the presence of divalent cations. In Arabidopsis, AtAPY1 and AtAPY2 function in part as ectoapyrases and have been shown to play important roles in controlling the concentration of extracellular nucleotides, which, in turn, can regulate pollen germination and growth, and cell expansion in diverse plant tissues. We used an NCBI nucleotide blast keyed to Apyrase Conserved Regions (ACRs) to identify five other AtAPYs (3-7). To assess the biological function of each of these five AtAPY genes, the phenotypes of their T-DNA insertion mutants were analyzed. We did not observe any obvious phenotypes from the T-DNA insertion single knockout of any of these genes. However, double knockout mutants of AtAPY6 and 7 exhibited late anther dehiscence and low male fertility. Transmission and scanning electron microscopy revealed that the pollen grains of double knockout mutant of AtAPY6 and 7 are largely deformed in shape and in most cases, the cell walls of the pollen grains are interconnected. Using an AtAPY6-YFP fusion protein in transgenic Arabidopsis, AtAPY6 was localized to intracellular vesicles. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) assays and promoter:GUS fusion analysis demonstrated that the transcripts of both AtAPY6 and 7 are expressed in mature pollen grains, AtAPY6 is also expressed in the veins and hydathode regions of rosette leaves, and AtAPY7 is expressed in more diverse tissues such as roots, leaves, stems, pistils and sepals. The tissue specificity of AtAPYs 3, 4 and 5 expression was also determined using qRT-PCR assays and promoter:GUS fusion analysis. AtAPY3 and AtAPY4 were primarily expressed in roots but not in rosette leaves. AtAPY5 was expressed primarily in rosette leaves but only weakly in roots. AtAPY5 and AtAPY7 were upregulated when the rosette leaves are wounded or exposed to drought stress. RNA interference (RNAi) was performed to simultaneously suppress the gene expression of AtAPYs 3, 4, 5 to around 10% of that of the wild type. However, we did not observe any obviously altered phenotypes in the RNAi lines. The suppression of AtAPYs 3, 4, 5 by RNAi in the background of AtAPY6 single knockout did not cause any phenotype either. A possible explanation for this lack of phenotype in the RNAi lines is that functional redundancy exists between AtAPYs 3-5 and AtAPYs 1-2 and/or AtAPYs 6-7. / text

Magister Scientiae - MSc / Male infertility in humans has increased in the last few decades and could be as high as 40%, while up to 50% of these men have ''unexplained'' (idiopathic) infertility. Although newly developed molecular techniques have great value in detecting subtle causes of male infertility, more detailed sperm functional tests are required to identify compromised fertility, especially in a clinical set-up. Since ethical constraints often preclude the pursuit of many basic research questions in humans, non-human primates (NHPs) have been identified as key models in human-related studies. NHPs are often used in studies on male fertility/infertility, IVF or assisted reproductive technology (ART) procedures, male contraception and reproductive toxicology. However, comparing results of NHP and human studies require that techniques used for assessment must be objective, standardized and sensitive to recognize compromised sperm function. The aim of this study was to evaluate standard sperm functional tests and develop new functional tests using NHP sperm, specifically from vervet monkeys (Chlorocebus aethiops), chacma baboons (Papio ursinus) and rhesus monkeys (Macaca mulatta), for application in human and NHP studies and to ultimately develop a basic primate model. The sperm functions investigated included sperm motility, longevity, vitality, DNA integrity, acrosome reaction, and hyperactivation. The sperm functional tests evaluated were: CASA motility analysis; Sperm Longevity test; Eosin-Nigrosin and Hoechst and Propidium Iodide staining, as well as the use of WST-1 cytotoxicity assay for vitality; the TUNEL assay for DNA integrity; Acrosome Intactness Test; and induction of hyperactivation via stimulants. The validity of each test was investigated by inhibiting sperm function through the use of copper sulphate and cadmium chloride. All functional tests were successfully performed across all three species, except the TUNEL assay for DNA integrity, and was further used for validation testing. Validation testing proved that all sperm functional parameters were significantly affected by the highest concentrations of the chemicals (250 µg/ml CuSO4 and 500 µg/ml CdCl2) and if not significant, trends of reduction were seen. The tests employed were therefore sensitive to the inhibitory effect of the metals. By evaluating these established sperm functional tests we found that primates would serve as good models for research study. Furthermore, we optimized and modified techniques for sperm and functional analysis in these three primate species and this study will standardize protocols for use in future studies on male infertility. Additionally, comparing human and NHP sperm function can possibly reveal or explain the high infertility rates in humans.