The plant cell wall is a vitally important interface connecting plant cells to their outside environment and neighboring cells. Acting as a hub for defense, signaling, and physiological processes, the plant cell wall was a crucial innovation in plant evolution. Current cell wall models are largely based on what has been observed in plants like Arabidopsis, Pisum sativum, Nicotiana tabacum, and Phaseolus vulgaris. These models are unable to consider the variety of polymers in a given wall, the mechanical and functional properties such polymers impart, and the complexity of interactions among polymeric cell wall constituents. This work deepened the understanding of wall composition of specialized walls that fall outside of the scope of current plant cell wall models. A detailed survey of cell wall polymer distribution in the transfer cell walls in three key bryophyte species the model moss Physcomitrium patens, hornwort Phaeoceros carolinianus, and liverwort Marchantia polymorpha was done utilizing histochemical techniques in the light and florescent microscopes coupled with immunocytochemical localization with monoclonal antibodies (MAbs) in the transmission electron microscope (TEM). This work demonstrated that the occurrence, abundance, and types of polymers differ among taxa and between the two generations, are more influenced by developmental and life history needs than the similar function of the cells in individual taxa. A notable difference between generations was seen in M. polymorpha with the LM2 and JIM13 MAbs targeting AGP epitopes. However, findings in P patens appear to lack the differential labeling observed in both M. polymorpha and P. carolinianus. Using these same techniques, the walls and matrices involved in the process of spermatogenesis were examined in the moss P. patens and noted differences in abundance and location of cell wall polymers during sperm cell differentiation. Another notable finding of this work was that high concentrations of arabinose as components of AGP and pectins are important in the walls of P. patens during the process of spermatogenesis. The final study focused on utilizing herbarium specimens to explore the application of immunogold localization on dried collections of the moss Polytrichum up to 100 years old. The studies compiled in this dissertation demonstrate that the major cell wall components, cellulose, pectins, hemicelluloses, and callose, are constituents of special walls in three bryophytes, but they are differentially expressed within cell types and across these plants. Taken together, these works contribute significant new data on the composition of plant cell walls by focusing on bryophytes and the unique cell walls vital to the life history processes of spermatogenesis and placental function. These findings also show that both field-collected and herbarium samples are successfully labeled with MAbs at the TEM level, unlocking the potential for further studies across time and taxa using plant collections.

Male infertility is a significant public health problem. Although male factors are estimated to contribute to 50% of infertility, epidemiologic research on predictors of male infertility is scarce, and few modifiable risk factors have been identified. In particular, not much is known about the risk factors that determine semen quality in healthy males attempting to conceive. This dissertation uses data from Pregnancy Study Online (PRESTO), a preconception cohort of pregnancy planners residing in North America, to examine the role of several anthropometric and lifestyle exposures on semen quality. A subset of male participants provided data on semen volume, sperm concentration, and sperm motility using a novel in-home semen testing device. In the first study, we examined the effects of three anthropometric factors, body mass index (BMI), waist circumference, and weight gained since age 17 years, on semen quality. We found that men in the highest categories of BMI and waist circumference had poorer semen quality, particularly sperm concentration, motility, and total motile sperm count. Results were slightly stronger for waist circumference. Adult weight gain, however, was not appreciably associated with semen quality. Few studies have investigated the effect of marijuana use on semen quality. In the second paper we used PRESTO data to investigate the relationship between current marijuana use and semen parameters. We found that current male marijuana use was not appreciably associated with semen quality. Further control for potential confounders, including BMI, had little influence on the study results. In addition, results were similar among non-smokers of tobacco. The third paper focused on sugar-sweetened beverages (SSB) consumption and semen quality. We found that men who consumed higher quantities of SSB had poorer semen quality, particularly lower sperm concentration, total sperm count, and total motile sperm count. Adjustment for caffeine intake or current BMI had little effect on the results; however, the association between total SSB consumption was stronger among overweight and obese men. In conclusion, we observed that higher BMI and waist circumference were associated with decreased semen quality. In addition, increased sugar-sweetened beverage consumption may increase the risk of being classified as having low semen quality. Given that these exposures are common and modifiable, they may be important targets for public health interventions. / 2024-08-31T00:00:00Z

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Yao, Yao. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 131-151). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.

Further investigation of possible regulatory pathway of NYD-SP24 demonstrated that the cell cycle of NYD-SP24 overexpressing cells was incompletely blocked at G2/M phase, and one of cell cycle-related genes, p21, shown to be an inducer of differentiation in different types of cell system, was found upregulated in a p53-independent manner, consistent with a role of NYD-SP24 in differentiation. (Abstract shortened by UMI.) / Spermatogenesis is a unique cell differentiation process consisting of three main phrases, namely mitosis, meiosis and postmeiosis. The differentiation of germ cells in the process involves distinct transcriptional programs, each under control of different transcription factor network. Many testis-specific transcription factors have been reported previously, however, few detailed studies have been done. This thesis describes the characterization and functional studies of a newly discovered testis-specific transcription factor, NYD-SP24, and the investigation of the possible regulatory pathway of NYD-SP24 in spermatogenesis. / The results demonstrated that in normal human tissues, NYD-SP24 was specifically and highly expressed in the testis but not in other somatic tissues, indicating its possible role in spermatogenesis. In the mouse model, mRNA and protein of NYD-SP24 mouse homolog gene (mNYD-SP24) were increased in the first wave of spermatogenesis. During the differentiation of germ cells, mNYD-SP24 mRNA and protein were confined to spermatocyte, round spermatid and spermatozoa. In hyperthermic mouse model, expression of mNYD-SP24 was decreased following the damage to germ cells by heat shock, but returned to normal level upon recovery of spermatogenesis. These results suggest the involvement of NYD-SP24 in spermatogenesis. / To identify the possible downstream targets of NYD-SP24, microarray and two-dimension gel technologies were performed in NYD-SP24 overexpressing cells and control cells. The results of microarray showed that 16 genes were upregulated and 4 genes were downregulated in NYD-SP24 overexpressing cells. In the two-dimension gel analysis, 12 protein spots were found to be altered significantly, with 8 increased and 4 decreased. Among these proteins, 3 were successfully identified by mass spectrometry. The nuclei localization in germ cells and the ability of NYD-SP24 to alter gene expression profile suggest that NYD-SP24 may be a testis-specific transcription factor, involved in gene regulation in spermatogenesis. / Zhu Hu. / "June 2005." / Adviser: Chan Hsiao Chang. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3607. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 136-146). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

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BACKGROUND:The SPE-8 group gene products transduce the signal for spermatid activation initiated by extracellular zinc in C. elegans. Mutations in the spe-8 group genes result in hermaphrodite-derived spermatids that cannot activate to crawling spermatozoa, although spermatids from mutant males activate through a pathway induced by extracellular TRY-5 protease present in male seminal fluid.RESULTS:Here, we identify SPE-8 as a member of a large family of sperm-expressed non-receptor-like protein-tyrosine kinases. A rescuing SPE-8::GFP translational fusion reporter localizes to the plasma membrane in all spermatogenic cells from the primary spermatocyte stage through spermatids. Once spermatids become activated to spermatozoa, the reporter moves from the plasma membrane to the cytoplasm. Mutations in the spe-8 group genes spe-12, spe-19, and spe-27 disrupt localization of the reporter to the plasma membrane, while localization appears near normal in a spe-29 mutant background.CONCLUSIONS:These results suggest that the SPE-8 group proteins form a functional complex localized at the plasma membrane, and that SPE-8 is correctly positioned only when all members of the SPE-8 group are present, with the possible exception of SPE-29. Further, SPE-8 is released from the membrane when the activation signal is transduced into the spermatid.

published_or_final_version / Zoology / Doctoral / Doctor of Philosophy