This thesis describes attempts to investigate the regulation of the Candida albicans hyphal-specific gene HYR1 by a functional dissection of the HYR1 promoter, protein localisation studies and analysis of HYR1 expression in C. albicans morphological mutants. Sequencing of the HYR1 promoter revealed several putative cis-acting elements within 700 bp of the determined HYR1 transcriptional start site. The possibility of using the LAC4 gene from Kluyveromyces lactis as a reporter for dissection of the HYR1 promoter in C. albicans was investigated. Expression of LAC4 in S. cerevisiae and C. albicans was driven by the C. albicans ADH1 promoter. LAC4 expression was carbon-source-dependent in Saccharomyces cerevisiae as shown by a plate assay and -galactosidase assay, and was confirmed by northern analyses which showed high levels of LAC4 mRNA. However, -galactosidase activity was not detectable in C. albicans transformants using the plate assay or the enzyme assay, and this lack of LAC4 expression was confirmed by northern analysis of the LAC4 mRNA. Preliminary Southern analysis revealed that the LAC4 sequences in S. cerevisae and C. albicans are maintained at approximately equal copy numbers between transformants. Hence LAC4 was not sufficiently sensitive to act as reporter of HYR1 expression and therefore the recently developed yEGFP gene was used for a preliminary HYR1 promoter dissection. However, the HYR1 promoter-yEGFP fusions failed to confirm a role for these elements in the regulation of HYR1 expression . Nevertheless, the hyphal-specific nature of HYR1 expression was confirmed by analysis of the HYR1-yEGFP mRNA by northern analysis. The yEGFP reporter also proved to be too insensitive for use as a reporter of HYR1 expression in C. albicans. To investigate the proposed localisation of the Hyr1p, an in-frame Hyr1-yEGFP fusion was created and expressed in C. albicans and S. cerevisiae. However, this work was inconclusive and the status of Hyr1p as a component of the hyphal cell wall remains to be confirmed.

Estimating the sex of unknown human skeletal remains is important to the fields of forensic anthropology, bioarchaeology, and other specialties. I studied sexual dimorphism on the first and second ribs to estimate sex from skeletal remains. I employed two approaches. I used geometric morphometrics to analyze landmark and semilandmark coordinate points to examine the overall shape of the ribs. I also examined the sternal end of the ribs for size using the superior-inferior height (SIH) and anteriorposterior breadth (APB) in a binary logistic regression (BLR) model. Differences in male and female first and second ribs are undetectable when landmark coordinate points are used to capture shape variability, but significant differences in the shape of the ribs, however, are detected through the use of semilandmark coordinate points. Using semilandmark points to estimate sex presented an accuracy rate of 80.7% from the first rib, and 72.9% from the second rib. The use of the sternal end presents consistent results in its ability to estimate sex with an accuracy rate of 84.2%. The BLR model reveals significant differences between males and females than the geometric morphometric approach; it is more applicable for discerning sexual dimorphism of unknown individuals. This study reveals that while geometric morphometrics provides a powerful approach to assessing morphological differences, it is not always better than simpler methods, in this case, simple measurements analyzed through BLR. / Includes bibliography. / Thesis (M.A.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

My dissertation focuses on the factors that influence variation in female reproductive success in plethodontid salamanders and in toads. Variation in reproductive success fuels evolutionary change. Although, females often have been overlooked in studies of reproductive success due to perceived lower levels of variation when compared to variation in male reproductive success, understanding factors influencing variation in female reproductive success is critical for several reasons. First, female reproduction is usually the limiting factor on population growth. Second, the factors affecting female reproduction provide the impetus for current and evolving patterns of sexual dimorphism. Lastly, male reproductive success inevitably is determined by the reproductive success of the females with which they mate. Recent theoretical developments of sexual conflict have contributed significantly to a renewed emphasis on studies of female reproductive success. Sexual conflict theory elucidates important factors, from the perspective of females, affecting female behavior and reproductive success. Sexual conflict assumes that a female will benefit, in terms of reproductive success and offspring viability, when she is able to freely choose among males, unconstrained by social and environmental factors. Female choice would be constrained if a non-preferred male (i.e., one that would be rejected by a freely choosing female) coerced a female to mate in order to increase his own mating success. The dynamics between discriminating females and non-preferred males will lead to a coevolutionary "arms race", referred to as sexual conflict. From this perspective, secondary male traits may not reflect their intrinsic quality, but rather their ability to manipulate or coerce female mating decisions. The current debate lies in the importance and pervasiveness of sexual conflict. To address the current view of sexual conflict, I investigated whether sexual conflict plays a role in the mating systems of amphibians. In particular, my results support the main assumption that females benefit from freely expressed female mate choice in toads. In addition, I explored the potential influence of sexual conflict in plethodontid salamanders. During mating trials, I documented novel female courtship behaviors. I also examined the effects of male courtship pheromones on female reproductive success to assess the potential role of male pheromones in sexual conflict. My results suggest that sexual conflict also may be an important factor in plethodontid mating systems. My investigations of sexual conflict theory have provided new insights and novel predictions for understanding sexual selection and sexual dimorphism. / Graduation date: 2005

Thesis (Ph. D.)--University of Kentucky, 2004. / Includes abstract and vita. Includes bibliographical references (p. 191-198). Also available in PDF format via internet.

Thesis (Ph. D.)--University of Kentucky, 2004. / Title from document title page (viewed Sept. 10, 2004). Document formatted into pages; contains x, 203 p. : ill. Includes abstract and vita. Includes bibliographical references (p. 191-198).

Thesis (M. Sc.)--Carleton University, 1988. / Also available in electronic format on the Internet.

Secondary sex characters appear in many heterotardigrades and a limited number of species of eutardigrades. In the eutardigrades Milnesium tardigradum and Pseudobiotus megalonyx, males are considered to always have modified claws on the first pair of legs; the basal branch of both claws in Milnesium and of the inner claw in Pseudobiotus is shaped like a robust hook. We examined one gonochoristic population of both Milnesium tardigradum and of Pseudobiotus megalonyx to evaluate the association of the modified claws with the presence of male germ cells in the testis. Three additional populations of Milnesium tardigradum were examined to provide data on the frequency of the modified claw among all individuals. In both species, molting animals were found with normal claws on the front legs of the old cuticle and modified claws on the front legs of the new cuticle. Examination of the gonad revealed that both species may have males with and without the modified claws. The appearance of the modified claw probably occurs at the last molt, and is used in mating when the male attaches to the female during copulation. Since this secondary sex character is not always present during the life of the tardigrade, but appears after a molt, a sex ratio determined only by the presence of the modified claw is not valid.

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Thesis (Ph.D.)--York University, 2003. Graduate Programme in Biology. / Typescript. Includes bibliographical references. Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNQ99195