The effect of intestinal microbiota and dietary supplementation of mannan oligosaccharides (MOS) on mucosal architecture and digestive physiology in broiler chicks was examined. In experiment 1, pre-sterilized eggs (Ross x Ross 308) were placed in three HEPA (high efficiency particulate air)-filtered isolator units at day 19 of incubation. Germ-free chicks in one isolator were conventionalized by exposure to cecal contents from a laying hen. Bacterial contamination occurred in one germ-free isolator such that these birds were monoassociated by a bacterium within the Acinetobacter spp. resulting in 3 categories of microbial status including germ-free (GF, n=10), conventionalized (CV, n=19) and monoassociated (Mono, n=13) birds. Dietary treatments assigned to each isolator consisted of a negative control (NC, 0 g/kg of MOS in the basal diet) and MOS (2 g/kg of MOS in the diet) resulting in a 2X3 factorial treatment arrangement. At 7 d of age, body weight was recorded and birds were killed to permit collection of visceral organs, intestinal tissues and cecal contents. Body weight, relative length of small intestinal segments and relative bursa weight were significantly increased in CV birds. These birds also had increased crypt depth and lamina propria area. Dietary MOS increased villus height and villus surface area in CV birds compared with GF and Mono birds. Transcripts for all housekeeping genes tested in ileal tissue were increased by MOS such that transcripts were normalized to unit mass of total RNA. In comparison to birds fed the NC diet, MOS significantly increased the abundance of proliferative cell nuclear antigen (PCNA), toll-like receptor (TLR)-4, avian β-defensin (GAL)-6, interleukin (IL)-8, peptide transporter 1 (PepT1) and sodium-dependent glucose transporter (SGLT)-1 transcripts in ileum per unit total RNA. However, the effect of microbial status on selected gene expression profiles was surprisingly limited. A second experiment was conducted to confirm the conventionalization protocol produced a complex microbiota similar to conventionally reared birds. Twenty day-old broiler chicks (Ross x Ross 308) were assigned to one of two wire-floored battery cages provided the NC and MOS diets ad libitum and killed at 7 d of age. Terminal restriction fragment length polymorphism (TRFLP) analysis demonstrated that microbial diversity indices (Richness, Evenness, Shannon, and Simpson) were greater in conventionalized gnotobiotic birds compared to the conventionally reared birds confirming a successful conventionalization strategy in the gnotobiotic trial. These studies demonstrate that under good hygienic conditions, CV chicks thrive similar to GF animals. Based on responses to MOS observed in GF birds, evidence indicates that MOS, independent of changes in microbial composition, directly modifies host response parameters including innate immune activation, digestive and absorptive function.

Pennisetum Rich, is one of the most important genera in the family Poaceae because it includes forage and crop species such as Pennisetum purpureum Schumach. and Pennisetum glaucum (L.) R. Br. Both P. purpureum and P. glaucum have a number of cultivars and varieties arising due to natural crossing which are very difficult to distinguish morphologically. P. purpureum and P. glaucum also hybridize naturally because they are protogynous and cross pollinated. The resulting hybrids are highly sterile and resemble P. purpureum. Lepidopteran stem borers cause great yield loss in maize produced by resource-poor farmers in Africa and are managed by habitat management or push-pull strategies, in which P. purpureum cultivars and hybrids are used as a trap crop. The aims of this project were to genotype different P. purpureum cultivars and hybrids using Amplified Fragment Length Polymorphism (AFLP) as well as Random Amplified Polymorphic DNA (RAPD) in order to identify cultivars and hybrids and possible misidentifications, assess the congruency of results between AFLPs and RAPDs and to attempt to relate these results to the oviposition preference of Chilo partellus for different P. purpureum cultivars. The individuals to be fingerprinted were collected from several countries in sub-Saharan Africa, a few from the USA and one from China. The AFLP analysis of these individuals were done with primer combinations EcoRI/MseI and Mlul/Msel on polyacrylamide gels and an ABI 3130 xl Genetic Analyzer respectively. The automated sequencer visualized more bands than the polyacrylamide gels. The RAPD technology was not developed any further after 17 primers were tested and no polymorphic bands detected. Overall results indicated that cultivars did not cluster according to geographical origin, and cultivars known by popular names did not always cluster together, indicating diversity within the cultivar or misidentifications. An example of a misidentification is the cultivar Green Gold being no other than cultivar Harare, or cultivar Swaziland 3 being cultivar Sanitas. Proper management by nursery managers cannot be stressed enough, as this will prevent plants getting mixed up, causing confusion. There was no relationship between the relatedness of cultivars and moth oviposition preference. The AFLP technology could be a powerful tool for the DNA fingerprinting and molecular characterization of this grass species, but poor germ plasm management negates its application. / Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2008.

In most animals, oogenesis involves a syncytial “cyst” stage. Cysts are produced by incomplete mitotic divisions of gonial precursor cells, leaving the resulting cystocytes interconnected by cytoplasmic bridges. The bridges subsequently break down, liberating the developing gametes. In some animals (e.g. meroistic insects) cysts are “polarized”, such that certain cystocytes differentiate as supportive nurse cells, rather than oocytes. The variability of cysts in animal oogenesis contrasts with the relative universality of spermatogenic cysts, making the functional importance of cysts in oogenesis unclear. I have studied oogenesis in a polychaete worm, Ophryotrocha labronica (Annelida: Dorvilleidae). These worms produce polarized, two-celled oogenic cysts with one nurse cell and one oocyte. Such cysts resemble their better-characterized counterparts in meroistic insects. However, using a variety of light- and electron-microscopic techniques, I show here that the resemblance between O. labronica and meroistic insects is largely superficial. Rather, the roles of nurse cells and the mechanisms underlying cystocyte differentiation are quite distinct in both groups. Therefore, similarities between these polychaetes and insects are probably examples of convergent evolution rather than homology. These observations underscore the plasticity of oogenesis among animals. Mechanisms by which germ cells become distinct from somatic cells in animals are also a subject of considerable research activity. Two general modes of germ-cell specification have been described in animals: deterministic specification, which is typical of established model species (e.g., Drosophila melanogaster and Caenorhabditis elegans) and inductive specification, which, though it is the more-common mode among animals, has not been well studied. As an annelid worm, O. labronica likely specifies its germ cells inductively, and therefore has potential to serve as a model species for studies of inductive germ cell specification. Realizing this potential, however, will require the development of genetic resources for this species. I describe the beginnings of such work here: the isolation and characterization of a vasa/PL10-like gene whose expression is largely restricted to germ cells, the construction of a cDNA library, and the refinement of methods for in situ hybridization and immunostaining to visualize gene expression in whole worms.

Pennisetum Rich, is one of the most important genera in the family Poaceae because it includes forage and crop species such as Pennisetum purpureum Schumach. and Pennisetum glaucum (L.) R. Br. Both P. purpureum and P. glaucum have a number of cultivars and varieties arising due to natural crossing which are very difficult to distinguish morphologically. P. purpureum and P. glaucum also hybridize naturally because they are protogynous and cross pollinated. The resulting hybrids are highly sterile and resemble P. purpureum. Lepidopteran stem borers cause great yield loss in maize produced by resource-poor farmers in Africa and are managed by habitat management or push-pull strategies, in which P. purpureum cultivars and hybrids are used as a trap crop. The aims of this project were to genotype different P. purpureum cultivars and hybrids using Amplified Fragment Length Polymorphism (AFLP) as well as Random Amplified Polymorphic DNA (RAPD) in order to identify cultivars and hybrids and possible misidentifications, assess the congruency of results between AFLPs and RAPDs and to attempt to relate these results to the oviposition preference of Chilo partellus for different P. purpureum cultivars. The individuals to be fingerprinted were collected from several countries in sub-Saharan Africa, a few from the USA and one from China. The AFLP analysis of these individuals were done with primer combinations EcoRI/MseI and Mlul/Msel on polyacrylamide gels and an ABI 3130 xl Genetic Analyzer respectively. The automated sequencer visualized more bands than the polyacrylamide gels. The RAPD technology was not developed any further after 17 primers were tested and no polymorphic bands detected. Overall results indicated that cultivars did not cluster according to geographical origin, and cultivars known by popular names did not always cluster together, indicating diversity within the cultivar or misidentifications. An example of a misidentification is the cultivar Green Gold being no other than cultivar Harare, or cultivar Swaziland 3 being cultivar Sanitas. Proper management by nursery managers cannot be stressed enough, as this will prevent plants getting mixed up, causing confusion. There was no relationship between the relatedness of cultivars and moth oviposition preference. The AFLP technology could be a powerful tool for the DNA fingerprinting and molecular characterization of this grass species, but poor germ plasm management negates its application. / Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2008.

The role of male germ cell death in spermatogenesis is an important one as it removes dysfunctional or genetically damaged germ cells and is necessary to maintain an optimal germ cell to Sertoli cell ratio. The formation of the bloodtestis barrier requires the elimination of excessive germ cells and a surge of germ cell apoptosis occurs prior to puberty regulating the ratio of germ cells to Sertoli cells. The aim of this study was to evaluate the presence of four apoptotic markers on sperm from patients with various grades of fertility using flow cytometry. Furthermore, any correlations between the apoptotic marker assays and the standard semen analysis results were identified. This study compares early and late parameters of apoptosis with morphological features in spermatozoa in the same samples. The three sample groups were identified as: teratozoospermic [G-pattern] (n=26), teratozoospermic [P-pattern] (n=98) and oligoteratozoospermic [Ppattern] (n=36). Standard semen analysis was conducted on the semen samples according to the WHO guidelines. Four apoptotic marker assays using flow cytometry was applied in this study to examine the apoptotic alterations in ejaculate sperm. These assays included the Annexin-V staining for the determination of phosphatidylserine exposure, APO-Direct to identify DNA fragmentation, caspase-3 to detect expression of this active protease during early apoptosis and Fas expression. For the Annexin-V and caspase-3 assays, statistically significant differences (P&lt / 0.05) were evident between the three groups. No significant differences (P&gt / 0.05) were found between the groups with respect to the APO-Direct assay. A significant difference (P&lt / 0.05) was found when comparing the teratozoospermic [G-pattern] group and the oligoteratozoospermic [P-pattern] group for the Fas assay. A strong positive correlation was evident between the Fas and the caspase-3 assays in the teratozoospermic [G-pattern] group. For the teratozoospermic [P-pattern group] the following positive correlations existed between the APO-Direct and the Fas assays, APO-Direct and caspase-3 assays and between caspase-3 and Fas assays. The only strong positive correlation was between the caspase-3 and APO-Direct assays in the oligoteratozoospermic [P-pattern] group. The presence of spermatozoa showing microscopic features resembling apoptosis has been identified in ten human ejaculate samples per sample group. Electron microscopy was used to identify morphological features of apoptosis in these human sperm samples. Classical apoptosis as observed in diploid cells could be identified in sperm and these included: loose fibrillarmicrogranular chromatin network, presence of vacuoles in the nuclear chromatin, membranous bodies within the vacuoles of the chromatin, partially disrupted nuclear membranes, plasma membrane protuberances and apoptotic bodies containing cytoplasmic vacuoles and dense masses. This study has confirmed that semen samples with abnormal semen parameters exhibit the presence of apoptotic markers in sperm. The identification of apoptotic markers on the sperm suggests that abnormalities occur during their developmental process, however, the exact mechanism thereof remains unclear. These findings may suggest that certain apoptotic markers may be an indicator of abnormal sperm function and possibly indicative of male infertility.

Copies of author's previously published articles inserted. / Bibliography: p. 199-254. / xii, 254 p., [34] leaves, [30] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / In eutherian mammals, the size of the testes and number of spermatozoa produced and stored in the excurrent ducts vary widely between species, with the hydromyine rodents of Australia exhibiting a greater range of interspecific variation than any other closely related group of species. This study compared the efficiency of germ cell production and sperm storage capacity in the extra-testicular ducts of two arid zone species, the plains rat, Pseudomys australis, and the spinifex hopping mouse, Notomys alexis, that have vast differences in testes size and number of stored spermatozoa. Results are discussed. / Thesis (Ph.D.)--University of Adelaide, Dept. of Anatomical Science, 2000

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Includes bibliographical references (leaf 138-155) Also available in print.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Includes bibliographical references (leaf 138-155) Also available online.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 76-86).