During vertebrate oocyte maturation, the chromosomes progress to and arrest at metaphase of meiosis II in preparation for fertilization. This process includes emission of the first polar body. The second polar body is emitted after fertilization. A number of proteins are accumulated during oocyte maturation. Inhibition of this de novo translation does not appear to affect the progression of meiosis during oocyte maturation. The role of these pools of proteins has yet to be elucidated. Curiously, several of the upregulated proteins are key players in mitosis, including INCENP, a subunit of the chromosome passenger complex implicated in chromosome segregation and cytokinesis. During early stages of development in Xenopus laevis, the embryo cycles through mitosis, also known as embryo cleavage, every 30min with little to no time for transcription/translation. Our goal is to determine if the de novo translation of these mitotic proteins during oocyte maturation has a role in early embryogenesis. We used morpholino oligonucleotides antisense to INCENP mRNA (INCENPmorpho) to inhibit de novo translation during oocyte maturation. Using confocal imaging and the host transfer technique, these injected oocytes were matured, fertilized and assessed for developmental competency. INCENPmorpho and a control morpholino (ctrlmorpho) had no discernable effect on 1st or 2nd polar body emission. Whereas ctrlmorpho embryos developed normally, INCENPmorpho embryos did not cleave. Thus, de novo translation of INCENP during oocyte maturation is necessary for embryogenesis. Specifically, accumulation of INCENP and other mitotic proteins during oocyte maturation may be a common strategy in this species to prepare for the rapid and synchronous mitoses during early embryogenesis.

Thesis (Ed. D.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains v, 116 p. Includes abstract. Includes bibliographical references (p. 62-79).

Thesis (Ph. D.)--University of Chicago, Committee on Human Development, August 2003. / Includes bibliographical references. Also available on the Internet.

Thesis (Ed. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 68-74). Also available on the Internet.

Thesis (Ed. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 68-74). Also available on the Internet.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(農学) / 甲第19026号 / 農博第2104号 / 新制||農||1030 / 31977 / 京都大学大学院農学研究科応用生物科学専攻 / (主査)教授 今井 裕, 教授 久米 新一, 教授 松井 徹 / 学位規則第4条第1項該当

Many factors such as rift history, crustal structure and distribution of high thermal conductivity salt bodies throughout the sediment pile affect the present day thermal structure of the deepwater Scotian Slope. Understanding the basin's thermal evolution is crucial in determining the hydrocarbon maturation potential of this deepwater frontier basin. The Late Jurassic Verrill Canyon Formation of the deepwater slope has been inferred as the primary source rock interval for the Scotian Basin. However, to date, only twelve boreholes have sampled the Scotian Slope, and of these, none penetrate beneath the uppermost Jurassic sediments. Therefore, the distribution and maturation of deeper source rock intervals through standard vitrinite reflectance analysis remains unknown. In this study we attempt to better constrain the thermal history and maturation potential of the central Scotian Slope using a combination of recently acquired seafloor heat flow data, 2D seismic reflection data, available well data, simple lithospheric rift models and 3D thermal and petroleum systems modelling. We have derived a method of combining seafloor heat flow data with simple lithospheric rift models to provide first order constraints on the hydrocarbon maturation potential of frontier basins in dynamic 3D thermal models for regions lacking vitrinite reflectance and temperature data from boreholes. In July 2008, 47 seafloor heat flow measurements were acquired across the central Scotian Slope in an attempt to better constrain the region's thermal structure. Locations seaward of the salt diapiric province, thus unaffected by the high thermal conductivity of salt, recorded seafloor heat flow values of ~41-46 mWm-2. Significant increases in seafloor heat flow were noted for stations overlying salt diapiric structures, reaching values upwards of 72 mWm-2. The seafloor heat flow data have been corrected to remove the conductive effects of salt and the cooling effects of seafloor sedimentation on measured heat flow. The corrected data are compared with basal heat flux predictions from simple lithospheric rift models as constrained using crustal ( ) and lithospheric ( ) stretching factors after Wu (2007) to constrain heat flux history through time. Seafloor heat flow and simple modelling results suggest present day basal heat flux does not vary significantly across the slope. Present day basal heat flux across the central Scotian Slope is ~44-46 mWm-2. Basal heat flux curves from simple lithospheric rift models are used to constrain the heat flux history in 3D thermal and petroleum systems models of the central Scotian Slope. Numerous basal heat flux histories were tested to determine which heat flux history yielded the best match between modelled and measured seafloor heat flow data and to determine how varying basal heat flux affects the modelled hydrocarbon maturation of Verrill Canyon source rocks. The basal heat flux history which yielded the best match to measured seafloor heat flow data suggests that the Late Jurassic source rock interval rests primarily within the late oil window. Variations in radiogenic heat production across the margin associated with thickening continental crust were tested and suggest that significant variations in both maturation and seafloor heat flow may occur if radiogenic heat producing elements occur in high enough concentrations in the crust.

Economic viability of Fraser River, Labrador Arctic charr (Salvelinus alpinus) aquaculture in Atlantic Canada may be greatly improved if grow-out could be completed in seawater (30 ppt), while having a low incidence of sexual maturation before harvesting. Growth and survival in seawater was investigated among individually PIT-tagged Arctic charr reared in tanks in the laboratory. Direct transfer from freshwater to brackish water (20 ppt), and then acclimation to 30 ppt was successful. The manipulation of photoperiod, temperature, and food ration can be used as practical applications in aquaculture to arrest maturation; this was investigated in two additional experiments. The most effective photoperiod was LD18:6 for 6 weeks starting December 21, which reduced maturation to 43% compared to 78% in controls. Restricted ration from December 21 through March 15 had no effect on maturation, however, rearing females in 5°C compared to 10°C reduced maturation to 15% compared to >80% in controls.

Co-variation in the genetic architecture, and co-localization of quantitative trait loci (QTL), for embryonic developmental rate and age at maturation in male rainbow trout (Oncorhynchus mykiss) was examined. Two lots (September and December spawning) of 2 x 5 (male x female) diallel crosses were performed and the resulting progeny were raised to maturity. Higher incidences of precocious maturation were observed in the September lot fish compared to December lot fish, which was uncoupled to developmental rate. However, precocious maturation and body size was higher in early hatching December lot fish. A genome scan was also completed across 4 linkage groups previously reported to possess embryonic developmental rate QTL and/or age at maturation QTL. No evidence of co-localization of QTL for the two traits was detected. However, the presence of QTL for embryonic developmental rate on RT-8 and RT-24 and one for age at maturation on RT-17 supports previous results.

Oocyte maturation and ovulation are two major events that occur in fish prior to spawning. While earlier studies have shown that 17α, 20β-dihydroxy-4-pregnen-3-one (17,20β-P) and the insulin-like growth factor (IGF) system are regulators of oocyte maturation in the zebrafish (Danio rerio), it is not known whether these hormones play a role in regulating prostaglandin synthesis which is thought to mediate ovulation. I determined if 17,20β-P and human IGF-1 affect the expression of genes involved in prostaglandin biosynthesis including phospholipase A2 (cpla2) and cyclooxygenase-1/2 (ptgs1/ptgs2), or prostaglandin F2α (PGF2α) levels. 17,20β-P and IGF-1 stimulated oocyte maturation in mid-vitellogenic (MV) and full grown (FG) follicles. In FG follicles, 17,20β-P increased cpla2 expression, whereas IGF-1 increased cpla2 and ptgs2 expression. Both 17,20β-P and IGF-1 increased PGF2α production. The phosphatidylinositol 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) signalling pathways were shown to mediate IGF-1- and 17,20β-P-induced oocyte maturation and cpla2 and ptgs2 expression. Collectively, these results demonstrate that 17,20β-P and IGFs are important regulators of oocyte maturation and prostaglandin synthesis in zebrafish.