Thesis (M.S.)--Virginia Polytechnic Institute and State University, 2001. / Title from PDF t.p. (viewed Dec. 17, 2005). Vita. Includes bibliographical references (p. 33-41).

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 2001. / Title from PDF t.p. (viewed on Dec. 11, 2005). Vita. Includes bibliographical references.

The work presented in this dissertation examines possible modes of action for growth inhibition by anthropogenic endocrine disrupting chemicals (EDCs) as well as endogenous hormones associated with growth in fish. Using the sheepshead minnow (SHM) (Cyprinodon variegatus) as a model, I developed methods to examine perturbations in the endocrine axis controlling fish growth, and also examined effects of EDCs on the whole fish. I used two relatively new techniques to study the endocrine growth axis, quantitative real-time PCR (TaqMan) and differential display analysis. TaqMan analysis is a highly sensitive method to measure specific sequences from a small amount of total RNA using a fluorescent probe and specific primer pairs. I optimized a TaqMan assay for SHM IGF-I to measure hepatic IGF-I mRNA concentrations. in fish injected with hormones known to influence fish growth (GH, T���, E���, insulin, or a carrier control). IGF-I mRNA levels increased in fish injected with GH, T��� and insulin, peaking at 12 h post-injection. IGF-I mRNA levels decreased significantly at 8 h and 12 h post-injection in fish injected with E���, suggesting that pharmacological levels of E��� may affect the GH/IGF-I axis and could have consequences for fish living in waters polluted by EDCs. Differences in growth were observed in fish exposed for 18 weeks to E��� or chlorpyrifos (an organophsophate). Fish exposed to the highest dose of E��� grew larger than controls only during the last week of the experiment. Fish exposed to the lower dose of E��� were not significantly different from controls. The fish exposed to all doses of chloryprifos grew significantly less than controls in a dose-dependent manner. No significant differences were found in hepatic IGF-I mRNA levels in any treatments. To establish patterns of gene up- or down-regulation, I performed differential display analysis on livers of several fish from the previous two experiments. Several genes were identified as being similar to fish including a microsatellite sequence, a choriogenin (vitelline envelope) protein mRNA sequence, a transferrin mRNA sequence and several ribosomal RNA sequences. This technique to evaluate gene expression will become more useful when more fish genes are added to the data bases. / Graduation date: 2003

Thesis (M. Sc.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on June 18, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Ecology, Department of Biological Sciences, University of Alberta. Includes bibliographical references.

Thesis (M.S. in genetics and cell biology)--Washington State University, May 2008. / Includes bibliographical references (p. 29-32).

Thesis (M.S.)--Oregon State University, 1986. / Typescript (photocopy). Includes bibliographical references (leaves 50-55). Also available on the World Wide Web.

Following a study of normal reproductive behavior of fathead minnows, Pimephales promelas, experiments were conducted to determine the stability/variability of behavior by sexually mature, territorial males under a variety of manipulated conditions. Collectively, these experiments indicate that although the individual behaviors of fathead minnows appear to be quite variable, the overall process, reproductive behavior, is stable.

Adequate levels of dissolved oxygen (DO) are essential to the health of most aquatic organisms. While diel fluctuations in DO concentration are a normal occurrence in aquatic ecosystems, anthropogenically-produced periods of prolonged hypoxia have the potential to cause changes in growth, reproduction and behaviour in animals. My thesis examined reproductive behaviour and physiology of fathead minnows (Pimephales promelas) following exposure to several concentrations of dissolved oxygen. Using a custom-built system that was able to maintain DO concentrations at precise levels, reproductive performance was analyzed under 3.5 mg/l, 4.5 mg/l, 5.5 mg/l and a control of 7.5 mg/l of DO. A second experiment evaluated reproductive performance at 5.0, 5.7, 6.5 and 7.5(control) mg/L.<p> Breeding attempts ceased altogether at 4.5 mg/l and lower. At higher concentrations, the effects of DO on reproductive output were contradictory between experiments. When DO was maintained at 5.5 mg/L in the first experiment, egg production was lower than in the controls. When DO levels of 5.7 mg/L were used in the second experiment, egg production was higher than in the controls. Courtship behaviour decreased significantly compared to the control at DO levels of 4.5 mg/L and lower. No significant differences were observed between treatments in morphometrics, survival, larval deformities, sex steroid levels, vitellogenin levels, hatching success, egg size, fertility, or gonad histology.<p> The results of this study demonstrate that reproductive behaviour may represent a sensitive early marker of reproductive impairment in fathead minnows. Inconsistencies between the two experiments suggest a possible hormetic effect in response to depressed DO in fathead minnows. My results have important implications with respect to Canadian water quality guidelines and applications in the restoration of aquatic systems with lowered DO due to human activities.

Adequate levels of dissolved oxygen (DO) are essential to the health of most aquatic organisms. While diel fluctuations in DO concentration are a normal occurrence in aquatic ecosystems, anthropogenically-produced periods of prolonged hypoxia have the potential to cause changes in growth, reproduction and behaviour in animals. My thesis examined reproductive behaviour and physiology of fathead minnows (Pimephales promelas) following exposure to several concentrations of dissolved oxygen. Using a custom-built system that was able to maintain DO concentrations at precise levels, reproductive performance was analyzed under 3.5 mg/l, 4.5 mg/l, 5.5 mg/l and a control of 7.5 mg/l of DO. A second experiment evaluated reproductive performance at 5.0, 5.7, 6.5 and 7.5(control) mg/L.<p> Breeding attempts ceased altogether at 4.5 mg/l and lower. At higher concentrations, the effects of DO on reproductive output were contradictory between experiments. When DO was maintained at 5.5 mg/L in the first experiment, egg production was lower than in the controls. When DO levels of 5.7 mg/L were used in the second experiment, egg production was higher than in the controls. Courtship behaviour decreased significantly compared to the control at DO levels of 4.5 mg/L and lower. No significant differences were observed between treatments in morphometrics, survival, larval deformities, sex steroid levels, vitellogenin levels, hatching success, egg size, fertility, or gonad histology.<p> The results of this study demonstrate that reproductive behaviour may represent a sensitive early marker of reproductive impairment in fathead minnows. Inconsistencies between the two experiments suggest a possible hormetic effect in response to depressed DO in fathead minnows. My results have important implications with respect to Canadian water quality guidelines and applications in the restoration of aquatic systems with lowered DO due to human activities.

Thesis (M.S.)--Wisconsin. / Includes bibliographical references (leaves 42-46).