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Temperature effects on the development of the zebrafish embryos and larvae and adults were examined. It was found that the earlier in development a temperature change was performed on an embryo, the more significant the change in survival and/or subsequent development. Thus, viable temperature ranges for zebrafish widened significantly as development proceeded. Adults reared and bred at 25oC produced embryos that were significantly more successful at the lower range of rearing temperatures compared to embryos produced from adults reared at 28oC. The majority of this study focused on the physiological effects of swim training during development in the zebrafish. The earlier in development the zebrafish larvae were trained, the greater the mortality. Trained free swimming larvae had a significantly higher routine oxygen consumption after 11 days of training, and a higher mass specific routine metabolic rate after 8 and 11 days of training. Trained free swimming larvae consumed significantly less oxygen during swimming and were more efficient at locomotion, compared to control larvae. Training enhanced survival during exposure to extreme hypoxia in all age groups. Performance aspects of training were investigated in attempt to quantify training effects and in most cases, trained fish performed significantly better than controls. As blood vessels formed during development, they decreased in cross sectional area from days two to six. It was also shown that the variability in visual stroke volume measurements could be reduced significantly by using a third dimension in the analysis with a more accurate volume equation. Finally, the ontogeny of cardiac control was evaluated. The adrenergic receptors were the first to respond to pharmacological stimulation but were closely followed by cholinergic pharmacological stimulation a few days later. There was a significant cholinergic tone present in day 15 zebrafish larvae which persisted. Although an adrenergic tone was not documented in this study, this does not prove its lack of existence.

Superior swimming stamina in adult fish is presumably passed on to their offspring, but the ontogeny of the appearance of superior stamina and the requisite enhanced cardio-respiratory support for locomotion in larval fishes has not been determined. Is the expression of the suite of parental traits enabling superior swimming stamina in their offspring dependent upon their achieving juvenile/adult morphology, or does it appear earlier in their larvae? To answer this, adults were classified into three groups based on swimming stamina, followed by measurement of length, mass, and width. Larval offspring from the two parental groups -high stamina larvae (HSL) and low stamina larvae (LSL)- were reared at 27°C in aerated water (21% O2). Routine and active heart rate, routine and active mass specific oxygen consumption were recorded through 21dpf, and cost of transport (COT) and factorial aerobic scope were derived from oxygen consumption measurements. Routine heart rate at 2dpf of LSL was 164 ± 1 b·min-1, compared to only 125 ± 2 b·min-1 for HSL. Routine heart rate subsequently peaked at 203 ± 1 b·min-1 at 5dpf in the HSL group, compared to 207 ± 1 b·min-1, at 4dpf in the LSP larvae. Active heart rate at 5 dpf of LSL was 218 ± 2 b·min-1 compared to 216 ± 2 b·min-1 for HSL. Active heart rate increased slightly to 227 ± 2 b·min-1 for LSL before decreasing again, while active heart rate remained relatively constant for HSL. Routine O2 consumption at 2dpf of HSL was 0.09 μmol·mg-1·hr-1, compared to 0.03 μmol·mg-1·hr-1 in LSL. Routine O2 consumption subsequently peaked at 0.70 μmol·mg-1·hr-1 at 9dpf in the HSL, compared to 0.71 μmol·mg-1·hr-1, at 9dpf in the LSL. These values dramatically decreased before leveling off at around 0.20 μmol·mg-1·hr-1 and 0.15 μmol·mg-1·h-1, respectively. Active O2 consumption at 5dpf for HSL was 0.38 μmol·mg-1·hr-1, compared to 0.57 μmol·mg-1·hr-1 for LSL. Active O2 consumption subsequently peaked at 0.97 μmol·mg-1·hr-1 at 10dpf in HSL, compared to 1.19 μmol·mg-1·hr-1 at 7dpf in LSL. These values also dramatically decreased and leveled off. Significant differences (p < 0.05) in heart rate and oxygen consumption persisted through 21dpf. The onset of differences observed in routine and active heart rate in early larvae, correlated with parent stamina, show that juvenile or adult features are not required as a precondition for the emergence of phenotypic physiological differences.

In the present study using zebrafish as the model organism, we have investigated the function of UII/UII-receptor (UIIR) signaling pathway during early embryogenesis. Herein we presented five lines of evidence supporting the hypothesis that UII/ UIIR signaling pathway is required for normal determination of asymmetric axis during early embryogenesis. First, function-loss of UII results in a concordant randomization of viscus asymmetries in embryos, including abnormalities in cardiac looping and positioning of visceral organs. Second, knockdown of UII randomizes the left-sided expression of asymmetrical genes including lefty2, spaw and pitx2c in the lateral plate mesoderm (LPM) and bmp4 in the developing heart domain and the LPM. Third, reduced UII levels interfere with the normal organogenesis of Kupffer's vesicle (KV), an organ implicated in the early steps of left-right (L-R) patterning of embryos. Fourth, repression of UII function perturbs the asymmetrical distribution of free Ca2+ (intracellular Ca2+) at the region surrounding embryo KV during early somitogenesis, which is one of the signaling mechanisms that propagandize and amplify the early clue of left-right (L-R) asymmetry. Fifth, depressing UII levels alters the normal pattern of Bmp and Nodal signaling, which modulate the establishment of L-R axis of developmental embryo. Collectively, these observations support a model in which UII/UIIR signal system takes part in the early molecular events of L-R asymmetry patterning of embryo by modulating Bmp and Nodal signaling, regulating KV normal morphogenesis, so then, maintaining the asymmetrical distribution of free intracellular Ca2+ at the peripheral region surrounding embryo KV. This study documents a role of UII/UIIR signaling pathway in the establishment of L-R axis of embryos which promises to reveal the molecular mechanisms responsible for human congenital diseases with heterotaxy. / Urotensin II (UII) is the most potent vasoconstrictor identified so far. This cyclic peptide stimulates its G protein-coupled receptor (GPR) to modulate cardiovascular system function in humans and in other animal species. / Li, Jun. / Advisers: Christopher HK Cheng; Mingliang He. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 143-168). / 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, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

The CCAAT/enhancer-binding protein delta (C/EBPδ) is a highly conserved transcription factor capable of regulating numerous cell fate processes, such as cell growth, differentiation, proliferation and apoptosis. C/EBPδ is inducible during cellular stress responses, including inflammation and responses to growth factor deprivation or thermal stress. C/EBPδ is stress-inducible in a diversity of fishes, including the zebrafish Danio rerio; however, little is known about its role in fish development. Here I show that overexpression of C/EBPδ leads to severe developmental defects, including reduced body length, edema, liver malformation and retinal abnormalities. The proportion of individuals that display developmental abnormalities is significantly greater in C/EBPδ-overexpressing embryos compared to control embryos and overexpression significantly reduces survival of larvae over time. TUNEL analysis suggests C/EBPδ-overexpressing embryos exhibit a pattern of apoptotic cell death which is spatially distinct from control embryos. These data support a critical role for C/EBPδ in numerous developmental processes, including promoting programmed cell death during development. Mutations in C/EBPδ have been implicated in the progression of human tumors, including those of myeloid, hepatocellular and breast cancers. Therefore, the C/EBPδ-overexpressing zebrafish will serve as a valuable model for examining the role of this gene during development, as a part of the cellular response to stress and in pathological states such as tumor progression.

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Bibliography: leaves 129-158. / xvii, 159, [11] leaves, [24] leaves of plates : ill. (some col.) ; 35 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The major estrogen inducible protein in zebra fish liver has been purified to homogeneity by FPLC using anion exchange chromatography (Mono-Q Pharmacia) with purification being monitored by SDS-PAGE electrophoresis. / Thesis (Ph.D.)--University of Adelaide, Dept. of Obstetrics and Gynaecology, 1995?

Thesis (Ph. D. in Biological Sciences)--Vanderbilt University, Dec. 2007. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--University of Oregon, 2003. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 95-102). Also available for download via the World Wide Web; free to University of Oregon users.

The development of spinal circuits underlying motor behaviors was examined in zebrafish. Zebrafish embryos showed three sequential, stereotyped behaviors: a transient period of spontaneous coiling contractions, followed by touch-evoked rapid coils, and swimming. Lesioning the hindbrain eliminated swimming and touch responses, but not the spontaneous contractions. / The first (spontaneous) behavior was chosen for further analysis in order to characterize the underlying circuit. In vivo patch clamp recordings were obtained from identified spinal neurons. These neurons showed periodic depolarizations that triggered rhythmic bursts of action potentials with a frequency and duration that were consistent with those of the spontaneous contractions. As with the behavior, transecting the spinal cord at the hindbrain border did not affect the rhythmic activity patterns of the neurons. Surprisingly the contractions and the periodic depolarizations were insensitive to both general and specific blockade of synaptic transmission. The periodic depolarizations were suppressed by heptanol and by intracellular acidification treatments that are known to uncouple gap junctions, indicating that electrotonic synapses could underlie network synchronization during the earliest motor behavior. / Paired recordings were obtained from identified spinal neurons. These showed that active ipsilateral neurons were electrically coupled in a simple network consisting initially of motoneurons and only three types of interneurons. Therefore, this early spinal circuit consists of rhythmically active and electrically coupled neurons. Furthermore, this circuit is also initially independent of the main neurotransmitter systems, sensory inputs, and descending hindbrain projections. The descending projections are required later in development for the onset of touch responses and swimming.