Tang, Walfred. / "November 2011." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 151-165). / Abstracts in English and Chinese. / Title Page --- p.i / Thesis/Assessment Committee (English) --- p.ii / Acknowledgements --- p.iii / Table of Content --- p.iv / List of Figures --- p.ix / List of Graphs --- p.xi / List of Tables --- p.xiv / Abbreviations --- p.xviii / Abstract (English) --- p.xx / Abstract (Chinese) --- p.xxii / Chapter Chapter 1: --- General Introduction / Chapter 1.1 --- Renal Development --- p.2 / Chapter 1.1.1 --- The three embryonic excretory systems --- p.2 / Chapter 1.1.1.1 --- Pronephros and mesonephros --- p.2 / Chapter 1.1.1.2 --- Metanephros --- p.4 / Chapter 1.1.2 --- Renal malformations --- p.6 / Chapter 1.1.2.1 --- Causes of renal malformations --- p.8 / Chapter 1.1.2.1.1 --- Physical obstruction --- p.9 / Chapter 1.1.2.1.2 --- Mutation --- p.9 / Chapter 1.1.2.1.3 --- Environmental insults --- p.10 / Chapter 1.2 --- Retinoic Acid --- p.11 / Chapter 1.2.1 --- "Retinoic acid synthesis, signaling and degradation in the Embryo" --- p.12 / Chapter 1.2.2 --- Retinoic acid and embryonic development --- p.14 / Chapter 1.2.2.1 --- Retinoic acid and renal development --- p.15 / Chapter 1.2.3 --- Retinoic acid teratogenicity --- p.17 / Chapter 1.2.3.1 --- Retinoic acid teratogenic mechanism --- p.18 / Chapter 1.2.3.2 --- Retinoic acid-induced renal agenesis mouse model --- p.21 / Chapter 1.2.4 --- Induction of RA deficiency --- p.24 / Chapter 1.3 --- Strategy of the Thesis --- p.28 / Chapter Chapter 2: --- General Materials and Methods / Chapter 2.1 --- Mouse Maintenance and Mating Method --- p.31 / Chapter 2.2 --- Bisdiamine Preparation --- p.32 / Chapter 2.3 --- All-trans Retinoic Acid Preparation --- p.32 / Chapter 2.4 --- Embryo Dissection --- p.32 / Chapter 2.5 --- Real-time Quantitative Reverse Transcription- Polymerase Chain Reaction (RT-PCR) --- p.33 / Chapter 2.5.1 --- Sample collection --- p.33 / Chapter 2.5.2 --- Total RNA extraction --- p.33 / Chapter 2.5.3 --- Reverse transcription --- p.34 / Chapter 2.5.4 --- Polymerase chain reaction --- p.35 / Chapter 2.5.5 --- Preparation of DNA standards --- p.36 / Chapter 2.6 --- Terminal Deoxynucleotidyl Transferase-mediated dUTP Nick-end Labeling (TUNEL) Staining --- p.38 / Chapter 2.6.1 --- "Fixation, dehydration and embedding" --- p.38 / Chapter 2.6.2 --- Microtome sectioning --- p.39 / Chapter 2.6.3 --- TUNEL staining --- p.39 / Chapter Chapter 3: --- Induction of Renal Malformations by Bisdiamine via RA Deficien --- p.cy / Chapter 3.1 --- Introduction --- p.43 / Chapter 3.1.1 --- Time and dose responses to bisdiamine-induced renal malformations --- p.43 / Chapter 3.1.2 --- Methods to detect endogenous RA in embryonic tissues --- p.44 / Chapter 3.2 --- Experimental Design --- p.46 / Chapter 3.3 --- Materials and Methods --- p.48 / Chapter 3.3.1 --- Time and dose responses to bisdiamine administration --- p.48 / Chapter 3.3.2 --- Quantification of RA and retinol content in whole embryo by high pressure liquid chromatography (HPLC) --- p.49 / Chapter 3.3.2.1 --- Bisdiamine injection and sample collection --- p.49 / Chapter 3.3.2.2 --- Chromatographic system --- p.50 / Chapter 3.3.2.3 --- Preparation of standards --- p.50 / Chapter 3.3.2.4 --- Extraction of embryo samples --- p.51 / Chapter 3.3.2.5 --- Conditions of HPLC --- p.52 / Chapter 3.3.2.6 --- Recovery of sample --- p.53 / Chapter 3.3.2.7 --- Bradford protein assay --- p.53 / Chapter 3.3.3 --- X-gal staining of RARE-hsp-lacZ embryos --- p.54 / Chapter 3.3.4 --- Quantification of RA content in metanephroi by the RA-responsive cell line --- p.55 / Chapter 3.3.4.1 --- Bisdiamine injection and sample collection --- p.55 / Chapter 3.3.4.2 --- Maintenance of the RA-responsive cell line --- p.56 / Chapter 3.3.4.3 --- Seeding of cells and addition of samples --- p.57 / Chapter 3.3.4.4 --- X-gal staining --- p.58 / Chapter 3.3.5 --- TUNEL staining --- p.59 / Chapter 3.3.6 --- Real-time quantitative RT-PCR --- p.60 / Chapter 3.3.7 --- Statistical analysis --- p.61 / Chapter 3.4 --- Results --- p.63 / Chapter 3.4.1 --- Time response to bisdiamine treatment --- p.63 / Chapter 3.4.1.1 --- Bisdiamine administration increased resorption and affected various growth parameters of the fetuses --- p.64 / Chapter 3.4.1.2 --- Bisdiamine administration resulted in renal malformations --- p.68 / Chapter 3.4.1.3 --- Bisdiamine administration resulted in non-renal malformations --- p.71 / Chapter 3.4.2 --- Dose response to bisdiamine treatment --- p.76 / Chapter 3.4.2.1 --- Dose response of resorption and various growth parameters --- p.77 / Chapter 3.4.2.2 --- Dose response to bisdiamine in inducing renal malformations --- p.80 / Chapter 3.4.2.3 --- Dose response to non-renal malformations --- p.83 / Chapter 3.4.3 --- RA deficiency induced by bisdiamine --- p.88 / Chapter 3.4.3.1 --- Comparison of endogenous RA and retinol levels in control and bisdiamine-treated whole embryos at different time points after treatment --- p.88 / Chapter 3.4.3.2 --- Comparison of RA signaling patterns in control and bisdiamine-treated embryos at different time points after treatment --- p.90 / Chapter 3.4.3.3 --- Comparison of endogenous RA levels in control and bisdiamine-treated metanephroi at different time points after treatment --- p.93 / Chapter 3.4.4 --- Increase in the number of apoptotic nuclei in the metanephros after bisdiamine treatment --- p.95 / Chapter 3.4.5 --- Alteration of genes expression in the metanephros after bisdiamine treatment --- p.96 / Chapter 3.5 --- Discussion --- p.99 / Figures / Graphs / Chapter Chapter 4: --- Rescuing Bisdiamine-treated Metanephroi by In Vitro Supplementation with Low Concentrations of RA / Chapter 4.1 --- Introduction --- p.107 / Chapter 4.1.1 --- Embryonic kidney culture --- p.107 / Chapter 4.1.2 --- In vitro culture of the RA-treated metanephros --- p.108 / Chapter 4.1.3 --- Effect of exogenous retinoic acid on in vitro development of metanephros --- p.109 / Chapter 4.2 --- Experimental Design --- p.111 / Chapter 4.3 --- Materials and Methods --- p.113 / Chapter 4.3.1 --- Supplementation of low concentrations of RA to metanephric explant culture --- p.113 / Chapter 4.3.1.1 --- Preparation of culture medium supplemented with low concentrations of RA --- p.113 / Chapter 4.3.1.2 --- Metanephric explant culture --- p.114 / Chapter 4.3.2 --- Whole-mount immunohistochemical staining of ureteric epithelium and nephric tubules in metanephric explants --- p.115 / Chapter 4.3.3 --- TUNEL staining of metanephric explants --- p.116 / Chapter 4.3.4 --- Real-time quantitative RT-PCR --- p.117 / Chapter 4.3.5 --- Statistical analysis --- p.117 / Chapter 4.4 --- Results --- p.119 / Chapter 4.4.1 --- Rescue of bisdiamine-treated metanephric explants by in vitro culture in medium supplemented with low concentrations of RA --- p.119 / Chapter 4.4.1.1 --- Assessment of metanephric development under various concentrations of RA by morphological grading of UB tips at different day of culture --- p.119 / Chapter 4.4.1.2 --- Effect of various concentrations of RA on the number of UB tips and nephric tubules in metanephric explants at day 6 of culture --- p.126 / Chapter 4.4.2 --- Effect of RA supplementation on apoptosis in bisdiamine-treated metanephric explants --- p.131 / Chapter 4.4.3 --- Effect of RA supplementation on genes expression in bisdiamine-treated metanephric explants --- p.133 / Chapter 4.5 --- Discussion --- p.136 / Figures / Graphs / Chapter Chapter 5: --- Conclusion and Future Perspectives --- p.141 / References --- p.150

Hao Yanli. / "July 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 113-134). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

骺軟骨板是位於長骨骨骺的一個軟骨結構，其主要功用為使骨骼延伸生長。 若人類骺軟骨板基因出現障礙，骨骼生長往往會受到嚴重的影響，使骨骼變得短小、畸形，造成殘障。此外，一些後天的系統性失調也會損害骺軟骨板的正常運作，導致矮小症。現今常用來醫治骨骼生長障礙的包括重組的人類生長荷爾蒙。然而，它的功效並非顯著，亦帶來很多的副作用；因此，我們希望能尋求更好的醫治方法。 / 近有的研究結果顯示，很多的內分泌及分泌因子能夠刺激骺軟骨板進行軟骨增生。但是，研究者卻往往未能將這些因子轉化及運用作醫療用途，原因是它們通常都是局部性地於骺軟骨板產出及發生效用。倘若以上提及的生長因子能給骺軟骨板的靶子蛋白鏈準確地被帶往骺軟骨板，那麼這些因子便能有效地被利用作治療用途，而其效能亦會給大大提高，副作用也會被減低。因此，我們現在進行研究的首要目標為於採用噬菌體展示和酵母展示方法， 尋找那些能認辨出骺軟骨板的靶子蛋白鏈及單鏈抗體。 / 於噬菌體展示庫裡，我們找出了兩條能認辨出小鼠骨骼軟骨細胞的靶子蛋白鏈 － C1 (RLDPTSYLRTFW) 和 C19 (HDSQLEALIKFM)。然而於體外測試實驗中， 它們對軟骨細胞及細胞外基質只擁有中度的親近性和特異性。此後，於酵母展示庫裡，我們亦發現三條可認辨某骺軟骨板蛋白的單鏈抗體 － 它們的親近性甚高 (達至1 nM)，而其對軟骨組織的特異性也為良好 (它們只認辨軟骨組織，但卻沒能認辨出其他的軟組織，包括腦、心臟、肝臟、肺臟、腎臟、脾臟、小腸及肌肉)。 其後，於小鼠胚胎免疫染色測試實驗中，這些單鏈抗體只亦選擇地認辨軟骨組織。再者，當這些單鏈抗體被注射入小鼠的靜脈中，它們也會準確地停留在軟骨組織裡，顯示出其特異性於體內測試實驗中亦存在。 / 總括而言，利用噬菌體展示和酵母展示方法，我們發現了一些能認辨出骺軟骨板的靶子蛋白鏈及單鏈抗體。這些單鏈抗體擁有對軟骨組織非常高的親近性和特異性。我們預計，若然將這些單鏈抗體和內分泌及分泌因子連結在一起，它們或能成為醫治骨骼生長障礙的新方法。 / The growth plate is a specialized cartilage structure at the ends of long bones that is responsible for bone elongation. Many human genetic disorders of the growth plate impair skeletal growth, often resulting in bones that are severely short and malformed, causing serious disability. Many acquired systemic disorders also impair growth plate function, causing short stature. Currently, recombinant human growth hormone is used to treat growth disorders, but it has limited efficacy for severe diseases and causes significant adverse effects. / Recent studies have identified many endocrine and paracrine factors that are capable of promoting chondrogenesis at the growth plate. However, the development of these molecules into effective therapies has been hampered by their action mechanism; they are produced locally and act locally in the growth plate and thus fail to lend themselves to systemic therapeutic approaches. We envisioned that, if these growth factors could be linked to growth plate-targeting peptides or polypeptides and then administered systemically, these molecules might provide a better treatment strategy for growth disorders because targeting might augment the therapeutic effect on the growth plate but diminish undesirable effects on non-target tissues. Toward this goal, we sought to identify peptides and antibody fragments that bind to cartilage tissue using phage display and yeast display technologies. / We used a phage display library that expressed linear peptides of 12 random amino acids on the phage surface and then selected for binding to murine primary cultured chondrocytes. This approach successfully identified two peptides, namely C1 (RLDPTSYLRTFW) and C19 (HDSQLEALIKFM), which exhibited moderate binding affinity and specificity to chondrocytes and extracellular matrix in vitro. We also used a yeast display library to identify three single-chain variable(scFv) antibody fragments that bound strongly to a growth plate-specific protein(EC50 values less than 1 nM). These antibody fragments demonstrated specific binding in vitro to homogenates of cartilage tissues, but not homogenates of brain, heart, liver, lung, kidney, spleen, small intestine, or muscle. Moreover, they also exhibited tissue-specific binding to cartilage structures in sections of mouse embryos. When these purified antibody fragments were injected intravenously in mice, they localized to cartilage and were not detectable in other tissues, including brain, heart, liver, lung, kidney, spleen, small intestine, or muscle, indicating that the antibody fragments were capable of specifically targeting cartilage tissue in vivo. / In conclusion, we employed phage display and yeast display methods to identify peptides and antibody fragments that bind to cartilage tissues. The selected antibody fragments showed particularly high binding affinity and specificity to cartilage. Conjugating these antibody fragments to endocrine and paracrine signaling molecules has the potential to provide targeted therapy for growth plate disorders. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Cheung, Sao Fong. / Thesis (Ph.D.) Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 89-102). / Abstracts also in Chinese.

Islet plasticity has proven to be an important platform for the engineering of alternative islet tissue for transplantation. In vitro studies have shown the ability of islets to transdifferentiate into duct-like epithelial structures (DLS) thought to possess progenitor cells capable of replenishing damaged tissue within the pancreas. The aim of this study was to investigate the natural history of human derived duct-like epithelial structures transplanted into nude mice. / Human islet derived duct-like structures from three cadaver pancreases were subcutaneously transplanted into 6-8 week old male HSD athymic nude-Foxn1 mice. Six mice were sacrificed at day 3, 7, 14 and 21 from each time period. DLS were also placed in matrigel for in-vitro control samples. DLS were processed for immunohistochemistry for endocrine markers, epithelial markers, cell death and proliferation markers, islet maturation markers and angiogenic factors. / Our results show that as DLS are transplanted, there is an increase in cell death and proliferation. This increase in cell death and proliferation causes an increase in PDX-1 expression as well as VEGF, an angiogenic factor. But over time, transplanted DLS do not show an increase in cell death and show a small decrease in cell proliferation from pre-transplanted DLS. At day 3 of engraftment, DLS show a significant expression of PDX-1. We see a small increase in endocrine tissue after 3 days of transplantation, then an increase in endocrine cell death, which returns the percentage of endocrine cells back to pre-transplantation levels at day 21. DLS were shown to express VEGF, and once transplanted into an initial hypoxic environment there is a substantial increase in expression, followed by a recruitment of microvessels. Although there is a dynamic change in expression of cell markers throughout engraftment, there is no significant change in DLS size, nuclei per DLS or cell morphology over time. / DLS have been shown to survive subcutaneous transplantation and possess an initial increase in cell proliferation leading to increases in PDX-1 and VEGF expression. Transplanted DLS have shown to possess significant angiogenic properties with the recruitment of microvessels into subcutaneous DLS grafts. Subcutaneous DLS transplantation could be used in combination with islet transplantation to alleviate current problems with islet transplantation such as islet cell death and insufficient blood supply.

To acquire its characteristic structural and functional complexity, the mammalian nervous system must undergo several critical developmental processes. One such process requires factors that regulate the decision of dividing progenitors to leave the cell cycle and activate the neuronal differentiation program. It is shown in this thesis that the murine runt-related gene Runx1 is expressed in proliferating cells on the basal side of the murine olfactory epithelium. Disruption of Runx1 function in vivo does not result in a change in the quantity of progenitors but leads to a decrease in precursor number and an increase in differentiated ORNs. These effects result in premature and ectopic ORN differentiation. Further, exogenous Runx1 expression in cultured olfactory neural progenitors causes an expansion of the mitotic cell population. In agreement with these findings, exogenous Runx1 expression also promotes cortical neural progenitor cell proliferation without inhibiting neuronal differentiation. These effects appear to involve transcriptional repression mechanisms. Consistent with this possibility, Runx1 represses transcription driven by the promoter of the cell cycle inhibitor p21Cip1 in cortical progenitors. Taken together, these findings suggest a previously unrecognized role for Runx1 in coordinating the proliferation and neuronal differentiation of selected populations of neural progenitors/precursors. / Another significant step in the development of the mammalian nervous system is the acquisition of distinctive neuronal traits. This thesis also shows that Runx1 is expressed in selected populations of postmitotic neurons of the murine embryonic central and peripheral nervous systems. In embryos lacking Runx1 activity, hindbrain branchiovisceral motor neuron precursors of the cholinergie lineage are correctly specified but then fail to enter successive stages of differentiation and undergo increased cell death resulting in neuronal loss in the mantle layer. Runx1 inactivation also leads to a loss of selected sensory neurons in trigeminal and vestibulocochlear ganglia. These findings uncover previously unrecognized roles for Runx1 in the regulation of neuronal subtype specification. / This thesis thus presents a novel factor which functions at several steps in the development of the mammalian nervous system and adds to the growing body of work on the processes involved in elaborating such a complex and vital structure.

Highly unsaturated marine lipids are common ingredients in salmon diets, and they are prone to oxidative change. The present study was undertaken to examine the growth and health of coho salmon (Oncorhynchus kisutch) fed diets containing herring oil autoxidized to different degrees. The efficacy of dietary vitamin E in ameliorating any adverse effect on performance was investigated. Herring oil was oxidized to one of two levels (relative to a control) by aeration and mild heating (40 °C). Peroxide values and iodine numbers were recorded to monitor the extent of autoxidation. Depletion of dietary linolenic acid series fatty acids (n3FA), and the labile vitamins A, C, and E, provided further evidence of the progress of lipid oxidation. The mean initial body weight was 5.1 g/fish, and growth (weight and length) was measured at 3 or 6 week intervals for 28 weeks. Experimental diets contained 16.8% lipid, primarily as herring oil. One diet was made with corn oil replacing herring oil, and another contained a combination of low and highly oxidized oil. Vitamin E (as dl-ɑ-tocopheryl acetate) was added at either 30 IU/kg dry diet or 1000 IU/kg dry diet. At 23 weeks, 1/3 of the fish were vaccinated against vibriosis. At 28 weeks the fish were twice challenged with live Vibrio sp. Immunocompetence was estimated by mortality and by plasma agglutination. The inclusion of autoxidized herring oil reduced the nutritive value of the diets. The poorer growth and feed efficiency of fish fed diets containing oxidized oils appears to have resulted from a combination of appetite suppression and nutrient deficiency. The relative importance of these factors in influencing growth and feed efficiency depended upon the extent of the oxidation, with appetite suppression being most apparent in fish fed diets containing moderately oxidized oil. Dietary supplementation with a high level of vitamin E had no ameliorating effect on growth or feed efficiency. Health and immunocompetence were not impaired by the presence of oxidized dietary lipid, or improved by the addition of vitamin E. / Land and Food Systems, Faculty of / Graduate

The extension of frozen-thawed epidermal strips prepared from the first centimetre below the hypocotyl hook of six day old dark grown Phaseolus vulgaris seedlings while immersed in various buffers and under various tensions was characterized. This was done in an attempt to determine if the acid wall loosening phenomenon, which according to the Acid-growth theory (Taiz, 1984) is thought to mimic part of the auxin mechanism of action, is mediated by unspecified wall loosening enzymes. Epidermal strips were found to be significantly loosened by media pH 6.0 to pH 2.6 (0.05M citric acid-O.lOM disodium phosphate) relative to pH 7.5. A minimum stress between 1.6 and 7.6 grams was required for the acid-extension of strips 4.5±0.5 mm wide. Regardless of tension, extension by tissues in an acid medium was largely transient For example, tissues tensioned by a 16.0 gram load reached a maximum extension rate of 6.18 ±1.37% of initial length per hour (L°/hr) between 4 and 6 minutes after immersion in pH 4.8. The rate was 1.29±0.17% L°/hr between 55 and 60 minutes and 1.05±0.14% L°/hr between 220 and 240 minutes. Total acid-extension over four hours was 4.24±0.57% L°. The extension response was found to be stable; newly harvested tissues whether frozen or not performed similarly to strips aged up to 15 days at -12°C before being extended. The performance of strips immersed in unbuffered solutions indicated that tissues were self-buffering at an acid pH probably because of the fixed carboxyls within the wall. The capacity for acid-extension by epidermal strips was lost in mature tissues harvested 4-5 cm below the hypocotyl hook. Temperature coefficients from extension rates were determined at several pHs. The results were highly variable. The acid-extension of strips boiled 15 minutes in ethanol or extracted in 3M NaCl for 4 hours at 4°C or 6M LiCl for 8 hours was determined in several pHs. The impact of the treatments was largely a suppression of the initial burst of acceleration. Extension rates following the initial surge were relatively unaffected. Glycosidase activities in untreated, ethanol-boiled, or salt extracted strips were determined. β-glucosidase was found to be most active in untreated strips with lesser levels of β-galactosidase and β-xylosidase and a trace of α-galactosidase being detected. Ethanol-boiling and LiCl-extraction removed or deactivated all four activities from the strips and NaCl-extraction lowered all four activities 70-80%. NaCl proved to have solubilized most of the missing β-glucosidase and β-galactosidase when the extraction solution was assayed following desalting and concentration. LiCl solubilized most of β-xylosidase. It was concluded that glycosidases and any other similarly soluble enzyme cannot be responsible for long term acid wall loosening in bean epidermis. If an enzyme is involved, it must be extremely stable and tightly bound to the wall. The acid-extension performance of frozen-thawed longitudinally halved hypocotyl sections in comparison to epidermal strips, as well as other evidence was considered support for another hypothesized mechanism of acid wall loosening, the displacement of calcium bridges. / Science, Faculty of / Botany, Department of / Graduate

The primary objective of this research was to determine if changes in iron availability influence the periodicity of blue-green algal growth. A secondary goal was to resolve how iron availability was related to events such as calcite (calcium carbonate) precipitation and sediment nutrient release. The biogeochemical regulation of blue-green algal succession was studied in three eutrophic hardwater lakes located upon the Thompson Plateau in south-central British Columbia. The experimental approaches included iri situ bottle and limnocorral experiments, sediment core analysis, monitoring of seasonal changes in water chemistry, and whole-lake manipulation by hypolimnetic aeration, or calcium hydroxide addition. Growth and primary production bioassays were used to evaluate iron availability. Microbial chelators were isolated from algal cultures and lake water, quantified by a chelation assay, and used to determine their in situ effects on algal productivity and bacterial heterotrophy. Microbes were able to regulate the bioavailability of iron. Algal siderophore isolates were rapidly assimilated in lake water and they were highly specific for iron chelation. Moreover, chelator concentrations in Black Lake usually exceeded the dissolved iron concentration. Algae excreted chelators that could suppress growth of some other species of algae by 90%, enhance the primary production of some other algal species by 30%, or suppress the heterotrophic activity of bacteria by 14-98%. The degree of iron limitation varied greatly during the summer. In Black Lake, iron limitation was more than ten-fold more intense in early summer than in late summer. Dense blooms of blue-green algae occurred in Black Lake only after the iron content of the lake increased from 20 to more than 100 ug/L. An increase in iron concentration in the water column of the three lakes was caused by a midsummer sediment release of iron. Although sediment pyrite formation converted available iron into refractory iron in both Chain and Frisken lakes, the degree of iron limitation varied greatly among the lakes. Unlike in Black Lake, the algae in Chain Lake were not limited by iron availability. Phosphorus solubility was a good index of iron availability. Black and Frisken lakes had too little iron for iron phosphate to precipitate, but the higher iron concentration in Chain Lake regulated phosphorus solubility. The differences among lakes was primarily a function of external iron loading, not sediment iron release. Chain Lake received 10³ more iron per m² than Frisken or Black lakes. Carbonate equilibria integrated the microbial responses to iron enrichment. When iron availability was increased in the epilimnion of Black Lake, algal productivity was enhanced which resulted in an increase in pH and the coprecipitation of more calcite and phosphorus than in control treatments. The precipitation of calcite could sediment as much as 90% of the algae and 97% of the phosphorus from the epilimnion. The hypolimnia of the iron-enriched limnocorrals had the lowest pH and highest dissolution of precipitated phosphorus. Three reactions, iron chelation, sediment iron release, and calcite precipitation, can regulate much of the periodicity of blue-green algal growth in hardwater lakes. / Science, Faculty of / Zoology, Department of / Graduate

This study provides comparative data on the effects of temperature on zygote and alevin survival, rate of development to 50 percent hatching and emergence, and alevin and fry size for five species of Pacific salmon (Oncorhynchus) and for rainbow trout (Salmo gairdneri). Fertilized eggs from each species were incubated in controlled temperature baths at five constant temperatures (2°, 5°, 8°, 11° and 14°C). At 2°C, survival for coho salmon zygotes was high (85 percent), moderate for sockeye salmon zygotes (40 percent) and low for chinook salmon zygotes (4 percent). No pink and chum salmon or rainbow trout zygotes survived at 2°C. However, at 14°C survival for chum salmon and rainbow trout zygotes was high (67 and 85 percent), moderate for chinook and pink salmon zygotes (50 and 55 percent) and low for sockeye salmon zygotes (10 percent). No coho salmon zygotes survived at 14°C. The same general pattern for temperature and survival holds for alevins. These data suggest that coho and sockeye salmon are adapted to lower incubation temperatures than the other species. All six species showed an inverse relationship between temperature and incubation time to 50 percent hatching and emergence. The data were analysed using linear regression but, even after a series of transformations, the relationship between temperature and development time remained curvilinear. The only exceptions were for chum salmon at hatching and pink salmon at emergence. Incubation temperature also influences both alevin and fry size. In general, low incubation temperatures produce larger alevins and fry than high incubation temperatures. In addition to data on constant incubation temperatures, the effects of varying temperature regimes on the survival, rate of development and size of coho salmon and rainbow trout alevins and fry were also documented. Fertilized eggs from coho salmon and rainbow trout were incubated at two varying temperature regimes. The varying temperature regimes either gradually increased from 5° to 14°C (the spring regime) or gradually decreased from 14° to 5°C (the fall regime). The increasing temperature regime produces higher survival in rainbow trout zygotes and alevins than the decreasing temperature regime. However, in coho salmon there was no clear difference in zygote and alevin survival with either regime. The rate of development to hatching for zygotes incubated at either varying temperature regime was similar within a species because of similar mean incubation temperatures between regimes. But, the rate of development to emergence for alevins incubated at either varying temperature regime was different because of different mean temperatures between regimes. The linear regressions to hatching and emergence for coho salmon and rainbow trout were used to predict rates of development for zygotes and alevins incubated with each varying temperature regime. The actual and predicted rates of development to hatching and emergence are similar within a species. Varying temperature regimes also affect both alevin and fry size. The decreasing temperature regime produces larger alevins and fry in coho salmon and rainbow trout than the increasing temperature regime. / Science, Faculty of / Zoology, Department of / Graduate

A feeding experiment was designed to examine how fish growth rates are affected by the size abundance of pelagic zooplankton. Juvenile chinook salmon, Oncorhynchus tshawytscha , were raised in 90 m³ mesh enclosures in Saanich Inlet, B.C. The enclosures permitted ample water and zooplankton circulation while retaining 5-6 gram juvenile salmon. The enclosed fish grew at an average rate of 1.8% wet body weight/day for a six week experimental period. Weekly growth rates ranged from 3.9%/day while food was abundant, to -0.5%/day when food was scarce. Several analytical methods were used to establish a relationship between fish gr.owth and the size and abundance of zooplankton in the enclosures. There is a strong relationship between the fish growth rates and the abundance of 1.4-4.5mm prey. Rates of successful search vary directly with the size and inherent contrast of a prey item. A minimum rate of successful search of 2.0m³/hour was estimated from a functional response curve for salmon feeding on 1.4-4.5mm zooplankton. This value is discussed in relation to a salmonids physical capabilities and results from previous field studies and tank experiments. Daily growth increments on the otoliths of the enclosed fish were examined with respect to daily variations in water temperature and zooplankton abundance. Extremes in food abundance appear to have a significant and consistent effect on the spacing of the growth rings. However, water temperatures would have to be kept constant in order to establish any closer relationship between food abundance and otolith growth rings. / Science, Faculty of / Zoology, Department of / Graduate