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Dissertations / Theses on the topic 'Biology, Plant Physiology. Chemistry, Biochemistry'
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1
Willett, Deanna Allyn. "Temperature-regulated proteins in plants." Thesis, The University of Arizona, 1999. http://hdl.handle.net/10150/291647.
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Studies in this thesis concern expression of one class of small HSPs (sHSPs) in field grown desert plant species and the isolation of a new HSP gene encoding an sHSP targeted to plant mitochondria. Expression of class I, cytosolic sHSPs was assessed in three desert species: Screwbean Mesquite, Baja Fairyduster, and Sweet Acacia. Total leaf protein, and if available, flower and pod protein, was extracted from samples and analyzed by SDS-PAGE and Western blotting. Sweet Acacia showed strong sHSP expression in leaves with an apparent diurnal pattern of increased expression in the hotter PM. Screwbean Mesquite pods showed significant sHSP expression, which was not correlated to temperature. The isolation and sequence analysis of a gene encoding a mitochondrion-localized sHSP from Arabidopsis was completed. Comparisons to other plant sHSPs verified it was most similar to other mitochondrial-localized sHSPs from plants.
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Tao, Titus. "Functional characterization of ZmGRP5, a glycine-rich protein specifically expressed in the cell wall of maize silk tissue." Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26780.
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Silk tissue is a specialized reproductive tissue of the maize plant, equivalent to the stigma and style portion of the female inflorescence. The moist and nutrient rich properties of maize silk tissue that facilitate pollen reception and the support of pollen tube growth also make maize silk a preferred site of infection by fungal pathogens such as Fusarium graminearum. The cDNA clone zmgrp5 was isolated in a previous study to identify silk tissue-specific genes. ZmGRP5, the encoded protein, was predicted to be a cell wall glycine-rich protein (GRP) and was experimentally characterized in this study. Using polyclonal antiserum, immunoblot analysis confirmed the silk tissue specificity of the protein. Additionally, subcellular fractionation studies confirmed ZmGRP5 localization in the cell wall fraction, and not in any other subcellular fractions. Interaction of ZmGRP5 with the cell wall matrix was observed to be disrupted by the addition of the reducing agent beta-ME. The reversible nature of disulfide bond formation and disruption under different redox conditions suggest that ZmGRP5 could potentially be important in the regulation of cell wall structural properties such as elasticity and rigidity in accordance with environmental and developmental changes. The variable immobilization of ZmGRP5 to the cell wall matrix could also serve as a potential mechanism of activation or inactivation of any non-structural functions. The identification of potential post-translational modifications such as phosphorylation and glycosylation, which are rarely observed in other cell wall GRPs, suggest that the functional significance of these modifications in ZmGRP5 is worthy of further study.
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Getzoff, Timothy Paul 1964. "Structure-function relationships for the small subunit (S) of ribulose-1,5-bisphosphate carboxylase/oxygenase: Foreign S expression and characterization of engineered protein." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282538.
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This dissertation addresses how small subunit (S) of higher plant Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) (EC4.1.1.39) might influence Rubisco function. Toward this analysis a pea RbcS 3A cDNA expression cassette was introduced into Arabidopsis thaliana Landsberg by Agrobacterium tumefaciens mediated transformation. Analysis of RNA blots and 2-D gels indicate pea RbcS 3A is expressed and the S protein product is transported into Arabidopsis chloroplasts, processed and assembled into a stable chimeric holoenzyme. Incorporation of only one pea S per Arabidopsis Rubisco was sufficient to allow biochemical analyses. Biochemical analyses determined that chimeric enzymes displayed lower carboxylase activity (Vc) than WT Arabidopsis Rubisco coincident and consistent with the amount of pea S present in holoenzymes. Lower Vc is likely the result of reduced carbamylation following activation. Enhancement of Vc following temperature treatment at 42°C is kinetic evidence of increased activity of active sites which not due to differences in carbamylation. Unlike wild-type Rubisco, chimeric enzymes do not display the expected increase in carboxylase activity following activation at 42°C. This indicates S plays a role in allowing increased activity of neighboring L. Thus, both carbamylation and activity are disrupted by the interaction of pea S and Arabidopsis L. Kinetic data and formulae offered here support a structural model whereby S influences activity by allowing S-dependent interaction between L active sites. Also, high-temperature treated Rubisco shows a more pronounced fallover. This suggests that 42°C caused changes within Rubisco which either increase the synthesis of inhibitors or the response to inhibitors. To enhance abundance of pea S relative to Arabidopsis S pea S expressing plants were transformed with oligo-antisense cassettes targeting the 5'UTR and transit peptide of endogenous Arabidopsis RbcS transcripts. These doubly transformed plants were grown on media with 3% sucrose to cause metabolite repression which can further reduce endogenous Arabidopsis RbcS expression. However, both antisense and metabolite repression reduce the amount of pea S relative to Arabidopsis S protein. Genetic crosses between independently transformed plants expressing pea S suggest that expression of different amounts of pea S can be achieved.
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Wehmeyer, Nadja. "Arabidopsis class I small heat shock proteins: Regulation and functional analysis during seed development." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284011.
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The goal of this dissertation was to analyze the regulation and function of cytoplasmic class I small heat shock proteins (sHSPs) during seed development in Arabidopsis thaliana. Results show that two class I sHSPs accumulate in late seed maturation, persist in the dry seed and decline rapidly during germination. HSP17.4 accounts for 90% of total class I sHSP in the dry seed. The temporal pattern of sHSP accumulation during seed development suggests that HSP17.4 may help establish seed properties that are acquired during late seed maturation, such as dormancy or desiccation tolerance. Several mutants with reduced seed dormancy were determined to accumulate wild type levels of HSP17.4, however, all desiccation intolerant seeds analyzed had decreased levels of HSP17.4. Thus, HSP17.4 reduction correlates with desiccation intolerance. In total, these data suggest that HSP17.4 is not sufficient for seed dormancy and that it may be necessary for desiccation tolerance. The localization and regulation of HSP17.4 were examined in developing Arabidopsis seeds by transforming plants with hsp17.4 promoter fused to the β-glucuronidase (GUS) gene. HSP17.4::GUS expression was detected in the cotyledons early in seed development and eventually throughout the embryo. Arabidopsis embryos showed a much different pattern of HSP17.4::GUS expression in response to heat indicating distinct mechanisms regulate sHSP transcription during heat shock and during development. To analyze seed specific transcriptional activator regulation of HSP17.4 transcription, HSP17.4::GUS transgenic plants were crossed to seed transcriptional activator mutants. Results showed aberrant localization of HSP17.4::GUS in fus3-3 and lec1-2 seeds and negligible levels in abi3-6. These results strongly implicate AB13 in the transcriptional regulation of HSP17.4. To analyze more specifically HSP17.4 function, transgenic antisense technology was used to suppress hsp17.4 expression to 30--50% of wild type. These lines exhibited a reduced dormancy phenotype as assayed by reduced sensitivity to germination on ABA and by the ability of fresh seed to germinate. These data provide insight into the localization, regulation and function of HSP17.4 during seed maturation. The seed-specific transcriptional activator ABI3 is implicated in controlling hsp17.4 expression during development. Overall, these results demonstrate the importance of HSP17.4 during seed maturation, and establish a role for sHSPs in dormancy.
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DiCenzo, Gregory Lawrence. "Elucidation of late steps in pisatin biosynthesis." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282830.
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Many plant species, in response to stresses, accumulate low molecular weight secondary metabolites called phytoalexins. Pea (Pisum sativum ) makes a pterocarpanoid phytoalexin called pisatin which is relatively unique among pterocarpans because its stereochemical configuration is different at two adjacent carbons from the corresponding carbons in pterocarpan phytoalexins synthesized by alfalfa, soybean, clover and other legumes. Previous research demonstrated that an (-) isoflavanone-synthesizing isoflavone reductase (EFR) is induced during (+) pisatin biosynthesis and the final step in the biosynthesis is the methylation of (+) cis-6a-hydroxymaackiain (HMK) by 6a-hydroxymaackiainmethyltransferase (HMM). And, contrary to a predominant model of (+) pisatin biosynthesis, the 6a-OH of pisatin was shown to involve oxygen from H₂O rather than O₂. This work describes the role of (-) isoflavanone (sophorol) in (+) pisatin biosynthesis. Radioactive tracer techniques were used both in vivo and in vitro to analyze metabolism of (-) sophorol and related isoflavonoids. I have found that, in vivo, the incorporation of (-) sophorol into (+) pisatin is more efficient than the incorporation of (+) sophorol and (+) maackiain, suggesting that the normal biosynthetic route to (+) pisatin utilizes (-) and not (+) sophorol and does not use maackiain. (+) Sophorol is not metabolized in vitro by pea protein extracts, although isoflavene, 7,2 '-Dihydroxy-4',5'-methylenedioxyisoflavanol (DMDI) and a novel diastereomer of HMK, trans-HMK, accumulate when (-) sophorol is used as substrate. A cDNA from pea, which encodes sophorol reductase (SOR), was cloned by homology to an alfalfa cDNA coding for isoflavanone reductase. The SOR cDNA was found to be transcribed in response to CuCl₂ treatment of pea seedlings, as was previously found for cDNAs of IFR and HMM, which are involved in pisatin biosynthesis. The SOR cDNA gene product specifically reduces (-) and not (+) sophorol in vitro. DMDI, the product formed by the activity from the recombinant protein, is incorporated in vivo into (+) pisatin. My current model of (+) HMK synthesis proposes that (-) sophorol and (3R) DMDI are normal in vivo pathway intermediates. However, trans-HMK is likely an artifact as it is a poor pisatin intermediate in vivo and is also a poor substrate in vitro for HMM.
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Wijeweera, Priyantha. "Phytochemical basis for the anxiolytic activity of the ayurvedic medicinal plant Centella asiatica (L) Urb (gotukola)." Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/26349.
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Gotukola (Centella asiatica L. Urban) (Apiaceae), its extracts and the pure compound asiaticoside were studied for anxiolytic activity in thirteen standardized rat trials. High performance liquid chromatography (HPLC) was used to conduct the phytochemical analysis. Among different models tested, the most promising positive response for anxiolytic activity was observed in the elevated plus maze test conducted with: (a) whole plant materials, (b) ethyl acetate and methanol fractions and (c) asiaticoside. The results show for the first time that asiaticoside and triterpene enriched fractions of gotukola have anxiolytic effects in animal models. Therefore, they are recommended for clinical trials. The findings of this study also support the ayurvedic use of gotukola for psychiatric disorders.
Other supplementary investigations conducted show that methyl jasmonate and full sunlight enhance the expression of asiaticoside in gotukola plants. The stolon explants were more successful compared to the leaf explants in in vitro propagation of gotukola.
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Gagnon, Jeffrey. "The proprotein convertases in the murine small intestine." Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/28225.
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The small intestine (SI) is a major endocrine organ with over 40 precursor hormones produced and proteolytically matured into active peptide hormones which signal throughout the body including the pancreas and CNS. One group of enzymes believed to be responsible for this maturation is the family of protein convertases (PCSKs). Using double immunofluorescent microscopy, the spatial localization of PCSK1, 2 and 3 in each region of the SI and colocalization with potential intestinal substrates was examined in mice. A unique regional expression pattern was observed for each of the PCSKs and several hormones examined exhibited high levels of colocalization. Next the gastrointestinal physiology of the PCSK2 knock out (KO) mouse was examined and correlated with the circulating levels of hormones known to mediate these functions. KO animals consume less food immediately after refeeding and have delayed intestinal transit. Several of the hormones responsible for feeding and intestinal motility were modulated in the PCSK KO animals. These studies suggest that the PCSK1 2 and 3 are present in the SI and required for normal functionality.
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Rashotte, Aaron Michael. "Epicuticular wax in Arabidopsis thaliana: A study of the genetics, chemistry, structure, and interactions with insects." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284206.
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Epicuticular wax (EW) forms the outermost layer over aerial portions of a plant. EW has been studied in plants for more than 100 years, yet there is a great deal that is still not known about epicuticular wax. The work in this dissertation has taken a broad view in investigating EW of Arabidopsis thaliana. In this dissertation I examined EW chemistry, EW structure, and mapped positions of existing and novel eceriferum or cer mutants. Additionally, I worked to develop new EW pathway models, establish correlations between EW chemistry and structure, and examine a possible functional role for EW in insect interactions. More specifically this dissertation project has attempted to expand the baseline knowledge of EW and of EW mutants in A. thaliana.
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Chen, Guohua 1966. "A potential role of iron-regulatory proteins in tumor growth /." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97925.
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Iron is indispensable for cell proliferation and growth, but it is potentially toxic when present in excess. Two homologous iron regulatory proteins (IRP1 and IRP2) control cellular iron homeostasis by binding to iron-responsive elements (IREs) and post-transcriptionally coordinating the expression of transferrin receptor 1 (TfR1) and ferritin. We have previously reported that overexpression of IRP1C437S, a constitutive IRP1 mutant, inhibits H1299 human lung cancer cell growth in vitro. In current study, we investigated the potential role of IRPs in tumor growth in vivo by the injection of H1299 cells expressing IRP1C437S or wild type IRP1 or IRP2 into the flanks of nude mice. We observed that overexpression of IRP1C437S or wild type IRP1 suppressed tumor growth in nude mice. In contrast, surprisingly, overexpression of wild type IRP2 promoted tumor growth. Our results suggest that IRP1 may exhibit tumor suppressor activity, while IRP2 may have oncogenic activity.
10
Hopewell, Shawn. "Effects of phosphatidylinositol on ApoA-I metabolism: Implications in HDL metabolism." Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/27987.
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Coronary heart disease (CHD) is the leading cause of morbidity and mortality in the developed world. Attempts to prevent CHD using LDL lowering medications have been only partly successful and new approaches are under investigation. Significant efforts are being made to develop therapeutics that raise plasma HDL levels to aid in the prevention of CHD. HDL levels are believed to be inversely associated with the risk of developing CHD. Naturally occurring phospholipids such as phosphatidylinositol (PI), have been shown to increase plasma apoA-I levels and HDL levels in animal models and human subjects; but the mechanism remains to be elucidated. Since in humans, HDL is primarily synthesized in the liver, the objective of the present study was to evaluate the underlying molecular mechanism of PI-induced apoA-I and HDL secretion from liver cells. We show that PI doubles apoA-I/HDL secretion at 24h in a model hepatocyte, HepG2, cell culture system. PI-induced apoA-I secretion is unaffected by PI-3-kinase inhibitors but is sensitive to various MAP kinase inhibitors. While the p38MAPK inhibitor SB203580 has no effect on PI-induced apoA-I secretion, the MEK1/2 inhibitor U0126 blocks PI-induced apoA-I secretion. Inhibition of the JNK MAPK pathway by SP600125 also blocks PI mediated apoA-I secretion. Real-time PCR shows no changes in cellular apoA-I mRNA and suggests that PI is not impacting the transcription of the apoA-I gene. However, the degradation of apoA-I is decreased in PI treated HepG2 cells. Collectively, the data from these investigations suggest that PI acts through mitogen and stress-activated protein kinase pathways to increase plasma apoA-I levels by decreasing the degradation of apoA-I.
11
Robert, Martin 1967. "Purification, characterization, and molecular processing of the precursor of a sperm motility inhibitor present in human seminal plasma." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40237.
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Human seminal plasma contains a protein factor that can inhibit the motility of both demembranated-reactivated and intact spermatozoa. This factor, named seminal plasma motility inhibitor (SPMI), was orignally isolated from seminal plasma and shown to orginate exclusively from the seminal vesicles, where its specific activity is 5- to 10-fold higher than it is in seminal plasma. The present study aimed at investigating the mechanism responsible for this difference in activity. Analysis of semen after ejaculation allowed to demonstrate that this difference in SPMI specific activity is due to the presence of a predominant 52 kDa SPMI precursor form in seminal vesicle fluid which is rapidly degraded after ejaculation by prostatic proteases. In addition, SPMI precursor was found to be associated with semen coagulum proteins and abnormal processing of the precursor in semen was associated with poor sperm motility.<br>A novel method was developed to purify SPMI precursor from seminal vesicle fluid and semen coagulum. Prostate-specific antigen (PSA) hydrolyzed SPMI precursor in a manner reminiscent of its processing in whole semen. Biochemical analysis of the precursor protein and its hydrolysis products provided evidence that SPMI precursor is identical to semenogelin, the main structural protein of semen coagulum. The purified precursor inhibited the motility of intact spermatozoa in a reversible and dose-dependent manner.<br>Finally, the characterization of SPMI molecular processing by PSA was addressed. The results directly demonstrate for the first time the restricted chymotrypsin-like specificity of PSA on its major physiological substrate. The sites of hydrolysis by PSA were identified along the precursor molecule and specific domains within the SPMI precursor responsible for biological activity and reactivity with various antibodies were mapped.<br>Overall, these results shed light on the photeolytic precessing of SPMI precursor occurring after ejaculation, and the associated change in SPMI activity on spermatozoa. The present findings provide evidence, for the first time, that a specific protein appears responsible for the observed low sperm motility in freshly ejaculated semen, and that its processing by PSA parallels the progressive increase in sperm motility observed during semen liquefaction.
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Landau, Anne M. "Effect of the substance P receptor antagonist, CP-96,345 on symptoms of inflammation in an acute rat model of inflammatory bowel disease." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79023.
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The possible role of substance P in mediating inflammation in inflammatory bowel disease (IBD) was evaluated by blocking the substance P (NK-1) receptor in an acute animal model. Ethanol and zymosan were administered via the rectum into the colon in anesthetized male Sprague-Dawley rats to induce the model. To assess the role of substance P, 5mg/kg of CP-96,345 was administered subcutaneously thirty minutes prior to induction of IBD and every hour for three hours, at which time testing was begun. In another group of rats, 3 00mug/kg of an antisense oligonucleotide targeted at NK-1 receptor mRNA was administered intraperitoneally twice daily for seven days prior to induction of IBD. Histological sections revealed an infiltration of inflammatory cells in the colons after ethanol/zymosan treatment. Plasma extravasation values in rats treated with ethanol/zymosan were significantly higher than in controls treated only with saline (P < 0.0001) or saline and ethanol (P = 0.0041). In ethanol/zymosan treated rats, those administered CP-96,345 had plasma extravasation values which were significantly less than in ethanol/zymosan treated controls (P < 0.0001). Administration of the antisense targeted at NK-1 receptor mRNA resulted in lower levels of plasma extravasation compared with controls (P < 0.01). NK-1 receptors may be involved in the expression of symptoms as a component of inflammation in IBD.
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Munzer, Jon Scott. "Comparative kinetic properties of tissue-specific Na,K-pumps." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28860.
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The catalytic $ alpha$ subunit of the heterodimeric Na,K-ATPase comprises three distinct isoforms which are expressed in a tissue-specific manner. For example, the $ alpha sb1$ isoform can be detected in virtually all mammalian tissues, whereas the appearance of the $ alpha sb2$ and $ alpha sb3$ isoforms is more restricted to particular tissues such as muscle and nervous tissue. Previous comparative functional studies of Na,K-ATPases isolated from various tissues indicated that there are differences, including apparent cation affinities, among these enzymes. While these differences often appear to correlate with the presence of distinct isozymes, their precise molecular bases remain to be determined. Moreover, certain studies suggest that the behavior of the same isoform can vary from tissue to tissue (e.g., the erythrocyte versus the kidney, both of which contain only the $ alpha sb1$ isoform). An hypothesis that may explain these observations is that the cell-specific membrane environment influences Na,K-ATPase activity. To investigate this possibility, polyethylene glycol-mediated membrane fusion was used to deliver pumps from high-specific-activity microsomes derived from various tissues into mammalian erythrocyte membranes. The success of this methodology was verified using two distinct experimental systems. In the first system, rabbit sarcoplasmic reticulum Ca-ATPase was delivered into human erythrocyte membranes. Cellular Ca$ sp{2+}$ uptake fueled by extracellular ATP was used as a measure of the functional delivery of the Ca-ATPase into these membranes. In the second system, ATP- and cardiac glycoside-dependent rubidium fluxes verified the functional delivery of axolemma or kidney Na,K-ATPases into mammalian erythrocytes. Among these studies was a series of experiments demonstrating that the L$ rm sb{p}$-antigen of sheep erythrocyte membranes is a distinct membrane component that interacts with and alters the behavior of rat kidney pumps fused into LK she
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Pellerin, Luc. "Studies on arachidonic acid release and metabolism by the 12-lipoxygenase pathway in rat brain slices." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70251.
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The present work was aimed at studying the release of arachidonic acid and formation of lipoxygenase metabolites in rat brain slices maintained in vitro, as well as exploring possible physiological roles for them in the mammalian central nervous system. A particularly active 12-(S)-lipoxygenase activity was found, which could be stimulated by various stimuli including the neurotransmitters norepinephrine and glutamate. Activation of $ alpha$-adrenergic and N-methyl- scD-aspartate (NMDA) receptor subtypes appear responsible for the effect observed in each case. Arachidonic acid on the other hand was found to have profound effects on synaptic transmission, inducing a long-lasting potentiation which appears dependent on the formation of lipoxygenase metabolites. In return, pharmacological conditions which can potentially lead to long-term potentiation (LTP) of synaptic transmission and for most of them activate NMDA receptors also induced arachidonic acid release. As these observations suggest, it is proposed that arachidonic acid and its lipoxygenase metabolites belong to a new group of messengers in the nervous system possibly acting as modulator of synaptic transmission both intra- and transcellularly. This new class of messengers constitutes an essential component of the molecular machinery involved in synaptic plasticity.
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Virdee, Inderpreet. "Biosynthesis and differential processing of Organellar Na+H+ exchangers." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81451.
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The Na+/H+ exchangers (NHE) mediate the electroneutral exchange of sodium for protons and play integral roles in sodium, acid-base and cell volume homeostasis. Presently, eight isoforms of the NHE (NHE1 to NHE8) have been identified that are targeted to distinct membrane compartments. The focus of this study is to characterize in greater detail the biosynthesis and differential sorting of two closely related organellar NHE isoforms, NHE6 and NHE7. Previous studies have established that NHE7 accumulates in the trans-Golgi network and associated endosomes, whereas the localization of NHE6 remains controversial. In one study, HeLa cells transiently expressing low levels of a green fluorescent protein-tagged construct of NHE6 showed close co-localization with mitochondrion-specific dyes. However, when NHE6 was overexpressed in COS7 cells, significant accumulation was observed throughout the cell in membrane vesicles derived from the endoplasmic reticulum. To further address this discrepancy, NHE6 engineered to contain the influenza virus hemagglutinin (HA) epitope at its C-terminus (NHE6HA), was subcloned into the ecdysone-inducible expression vector pIND and stably transfected into Chinese hamster ovary cells that constitutively express the ecdysone receptor. NHE6HA expression was stimulated by ponasterone A, an ecdysone analogue. The localization of NHE6 was determined biochemically by subcellular fractionation of cell lysates and visually by immunofluorescence confocal microscopy of intact cells using antibodies that recognize the HA-epitope and various organellar specific markers. Similar studies were conducted with an NHE7-inducible mammalian expression system. Our findings indicate that NHE6 is differentially processed through distinct Golgi-dependent and -independent pathways, ultimately accumulating in recycling endosomal vesicles. Little evidence was found to support sorting to mitochondria. Furthermore, we show that NHE6 is synthesiz
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Pulido-Cejudo, Gabriel. "Chemical and biological properties of iron-pyruvate-transferrin complexes." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74529.
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The preparation of a novel complex, ferric bromopyruvate, is described. In solutions from which most of the carbonate has been removed, ferric bromopyruvate can be used both as an iron and pyruvate source for the full iron saturation of apotransferrin. Using ferric bromopyruvate as an iron donor, iron incorporation into human apotransferrin is biphasic; the N-terminal domain is saturated three times faster than its homologous C-terminal iron binding site. Following the reaction of apotransferrin with ferric bromopyruvate, 4 moles of pyruvate per mole of transferrin are covalently bound. Based on the effect of acetylation on pyruvate and iron binding, it is suggested that lysyl residues could be the target of pyruvate bonding. However, the reaction of pyruvate with other positively charged amino acid residues cannot be excluded. The possible sites of pyruvate binding within the N-terminal domain of human serum transferrin are discussed. Covalent attachment of pyruvate to cationic amino acid residues decreased both in vitro and in vivo iron release, preferentially from the N-terminal domain of transferrin. The decreased rate of iron incorporation from iron-pyruvate-transferrin complexes by rabbit reticulocytes caused a lower iron incorporation into heme. It is suggested that an impairment of iron release from transferrin may decrease the rate of heme synthesis in reticulocytes. In vitro studies on the iron removal from iron-pyruvate-transferrin complexes showed that pyrophosphate can remove iron from this complex at an acid pH to a similar extent to the cellular mediated iron release from this complex. Based on this data, a model for the intravesicular iron release from transferrin is proposed.
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Segall, Laura. "Structurefunction analysis of the Na,K-ATPase with emphasis on isoform-specific conformational transitions." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84432.
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The Na,K-ATPase or sodium pump is an integral membrane protein found in the plasma membrane of virtually all animal cells. It exists as an alphabeta heterodimer for which several isoforms have been described. During its reaction cycle, the sodium pump extrudes three Na+ ions from the cell in exchange for two extracellular K+ ions using the energy of hydrolysis of one ATP molecule. The electrochemical sodium gradient generated provides the driving force for secondary solute transport. Structure/function analysis of the catalytic subunit, alpha, provides strong evidence for interactions between the actuator domain which comprises the cytoplasmic N-terminus and the M2--M3 loop, and the M4--M5 loop containing the ATP binding and phosphorylation sites. This thesis describes two major aspects of Na,K-ATPase structure and function. First, the role of the unique N-terminus of the ubiquitous al isoform of the rat Na,K-ATPase in E1/E2 conformational transitions is investigated as this region extends beyond that of the well-characterized and related SERCA pump for which high resolution structures have been obtained. Furthermore, the N-terminus is the region of greatest primary sequence diversity among the otherwise homologous alpha1, alpha2 and alpha3 isoforms. The results provide strong evidence for a self-regulatory domain within the N-terminus that modulates conformational transitions via novel intramolecular interactions within the N-terminus and between the N-terminus and regions within the cytoplasmic M2--M3 and M4--M5 loops. Another aspect of this thesis concerns a comparative study of the isoform-specific ligand affinity differences. For this study, the alpha2 and alpha3 isoforms were compared with the ubiquitous alpha1 isoform. The results demonstrate that alpha3-specific ligand affinities can be explained by its distinct reactivities with alkali cations, as well as by differences in the rates of partial reactions. The distinct kinetics of a
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Khanna, Rajesh. "L-Histidine ammonia-lyase immobilized by microencapsulation within artifiical cells : enzyme kinetics, stability, and in vitro simulation of histidine depletion for histodinemia." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59405.
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L-histidine ammonia-lyase (histidase) was encapsulated within cellulose nitrate artificial cells, and its kinetic parameters were evaluated. Microencapsulated histidase had an apparent activity of approximately 50% of the activity of histidase in solution. Encapsulation did not alter the K$ sb{ rm M}$ of histidase. The K$ sb{ rm M}$ of histidase solution and the K$ sb{ rm M}$ apparent of microencapsulated histidase were both 20mM. Encapsulation of histidase resulted in increased stability of enzymatic activity of storage temperatures of 4$ sp circ$C and 37$ sp circ$C. At 37$ sp circ$C histidase solution reached 50% of its original activity after 9.5 days of storage, while microencapsulated histidase reached the same level after 15 days. At 4$ sp circ$C histidase solution had 63% of its original activity after 21 days of storage, while encapsulated histidase had 95%. In vitro experiments to evaluate the feasibility of microencapsulated histidase for possible experimental therapy in histidinemia were carried out. These experiments evaluated the effectiveness of encapsulated histidase in depleting histidine. Three different volume ratios of histidase loaded artificial cells to substrate solution were tested. A ratio of 1:100 allowed 25% histidine depletion after 120 hours. A 1:50 ratio allowed 35% histidine depletion after 72 hours. A 1:25 ratio allowed 40% histidine depletion after 24 hours.
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Rajabi, Mohammad R. (Mohammad Refai). "Biochemical mechanism and hormonal regulation of dilatation of the uterine cervix at parturition." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74615.
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Studies were designed to investigate the biochemical mechanism and hormonal regulation of dilatation of the uterine cervix at parturition. The suitability of the guinea pig animal model was established by demonstrating collagenolysis in the uterine cervix similar to the changes reported in women by light and electron microscopy. By 50 days gestation, there was a 50% decrease in collagen content in the cervix. At parturition (68 $ pm$ 2 days) there was a 6-fold increase in procollagenase, a 26-fold increase in the tissue inhibitor of metalloproteinase (TIMP) and a 2-fold increase in net collagenase activity in cervical extracts. Cervices in organ culture obtained at birth produced 2.9 times more procollagenase, 1.6 times more TIMP and a 10-fold increase in net collagenase activity when compared to nonpregnant or 25 days pregnant animals. Estradiol stimulated the production of procollagenase, TIMP and net collagenase activity in cervical organ cultures. Using primary monolayer cervical cell cultures derived from 50 day pregnant guinea pigs, procollagenase enzyme and its mRNA were stimulated up to 2-fold by recombinant human interleukin 1$ beta$ (IL-1$ beta$), estrogens and progesterone. Procollagenase production was completely abolished by cycloheximide and by actinomycin D indicating the need for translation and transcription respectively. The mechanism of signal transduction of procollagenase was also investigated. A rabbit polyclonal antiserum (R4718) that specifically reacts with epitopes on denatured and degraded $ alpha$2 chain of guinea pig type I collagen was used to demonstrate degradation of type I collagen in the extracellular matrix of the dilated cervix at parturition. Physiological concentrations of 17$ beta$-estradiol stimulated degradation of type I collagen in the nonpregnant cervix in organ culture. This effect was completely blocked by progesterone (100 $ mu$M). These studies indicate that cervical dilatation at parturition involves estrogen-indu
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Hu, Keli. "Signal transduction systems involved in ischemic preconditioning and ATP-sensitive K+ channels." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0002/NQ44456.pdf.
Full text
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Saengsirisuwan, Vitoon. "Interactions of exercise training and the antioxidant alpha-lipoic acid on insulin action in obese Zucker rats." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280385.
Full textAbstract:
The insulin resistance syndrome is a multifaceted condition characterized by a clustering of metabolic and cardiovascular abnormalities, including insulin resistance of skeletal muscle glucose metabolism, hyperinsulinemia, glucose intolerance, dyslipidemia, essential hypertension, and central adiposity. Individual interventions with antioxidants or endurance exercise training enhanced insulin action on skeletal muscle and whole body insulin sensitivity in the markedly insulin-resistant, hyperinsulinemic, and dyslipidemic obese Zucker (fa/fa) rat. Individually, antioxidant treatment and exercise training by the obese Zucker rat resulted in a decrease in protein carbonyls (reflective of local oxidative stress), plasma free fatty acids, and intramuscular triglycerides, as well as an upregulation of the protein expression of insulin receptor substrate-1 (IRS-1), a critical component of the insulin signaling pathway. Whereas exercise training alone enhanced the protein expression of GLUT-4 glucose transporter isoform, this protein expression was not affected by antioxidant treatment. Most importantly, this study has investigated the interactions of antioxidant and exercise training in combination on whole body insulin sensitivity and skeletal muscle insulin action in the obese Zucker rat. The combination of antioxidant and exercise training functioned in an additive fashion and brought about the greatest increases in insulin action on skeletal muscle glucose transport activity and IRS-1 protein expression compared with either intervention individually. In addition, the IRS-1 protein expression, following the individual or combined intervention of antioxidant and exercise training, was correlated with insulin-mediated glucose transport in skeletal muscle. It is therefore likely that, in response to insulin, the downstream signaling from the expanded IRS-1 protein pool, in skeletal muscle from obese Zucker rats treated with antioxidant and exercise training in combination, acts on the expanded GLUT-4 pool (derived from exercise training) to bring about the greatest incorporation of GLUT-4 into the plasma membrane, with a corresponding enhancement of glucose transport activity. This study supports the utility of the combination of exercise training and antioxidant for the prevention and treatment of insulin resistance and type 2 diabetes.
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Veereswaran, Vasanthi. "High density lipoprotein intracellular metabolism in the kidney." Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26792.
Full textAbstract:
Experiments were undertaken to evaluate the factors that control the re-absorptive salvage of high density lipoproteins (HDL) in the kidney. HDL is readily taken up at the apical surface of polarized human proximal tubule epithelial cells (HKC-8). HKC-8 cells do not degrade HDL apolipoproteins, but instead transport and re-secrete the lipoprotein from the opposite, basolateral surface. Only ∼10% of the HDL lipids taken up are re-secreted, while ∼60% of the internalized HDL proteins are re-secreted. The composition and charge of HDL directly affects their ability to be internalized and transported through HKC-8 cells. HDL-apolipoproteins stimulate the transport of HDL components to the basolateral surface, while HDL-lipids inhibit the process. Enrichment of HDL with phosphatidylinositol (PI) increases HDL negative charge and inhibits its transport and secretion from the basolateral surface. Enrichment with phosphatidylcholine (PC) decreases HDL charge and enhances the transcytosis of HDL. These results show that HDL composition and charge regulate the re-absorptive salvage of HDL apolipoproteins in the kidney by controlling the intracellular metabolism of this lipoprotein. Our data suggest that apical to basolateral transport within proximal tubule cells could serve to recover HDL from the glomerular filtrate and return it back to the circulation. A stimulation of this process may decrease the loss of HDL from the circulation and therefore be anti-atherogenic.
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Ganesh, Devi. "Effect of superoxide dismutase mimetic, AEOL 10150 on the regulation of the endothelinergic system in lungs and heart of rats exposed to air pollutants." Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/27135.
Full textAbstract:
Epidemiological studies have associated cardiopulmonary morbidity and mortality with air pollution. Inhalation of pollutants increases plasma levels of the vasoconstrictor peptide endothelin (ET)-1 and its precursor bigET-1 in experimental animals and human subjects, and induces an oxidative stress in the lungs. Changes of circulating ET-1 is attributed to increased de novo synthesis in lung endothelial cells and spillover in the systemic circulation. Clinical studies indicate that excess ET-1 can be detrimental to individuals with cardiovascular and pulmonary diseases. My hypothesis is that oxidative stress pathways in the alveoli mediate the regulation of the endothelinergic system in response to inhalation of air pollutants. I have tested this hypothesis in male Fischer-344 rats by blocking a potential superoxide surge during or after inhalation of pollutants with a superoxide dismutase (SOD) mimetic drug, AEOL 10150. Rats were injected with 2mg/kg of AEOL 10150 two hours prior to inhalation exposure for four hours to pollutants, and sacrificed immediately or 24 hours post exposure. Treatment with the SOD mimetic abrogated the increase in expression of preproET-1 mRNA and ECE-1 mRNA and plasma ET-1 levels caused by the air pollutants. This suggests that oxidative stress pathways contribute to the regulation of endothelinergic system.
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Maric, Jovana. "Lipid acquisition by apolipoprotein A-I in ER and Golgi compartments of primary mouse hepatocytes." Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/27153.
Full textAbstract:
It was previously unknown what the significance and location of intracellular lipidation of newly synthesized apoA-I in hepatocytes were in plasma HDL formation. By labeling primary mouse hepatocytes with 3H-choline, we showed that phospholipidation of apoA-I is most significant in endoplasmic reticulum (ER) and medial Golgi compartments with minor lipidation upon export from the cell. Intracellular LDL-cholesterol lipidation of apoA-I is absent, with rapid cholesterol accumulation at the plasma membrane. De novo synthesized cholesterol was able to lipidate apoA-I intracellularly to a small but significant level. In hepatocytes lacking ABCA1, phospholipidation and lipidation by de novo cholesterol were both reduced in Golgi, while ER lipidation remained mostly unchanged. Plasma membrane lipidation by LDL-cholesterol was also significantly reduced. This implies that HDL formation begins with apoA-I phospholipidation in the ER, followed by modest cholesterol lipidation in the Golgi, dependent on ABCA1, with the bulk of cholesterol lipidation occurring at the plasma membrane.
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MacLellan, James Darcy. "Effects of the mitochondrial uncoupling protein 3 on fuel substrate oxidation and reactive oxygen species formation in rat L6 muscle cells." Thesis, University of Ottawa (Canada), 2007. http://hdl.handle.net/10393/27533.
Full textAbstract:
Uncoupling protein 3 (UCP3) is an integral mitochondrial membrane protein thought to disassociate fuel substrate oxidation by allowing proton re-entry into the mitochondrial matrix. Expression of UCP3 has been correlated with fatty acid and glucose metabolism, and reactive oxygen species (ROS) formation. To improve our understanding of the potential involvement of UCP3 in such pathways we investigated the effects of a UCP3 overexpression (2.2-2.5 fold) in the L6 muscle cell line. These findings were compared to those of UCP2 overexpression and DNP exposure. Palmitate oxidation was significantly increased by overexpressing UCP3 but unaffected by the other treatment conditions. Both glucose oxidation and oxygen consumption were unaffected by UCP2 and UCP3 overexpression but were significantly increased by DNP treatment. ROS production was decreased by UCP2, UCP3 and DNP treatment. These findings suggest a role for UCP3 in the regulation of fatty acid oxidation and ROS formation but not in glucose oxidation.
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Kongmanas, Kessiri. "Significance of sulfogalactosylglycerolipid in male fertility: Studies using Cgt heterozygous mice." Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/27996.
Full textAbstract:
Sulfogalactosylglycerolipid (SGG) is a sulfoglycolipid present specifically at a substantial level in mammalian male germ cells. It has been shown to function as an adhesion molecule important for sperm-egg interaction and a structural lipid involved in formation of sperm lipid rafts during capacitation in vitro. Due to the unique characteristics and functions, SGG can potentially serve as a biomarker for sperm fertility as well as a target for development of a non-hormonal contraceptive. To confirm the in vivo roles of SGG, we sought for transgenic mice with reduced amounts of sperm SGG. Cgt knockout male mice, transgenetically deficient in UDP-galactose:ceramide galactosyltransferase (CGT), an enzyme involved in SGG synthesis, are infertile due to spermatogenesis disruption. However, the Cgt+/- males can still produce sperm and sire offspring. We hypothesized that Cgt+/- males, expected to have reduced SGG amounts, would have compromised fertilizing ability and could serve as in vivo models for studying roles of SGG in fertilization and spermatogenesis. Unexpectedly, our results revealed that Cgt+/- males exhibited unimpaired spermatogenesis and fecundity. Moreover, the levels of SGG as well as lipid profiles of sperm and testes of Cgt+/- mice were similar to those of the wild type, suggesting that compensatory mechanisms must have occurred to maintain SGG levels in the Cgt+/- mice. Although these results revealed that Cgt+/- mice could not be used as the animal models, they implicated significance of normal testis and sperm SGG levels in maintaining normal spermatogenesis and fertility. The possible compensatory mechanisms regulating SGG levels were further investigated in Cgt+/- mice. As expected, only half of Cgt mRNA expression level of the wild type was transcribed in the Cgt+/- testes; however, testicular CGT polypeptides as well as their enzymatic activities in the Cgt+/- mice were found at a comparable level to those of the wild type. On the other hand, no change was found in terms of mRNA levels, polypeptide levels or enzymatic activities of arylsulfatase A (ASA), the enzyme responsible for SGG degradation in the testis. In conclusion, the compensatory mechanisms for SGG level adjustment in Cgt +/- mice occurred through the biosynthetic pathway, rather than the degradation pathway, by increasing the CGT polypeptide expression level. Therefore, identification of specific spermatogenic cell stages, contributing to normal expression levels of CGT and SGG in the Cgt+/- testes warrants further studies, as these studies should provide useful information regarding CGT and SGG importance during male germ cell development. In addition, a new approach to produce the animal models that can produce sperm with reduced SGG levels should be attempted. The RNA interference (RNAi) techniques may be tried to achieve this goal.
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Di, Falco Marcos Rafael. "Development of growth factor-cytokine fusion proteins with increased hematopoietic activity : physiological and cellular effects." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82853.
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Hematopoietic precursor cells express cell surface receptors for a variety of cytokines and growth factors. These hematopoietic secreted humoral factors can influence the proliferation, differentiation, survival and mobilisation of blood stem cells. Moreover, simultaneous exposure to different combinations of hematopoietic hormones can synergistically affect one or more of these cellular responses. Our laboratory has been involved in studying the role played by insulin-like growth factors (IGFs) in hematopoiesis. IGFs are known to stimulate the expansion of precursor cells from various hematopoietic lineages when administered in vivo. However, difficulties in producing recombinant IGFs with conventional bacterial or yeast expression systems make the use of IGFs as therapeutic hematopoietic agents a cost prohibitive concept. A baculovirus based expression system was developed for the production of large amounts of properly folded and biologically active secreted IGF analogues (BOMIGFs). This system was later adapted for the synthesis of a fusion protein consisting of BOMIGF and intedeukin-3 (BOMIGF-IL-3). The in vitro and in vivo activities of this chimeric molecule were subsequently studied.<br>The BOMIGF-IL-3 chimera promoted greater thymidine incorporation activity into TF-1 and bovine fetal erythroid cells than observed with the combined administration of BOMIGF and IL-3. This chimera also stimulated the formation of BFU-Es, CFU-GMs and, in particular, the highly proliferative macroscopic colonies in peripheral blood cell hematopoietic colony formation assays. These effects were reproduced in colony formation assays from bone marrow- and spleen-derived colony-forming cells from mice treated with BOMIGF-IL-3. This chimera also helped in the recovery of weight loss, anemia and neutropenia in an AZT-mediated myelossuppression mouse model. The chimera was shown to be significantly better than the corresponding equimolar mixture of the single factors at promoting the survival of TF-1 cells. This effect is associated with a sustained activation of PI-3 kinase, STAT5 phosphorylation and BclxL expression. The chimera was also better than the co-addition of BOMIGF and IL-3 at stimulating the migration of TF-1 cells across Transwell plates. The chimera-dependent potentiation of migration appears to be mediated by at the very least, an enhancement of PI-3 kinase activity.<br>This recombinant BOMIGF-IL-3 fusion molecule could prove useful for the therapeutic treatment of conditions with decreased production of blood cells such as in AZT- or chemotherapy-induced anemia. Other useful applications may include the mobilisation of stem cells and their ex vivo expansion for the purpose of stem cell transplantation.
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Saleh, Maya. "Protein-protein interactions and cell signaling in the regulation of HOX.PBX functions." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37620.
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HOX proteins are homeodomain-containing transcription factors essential for embryonic patterning. Despite amino acid differences, all HOX homeodomains recognize highly similar sites on DNA. One mechanism by which HOX proteins achieve specificity is through interaction with cofactors of the PBX and MEIS/PREP1 families. Higher order complexes between HOX, PBX and MEIS/PREP1 proteins form in vivo and are essential for target recognition and transcriptional regulation. Another level of control of HOX function is the nuclear availability of its cofactors. This thesis addresses the regulation of the nuclear availability of the PBX protein by MEIS/PREP1 family members. We identified two nuclear localization signals (NLS) in the PBX homeodomain and showed that the NLS are masked in the absence of MEIS/PREP1. Upon a conformational change in PBX induced by MEIS/PREP1 binding, the NLS are exposed and a receptor-mediated active transport of PBX into the nucleus is allowed. This thesis also investigates the mechanisms of transcriptional regulation by the HOX·PBX complexes. We show that HOX·PBX complexes repress transcription and are switched to transcriptional activators in response to cell signaling. We demonstrate that PBX mediates the repression function by recruiting histone deacetylases (HDACs) to HOX target promoters. Inhibition of HDAC activity or stimulation of protein kinase A (PKA) signaling converts the HOX·PBX complex into a net activator of transcription. The activation function is mediated by the HOX protein through its recruitment of CREB-binding protein (CBP), a coactivator with histone acetyl-transferase (HAT) activity. We propose a model whereby HOX·PBX transcriptional activity is determined by cell signaling, and is mediated by the local modification of chromatin structure in the promoter of downstream targets.
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Haghighat, Ashkan. "Studies on the mechanisms of mRNA binding to ribosomes in eukaryotes." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34730.
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The binding of eukaryotic ribosomes to mRNA is a complex process that is considered to be rate-limiting in translation initiation, and consequently a key target for translational regulation. Ribosome binding to mRNA is facilitated by the 5' cap structure, m7GpppN (where N is any nucleotide). The initiation factor eIF4F plays a key role in regulating translation rates. eIF4F is a three-subunit complex composed of eIF4E, the cap-binding protein; eIF4A, an RNA helicase; and eIF4G (p220), which bridges eIF4E and eIF4A, and enhances dramatically the interaction of eIF4E with the mRNA 5' cap structure. eIF4F in conjunction with another initiation factor, eIF4B, is thought to unwind the mRNA 5 '-secondary structure to facilitate the binding of mRNA to ribosomes The activity of eIF4F, and the regulation of mRNA binding to ribosomes is tightly correlated with the growth status of the cell. Recently, proteins that interact with eIF4E, termed 4E-BPs, have been identified; these proteins link translation initiation and growth promoting signal transduction pathways. Phosphorylation of 4E-BPs in response to insulin and mitogens decreases their affinity for eIF4E. 4E-BPs compete with eIF4G for binding to eIF4E through binding domains that share common sequence motifs. Consequently, 4E-BPs restrain eIF4E from forming an active cap-binding complex, eIF4F, and prevent subsequent binding of 40S ribosomal subunit to capped mRNAs. Under these conditions, the binding of eIF4E to the mRNA cap structure is extremely inefficient. As a result, cap- and eIF4E-dependent translation is downregulated. Modulation of eIF4F activity is also observed following infection by certain viruses. One of the most dramatic examples of this occurs upon picornaviral infection. As we report here, eIF4G alone is a relatively poor substrate for cleavage by the rhinovirus 2A proteinase (2Apro). However, an eIF4G-eIF4E complex is cleaved efficiently by the 2Apro suggesting that eIF4F is a preferred target for di
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Kuhn, Hallie. "Regulation of Yolk Catabolism in Early Embryogenesis." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:23845424.
Full textAbstract:
Yolk provides an important source of nutrients during the early development of oviparous (non-platental) organisms. In addition to phosphate and lipids, it is com- posed mainly of vitellogenin proteins packed into membrane-bound compartments called yolk platelets. Catabolism of yolk is initiated by acidification of the yolk platelet, leading to the activation of cathepsin-like proteases that degrade yolk contents, but it is unknown how this process is triggered. Using maternal shRNA technology in Drosophila melanogaster embryos we find that yolk catabolism depends on components of the Tor pathway, a well-characterized regulator of cellular metabolism. Knockdown of Tor also leads to severe nuclear fragmentation, abnormal gastrulation, and an increased ratio of AMP/ATP. This phenotype is more severe than inhibition of Tor in later development, or in cell culture models, suggesting that Tor may have additional functions during early development.
Additionally, we identify a downstream target of Tor, Atg1, as necessary for yolk catabolism. Atg1 is responsible for initiation of autophagy, a process that de- grades both protein and organelles within the cell. While Atg1 is required for a burst of spatially-regulated autophagy during late cellularization, autophagy is not required for yolk catabolism. We find that knockdown of Atg1, but not downstream autophagy proteins, can rescue shRNA-Tor embryos, suggesting that Atg1’s role in yolk cataboilism may be through regulation of Tor. Last, we find that Rheb, a GTPase responsible for activation of Tor on the lysosome membrane, is present on Xenopus laevis yolk platelets. Therefore, regulation of yolk catabolism by the Tor pathway may function in a similar manner to Tor’s activity on the lysosome. Together, this work connects the conserved Tor and Atg1 metabolic sensing pathways to yolk catabolism, and may provide insight into the metabolic regulation of lysosomes more generally.<br>Systems Biology
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Szymanska, Irena. "Exploration of lentiviral vectors and TAT-fusion proteins for the delivery of XIAP protein to neonatal retinal progenitor cells." Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/27790.
Full textAbstract:
Post-transplant apoptosis is a major obstacle to successful cell replacement therapy for retinitis pigmentosa. Over-expression of the X-linked inhibitor of apoptosis (XIAP) protein could increase transplant survival leaving a greater numbers of cells available to replenish photoreceptors lost during retinal degeneration. Sonic Hedge hog expanded C57BL/6 mouse neonatal retinal progenitor cells (Hh-RPCs) were infected with two lentiviral constructs, encoding XIAP/GFP or GFP only, as well as with the TAT-fusion protein, TAT-eGFP. The optimal delivery conditions and expression patterns were assessed. It was found that lentiviral infection, in conjunction with fluorescence activated cell sorting (FACS) allowed for the creation of a nearly pure line of Hh-RPCs which over-expressed XIAP protein for at least one month. Although the TAT-fusion protein efficiently transduced Hh-RPCs, its nuclear localization made it unsuitable for XIAP protein delivery. These results demonstrated two methods of transducing primary retinal progenitor cells and represent an important first step towards efficient cell replacement therapy in the retina.
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Sheng, Yinglun. "G protein signaling and G protein coupled receptor (GPCR) pathway in Xenopus oocyte maturation." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/29262.
Full textAbstract:
Xenopus laevis oocytes are physiologically arrested at the first meiotic prophase. Progesterone reinitiates meiosis (maturation) through inhibition of an oocyte adenylyl cyclase (AC) and reduction of intracellular cAMP. However, the mechanism by which progesterone regulates AC activity and cAMP level still remains unclear.
In this thesis, I summarize work I conducted that collectively helps elucidate how high levels of cAMP might be achieved in G2 arrested oocytes. In Chapter 2, I describe our finding that inhibiting endogenous G-protein betagamma subunits, through the use of two structurally distinct Gbetagamma scavengers, causes hormone-independent oocyte maturation. In contrast, overexpression of Xenopus Gbeta1, alone or together with bovine Ggamma2, inhibits progesterone-induced oocyte maturation. These results for the first time implicate that an endogenous G protein coupled receptor system releases a Gbetagamma complex as the dominant meiosis inhibitor.
Chapter 3 describes my research aiming to reveal the identity of the oocyte AC responsible for generating meiosis-inhibiting cAMP. I provide further evidence here that the ability of Gbetagamma to inhibit meiosis is attributed to the activation of an endogenous AC, rather than other possible Gbetagamma effectors. Through molecular cloning and biochemical characterization, I discovered that the likely AC candidate is Xenopus AC7, an isoform that is activated by Gbetagamma, but only in the presence of GTP-bound Gsalpha. The identification of xAC7 suggests that the maintenance of high levels of cAMP may require the cooperation of Gsalpha and Gbetagamma.
Finally, in Chapter 4, I describe our efforts in identifying the GPCR(s) responsible for activating the cAMP signaling in prophase-arrested oocytes. A screening of known antagonists of GPCR(s) led to the identification of ritanserin, a potent antagonist of serotonin receptors, as a potent maturation inducer in Xenopus oocytes. Pharmacological and molecular studies, however, have ruled out the involvement of a known serotonin receptor in meiosis arrest. Instead, the most likely candidate is a "constitutively activated" GPCR that bears structural similarities to Xenopus serotonin receptor 7.
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Schmelz, Eric Alexander. "The role of phytoecdysteroids in spinach (Spinacia oleracea): Physiological responses to below ground herbivory support a plant defense hypothesis." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/288960.
Full textAbstract:
Polyhydroxylated steroids with insect molting hormone activity were discovered in plants over thirty years ago. The major endogenous molting hormone of insects is believed to be 20-hydroxyecdysone (20E) and interestingly, it is also the most commonly encountered phytoecdysteroid (PE) in plants. Ecdysteroids control developmental programs in both immature and adult insects however, the role of PEs in plants has not been demonstrated. PEs are hypothesized to function as either plant hormones or plant defenses against phytophagous insects. Many toxic secondary metabolites are concentrated in apical meristems where herbivory would result in the greatest reduction in plant fitness. Similarly, the highest concentrations of 20E in spinach were associated with the stems and vasculature while old leaves and roots displayed low levels. In plants, concentrations of toxic or deterrent metabolites are often rapidly induced following attack. In spinach roots, both mechanical damage and insect herbivory resulted in rapid increases in 20E concentrations. The plant wound signal, jasmonic acid was strongly implicated in signaling this response. Known plant hormones and chemical defenses are regulated differently. Pulse chase studies with [2-¹⁴C] mevalonic acid demonstrated that de novo root 20E biosynthesis occurred during the induction and, once synthesized, 20E was stable for over one month. This result is does not support the plant hormone hypothesis, as plant hormones typically undergo rapid conjugation or catabolism. The induction of root 20E concentrations occurred without similar changes in related membrane phytosterols. Simply, pathway specificity was demonstrated as increased 20E accumulation was not part of an overall increase in steroids. To empirically examine the hypothesis that PEs function as plant defenses against insects, a series of experiments were designed with the fungus gnat Bradysia impatiens. Results indicated that root herbivory by larvae induced 20E levels in roots, larval preference for diets containing induced 20E levels was reduced, larval survivorship on 20E containing diets was lower, and plants with induced root 20E levels were better protected from attack. Together, these results support the plant defense hypothesis at both the physiological and ecological level.
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Maianti, Juan Pablo. "Therapeutic potential and physiological roles of Insulin-Degrading Enzyme illuminated by a DNA-templated macrocyclic inhibitor." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17467523.
Full textAbstract:
Insulin-Degrading Enzyme (IDE) is a zinc-metalloprotease responsible for the clearance of insulin in peripheral tissues. Despite decades of speculation that inhibiting endogenous insulin degradation might treat Type-2 Diabetes, the functional relationship between IDE and glucose homeostasis remains unclear. IDE inhibitors that are active in vivo are therefore needed to elucidate IDE’s physiological roles and to determine its potential to serve as a target for the treatment of diabetes.
In this thesis I describe the development of the first highly specific IDE in vivo probe, identified from a DNA-templated library of macrocycles, which enabled the first study of the physiological consequences of IDE inhibition. An X-ray structure of the macrocycle bound to IDE reveals that it engages a novel binding pocket away from the catalytic site, which explains its remarkable specificity and its suitability to study IDE in vivo. Treatment of lean and obese mice with this inhibitor revealed that IDE regulates multiple metabolic hormones, including glucagon and amylin, in addition to insulin. Under physiological conditions that mimic a meal, such as oral glucose administration, acute IDE inhibition leads to substantial improvement in glucose tolerance, owing to the potentiation of endogenous insulin and amylin levels over glucagon signaling. These studies demonstrated the feasibility of modulating IDE activity as a therapeutic strategy to treat diabetes and expanded our understanding of the roles of IDE in glucose and hormone regulation.
Based on these studies we sought to develop substrate-selective inhibitors that block IDE’s ability to degrade insulin but not its ability to degrade glucagon, which would represent a major step forward towards IDE-targeted therapeutics. The first-generation DNA-templated inhibitor was retailored into a fluorescent anisotropy tool for high-throughput screening of diverse small-molecule libraries. We discovered and characterized a family of IDE inhibitors with sub-micromolar potencies that inherited the remarkable specificity for IDE over other metalloproteases, and selectively obstruct IDE-mediated insulin degradation in a way that accommodates for glucagon cleavage.
In conclusion, these findings offer new insights into the biological roles of IDE and establish a novel strategy to selectively potentiate the physiological insulin response in order to improve blood sugar control in Type-2 Diabetes.<br>Chemistry and Chemical Biology
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Bojic, Teodora. "Host involvement in the replication of potato spindle tuber viroid and the evolutionary relationship between plant viroids and the hepatitis delta virus." Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28353.
Full textAbstract:
The present study examines the interaction between host RNA polymerase II (RNAP II) and potato spindle tuber viroid (PSTVd), with the goal of locating and characterizing a putative RNAP II promoter within the viroid's RNA genome. By using a co-immunoprecipitation approach coupled with deletion and mutational analysis, RNAP II was shown to specifically bind the left terminal hairpin loop of PSTVd(+) RNA. The interaction with RNAP II appears to be dependent on PSTVd secondary structure features, rather than a particular sequence. These findings provide direct evidence of association between RNAP II and PSTVd RNA, and render a unique example of a possible RNA promoter for RNAP II.
The second part of the study examines the evolutionary relationship between viroids and the hepatitis delta virus (HDV), as these pathogens share key structural and functional characteristics. We conclude, based on infection experiments, that HDV and viroids share common strategies and host factors to fulfill their respective life-cycles. We found that both HDV and an HDV mutant lacking the HDAg protein-coding region (miniHDV) can replicate in a plant host. However, miniHDV and PSTVd can replicate in human cells only in the presence of the small delta antigen (HDAg-S). Together, these results provide support for the hypothesis that HDV evolved from a viroid-like element through the capture of a cellular transcript necessary for its adaptation to a human host.
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Azizeh, Bassem Yousef. "Structure-activity relationship analysis: Developing glucagon agonists and antagonists for studies of glucagon action in normal and diabetic states." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282252.
Full textAbstract:
Several glucagon analogues containing substitutions in the N-terminal region, in particular residues 1, 5, 6, 9 and 10 (histidine, threonine, phenylalanine, aspartic acid and tyrosine, respectively), were synthesized. In addition four β-methylphenylalanine isomers were introduced at position ten to assess the role of these topographical modifications on hormone activity, and to study the effect of constraint and biased conformational preferences of the side chain moieties on biological activity. All the analogues were synthesized by solid-phase methodology, purified to homogeneity by reverse-phase high-performance liquid chromatography, and characterized by electrospray mass spectroscopy, amino acid analysis and thin layer chromatography. Following characterization they were analyzed using rat liver plasma membranes for receptor-binding affinity as well as their ability to stimulate adenylate cyclase. Structure-activity relationship analysis provided critical information about the conformational, chemical and structural properties of amino acid residues required for receptor recognition and signal transduction in the glucagon sequence. His¹ was confirmed to operate along with Asp⁹ for the activation and binding to the glucagon receptor. These new findings should permit the design of more pure and potent glucagon receptor antagonists by focusing on the role of Phe⁶ and other residues in the N-terminal region. A newly developed assay for examining low levels of cAMP accumulation in response to glucagon antagonists, agonists and partial agonists was developed. Previously reported glucagon receptor antagonists had partial agonist activity in rat hepatocytes. This assay system, in conjunction with binding and adenylate cyclase studies in both hepatocytes and liver plasma membranes, redefines the major characteristics of pure glucagon antagonists. The most potent glucagon receptor antagonist [des-His¹, des-Phe⁶, Glu⁹]glucagon-NH₂ was studied using conformational analysis and 2D NMR techniques to analyze the secondary structure of the analogue. Proton resonance assignments using COSY, NOESY and TOCSY in d₆-DMSO were made.
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Robinson, Patrick 1964. "Characterization of POMC-derived peptides from guinea-pig and human pituitaries." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22795.
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The biochemical characterization of the pro-opiomelanocortin (POMC) products, isolated and purified from a human anterior lobe pituitary adenoma associated with Cushing's Syndrome, illustrates the processing of this prohormone. In the tumor, 87% of the acidic joining peptide (AJP) is found as a dimer rather than as a monomer, the prevalent form found in normal pituitary tissue. The corticotropin (ACTH) purified and characterized from the tumor was found not to be phosphorylated. In contrast, human ACTH of normal pituitary origin is found to be 30% phosphorylated at the serine residue at position 31. No evidence of cleavage at residues 49-50 to produce $ tau sb3$-MSH and the 1-49 fragment was found.<br>ACTH was purified from extracts of guinea-pig anterior pituitaries and characterized in terms of its amino acid composition and molecular weight using IS-MS and HPLC. Guinea-pig ACTH was found to have a similar activity to that of human ACTH with respect to the maximal steroid output of corticosterone and aldosterone. However, it proved to be slightly more potent in terms of the concentration which elicited half-maximal steroid secretion. Under the assay conditions used, guinea-pig ACTH does not seem to a superagonist as suggested by a previous study. Combining amino acid compositions, mass spectrometric data, and the recent determination of the cDNA sequence for guinea-pig ACTH, the identification of various purified biosynthetic derivatives of guinea-pig POMC was facilitated.<br>Joining peptide, a major product of POMC processing, was found in extracts of both anterior and neurointermediate lobes. The purified peptide corresponded exactly in amino acid composition and mass to the predicted structure established by the CDNA sequence. Also, by using ion-spray mass spectrometry, post-translational modifications of other products of intermediate lobe processing were observed. N- and O-acetylation of $ alpha$-melanotrophin, partial O-phosphorylation of corticotrophin-like intermediate lobe peptide and carboxyl-terminal amidation of $ beta$-melanotrophin were identified. (Abstract shortened by UMI.)
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Cooper, Roland Arthur 1963. "Pyrrolizidine alkaloids: Chemical basis of toxicity." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/290581.
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In humans, livestock and experimental animals, pyrrolizidine alkaloids (PAs) are toxic as a consequence of their hepatic metabolism to reactive pyrrolic esters, or dehydroalkaloids (DHAs). Despite their similarity in structures, PAs often vary markedly in their lethality (LD₅₀s) and in the organs in which toxicity is expressed. We have examined whether there are differences in the physicochemical properties of certain DHAs which are associated with differences in patterns of metabolism and toxicity produced by the parent PA. Using a potentiometric method to measure hydrolysis, it was determined that the half-lives of the corresponding DHAs of retrorsine, seneciphylline, monocrotaline and trichodesmine were 1.06, 1.60, 3.39 and 5.36 sec, respectively. These values were supported by similar results from experiments measuring reactivity of DHAs toward 4-(p-nitrobenzyl)pyridine. Studies from the isolated rat liver perfused with PAs show that DHA stability is related to patterns of metabolism and toxicity. Perfusion of the primarily hepatotoxic retrorsine and seneciphylline is associated with a greater proportion of metabolite released as non-toxic 7-glutathionyl-6,7-dihydro-1-hydroxymethyl-5H-pyrrolizine (7-GSDHP), a greater proportion alkylating liver macromolecules, and a lower proportion released as DHA into the circulation. Perfusion with monocrotaline and trichodesmine, PAs producing extrahepatic toxicity, produced lower proportions of 7-GSDHP release and liver alkylation, and higher proportions of DHA released into the circulation. Other studies characterizing DHAs included the use of an in vitro enzyme assay in which DHAs were shown to inhibit the phosphotransferase activity of yeast and rat brain hexokinase. Parent PAs, and the hydrolysis product of DHAs, (±)-6,7dihydro-1-hydroxymethyl-5H-pyrrolizine (DHP) did not affect enzyme activity. In vivo studies in rats have established that glutathione and cysteine-conjugated pyrrolic metabolites of PAs likely represent detoxication pathways, providing further support for DHAs as the primary toxic metabolite. We have examined the chemical form of sulfur-bound pyrroles to establish the importance of the 7-ester position in PA toxicity. Additionally, we have developed an efficient technique for the rapid separation and purification of large quantities of PAs using high-speed counter-current chromatography.
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Billinghurst, Robert Clark. "The identification of collagenase-generated cleavage products of type II collagen using anti-neoepitope antibodies." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0004/NQ36955.pdf.
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Born, Stephanie Lynn 1968. "Characterization of canine cytochromes P450 2B and 3A." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/290587.
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The objective of these studies was to functionally characterize canine cytochromes P450 from subfamilies 2B and 3A. Studies of the canine hepatic 2B form PBD-2 had previously revealed that this enzyme exhibits a species specific ability to metabolize 2,2',4,4',5,5'-hexachlorobiphenyl (245-HCB) and catalyze progesterone 21-hydroxylation. Expression of the putative PBD-2 cDNA, 2B11, in three different heterologous systems revealed that the recombinant enzymes' apparent substrate specificities varied based upon the expression system. 2B11 expressed in COS cells and yeast did not metabolize progesterone in a manner consistent with that of the purified hepatic enzyme, suggesting that 2B11 did not encode PBD-2. However, subsequent expression of 2B11 in E. coli confirmed that this recombinant enzyme did metabolize progesterone into 21- and 16α-hydroxyprogesterone. The structural determinants of 2B11-mediated progesterone 21-hydroxylation were then examined via site-directed mutagenesis of amino acid residues 114, 290, 363, and 365. Consistent with the importance of these residues in androstenedione and 245-HCB metabolism, amino acid alterations Val 114 $\to$ Ile, Asp-290 → Ile, and Ile-363 → Val each decreased 2B11 progesterone 21-hydroxylation. 2B11 mutants at position 365 differed in their regioselective metabolism of progesterone, whereas these mutations had little affect on the stereoselective metabolism of androstenedione. Cytochrome P450 3A forms are of intense interest due to the wide range of therapeutic compounds metabolized by these enzymes. To determine if canine liver contained multiple 3A forms which exhibit substrate specificities similar to those of other species, the canine 3A form PBD-1 (3A12) was expressed in E. coli. 3A12, rabbit 3A6 and human 3A4 metabolized steroids and macrolide antibiotics into the same products at comparable rates. A 3-fold difference in the rate of troleandomycin demethylation between liver microsomes and 3A12, the identification of a novel putative 3A hepatic protein via NH₂-terminal sequencing, and isolation of a distinct 3A cDNA provided evidence for 3A multiplicity in canine liver microsomes. The identification of functionally distinct canine 3A forms could provide the framework for structure-function analysis of these clinically important enzymes. Furthermore, 3A multiplicity and the conservation of substrate specificity between canine and human forms suggests that the canine may be an appropriate model of human 3A metabolism.
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Liang, Yan. "Identification and Characterization of Galactosyltransferases and Fucosyltransferases Involved in Arabinogalactan-Protein Glycosylation." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1343410954.
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Byrd, Alyson. "Evidence for a receptor binding 24R, 25-dihydroxyvitamin D3 in developing bone." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21519.
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Although 24R,25(OH)2D3 has been implicated in bone development, its biological role and mechanism of action remain controversial. In search for evidence of a receptor, nuclear and cytosol extracts were isolated from mandibles and calvaria of E17.5 mice. Competition and saturation analysis identified a saturable, specific and high affinity (Kd=1.1nM) 24R,25(OH) 2D3 binding-protein. The results of these and sucrose sedimentation studies indicate that this protein is not vitamin D receptor (VDR) or vitamin D binding protein (DBP). Tissue specificity experiments suggest that this putative receptor is also present in liver but not brain.<br>pBDGal4-hRXRalpha bait was used to screen neonate and embryonal mandible/calvaria cDNA libraries using the yeast two-hybrid system. PCR screening was also performed using primers from the zinc-finger region of the VDR. To date no positive clones have been identified. Isolation of this putative receptor will provide valuable insight into the mechanism of this metabolite's role in bone development.
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D'Agnillo, Felice. "A novel red blood cell substitute based on crosslinked hemoglobin, superoxide dismutase, and catalase." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0024/NQ29915.pdf.
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Via, Stephen M. "From Seed to Sky: Impacts of explosive compounds on vegetation across spatial and developmental scales." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4476.
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Explosive compounds are broadly distributed across the globe as a result of nearly two centuries of munitions use in warfare and military activities. Two explosive compounds have seen disproportionate use; RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) and TNT (2-methyl- 1,3,5-trinitrobenzene), being the most commonly found explosives in the environment. The effects of explosives on biota have been studied in great detail; however, there is a general lack of understanding with regard to broader ecological impacts of these contaminants. My dissertation objective was to follow the impacts of explosive compounds on vegetation across scales. Impacts on vegetation at the species scale alter community composition via species-specific and age-specific responses to explosives. Results presented here showed that contaminated soils induced a variety of responses in vegetation, yet impacts to water relations were similar regardless of species. Use of novel metrics in monitoring plant responses to explosives compounds aided in delineation of reference and treatment groups. At the community scale the presence of explosives induced species and functional composition shifts. The observed shifts are likely due to physiological impairment as individuals in the field exhibited significant impacts to physiological functions. Effects of explosives contamination also detectable using remote sensing techniques. Impacts to plant morphology and physiology are directly related to community level shifts observed in long contaminated areas. This highlights the long lasting impacts that these largely overlooked contaminants can have on a system and opens avenues for new, at range, vegetation based contaminant detection systems.
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Pace, Brian A. "Physiology, Photochemistry, and Fitness of Mexican Maize Landraces in the Field." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1545421491370678.
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Kamat, Rohit Babli. "Phytoremediation for dye decolorization." Diss., Kansas State University, 2014. http://hdl.handle.net/2097/17548.
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Doctor of Philosophy<br>Department of Biochemistry and Molecular Biophysics<br>Lawrence C. Davis<br>Synthetic dyes are capable of producing the whole color spectrum on account of their structural diversity but this diversity poses challenges in the degradation of dyeing wastes. Laccases and peroxidases from bacterial or fungal sources and parts of plants in the presence of hydrogen peroxide (H₂O₂) plus a mediator have been exploited in the bioremediation of synthetic dyes. However, intact plants have not found much favor despite their phytoremediation potential. The goal of this research was to further clarify ways by which whole plants bring about decolorization of different types of synthetic dyes. Hydroponically cultivated plants from two dicot families namely Arabidopsis thaliana and sunflowers (Helianthus annuus) were exposed to representative dyes from several classes: monoazo (Methyl Red and Methyl Orange), disazo (Trypan Blue, Evans Blue and Chicago Blue 6B), and arylmethane (Brilliant Blue G, Bromocresol Green, Malachite Green and Phenol Red). Tests were done in presence or absence of externally added H₂O₂, with or without a free radical mediator, 1-hydroxybenzotriazole, using UV-Visible spectrophotometry. The initial rate of decolorization and the overall percentage decolorization was calculated for each dye in the different treatments. Decolorization of the dyes from different classes varied between plant species and depending on the treatment. Except for Methyl Red, all dyes required added H₂O₂ as well as mediator to achieve rapid decolorization. Added H₂O₂ was found to be the limiting factor since it was degraded by plants within a few hours. Both species were able to slowly decolorize dyes upon daily addition of fresh dye even in the absence of added H₂O₂ and mediator, provided that nutrients were supplied to the plants with the dye. A. thaliana was found to be more effective in dye decolorization per gram tissue than sunflower when treated under similar conditions. Analysis of the residual dye solution by ESI/MS did not reveal any potential by-products following the decolorization treatment with plants, suggesting that the plant roots might be trapping the by-products of dye decolorization and preventing their release into the solution. All these findings support the potential application of whole plants for larger scale remediation.
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Johansson, Emmy. "Disinfection of Wastewater with Sodium Hypochlorite : And how it Might be Applied at Slottshagen Wastewater Treatment Plant." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-175172.
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The disinfection of wastewater is not something that is currently in use at any wastewater treatmentplant in Sweden. The government has however stated some requirements for some wastewatertreatment plants to have a plan to implement disinfection in their treatment process, if asked.Therefore the goal of the project is to research if disinfection with sodium hypochlorite can beimplemented at Slottshagen wastewater treatment plant. There are several factors that will affect the efficacy of the disinfection of the wastewater. Firstly, thedisinfection process is dependent on the pH of the water solution. This is because the weakhypochlorous acid has better disinfection than the hypochlorite ion, and hypochlorous acid is presentthe most in the solution at pH 3-6. Another factor that is important to consider is the amounts ofnutrients present in the solution, since the chlorine oxidizes the nutrients rather than reacting with theorganisms in the solution. Some of the products from the oxidation of the nutrients are bad for bothhuman health and the environment. Also the temperature of the water and the concentration of thechlorine will affect the disinfection. Lastly, depending on which organism that is sought out to bedisinfected, the chlorine will have more or less effect on that particular organism. To research the chlorination effect, different additions of sodium hypochlorite were added to samplesolutions from the treatment plant and got to react in the solution for 5 minutes. Following thesamples were neutralized with ascorbic acid, and the amount of E. coli , coliform bacteria andintestinal enterococci were analyzed. The disinfection of the water during 1,5 minutes and at a shortertemperature were also analyzed. The results showed that the temperature, the contact time with thesolution and the concentration all are important factors to reach a proper disinfection, but the resultsalso showed that the amount of bacteria in the solution also is an aspect to take into considerationwhen treating wastewater. Finally, the considerations of disinfection of the wastewater with sodium hypochlorite is discussed.The point of addition of the chlorine was concluded to best be directly after the last chemicaltreatment step. When analysing if the disinfection would be possible, the disinfection was from theresults possible, but it was noticed that the results fluctuated a lot. The most probable reason why isbecause of the water quality. The water quality in general fluctuates regularly throughout the day, aswell as in between days of the week. Therefore throughout the disinfection process, the additions ofchlorine would need to be depending on several parameters, making the disinfection difficult toimplement. One solution to this could be to add a lot of chlorine to the bulk water at all times, but itwould cost too much if treating the water for a longer time, as well as it would be a higher risk to theenvironment. A solution to this problem could be to possibly neutralize the water before it is releasedas well, however when analyzing the cost of the ascorbic acid that was used as neutralization in thisproject, the cost to neutralize the water completely would be too high. Lastly it was discussed that theonly time disinfection of the wastewater would give any desirable results, is if the specific organismsthat are being sought out to be treated are bacteria or some viruses. If the particular organism that iswished to be treated is parasites, the disinfection with chlorine would not work.
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Kalra, Isha. "Role of Cyclic Electron Flow (CEF) and Photosystem I (PSI) Supercomplex Formation During Acclimation to Long-Term Salinity Stress in Green Algae: A Comparative Study." Miami University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=miami1626448523546503.
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Cristea, Laura G. "The Expression, Identification and Biochemical Characterization of the Extracellular Domain of Arabidopsis AFH2." Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1417707960.
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Alghamdi, Norah. "THE ROLE OF RNASE L IN THE KIDNEY FUNCTION." Cleveland State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=csu1557424763775669.
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