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Muscular activity regulates the expression of ColQ subunit of acetylcholinesterase : a signaling pathway mediated by Ca2̳+̳/ calmodulin-dependent protein kinase II /Lau, Faye. January 2007 (has links)
Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2007. / On t.p. "2̳+̳" is superscript. Includes bibliographical references (leaves 137-155). Also available in electronic version.
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EFA6A/ARF6 signaling and functions in glioblastoma carcinogenesis /Li, Ming, January 2006 (has links)
Thesis (Ph. D.)--University of Hong Kong, 2006. / Also available online.
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Mathematical modeling of species-specific diacylglycerol dynamics in the RAW 264.7 macrophage following P2Y₆ receptor activation by uridine 5'-diphosphateCallender, Hannah L. January 2007 (has links)
Thesis (Ph. D. in Mathematics)--Vanderbilt University, Aug. 2007. / Title from title screen. Includes bibliographical references.
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Ras signalling pathway and MLL-rearranged leukaemias /Ng, Ming-him. January 2006 (has links)
Thesis (M. Phil.)--University of Hong Kong, 200. / Also available online.
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Physiological signal transduction from the photosynthetic apparatus in the green alga Dunaliella salinaLogie, Malcolme Ronald Ruxton January 1995 (has links)
The transduction of stress signals in plants is known to involve complex hysiological responses. In D. salina a range of stresses results in hyperaccumulation of ft-carotene and an understanding of stress responses in this organism has important biotechnological implications. In this thesis an attempt was made to elucidate the physiological components involved and establish a role for pH in response to high light stress. In order to achieve this the effect of high light stress on photosynthesis and cell productivity was measured. Results showed that photosynthetic carbon assimilation, oxygen evolution and cellular productivity was initially inhibited by exposure to high light intensities, but this inhibition was transient and was overcome by a rapid increase in all three parameters. The response of the carbon pool intermediates was also investigated. It was shown that on exposure to high light ft-carotene declined but then showed a rapid increase after about 4 hours of exposure. It was also demonstrated that the initial loss of ft-carotene was due to loss of this pigment from the photosynthetic pigment bed and that the hyper-accumulation of ft-carotene was due to accumulation of ft-carotene in lipoidal globules located in the chloroplast stroma. It was further demonstrated that there was mass movement of carbon in the xanthophyll cycle shortly after exposure to high light. This was characterized by the de-epoxidation of violaxanthin to antheraxanthin with a further de-epoxidation to zeaxanthin, thereby decreasing the epoxidation state of the cycle. Furthermore, it was shown that there was relocation of carbon from violaxanthin to the plant growth regulator abscisic acid. It was also shown for the first time in D. salina that the production of ft-carotene and operation of the epoxidation state of the xanthophyll cycle has a periodicity which is established after exposure to successive cycles of a light regime. Chlorophyll fluorescence was used together with well established ammonia stress responses to acquire a general overview of energy dissipation from the photosynthetic pigment bed. In conjunction with an understanding of xanthophyll cycle operation during exposure to high light stress it has been possible to establish a relationship between chlorophyll florescence, xanthophyll cycle operation and intracellular pH. It was also shown using chlorophyll fluorescence that after 4 hour exposure to high light a maximum fluorescence peak could no longer be induced indicating a transition at about this point from a state of reversibility to commitment of the full stress response. Nuclear magnetic resonance was used to follow intracellular pH fluxes during exposure to high light. A novel technique was developed for studying photosynthetically active organisms in the dark using nuclear magnetic resonance. These results showed that on exposure to high light stress there is rapid acidification of the chloroplast stroma and to a lesser degree of the acidic vacuole. The pH of these compartments is re-established after about 4 hours which is co-incident with the onset of fl-carotene hyper-accumulation and the loss of the induction of the chlorophyll fluorescence peak indicating an intimate relationship for fl-carotene, chlorophyll fluorescence, xanthophyll cycle operation and pH. The results from this study allow for the proposal of a general physiological stress transduction response mechanism for D. salina which is common for a range of different stresses and where intracellular pH plays a central role.
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Gene Regulation in BiofilmsSamanta, Priyankar January 2011 (has links)
Sessile bacterial communities which form on the solid surface or solid-liquid interface
are known as biofilms. Both single species and multispecies biofilms are characterized
by an extracellular matrix of polymeric substances which gives them several hundred
times more antibiotic resistances than a planktonic bacterial culture. Though bacteria
are the most common causative agent of various diseases, because of the high
antibiotic resistance, biofilms cause complications of various diseases like cystic
fibrosis, prosthetic valve endocarditis, chronic pulmonary diseases, catheter-associated
urinary tract infections and several other diseases. From past studies,
quorum sensing has been established as a novel target mechanism against biofilms; in
this study, the two-component signal transduction systems (2CSTSs) have been
focused. Once better understood, 2CSTSs can serve as a novel drug target and
prevention mechanism for biofilm associated diseases.
According to prior high-throughput experiments and phenotype microarray
experiments by our lab, several 2CSTSs like OmpR-EnvZ, RcsCDB along with the
global regulator FlhD/FlhC were hypothesized to have an important effect on various
developmental stages of biofilm formation. From that past study, we postulated that
acetate metabolism may be an important aspect for biofilm formation. In this study,
we tested and confirmed this hypothesis. We observed biofilms formed by several
mutants in 2CSTS, as well as mutants in acetate metabolism, using Scanning Electron
Microscopy (SEM). We found quantitative and qualitative differences in the biofilm of
the acetate mutants when compared to their isogenic parental Escherichia coli strain.
An additional mutation in rcsB with acetate mutant strains forms less clumpy biofilms
whereas an additional mutation in dcuR results in the formation of less biofilms. So
the structural and the quantitative differences of acetate mutant biofilms depend on
additional mutations in rcsB and dcuR. Though a number of studies have been done on the temporal gene expression within biofilms, spatial gene expression of the mature biofilm is a big gap of knowledge. The
future aim of this study is to study the temporal as well as the spatial gene expression
of different 2CSTSs in the biofilm. In my MS thesis, I have constructed selected
promoter fused GFP /RFP plasmids and some other fusion plasmids were purchased
from the promoter collections from Open Biosystems, lastly E. coli AJW678 bacterial
strains were transformed with these GFP /RFP fused plasmids. A 96 well microtiter
plate assay was performed to study the temporal expression from the promoters by
quantifying the fluorescence intensity in the planktonic culture. According to this
experiment, the highest expression of flhD was after 20 hours whereas, the expression
of ompR increases up to 7 days, which indicates that the flhD expresses earlier than
ompR. The decreasing phase of flhD expression was paralleled by the sharpest
increase in ompR expression as phosphorylated OmpR is an inhibitor of flhD
expression. / National Institutes of Health (NIH grant 1R15AI089403) / United States. Animal and Plant Health Inspection Service
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Investigations into roles for endocytosis in LIN-12/Notch signaling and its regulationChan, Jessica Yu January 2020 (has links)
The LIN-12/Notch signaling pathway is highly conserved in all animals, and is crucial for proper development. It is a key pathway in specifying cell fate in many cellular contexts, and dysregulation of the pathway can have deleterious consequences. Therefore, understanding how LIN-12/Notch signaling is regulated in different contexts has been a main area of interest in the field. Previous studies in different model organisms have identified many modes of regulation of the signaling pathway, one of which is endocytosis of the ligand and receptor. Here, I further investigated the role of endocytosis in LIN-12/Notch signaling in multiple developmental contexts in Caenorhabditis elegans. Work in Drosophila and vertebrates had previously established that ligand-mediated activation of Notch requires ubiquitination of the intracellular domain of the transmembrane ligand and the activity of the endocytic adaptor Epsin in the signaling cell. The consensus in the field is that Epsin-mediated endocytosis of mono-ubiquitinated ligand generates a pulling force that exposes a cleavage site in Notch for an ADAM protease, a critical step in signal transduction. In contrast, in this thesis, I examined two different transmembrane ligands in several different cell contexts and found that activation of LIN-12/Notch and the paralogous GLP-1/Notch in C. elegans does not require either Epsin-mediated endocytosis or ubiquitination of the intracellular domain of the ligand. Results obtained by a collaborator indicate that C. elegans ligand and receptor interactions are tuned to a lower force threshold than are Drosophila ligand and receptor interactions, potentially accounting for these differences.
I also looked at the role of endocytosis in regulating LIN-12 signaling in the context of vulval development. The cell fate pattern of six vulval precursor cells (VPCs) is mediated by EGFR and LIN-12/Notch signaling. Previous work using multicopy transgenes in fixed specimens indicated that LIN-12 is post-translationally downregulated via endocytosis in response to EGFR activation in the VPC named P6.p, an event that appeared essential for ligands to activate LIN-12/Notch in neighboring VPCs. In this thesis, I manipulate the endogenous lin-12 gene and examine live specimens to show that LIN-12 appears to be regulated transcriptionally in P6.p and evidence that there may be additional potential endocytic motifs that may regulate LIN-12 in this context.
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Alterations of signal transduction in lymphocytes cultured from patients with bipolar disorderConstant, Peggy. January 2001 (has links)
No description available.
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Nod factor recognition and response by soybean (Glycine max [L.] Merr) under abiotic and biotic stress conditionsDuzan, Haifa January 2003 (has links)
No description available.
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Characterization of Dante, a novel member of the DANCerberus family TGF-[beta] inhibitorsPopescu, Olivia January 2003 (has links)
No description available.
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