No description available.

No description available.

No description available.

<p>The cells of the budding yeast Saccharomyces cerevisiae undergo a robust morphological cycle, involving reorganization of the actin cytoskeleton, septin ring formation, and polarized growth. These events are crucial to the formation of a fully-equipped and properly-shaped bud, which gives rise to the daughter cell. The budding yeast, as a well-established genetic model system, has attracted numerous investigations aimed at uncovering the underlying principles of morphogenesis. </p><p>Despite the important roles of the septin ring and collar in morphogenesis and cytokinesis, little is known about how they are assembled. We found that septins are recruited to the ring and collar following a tri-linear assembly/disassembly scheme. </p><p>Polarization of actin cables enable directed secretion and growth. The formin Bni1p, an actin nucleator, is thought to polarize actin cables in response to the direct regulation by the master polarity regulator, Cdc42p. However, we found that all the known Bni1p-regulatory pathways are dispensable, including the direct regulation by Cdc42p, and we uncovered a novel pathway linking Bni1p to Cdc42p via the Cdc42p effector, Gic2p.</p><p>Yeast morphogenesis is tightly coupled with the cell cycle. Contrary to the prevailing model, we found that G1-CDK activity, albeit required for bud emergence, is not needed to trigger polarization. This finding suggests that cells are in a default polarized state, which is negatively regulated by the G2-CDK.</p> / Dissertation

Thesis (M. Phil.)--University of Hong Kong, 2000. / Includes bibliographical references (leaf 64).

Thesis (M. Phil.)--University of Hong Kong, 1996. / Includes bibliographical references (leaf 60-61).

Thesis (M.Phil.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 64) Also available in print.

Thesis (M.Eng.)(Electronic)--University of Pretoria, 2000. / Includes summary. Title from opening screen as viewed 5th November 2005. Includes bibliographical references.

A one-dimensional linear hybrid cellular automaton (CA) is a specialised form of linear finite state machine. These machines are of interest, both for their theoretical properties and for their applications in VLSI built-in-self-test, random number generation, cryptography, coding theory, and other areas. This work is a study of the algebraic properties of the characteristic polynomials of CA, primarily for machines defined over GF(2). Several problems, previously open, are solved: the efficient synthesis of a CA from an irreducible polynomial, the existence and uniqueness of CA for irreducible polynomials, the reducibility of the characteristic polynomial of a cyclic-boundary CA, and the form of a similarity transform between CA and linear feedback shift registers. A probabilistic algorithm for the synthesis of CA over finite fields other than GF(2) is presented. Various other results concerning the characteristic polynomial of CA are derived, and possible directions for future research are discussed. / Graduate

Our laboratory identified Adiporedoxin (Adrx), an endoplasmic reticulum localized oxidoreductase whose expression in adipose tissue is many fold greater than other tissues. In gain and loss of function experiments in cultured adipocytes Adrx knock down decreased the secretion of numerous adipokines, extracellular matrix, and transmembrane proteins and over expression increased secretion. Together, these results suggest Adrx regulates an early step in protein secretion from the ER. Immunofluorescence and proteolytic protection assays demonstrated that Adrx is located in the ER membrane with an ER luminal active site. We demonstrated that Adrx regulated protein secretion by affecting the oxidation state of ER redox chaperones. Using a cysteine-modifying PEGylation reagent, we showed Adrx oscillated between a reduced and oxidized form through the -CxxC- active site residues in response to the redox environment of the ER. Consequently, knocking down Adrx impaired the re-oxidation of protein disulfide isomerase, indicating an overlapping function with known regulators of ER redox homeostasis, namely endoplasmic reticulum oxidoreductase 1, and peroxiredoxin 4. Adrx is oxidized within the ER after treatment with hydrogen peroxide (H2O2) and can reduce H2O2 in vitro, suggesting it also acts as an antioxidant. The overexpression of Adrx in adipocytes protected the ER from oxidative stress and rescued adipokine secretion. Pancreatic islets are also highly secretory Adrx is expressed in isolated murine islets. In cultured islet cells, Adrx expression also decreased oxidative stress and correlated with the secretion of insulin, the main regulator of glucose homeostasis. In summary, Adrx expression controls secreted proteins and here we describe its ability to regulate the formation and release of disulfide-bonded proteins by reoxidizing ER chaperones and alleviating oxidative stress. Secreted proteins affect many aspects of metabolism including the control of appetite, glucose homeostasis, inflammation, and adipose tissue fibrosis. Overall, these data suggest that by mediating secreted proteins Adrx functions as important regulator of overall metabolism. / 2017-03-03T00:00:00Z