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Author: Norbert Seabrook Hill
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 228
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Book Description
DNA replication, nucleoid segregation, and cell division must be coordinated with growth and cell size to ensure viability in all organisms. Failure to do so yields progeny with an inappropriate fraction of genetic and cytosolic material, reducing the fitness of the organism. This dissertation has sought to understand the role of cell size in two fundamental aspects of bacterial physiology: 1) How do bacteria regulate cell size in response to nutrient availability? 2) Does cell size govern progression of the cell cycle? Growth rate and nutrient availability are primary determinants of cell size in single-celled organisms. Bacterial cells cultured in nutrient-rich circumstances are twice the size of cells grown in nutrient-poor conditions. How bacteria are able to perceive nutrient levels and amend cell size is largely undefined. In Chapter 2, I report the identification and characterization of the glucosyltransferase OpgH as a uridine diphosphate (UDP) glucose-dependent effector that coordinates Escherichia coli cell size with growth rate and nutritional status. High intracellular levels of UDP-glucose accumulate during growth in nutrient-rich conditions. In turn, UDP-glucose activates OpgH to sequester the essential division protein FtsZ, which obstructs assembly and/or maturation of the cytokinetic ring, delaying division to increase cell size. In this way, OpgH directly gauges nutrient status and modifies cell size through the timing of division. Cell cycle progression is regulated by cell size in all organisms. In bacteria, it has long been postulated that the achievement of a particular cell size triggers chromosomal replication. Chapter 3 of this dissertation describes a comparative study between E. coli and Bacillus subtilis examining whether cell mass determines the timing of initiation of DNA replication. Using mutants defective for cell size, my data confirms that E. coli directly ties the initiation event to cell mass. However, counter to the paradigm, the phenomenon of initiation mass is not conserved to B. subtilis, which appears to coordinate DNA replication through a cell cycle timer device. This dissertation yields several original conclusions. First, the discovery of OpgH as a UDP-glucose-activated antagonist of FtsZ polymerization is a significant advance in the understanding of cell size control in bacteria. However, these results in tandem with the cognate pathway in B. subtilis reveal a remarkable instance of convergent evolution. Based on this, I propose that UDP-glucose and cognate UDP-glucose binding proteins are a widely conserved strategy to direct nutrient-dependent changes in cell size. In addition, the revelation that initiation of DNA replication is cell size-independent in B. subtilis adds to a growing sentiment that mechanisms controlling DNA replication are fundamentally divergent throughout bacteria.
Author: Norbert Seabrook Hill
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 228
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Book Description
DNA replication, nucleoid segregation, and cell division must be coordinated with growth and cell size to ensure viability in all organisms. Failure to do so yields progeny with an inappropriate fraction of genetic and cytosolic material, reducing the fitness of the organism. This dissertation has sought to understand the role of cell size in two fundamental aspects of bacterial physiology: 1) How do bacteria regulate cell size in response to nutrient availability? 2) Does cell size govern progression of the cell cycle? Growth rate and nutrient availability are primary determinants of cell size in single-celled organisms. Bacterial cells cultured in nutrient-rich circumstances are twice the size of cells grown in nutrient-poor conditions. How bacteria are able to perceive nutrient levels and amend cell size is largely undefined. In Chapter 2, I report the identification and characterization of the glucosyltransferase OpgH as a uridine diphosphate (UDP) glucose-dependent effector that coordinates Escherichia coli cell size with growth rate and nutritional status. High intracellular levels of UDP-glucose accumulate during growth in nutrient-rich conditions. In turn, UDP-glucose activates OpgH to sequester the essential division protein FtsZ, which obstructs assembly and/or maturation of the cytokinetic ring, delaying division to increase cell size. In this way, OpgH directly gauges nutrient status and modifies cell size through the timing of division. Cell cycle progression is regulated by cell size in all organisms. In bacteria, it has long been postulated that the achievement of a particular cell size triggers chromosomal replication. Chapter 3 of this dissertation describes a comparative study between E. coli and Bacillus subtilis examining whether cell mass determines the timing of initiation of DNA replication. Using mutants defective for cell size, my data confirms that E. coli directly ties the initiation event to cell mass. However, counter to the paradigm, the phenomenon of initiation mass is not conserved to B. subtilis, which appears to coordinate DNA replication through a cell cycle timer device. This dissertation yields several original conclusions. First, the discovery of OpgH as a UDP-glucose-activated antagonist of FtsZ polymerization is a significant advance in the understanding of cell size control in bacteria. However, these results in tandem with the cognate pathway in B. subtilis reveal a remarkable instance of convergent evolution. Based on this, I propose that UDP-glucose and cognate UDP-glucose binding proteins are a widely conserved strategy to direct nutrient-dependent changes in cell size. In addition, the revelation that initiation of DNA replication is cell size-independent in B. subtilis adds to a growing sentiment that mechanisms controlling DNA replication are fundamentally divergent throughout bacteria.
Author: Ariel Amir
Publisher: Frontiers Media SA
ISBN: 2889631567
Category :
Languages : en
Pages : 246
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Book Description
The 1st volume of our Research Topic "The Bacterial Cell: Coupling between Growth, Nucleoid Replication, Cell Division and Shape” was published as an eBook in May 2016 (see: http://journal.frontiersin.org/researchtopic/2905/the-bacterial-cell-coupling-between-growth-nucleoid-replication-cell-division-and-shape). As a sign of growing interest to the topic, two workshops followed the same year: "Stochasticity in the Cell Cycle" in Jerusalem (Israel) by the Hebrew University’s Institute of Advanced Studies and EMBO's "Cell Size Regulation" in Joachimsthal (Germany). From the time of launching the first edition, several new groups have entered the field, and many established groups have made significant advances using state-of-the-art microscopy and microfluidics. Combining these approaches with the techniques pioneered by quantitative microbiologists decades ago, these approaches have provided remarkable amounts of numerical data. Most of these data needed yet to be put into a broader theoretical perspective. Moreover, the molecular mechanisms governing coordination and progression of the main bacterial cell cycle processes have remained largely unknown. These outstanding fundamental questions and the growing interest to the field motivated us to launch the next volume titled “The Bacterial Cell: Coupling between Growth, Nucleoid Replication, Cell Division, and Shape, Volume 2” shortly after completion of the first edition in October 2016. The issue contains 17 contributions from a diverse array of scientists whose field of study spans microbiology, biochemistry, genetics, experimental and theoretical biophysics. The specific questions addressed in the issue include: What triggers initiation of chromosome replication? How is cell division coordinated with replication both spatially and temporally? How is cell size controlled and linked to the rate of mass growth? What role plays physical organization of the chromosomes in their segregation and in regulation of cell division? The publications covering these questions are divided into three topical areas: 1) Cell Cycle Regulation, 2) Growth and Division, and 3) Nucleoid Structure and Replication. New ideas and techniques put forward in these articles bring us closer to understand these fundamental cellular processes, but the quest to resolve them is far from being complete. Plans for the next edition are under way along with further meetings and workshops, e.g., an EMBO Workshop on Bacterial cell biophysics: DNA replication, growth, division, size and shape in Ein Gedi (Israel), May 2020. We hope that via such interdisciplinary exchange of ideas we will come closer to answering the above-mentioned complex and multifaceted questions.
Author: Ron Milo
Publisher: Garland Science
ISBN: 1317230698
Category : Science
Languages : en
Pages : 400
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Book Description
A Top 25 CHOICE 2016 Title, and recipient of the CHOICE Outstanding Academic Title (OAT) Award. How much energy is released in ATP hydrolysis? How many mRNAs are in a cell? How genetically similar are two random people? What is faster, transcription or translation?Cell Biology by the Numbers explores these questions and dozens of others provid
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309066344
Category : Science
Languages : en
Pages : 171
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Book Description
How small can a free-living organism be? On the surface, this question is straightforward-in principle, the smallest cells can be identified and measured. But understanding what factors determine this lower limit, and addressing the host of other questions that follow on from this knowledge, require a fundamental understanding of the chemistry and ecology of cellular life. The recent report of evidence for life in a martian meteorite and the prospect of searching for biological signatures in intelligently chosen samples from Mars and elsewhere bring a new immediacy to such questions. How do we recognize the morphological or chemical remnants of life in rocks deposited 4 billion years ago on another planet? Are the empirical limits on cell size identified by observation on Earth applicable to life wherever it may occur, or is minimum size a function of the particular chemistry of an individual planetary surface? These questions formed the focus of a workshop on the size limits of very small organisms, organized by the Steering .Group for the Workshop on Size Limits of Very Small Microorganisms and held on October 22 and 23, 1998. Eighteen invited panelists, representing fields ranging from cell biology and molecular genetics to paleontology and mineralogy, joined with an almost equal number of other participants in a wide-ranging exploration of minimum cell size and the challenge of interpreting micro- and nano-scale features of sedimentary rocks found on Earth or elsewhere in the solar system. This document contains the proceedings of that workshop. It includes position papers presented by the individual panelists, arranged by panel, along with a summary, for each of the four sessions, of extensive roundtable discussions that involved the panelists as well as other workshop participants.
Author:
Publisher:
ISBN: 9780815332183
Category : Cells
Languages : en
Pages : 0
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Book Description
Author: Stephen Cooper
Publisher: Elsevier
ISBN: 008091747X
Category : Science
Languages : en
Pages : 528
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Book Description
How does a bacterial cell grow during the division cycle? This question is answered by the codeveloper of the Cooper-Helmstetter model of DNA replication. In a unique analysis of the bacterial division cycle, Cooper considers the major cell categories (cytoplasm, DNA, and cell surface) and presents a lucid description of bacterial growth during the division cycle. The concepts of bacterial physiology from Ole Maaløe's Copenhagen school are presented throughout the book and are applied to such topics as the origin of variability, the pattern of DNA segregation, and the principles underlying growth transitions. The results of research on E. coli are used to explain the division cycles of Caulobacter, Bacilli, Streptococci, and eukaryotes. Insightful reanalysis highlights significant similarities between these cells and E.coli. With over 25 years of experience in the study of the bacterial division cycle, Cooper has synthesized his ideas and research into an exciting presentation. He manages to write a comprehensive volume that will be of great interest to microbiologists, cell physiologists, cell and molecular biologists, researchers in cell-cycle studies, and mathematicians and engineering scientists interested in modeling cell growth. - Written by one of the codiscoverers of the Cooper-Helmstetter model - Applies the results of research on E. coli to other groups, including Caulobacter, Bacilli, Streptococci, and eukaryotes; the Caulobacter reanalysis highlights significant similarities with the E. coli system - Presents a unified description of the bacterial division cycle with relevance to eukaryotic systems - Addresses the concepts of the Copenhagen School in a new and original way
Author: R. J. C. Harris
Publisher: Academic Press
ISBN: 1483282007
Category : Science
Languages : en
Pages : 352
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Book Description
Cell Growth and Cell Division is a collection of papers dealing with the biochemical and cytological aspects of cell development and changes in bacterial, plant, and animal systems. One paper discusses studies on the nuclear and cytoplasmic growth of ten different strains of the genus Blepharisma, in which different types of nutrition at high and low temperatures alter the species to the extent that they became morphologically indistinguishable. The paper describes the onset of death at high and low temperatures as being preceded by a decrease in the size of the cytoplasm and a corresponding decrease in the size of the macronucleus. The moribund organisms, still possessing structure, are motionless with no distinguishable macronuclear materials. Another paper presents the response of meiotic and mitotic cells to azaguanine, chloramphenicol, ethionine, and 5-methyltryptophan. The paper describes the failure of spindle action, arrest of second division, inhibition of cytokinesis, aberrant wall synthesis, and alterations in chromosome morphology in meiosis cells. In the case of mitosis, a single enzyme—thymidine phosphorylase—shows that reagents which inhibit protein synthesis also inhibit the appearance of that enzyme if the reagent is applied one day before it normally appears. Other papers discuss control mechanisms for chromosome reproduction in the cell cycle, as well as the force of cleavage of the dividing sea urchin egg. The collection can prove valuable for bio-chemists, cellular biologists, micro-biologists, and developmental biologists.
Author: Jan Löwe
Publisher: Springer
ISBN: 331953047X
Category : Science
Languages : en
Pages : 457
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Book Description
This book describes the structures and functions of active protein filaments, found in bacteria and archaea, and now known to perform crucial roles in cell division and intra-cellular motility, as well as being essential for controlling cell shape and growth. These roles are possible because the cytoskeletal and cytomotive filaments provide long range order from small subunits. Studies of these filaments are therefore of central importance to understanding prokaryotic cell biology. The wide variation in subunit and polymer structure and its relationship with the range of functions also provide important insights into cell evolution, including the emergence of eukaryotic cells. Individual chapters, written by leading researchers, review the great advances made in the past 20-25 years, and still ongoing, to discover the architectures, dynamics and roles of filaments found in relevant model organisms. Others describe one of the families of dynamic filaments found in many species. The most common types of filament are deeply related to eukaryotic cytoskeletal proteins, notably actin and tubulin that polymerise and depolymerise under the control of nucleotide hydrolysis. Related systems are found to perform a variety of roles, depending on the organisms. Surprisingly, prokaryotes all lack the molecular motors associated with eukaryotic F-actin and microtubules. Archaea, but not bacteria, also have active filaments related to the eukaryotic ESCRT system. Non-dynamic fibres, including intermediate filament-like structures, are known to occur in some bacteria.. Details of known filament structures are discussed and related to what has been established about their molecular mechanisms, including current controversies. The final chapter covers the use of some of these dynamic filaments in Systems Biology research. The level of information in all chapters is suitable both for active researchers and for advanced students in courses involving bacterial or archaeal physiology, molecular microbiology, structural cell biology, molecular motility or evolution. Chapter 3 of this book is open access under a CC BY 4.0 license.
Author: Robert C. Bast, Jr.
Publisher: John Wiley & Sons
ISBN: 111900084X
Category : Medical
Languages : en
Pages : 2004
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Book Description
Holland-Frei Cancer Medicine, Ninth Edition, offers a balanced view of the most current knowledge of cancer science and clinical oncology practice. This all-new edition is the consummate reference source for medical oncologists, radiation oncologists, internists, surgical oncologists, and others who treat cancer patients. A translational perspective throughout, integrating cancer biology with cancer management providing an in depth understanding of the disease An emphasis on multidisciplinary, research-driven patient care to improve outcomes and optimal use of all appropriate therapies Cutting-edge coverage of personalized cancer care, including molecular diagnostics and therapeutics Concise, readable, clinically relevant text with algorithms, guidelines and insight into the use of both conventional and novel drugs Includes free access to the Wiley Digital Edition providing search across the book, the full reference list with web links, illustrations and photographs, and post-publication updates
Author: J. M. Mitchison
Publisher: CUP Archive
ISBN: 9780521082518
Category : Science
Languages : en
Pages : 324
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Book Description
