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NUS-led research team discovers how bacteria sense salt stress
July 10, 2012
The scientists' finding is a major breakthrough in understanding decades-old problem of how bacteria detect environmental changes A team of scientists led by Assistant Professor Ganesh S Anand and Professor Linda J. Kenney from the National University of Singapore (NUS) Department of Biological Sciences (DBS) and the Mechanobiology Institute (MBI) has discovered how bacteria respond to salts in their environment and the ways in which salts can alter the behaviour of specialised salt sensor bacterial proteins. This novel finding sheds light on how microbes detect levels of salts or sugars in their watery environments - a problem in biology that has been studied for more than 30 years. The NUS scientists found that microbes do this by specialised molecules or proteins on the bacterial surface that change shape in response to changes in salt concentration. This is relevant not only to bacteria, but also cells from all organisms which detect and respond to changes in environmental salts and sugars. The scientists from NUS and the University of Illinois-Chicago (UIC) first published their findings in the EMBO Journal on 30 May 2012. Salt detecting proteins are like springs Bacteria have elaborate mechanisms for sensing and responding to changes in the environment. One of the important environmental stresses for bacteria is the changing concentration of salts. For instance, some can live in fresh water (a low salt environment) or in the guts of humans (high salt environment). Using a powerful combination of a tool called amide hydrogen/deuterium exchange mass spectrometry (HDXMS), accompanied by molecular biology and biochemistry, the scientists from NUS probed how changes in salt concentrations are sensed by a receptor protein. They found that salt detecting proteins are like molecular springs, or "slinky toys". The proteins are constantly shifting from a condensed spring form to an extended form. Increasing the salt concentration dampens this spring-like movement, which activates the protein. In other words, the less spring-like the protein, the higher is its activity. This protein movement may provide a unified model of how bacteria sense their environment. Application of the phenomenon This study is an example of basic science with immediate applications. Recognising that diverse proteins operate as molecular springs whose spring-like movement can be dampened is fundamental to understanding how these proteins work. This study also underscores the role of water in biology. It demonstrates how salts and sugars can alter biological properties of proteins through the effects on water and is relevant for understanding life processes across species from bacteria to humans. Further research The NUS research team is now working on studying the protein in its native membrane by embedding the bacterial sensor protein in an artificial membrane. They hope to understand how the membrane contributes to overall protein activity, structure, stability and responses to salts. National University of Singapore

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Mechanobiology Handbook
by Jiro Nagatomi (Editor)
Mechanobiology—the study of the effects of mechanical environments on the biological processes of cells—has evolved from traditional biomechanics via the incorporation of strong elements of molecular and cell biology. Currently, a broad range of organ systems are being studied by surgeons, physicians, basic scientists, and engineers. These mechanobiologists aim to create new therapies and further biological understanding by quantifying the mechanical environment of cells and the molecular mechanisms of mechanically induced pathological conditions. To achieve these goals, investigators must be familiar with both the basic concepts of mechanics and the modern tools of cellular/molecular biology. Unfortunately, current literature contains numerous studies that misuse standard...
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Introduction to Cell Mechanics and Mechanobiology
by Christopher R. Jacobs (Author), Hayden Huang (Author), Ronald Y. Kwon (Author)
Introduction to Cell Mechanics and Mechanobiology is designed for a one-semester course in the mechanics of the cell offered to advanced undergraduate and graduate students in biomedical engineering, bioengineering, and mechanical engineering. It teaches a quantitative understanding of the way cells detect, modify, and respond to the physical properties within the cell environment. Coverage includes the mechanics of single molecule polymers, polymer networks, two-dimensional membranes, whole-cell mechanics, and mechanobiology, as well as primer chapters on solid, fluid, and statistical mechanics. Introduction to Cell Mechanics and Mechanobiology is the first cell mechanics textbook to be geared specifically toward students with diverse backgrounds in engineering and...
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Skeletal Function and Form: Mechanobiology of Skeletal Development, Aging, and Regeneration
by Dennis R. Carter (Author), Gary S. Beaupré (Author)
The intimate relationship between form and function inherent in the design of animals is perhaps nowhere more evident than in the musculoskeletal system. This book, about how function determines form, addresses the role of mechanical factors in the development, adaptation, maintenance, aging, and repair of skeletal tissues. The authors refer to this process as mechanobiology and develop their theme within an evolutionary framework. They show how degenerative disorders such as arthritis and osteoporosis are regulated by the same mechanical processes that influence normal development and growth. Skeletal Function and Form bridges important gaps among disciplines, providing a common ground for a multidisciplinary understanding.
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Basic Orthopaedic Biomechanics and Mechano-Biology, 3rd ed.
by Van C. Mow (Editor), Rik Huiskes (Editor)
Completely revised and updated, the Third Edition of this classic text reflects the latest advances in research on orthopaedic biomechanics and the successful applications of biomechanical principles in fracture fixation, prosthetic implant design, and hip and knee arthroplasty. For this Third Edition, Dr. Mow is joined by new co-editor Rik Huiskes, PhD, an Editor-in-Chief of the Journal of Biomechanics and an internationally renowned authority in the field. New chapters cover biomaterials, biomechanical principles of cartilage and bone tissue engineering, and biomechanics of fracture fixation and fracture healing.
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Mechanobiology of Cell-Cell and Cell-Matrix Interactions
by A. Wagoner Johnson (Editor), Brendan Harley (Editor)
Mechanobiology of Cell-Matrix Interactions focuses on characterization and modeling of interactions between cells and their local extracellular environment, exploring how these interactions may mediate cell behavior. Studies of cell-matrix interactions rely on integrating engineering, (molecular and cellular) biology, and imaging disciplines. Recent advances in the field have begun to unravel our understanding of how cells gather information from their surrounding environment, and how they interrogate such information during the cell fate decision making process. Topics include adhesive and integrin-ligand interactions; extracellular influences on cell biology and behavior; cooperative mechanisms of cell-cell and cell-matrix interactions; the mechanobiology of pathological processes;...
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Mechanobiology: Cartilage and Chondrocyte (Biomedical and Health Research, V. 42)
by J. F. Stoltz (Editor)
Until the '90s, research in biomechanics and biorheology mainly focused on tissues and cell priorities, so as to identify the bioclinical problems linked to the rheology properties of cells and tissues or to develop substitutes. Advances in molecular biology and new knowledge in cellular biology over the last ten years have given access to a more physiological approach to the effects of stress on cells and tissues. All cells and tissues in the body are constantly exposed to physical forces and these forces can influence the biological behaviour of cells and hence affect gene expression, phenotype, paracrine or autocrine factor secretion and metabolism. These mechanically-induced cellular alterations may constitute major factors affecting the physiological and pathological condition of the...
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Mechanobiology: Cartilage and Chondrocyte - Volume 5 - Volume 73 Biomedical and Health Research - Book Edition of Bioreheology (Biomedical and Health Research)
by J.-F. Stoltz (Author)
This book covers the proceedings of the Fifth Symposium on Mechanobiology of Cartilage and Chondrocyte. Mechanobiology can be now considered as a vigorous branch of biomechanics, biorheology and physiology mainly concerned with the study of the influence of mechanical forces on cells and tissues and their clinical or therapeutical applications. As we are now in the age of proteomics, genomics and cell micromechanical approaches, suing methods like laser tweezers or confocal microscopy, mechanobiology brings new challenges. With such new research, mechanobiology promises new diagnostic and therapeutic approaches. In other respect there has been increasing interest over recent years in the fundamental role played by local mechanical parameters in chondrocyte regulations and cartilage...
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Biomaterials as Stem Cell Niche (Studies in Mechanobiology, Tissue Engineering and Biomaterials)
by Krishnendu Roy (Editor)
Recent developments in stem cell biology have opened new directions in cell therapy. This book provides the state-of-the-art developments in using biomaterials as artificial niches for engineering stem cells, both for the purpose of better understanding their biology under 3D biomimetic conditions as well as for developing new strategies for efficient long term maintenance and directed differentiation of stem cells into various therapeutic lineages. Animal and human stem cells of both embryonic and adult origin are discussed with applications ranging from nerve regeneration, orthopedics, cardiovascular therapy, blood cell generation and cancer therapy. Both synthetic and natural biomaterials are reviewed with emphasis on how material-stem cell interactions direct specific signaling...
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Skeletal Aging and Osteoporosis: Biomechanics and Mechanobiology (Studies in Mechanobiology, Tissue Engineering and Biomaterials)
by Matthew J. Silva (Editor)
The focus of this book is on mechanical aspects of skeletal fragility related to aging and osteoporosis. Topics include: Age-related changes in trabecular structure and strength; age-related changes in cortical material properties; age-related changes in whole-bone structure; predicting bone strength and fracture risk using image-based methods and finite element analysis; animal models of osteoporosis and aging; age-related changes in skeletal mechano responsiveness; exercise and physical interventions for osteoporosis.
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Neural Tissue Biomechanics (Studies in Mechanobiology, Tissue Engineering and Biomaterials)
by Lynne E. Bilston (Editor)
Damage to the central nervous system resulting from pathological mechanical loading can occur as a result of trauma or disease. Such injuries lead to significant disability and mortality. The peripheral nervous system, while also subject to injury from trauma and disease, also transduces physiological loading to give rise to sensation, and mechanotransduction is also thought to play a role in neural development and growth. This book gives a complete and quantitative description of the fundamental mechanical properties of neural tissues, and their responses to both physiological and pathological loading. This book reviews the methods used to characterize the nonlinear viscoelastic properties of central and peripheral neural tissues, and the mathematical and sophisticated computational...
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