The fusion of two biological membranes is an important step in many processes on the cellular and sub-cellular level. Understanding the involved interplay of different lipid species, a specialized protein machinery and water on length scales of few nanometers poses a significant challenge to current structural biology. Among several complementary approaches, one strategy is to study the structural rearrangements of the lipid matrix. As the initial step, lipid bilayers must be forced into close contact to form a non-bilayer intermediate termed a stalk. This has been the subject of numerous theoretical studies and simulations, but experimental data on stalks are largely lacking. Currently, the only way to obtain structural information at the required sub-nanometer resolution is x-ray diffraction on the recently discovered stalk phaseʺ formed by certain lipids. We apply this method to elucidate the effect of lipid composition on stalk geometry and the repulsive forces between lipid bilayers prior to stalk formation. An approach based on differential geometry of electron density isosurfaces is introduced to analyze the curvatures and bending energies of the lipid monolayers. For the first time, this connects experiment-based structures of stalks and the associated bending and hydration energies. In addition, this thesis aims to provide a self-contained introduction to the required background in x-ray diffraction on lipid mesophases and electron density reconstruction.

This handbook provides a unique overview of lipid membrane fundamentals and applications. The fascinating world of lipids that harbor and govern so many biological functionalities are discussed within the context of membrane structures, interactions, and shape evolution. Beyond the fundamentals in lipid science, this handbook focuses on how scientists are building bioinspired biomimetic systems for applications in medicine, cosmetics, and nanotechnology. Key Features: Includes experimental and theoretical overviews on the role of lipids, with or without associated biomolecules, as structural components imparting distinct membrane shapes and intermembrane interactions Covers the mechanisms of lipid-membrane curvature, by peptide and protein binding, and the roles of signalling lipids and the cytoskeleton in plasma membrane shape evolution Covers advanced X-ray and force measurement techniques Discusses applications in biomedicine, cosmetics, and nanotechnology, including lipid vectors in nucleic acid, drug delivery in dermal applications, and lipid-based sensors and artificial biointerfaces Covers artificial membranes from block copolymers, synthetic copolypeptides, and recombinant proteins Includes an exciting section that explores the role of lipids in the origin of life in hydrothermal conditions This book is a highly informative companion for professionals in biophysics, biochemistry, physical chemistry, and material and pharmaceutical sciences and bioengineering.

The main goal of this thesis was to extend and apply time resolved x-ray scattering experiments at in-house, synchrotron and free electron laser sources to soft matter sample systems, in particular aligned lipid multilayers on solid support. A special emphasis was placed on a characterization of the non-equilibrium fast time response of the multilamellar stack to shortly pulsed optical excitation as well as the acousto-electric field accompanying a surface acoustic wave (SAW). In addition to fundamental questions associated with non-equilibrium dynamics of soft matter films such as driven membrane undulations, this thesis addresses technological challenges of time resolved x-ray diffraction, in particular concerning the timing scheme that has been implemented at the synchrotron storage ring Petra III, DESY, Hamburg. Importantly, a conceptually new pulse resolved x-ray detection scheme, well exceeding the performance of present detector concepts, has been developed and is described in detail.

This book mainly focuses on key aspects of biomembranes that have emerged over the past 15 years. It covers static and dynamic descriptions, as well as modeling for membrane organization and shape at the local and global (at the cell level) scale. It also discusses several new developments in non-equilibrium aspects that have not yet been covered elsewhere. Biological membranes are the seat of interactions between cells and the rest of the world, and internally, they are at the core of complex dynamic reorganizations and chemical reactions. Despite the long tradition of membrane research in biophysics, the physics of cell membranes as well as of biomimetic or synthetic membranes is a rapidly developing field. Though successful books have already been published on this topic over the past decades, none include the most recent advances. Additionally, in this domain, the traditional distinction between biological and physical approaches tends to blur. This book gathers the most recent advances in this area, and will benefit biologists and physicists alike.

The first volume of the Handbook deals with the amazing world of biomembranes and lipid bilayers. Part A describes all aspects related to the morphology of these membranes, beginning with the complex architecture of biomembranes, continues with a description of the bizarre morphology of lipid bilayers and concludes with technological applications of these membranes. The first two chapters deal with biomembranes, providing an introduction to the membranes of eucaryotes and a description of the evolution of membranes. The following chapters are concerned with different aspects of lipids including the physical properties of model membranes composed of lipid-protein mixtures, lateralphase separation of lipids and proteins and measurement of lipid-protein bilayer diffusion. Other chapters deal with the flexibility of fluid bilayers, the closure of bilayers into vesicles which attain a large variety of different shapes, and applications of lipid vesicles and liposomes. Part B covers membrane adhesion, membrane fusion and the interaction of biomembranes withpolymer networks such as the cytoskeleton. The first two chapters of this part discuss the generic interactions of membranes from the conceptual point of view. The following two chapters summarize the experimental work on two different bilayer systems. The next chapter deals with the process ofcontact formation, focal bounding and macroscopic contacts between cells. The cytoskeleton within eucaryotic cells consists of a network of relatively stiff filaments of which three different types of filaments have been identified. As explained in the next chapter much has been recently learned aboutthe interaction of these filaments with the cell membrane. The final two chapters deal with membrane fusion.

Biological Soft Matter Explore a comprehensive, one-stop reference on biological soft matter written and edited by leading voices in the field Biological Soft Matter: Fundamentals, Properties and Applications delivers a unique and indispensable compilation of up-to-date knowledge and material on biological soft matter. The book presents a thorough overview about biological soft matter, beginning with different substance classes, including proteins, nucleic acids, lipids, and polysaccharides. It goes on to describe a variety of superstructures and aggregated and how they are formed by self-assembly processes like protein folding or crystallization. The distinguished editors have included materials with a special emphasis on macromolecular assembly, including how it applies to lipid membranes, and proteins fibrillization. Biological Soft Matter is a crucial resource for anyone working in the field, compiling information about all important substance classes and their respective roles in forming superstructures. The book is ideal for beginners and experts alike and makes the perfect guide for chemists, physicists, and life scientists with an interest in the area. Readers will also benefit from the inclusion of: An introduction to DNA nano-engineering and DNA-driven nanoparticle assembly Explorations of polysaccharides and glycoproteins, engineered biopolymers, and engineered hydrogels Discussions of macromolecular assemblies, including liquid membranes and small molecule inhibitors for amyloid aggregation A treatment of inorganic nanomaterials as promoters and inhibitors of amyloid fibril formation An examination of a wide variety of natural and artificial polymers Perfect for materials scientists, biochemists, polymer chemists, and protein chemists, Biological Soft Matter: Fundamentals, Properties and Applications will also earn a place in the libraries of biophysicists and physical chemists seeking a one-stop reference summarizing the rapidly evolving topic of biological soft matter.

Plasmodesmata (PD) are plant-specific intercellular nanopores defined by specialised domains of the plasma membrane (PM) and the endoplasmic reticulum (ER), both of which contain unique proteins, and probably different lipid compositions than the surrounding bulk membranes. The PD membranes form concentric tubules with a minimal outer diameter of only 50 nm, and the central ER strand constricted to ~10-15 nm, representing one of the narrowest stable membrane tubules in nature. This unique membrane architecture poses many biophysical, structural and functional questions. PM continuity across PD raises the question as to how a locally confined membrane site is established and maintained at PD. There is increasing evidence that the PM within PD may be enriched in membrane ‘rafts’ or TET web domains. Lipid rafts often function as signalling platforms, in line with the emerging view of PD as central players in plant defense responses. Lipid-lipid immiscibility could also provide a mechanism for membrane sub- compartmentalisation at PD. Intricate connections of the PM to the wall and the underlying cytoskeleton and ER may anchor the specialised domains locally. The ER within PD is even more strongly modified. Its extreme curvature suggests that it is stabilised by densely packed proteins, potentially members of the reticulon family that tubulate the cortical ER. The diameter of the constricted ER within PD is similar to membrane stalks in dynamin-mediated membrane fission during endocytosis and may need to be stabilised against spontaneous rupture. The function of this extreme membrane constriction, and the reasons why the ER is connected between plant cells remain unknown. Whilst the technically challenging search for the protein components of PD is ongoing, there has been significant recent progress in research on biological membranes that could benefit our understanding of PD function. With this Research Topic, we therefore aim to bring together researchers in the PD field and those in related areas, such as membrane biophysics, membrane composition and fluidity, protein-lipid interactions, lateral membrane heterogeneity, lipid rafts, membrane curvature, and membrane fusion/fission. We wish to address questions such as: - What mechanisms restrict lateral mobility of proteins and lipids along the PD membranes? - How can specific proteins be targeted to and turned over from membrane domains with restricted lateral access? - What elements (lipids, proteins, membrane curvature, packing order, thickness etc.) may contribute to the identity of PD membranes? - How do the structural and functional features of PD compare to other ER-PM contact sites? - How is the high curvature of the PD ER stabilised and what are possible functions of such a tightly constricted membrane tubule? - Do PD need to be prevented from spontaneous collapse and sealing? - What technologies are available to address these questions that can underpin PD research? We welcome interested individuals to contribute their expertise and develop new hypotheses on the particular biological and biophysical questions posed by PD. We are particularly looking for articles (Original Research Articles, Technical Advances and State-of-the-Art reviews) that would expand on or challenge current perceptions of PD and stimulate discussion.

The Textbook of Influenza is a comprehensive resource covering all aspects of influenza, from the genetic and molecular biology of the virus through to clinical aspects of the disease and the latest drug developments and treatments. This new edition has been completely revised and reflects the integration of disciplines concerning the emergence, evolution, pathogenesis and control of influenza viruses in the field of human and veterinary public health. Textbook of Influenza examines the lessons learnt from the latest pandemic and provides the current state of knowledge for many yet unresolved issues related to virus origin, spread, pathogenesis and disease severity to better prepare for future pandemics. It covers the background to recent advances in influenza genomics and reverse genetics which have allowed the identification of virus virulence factors and the analysis and reconstruction of influenza viruses such as the 1918 Spanish flu strain. This new edition is divided into eight key sections, containing chapters co-written by international experts from both the clinical and scientific communities, covering: • Influenza Perspectives • Structure and Replication • Evolution and Ecology • Epidemiology and Surveillance • Immunology • Vaccines and Vaccine Development • Clinical Aspects and Antivirals • Public Health Textbook of Influenza is for all those working in the area of influenza including clinical and basic scientists, immunologists, molecular and structural virologists, public health officials and global pandemic control planners.

This book presents a compendium of methodologies for the study of membrane lipids, varying from traditional lab bench experimentation to computer simulation and theoretical models. The volume provides a comprehensive set of techniques for studying membrane lipids with a strong biophysical emphasis. It compares the various available techniques including the pros and cons as seen by the experts.