Actin Based Motility

Since the discovery of actin by Straub in the 1950’s and the pioneering work of Oosawa on actin self-assembly in helical laments in the 1960’s, many books and conference proceedings have been published. As one of the most essential p- teins in life, essential for movement in organisms rangingfrom bacteria to higher eukaryotes, it is no surprise that actin has fascinated generations of scientists from many different elds. Actin can be considered as a “living treasure” of biology; the kinetics and thermodynamics of self-assembly, the dissipative nature of actin po- merization, the molecular interactions of monomeric and polymerized actin with regulators, the mechanical properties of actin gels, and more recently the force p- ducing motile and morphogenetic processes organized by the actin nanomachine in response to signaling, are all milestones in actin research. Discoveries that directly derive from and provide deeper insight into the fundamental properties of actin are constantly being made, making actin an ever appealing research molecule. At the same time, the explosion in new technologies and techniques in biological sciences has served to attract researchers from an expanding number of disciplines, to study actin. This book presents the latest developments of these new multiscale approaches of force and movement powered by self-assembly processes, with the hope to opening our perspectives on the many areas of actin-based motility research.

A current review of basic research on Rickettsiales biology and pathogenesis in one comprehensive volume. • Details the scientific knowledge about how these obligate intracellular bacteria invade, survive and replicate inside eukaryotic cells. • Describes the spectrum of disease caused by an infection and the role of vectors in transmission. • Discusses protective and pathologic immune responses and establishment of persistent infection. • Describes the latest developments including genomics and progress in vaccine development. • Serves as a significant research book for scientists, physicians, medical students, public health professionals, epidemiologists, biocomputational scientists and government policy makers.

The cell is no longer considered to be a bag full of enzymes dissolved in a liquid cytoplasm. It is now known that the cytoplasm is an exquisitely ordered structure of properly placed organelles and enzyme complexes that are suspended from an intricate network of structural protein polymers termed the cytoskeleton. All movement of organelles and vesicles within the cell is regulated by this cytoskeleton, and it is clear that the cytoskeleton is responsible for all of the cell's external movement as well. In this lecture, we will consider how the cytoskeleton elicits cell migration.The three main elements of the cytoskeleton are microtubules, intermediate filaments, and actin filaments. Microtubules are essential for (a) intracellular transport within the cytoplasm and transport between the nucleus and cytoplasm, (b) the structure and movement of all cilia and flagella, and (c) the structure of the mitotic spindle and movement of chromosomes on the spindle during cell division. Intermediate filaments give structural integrity to virtually all cells and tissues by providing an intracellular network of flexible cables that strengthen internal cell structure and stabilize cell-to-cell adhesion. It is this intercellular binding property that stably joins epithelial cells together to provide the protective functions of skin and the integrity of the intestinal mucosa.Actin is a highly conserved protein ubiquitous to all eukaryotic cells. Actin is absolutely required for (a) cell migration, (b) the contraction of muscle (both striated and smooth), (c) the structure and function of many cell protrusions (e.g., microvilli, filopodia, lamellopodia, blood platelet projections), (d) division of the cytoplasm (cytokinesis) during telophase of cell mitosis, and (e) movement and placement of organelles within the cell. Actin filaments are also called thin filaments because of their very slender (70 Ã…) diameter.