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  • Springer Nature  (45.107)
  • American Meteorological Society
  • Annual Reviews
  • Springer Science + Business Media
  • 2000-2004  (58.115)
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  • 101
    Digitale Medien
    Digitale Medien
    CAVITATION IN VORTICAL FLOWS (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 34 (2002), S. 143-175 
    Details
    ISSN: 0066-4189
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Maschinenbau , Physik
    Notizen: Abstract Cavitation in vortical structures is a common, albeit complex, problem in engineering applications. Cavitating vortical structures can be found on the blade surfaces, in the clearance passages, and at the hubs of various types of turbomachinery. Cavitating microvortices at the trailing edge of attached sheet cavitation can be highly erosive. Cavitating hub vortices in the draft tubes of hydroturbines can cause major surges and power swings. There is also mounting evidence that vortex cavitation is a dominant factor in the inception process in a broad range of turbulent flows. Most research has focused on the inception process, with limited attention paid to developed vortex cavitation. Wave-like disturbances on the surfaces of vapor cores are an important feature. Vortex core instabilities in microvortices are found to be important factors in the erosion mechanisms associated with sheet/cloud cavitation. Under certain circumstances, intense sound at discrete frequencies can result from a coupling between tip vortex disturbances and oscillating sheet cavitation. Vortex breakdown phenomena that have some commonalities are also noted, as are some differences with vortex breakdown in fully wetted flow. Simple vortex models can sometimes be used to describe the cavitation process in complex turbulent flows such as bluff body wakes and in plug valves. Although a vortex model for cavitation in jets does not exist, the mechanism of inception appears to be related to the process of vortex pairing. The pairing process can produce negative peaks in pressure that can exceed the rms value by a factor of ten, sometimes exceeding the dynamic pressure by a factor of two. A new and important issue is that cavitation is not only induced in vortical structures but is also a mechanism for vorticity generation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.fluid.34.082301.114957
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  • 102
    Digitale Medien
    Digitale Medien
    MICROSTRUCTURAL EVOLUTION IN POLYMER BLENDS (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 34 (2002), S. 177-210 
    Details
    ISSN: 0066-4189
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Maschinenbau , Physik
    Notizen: Abstract Microstructure in an immiscible polymer blend consists of the size, shape, and orientation of the phases. Blends exhibit many interesting behaviors, including enhanced elasticity at small strains, drop-size hysteresis, enhanced shear thinning, and stress relaxation curves whose shapes are sensitive to deformation history. These behaviors are directly related to changes in the microstructure, which result from phase deformation, coalescence, retraction, and different types of breakup. These phenomena are reviewed, together with models that describe them. Rheological measurements can probe the microstructure because microstructure contributes directly to stress through interfacial tension. Rheo-optical experiments also provide important insights. Droplet theories explain most of the phenomena for Newtonian phases at low concentrations. Behaviors at high volume fractions or with strongly non-Newtonian phases are less well understood.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.fluid.34.082301.144051
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  • 103
    Digitale Medien
    Digitale Medien
    MOLECULAR ORIENTATION EFFECTS IN VISCOELASTICITY (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 34 (2002), S. 417-444 
    Details
    ISSN: 0066-4189
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Maschinenbau , Physik
    Notizen: Abstract Recent advances in the computational modeling of molecular conformational and orientational effects in the flow of viscoelastic fluids are described. These advances involve the coupling of molecular models for the underlying microstructure of macromolecules with the macroscopic equations of change. The kinetic theory for polymeric liquids is described along with the most useful micromechanical models for computing the fluid flow of polymeric liquids. Three levels of description are covered for the computation of molecular orientation effects: methods for molecular models for which closed-form, continuum-like evolution equations for average quantities describing molecular conformations can be obtained, hybrid methods that involve coupling direct solution of the Fokker-Planck equation describing the distribution function for molecular orientations with the equations of change, and hybrid methods that couple stochastic simulations of individual molecule trajectories with the macroscopic equations of change. Illustrative results for rheometric flows (flows with homogeneous, fixed kinematics) and complex flows are given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.fluid.34.083101.134818
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  • 104
    Digitale Medien
    Digitale Medien
    FLUID DYNAMICS OF El NINO VARIABILITY (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 34 (2002), S. 531-558 
    Details
    ISSN: 0066-4189
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Maschinenbau , Physik
    Notizen: Abstract The El Nino variability in the equatorial Tropical Pacific is characterized by sea-surface temperature anomalies and associated changes in the atmospheric circulation. Through an enormous monitoring effort over the last decades, the relevant time scales and spatial patterns are fairly well documented. In the meantime, a hierarchy of models has been developed to understand the physics of this phenomenon and to make predictions of future variability. In this review, the robust and relevant details of the observations, the fluid mechanical "building blocks," the theory of the deterministic part of the variability, and the impact of small-scale ("noise") and remote ("external") processes are evaluated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.fluid.34.090501.144936
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  • 105
    Digitale Medien
    Digitale Medien
    STANLEY CORRSIN: 1920-1986 (2003)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 1-10 
    Details
    ISSN: 0066-4189
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.fluid.35.101101.161055
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  • 106
    Digitale Medien
    Digitale Medien
    MECHANISMS ON TRANSVERSE MOTIONS IN TURBULENT WALL FLOWS (2003)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 45-62 
    Details
    ISSN: 0066-4189
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Maschinenbau , Physik
    Notizen: Abstract Drag reduction in wall-bounded flows can be achieved by transverse motions imposed by passive means, e.g., riblets, or by external forcing, such as wall oscillation or transverse traveling-wave excitation. In this article, we review possible physical mechanisms responsible for turbulent drag reduction and corresponding near-wall flow modification.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.fluid.35.101101.161213
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  • 107
    Digitale Medien
    Digitale Medien
    AERODYNAMICS OF SMALL VEHICLES (2003)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 89-111 
    Details
    ISSN: 0066-4189
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Maschinenbau , Physik
    Notizen: Abstract In this review we describe the aerodynamic problems that must be addressed in order to design a successful small aerial vehicle. The effects of Reynolds number and aspect ratio (AR) on the design and performance of fixed-wing vehicles are described. The boundary-layer behavior on airfoils is especially important in the design of vehicles in this flight regime. The results of a number of experimental boundary-layer studies, including the influence of laminar separation bubbles, are discussed. Several examples of small unmanned aerial vehicles (UAVs) in this regime are described. Also, a brief survey of analytical models for oscillating and flapping-wing propulsion is presented. These range from the earliest examples where quasi-steady, attached flow is assumed, to those that account for the unsteady shed vortex wake as well as flow separation and aeroelastic behavior of a flapping wing. Experiments that complemented the analysis and led to the design of a successful ornithopter are also described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.fluid.35.101101.161102
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  • 108
    Digitale Medien
    Digitale Medien
    MIXING EFFICIENCY IN STRATIFIED SHEAR FLOWS (2003)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 135-167 
    Details
    ISSN: 0066-4189
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Maschinenbau , Physik
    Notizen: Abstract The issue of the physical mechanism(s) that control the efficiency with which the density field in stably stratified fluid is mixed by turbulent processes has remained enigmatic. Similarly enigmatic has been an explanation of the numerical value of ~0.2, which is observed to characterize this efficiency experimentally. We review recent work on the turbulence transition in stratified parallel flows that demonstrates that this value is not only numerically predictable but also that it is expected to be a nonmonotonic function of the Richardson number that characterizes preturbulent stratification strength. This value of the mixing efficiency appears to be characteristic of the late-time behavior of the turbulent flow that develops after an initially laminar shear flow has undergone the transition to turbulence through an intermediate instability of Kelvin-Helmholtz type.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.fluid.35.101101.161144
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  • 109
    Digitale Medien
    Digitale Medien
    SMALL-SCALE HYDRODYNAMICS IN LAKES (2003)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 373-412 
    Details
    ISSN: 0066-4189
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Maschinenbau , Physik
    Notizen: Abstract Recent small-scale turbulence observations allow the mixing regimes in lakes, reservoirs, and other enclosed basins to be categorized into the turbulent surface and bottom boundary layers as well as the comparably quiet interior. The surface layer consists of an energetic wave-affected thin zone at the very top and a law-of-the-wall layer right below, where the classical logarithmic-layer characteristic applies on average. Short-term current and dissipation profiles, however, deviate strongly from any steady state. In contrast, the quasi-steady bottom boundary layer behaves almost perfectly as a logarithmic layer, although periodic seiching modifies the structure in the details. The interior stratified turbulence is extremely weak, even though much of the mechanical energy is contained in baroclinic basin-scale seiching and Kelvin waves or inertial currents (large lakes). The transformation of large-scale motions to turbulence occurs mainly in the bottom boundary and not in the interior, where the local shear remains weak and the Richardson numbers are generally large.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.fluid.35.101101.161220
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  • 110
    Digitale Medien
    Digitale Medien
    FLOW AND DISPERSION IN URBAN AREAS (2003)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 469-496 
    Details
    ISSN: 0066-4189
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Maschinenbau , Physik
    Notizen: Abstract Increasing urbanization and concern about sustainability and quality of life issues have produced considerable interest in flow and dispersion in urban areas. We address this subject at four scales: regional, city, neighborhood, and street. The flow is one over and through a complex array of structures. Most of the local fluid mechanical processes are understood; how these combine and what is the most appropriate framework to study and quantify the result is less clear. Extensive and structured experimental databases have been compiled recently in several laboratories. A number of major field experiments in urban areas have been completed very recently and more are planned. These have aided understanding as well as model development and evaluation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.fluid.35.101101.161147
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  • 111
    Digitale Medien
    Digitale Medien
    BIFURCATING AND BLOOMING JETS (2003)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 295-315 
    Details
    ISSN: 0066-4189
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Maschinenbau , Physik
    Notizen: Abstract It is classically assumed that the far field of a round turbulent jet discharging into quiescent fluid has a unique behavior characterized only by its momentum flux. However, there is now considerable evidence that different discharge conditions at the jet nozzle exit can give rise to very different far-field flows. Perhaps the most striking examples of these are the bifurcating and blooming jets produced by appropriate combinations of controlled axial and circumferential excitations at the nozzle exit. With the right excitations, a jet can be made to divide into two separate jets (bifurcating jet), each of which carries half the axial momentum and spreads in a manner similar to a single jet. Trifurcating jets can also be produced. Other excitations can produce blooming jets, in which the jet explodes into a shower of vortex rings, producing a far-field flow that is quite unlike a normal unexcited jet. Bifurcating and blooming jets exhibit much greater mixing than normal jets, suggesting possible applications in flow control. This article summarizes our work on bifurcating and blooming jets, which began with our discovery of them in the early 1980s and continued through the mid- 1990s. One of us (D.E.P.) continued exploration of flow control using excited jets, first at the McDonnell Douglas Corporation, and more recently at the Georgia Institute of Technology. The key to flow control is the manipulation of the large vortical structures in the near field of the jet. Ultimately this work, and that of others, led to full-scale testing of jet engine exhaust mixing control. There it was shown that the jet temperature downstream of the engine can be very significantly reduced by application of well-designed and easily implemented excitation at the engine discharge, thereby solving problems encountered during ground operations. Related jet control work by other investigators is included in this review.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.fluid.35.101101.161128
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  • 112
    Digitale Medien
    Digitale Medien
    STABILITY AND TRANSITION OF THREE-DIMENSIONAL BOUNDARY LAYERS (2003)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 413-440 
    Details
    ISSN: 0066-4189
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Maschinenbau , Physik
    Notizen: Abstract The recent progress in three-dimensional boundary-layer stability and transition is reviewed. The material focuses on the crossflow instability that leads to transition on swept wings and rotating disks. Following a brief overview of instability mechanisms and the crossflow problem, a summary of the important findings of the 1990s is given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.fluid.35.101101.161045
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  • 113
    Digitale Medien
    Digitale Medien
    DYNAMIC LOCALIZATION OF BACTERIAL AND PLASMID CHROMOSOMES (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 34 (2000), S. 21-59 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Plasmid-encoded partition genes determine the dynamic localization of plasmid molecules from the mid-cell position to the 1/4 and 3/4 positions. Similarly, bacterial homologs of the plasmid genes participate in controlling the bidirectional migration of the replication origin (oriC) regions during sporulation and vegetative growth in Bacillus subtilis, but not in Escherichia coli. In E. coli, but not B. subtilis, the chromosomal DNA is fully methylated by DNA adenine methyltransferase. The E. coli SeqA protein, which binds preferentially to hemimethylated nascent DNA strands, exists as discrete foci in vivo. A single SeqA focus, which is a SeqA-hemimethylated DNA cluster, splits into two foci that then abruptly migrate bidirectionally to the 1/4 and 3/4 positions during replication. Replicated oriC copies are linked to each other for a substantial period of generation time, before separating from each other and migrating in opposite directions. The MukFEB complex of E. coli and Smc of B. subtilis appear to participate in the reorganization of bacterial sister chromosomes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.34.1.21
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  • 114
    Digitale Medien
    Digitale Medien
    POLYGENIC AND MULTIFACTORIAL DISEASE GENE ASSOCIATION IN MAN: Lessons from AIDS1 (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 34 (2000), S. 563-591 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract In an age when the majority of monogenic human disease genes have been identified, a particular challenge for the coming generation of human geneticists will be resolving complex polygenic and multifactorial diseases. The tools of molecular and population genetic association have much potential as well as peril in uncovering small cryptic genetic effects in disease. We have used a candidate gene approach to identify eight distinct human loci with alleles that in different ways influence the outcome of exposure to HIV-1, the AIDS virus. The successes in these gene hunts have validated the approach and illustrate the strengths and limitations of association analysis in an actual case history. The integration of genetic associations, well-described clinical cohorts, extensive basic research on AIDS pathogenesis, and functional interpretation of gene connections to disease offers a formula for detecting such genes in complex human genetic phenotypes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.34.1.563
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  • 115
    Digitale Medien
    Digitale Medien
    COMPLEX TRAIT ANALYSIS IN THE MOUSE: The Strengths, The Limitations and The Promise Yet To Come (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 34 (2000), S. 653-686 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract In 1990, David Baltimore predicted that the 1990s would be the decade of the mouse (1). This certainly proved to be true: The mouse has contributed immensely to biological research through transgenic, embryonic stem cell (ES) knockout, and classical genetic technologies. But its usefulness as a model organism is by no means over; indeed it is still rising to its peak: The mouse as a model mammalian organism still has much to offer. This article reviews use of the mouse to dissect complex genetic traits using quantitative trait analysis, with a particular emphasis on medically important diseases.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.34.1.653
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  • 116
    Digitale Medien
    Digitale Medien
    ANIMAL MODELS OF TUMOR-SUPPRESSOR GENES (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 209-241 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract The development of cancer requires multiple genetic alterations perturbing distinct cellular pathways. In human cancers, these alterations often arise owing to mutations in tumor-suppressor genes whose normal function is to either inhibit the proliferation, apoptosis, or differentiation of cells, or maintain their genomic integrity. Mouse models for tumor suppressors frequently provide definitive evidence for the antitumorigenic functions of these genes. In addition, animal models permit the identification of previously unsuspected roles of these genes in development and differentiation. The availability of null and tissue-specific mouse mutants for tumor-suppressor genes has greatly facilitated our understanding of the mechanisms leading to cancer. In this review, we describe mouse models for tumor-suppressor genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.090432
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  • 117
    Digitale Medien
    Digitale Medien
    CHROMATIN INSULATORS AND BOUNDARIES: Effects on Transcription and Nuclear Organization (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 193-208 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Chromatin boundaries and insulators are transcriptional regulatory elements that modulate interactions between enhancers and promoters and protect genes from silencing effects by the adjacent chromatin. Originally discovered in Drosophila, insulators have now been found in a variety of organisms, ranging from yeast to humans. They have been found interspersed with regulatory sequences in complex genes and at the boundaries between active and inactive chromatin. Insulators might modulate transcription by organizing the chromatin fiber within the nucleus through the establishment of higher-order domains of chromatin structure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.090349
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  • 118
    Digitale Medien
    Digitale Medien
    HOMOLOGOUS RECOMBINATION NEAR AND FAR FROM DNA BREAKS: Alternative Roles and Contrasting Views (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 243-274 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Double-strand breaks and other lesions in DNA can stimulate homologous genetic recombination in two quite different ways: by promoting recombination near the break (roughly within a kb) or far from the break. Recent emphasis on the repair aspect of recombination has focused attention on DNA interactions and recombination near breaks. Here I review evidence for recombination far from DNA breaks in bacteria and fungi and discuss mechanisms by which this can occur. These mechanisms include entry of a traveling entity ("recombination machine") at a break, formation of long heteroduplex DNA, priming of DNA replication by a broken end, and induction of recombination potential in trans. Special emphasis is placed on contrasting views of how the RecBCD enzyme of Escherichia coli promotes recombination far (tens of kb) from a double-strand break. The occurrence of recombination far from DNA breaks and of correlated recombination events far apart suggests that "action at a distance" during recombination is a widespread feature among diverse organisms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.090509
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  • 119
    Digitale Medien
    Digitale Medien
    MECHANISMS OF RETROVIRAL RECOMBINATION (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 275-302 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Recombination is a major source of genetic variability in retroviruses. Each viral particle contains two single-stranded genomic RNAs. Recombination mostly results from a switch in template between these two RNAs during reverse transcription. Here we emphasize the main mechanisms underlying recombination that are emerging from recent advances in biochemical and cell culture techniques. Increasing evidence supporting the involvement of RNA secondary structures now complements the predominant role classically attributed to enzyme pausing during reverse transcription. Finally, the implications of recombination on the dynamics of emergence of genomic aberrations in retroviruses are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.090551
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  • 120
    Digitale Medien
    Digitale Medien
    NEW PERSPECTIVES ON NUCLEAR TRANSPORT (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 341-364 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract A central aspect of cellular function is the proper regulation of nucleocytoplasmic transport. In recent years, significant progress has been made in identifying and characterizing the essential components of the transport machinery. Despite these advances, some facets of this process are still unclear. Furthermore, recent work has uncovered novel molecules and mechanisms of nuclear transport. This review focuses on the unresolved and novel aspects of nuclear transport and explores issues in tRNA, snRNA, and mRNA export that highlight the diversity of nuclear transport mechanisms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.090720
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  • 121
    Digitale Medien
    Digitale Medien
    THE GENETIC ARCHITECTURE OF QUANTITATIVE TRAITS (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 303-339 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Phenotypic variation for quantitative traits results from the segregation of alleles at multiple quantitative trait loci (QTL) with effects that are sensitive to the genetic, sexual, and external environments. Major challenges for biology in the post-genome era are to map the molecular polymorphisms responsible for variation in medically, agriculturally, and evolutionarily important complex traits; and to determine their gene frequencies and their homozygous, heterozygous, epistatic, and pleiotropic effects in multiple environments. The ease with which QTL can be mapped to genomic intervals bounded by molecular markers belies the difficulty in matching the QTL to a genetic locus. The latter requires high-resolution recombination or linkage disequilibrium mapping to nominate putative candidate genes, followed by genetic and/or functional complementation and gene expression analyses. Complete genome sequences and improved technologies for polymorphism detection will greatly advance the genetic dissection of quantitative traits in model organisms, which will open avenues for exploration of homologous QTL in related taxa.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.090633
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  • 122
    Digitale Medien
    Digitale Medien
    TRANSLATIONAL REGULATION AND RNA LOCALIZATION IN DROSOPHILA OOCYTES AND EMBRYOS (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 365-406 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Translational control is a prevalent means of gene regulation during Drosophila oogenesis and embryogenesis. Multiple maternal mRNAs are localized within the oocyte, and this localization is often coupled to their translational regulation. Subsequently, translational control allows maternally deposited mRNAs to direct the early stages of embryonic development. In this review we outline some general mechanisms of translational regulation and mRNA localization that have been uncovered in various model systems. Then we focus on the posttranscriptional regulation of four maternal transcripts in Drosophila that are localized during oogenesis and are critical for embryonic patterning: bicoid (bcd), nanos (nos), oskar (osk), and gurken (grk). Cis- and trans-acting factors required for the localization and translational control of these mRNAs are discussed along with potential mechanisms for their regulation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.090756
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  • 123
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    Digitale Medien
    MODELS AND DATA ON PLANT-ENEMY COEVOLUTION (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 469-499 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Although coevolution is complicated, in that the interacting species evolve in response to each other, such evolutionary dynamics are amenable to mathematical modeling. In this article, we briefly review models and data on coevolution between plants and the pathogens and herbivores that attack them. We focus on "arms races," in which trait values in the plant and its enemies escalate to more and more extreme values. Untested key assumptions in many of the models are the relationships between costs and benefits of resistance in the plant and the level of resistance, as well as how costs of virulence or detoxification ability in the enemy change with levels of these traits. A preliminary assessment of these assumptions finds only mixed support for the models. What is needed are models that are more closely tailored to particular plant-enemy interactions, as well as experiments that are expressly designed to test existing models.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.090954
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  • 124
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    Digitale Medien
    GENETIC ANALYSIS OF CALMODULIN AND ITS TARGETS IN SACCHAROMYCES CEREVISIAE (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 647-672 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Calmodulin, a small, ubiquitous Ca2+-binding protein, regulates a wide variety of proteins and processes in all eukaryotes. CMD1, the single gene encoding calmodulin in S. cerevisiae, is essential, and this review discusses studies that identified many of calmodulin's physiological targets and their functions in yeast cells. Calmodulin performs essential roles in mitosis, through its regulation of Nuf1p/Spc110p, a component of the spindle pole body, and in bud growth, by binding Myo2p, an unconventional class V myosin required for polarized secretion. Surprisingly, mutant calmodulins that fail to bind Ca2+ can perform these essential functions. Calmodulin is also required for endocytosis in yeast and participates in Ca2+-dependent, stress-activated signaling pathways through its regulation of a protein phosphatase, calcineurin, and the protein kinases, Cmk1p and Cmk2p. Thus, calmodulin performs important physiological functions in yeast cells in both its Ca2+-bound and Ca2+-free form.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.091302
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  • 125
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    Digitale Medien
    IDENTIFICATION OF EPILEPSY GENES IN HUMAN AND MOUSE1 (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 567-588 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract The development of molecular markers and genomic resources has facilitated the isolation of genes responsible for rare monogenic epilepsies in human and mouse. Many of the identified genes encode ion channels or other components of neuronal signaling. The electrophysiological properties of mutant alleles indicate that neuronal hyperexcitability is one cellular mechanism underlying seizures. Genetic heterogeneity and allelic variability are hallmarks of human epilepsy. For example, mutations in three different sodium channel genes can produce the same syndrome, GEFS+, while individuals with the same allele can experience different types of seizures. Haploinsufficiency for the sodium channel SCN1A has been demonstrated by the severe infantile epilepsy and cognitive deficits in heterozygotes for de novo null mutations. Large-scale patient screening is in progress to determine whether less severe alleles of the genes responsible for monogenic epilepsy may contribute to the common types of epilepsy in the human population. The development of pharmaceuticals directed towards specific epilepsy genotypes can be anticipated, and the introduction of patient mutations into the mouse genome will provide models for testing these targeted therapies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.091142
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  • 126
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    Digitale Medien
    MOLECULAR GENETICS OF HEARING LOSS (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 589-645 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Hereditary isolated hearing loss is genetically highly heterogeneous. Over 100 genes are predicted to cause this disorder in humans. Sixty loci have been reported and 24 genes underlying 28 deafness forms have been identified. The present epistemic stage in the realm consists in a preliminary characterization of the encoded proteins and the associated defective biological processes. Since for several of the deafness forms we still only have fuzzy notions of their pathogenesis, we here adopt a presentation of the various deafness forms based on the site of the primary defect: hair cell defects, nonsensory cell defects, and tectorial membrane anomalies. The various deafness forms so far studied appear as monogenic disorders. They are all rare with the exception of one, caused by mutations in the gene encoding the gap junction protein connexin26, which accounts for between one third to one half of the cases of prelingual inherited deafness in Caucasian populations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.091224
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  • 127
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    Digitale Medien
    DISSEMINATING THE GENOME: Joining, Resolving, and Separating Sister Chromatids During Mitosis and Meiosis (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 673-745 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract The separation of sister chromatids at the metaphase to anaphase transition is one of the most dramatic of all cellular events and is a crucial aspect of all sexual and asexual reproduction. The molecular basis for this process has until recently remained obscure. New research has identified proteins that hold sisters together while they are aligned on the metaphase plate. It has also shed insight into the mechanisms that dissolve sister chromatid cohesion during both mitosis and meiosis. These findings promise to provide insights into defects in chromosome segregation that occur in cancer cells and into the pathological pathways by which aneuploidy arises during meiosis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.091334
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  • 128
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    Digitale Medien
    EPITHELIAL CELL POLARITY AND CELL JUNCTIONS IN DROSOPHILA (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 747-784 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract The polarized architecture of epithelial cells and tissues is a fundamental determinant of animal anatomy and physiology. Recent progress made in the genetic and molecular analysis of epithelial polarity and cellular junctions in Drosophila has led to the most detailed understanding of these processes in a whole animal model system to date. Asymmetry of the plasma membrane and the differentiation of membrane domains and cellular junctions are controlled by protein complexes that assemble around transmembrane proteins such as DE-cadherin, Crumbs, and Neurexin IV, or other cytoplasmic protein complexes that associate with the plasma membrane. Much remains to be learned of how these complexes assemble, establish their polarized distribution, and contribute to the asymmetric organization of epithelial cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.091415
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  • 129
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    Digitale Medien
    INFORMED CONSENT AND OTHER ETHICAL ISSUES IN HUMAN POPULATION GENETICS (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 785-800 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Human population genetics has entered a new era of public interest, of controversy, and of ethical problems. Population genetics raises novel ethical problems because both the individuals and the populations being studied are, in effect, "subjects" of the research. Those populations are collectively subject to possible benefits and harms from the research and have interests, somewhat different from those of the individuals, that must be considered from both ethical and practical standpoints. The chapter first describes the new setting for research in human population genetics. It then examines the most controversial ethical issue in population genetics-whether researchers must obtain the informed consent of both the individual subjects and the group as a collectivity. Other vexing issues, including special problems caused by researchers' commercial interests, confidentiality, control over research uses and materials, and return of information to the population are also considered.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.091453
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  • 130
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    Digitale Medien
    G. LEDYARD STEBBINS AND THE EVOLUTIONARY SYNTHESIS (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 803-814 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Figure 1 G. LEDYARD STEBBINS Reproduction from Original Negative by Ansel Adams, Courtesy UCR/California Museum of Photography, Sweeney/Rubin Ansel Adams FIAT LUX Collection, University of California at Riverside. Figure 1 G. LEDYARD STEBBINS Reproduction from Original Negative by Ansel Adams, Courtesy UCR/Californ... More than any other individual, Stebbins synthesized knowledge from a disparate set of areas that included plant genetics, systematics, and evolution. This work culminated in 1950 with the appearance of his magnum opus, Variation and Evolution in Plants. This book gave plant evolution a coherent framework that was compatible with that emerging from the work of Theodosius Dobzhansky, Ernst Mayr, G. G. Simpson, and Julian Huxley, and others associated with establishing the synthetic theory of evolution. For this work he is regarded as the botanical "architect" of the evolutionary synthesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.091525
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  • 131
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    Digitale Medien
    THE SOS RESPONSE: Recent Insights into umuDC-Dependent Mutagenesis and DNA Damage Tolerance (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 34 (2000), S. 479-497 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Be they prokaryotic or eukaryotic, organisms are exposed to a multitude of deoxyribonucleic acid (DNA) damaging agents ranging from ultraviolet (UV) light to fungal metabolites, like Aflatoxin B1. Furthermore, DNA damaging agents, such as reactive oxygen species, can be produced by cells themselves as metabolic byproducts and intermediates. Together, these agents pose a constant threat to an organism's genome. As a result, organisms have evolved a number of vitally important mechanisms to repair DNA damage in a high fidelity manner. They have also evolved systems (cell cycle checkpoints) that delay the resumption of the cell cycle after DNA damage to allow more time for these accurate processes to occur. If a cell cannot repair DNA damage accurately, a mutagenic event may occur. Most bacteria, including Escherichia coli, have evolved a coordinated response to these challenges to the integrity of their genomes. In E. coli, this inducible system is termed the SOS response, and it controls both accurate and potentially mutagenic DNA repair functions [reviewed comprehensively in (25) and also in (78, 94)]. Recent advances have focused attention on the umuD+C+-dependent, translesion DNA synthesis (TLS) process that is responsible for SOS mutagenesis (70, 86). Here we discuss the SOS response of E. coli and concentrate in particular on the roles of the umuD+C+ gene products in promoting cell survival after DNA damage via TLS and a primitive DNA damage checkpoint.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.34.1.479
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  • 132
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    Digitale Medien
    Population Genetics and Evolution of Genomic Imprinting (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 34 (2000), S. 457-477 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract At a small number of mammalian loci, only one of the two copies of a gene is expressed. Just which copy is expressed depends on the sex of the parent from which that copy was inherited. Such genes are said to be imprinted. The functional haploidy implied by imprinting has a number of population genetic consequences. Moreover, since diploidy is widely believed to be advantageous, the evolution of this non-Mendelian form of expression requires an explanation. Here I examine some of the theoretical and mathematical models investigating these two aspects of imprinting. For instance, the dynamics and equilibrium properties of many models of natural selection at imprinted loci are formally equivalent to models without imprinting. And different approaches to modeling the problem of the evolution of imprinting reveal the weakness of several of the apparent predictions of various verbal hypotheses about why imprinting has evolved.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.34.1.457
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  • 133
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    Digitale Medien
    GENETIC MODELS OF OBESITY AND ENERGY BALANCE IN THE MOUSE (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 34 (2000), S. 687-745 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Obesity is a health problem of epidemic proportions in the industrialized world. The cloning and characterization of the genes for the five naturally occurring monogenic obesity syndromes in the mouse have led to major breakthroughs in understanding the physiology of energy balance and the contribution of genetics to obesity in the human population. However, the regulation of energy balance is an extremely complex process, and it is quickly becoming clear that hundreds of genes are involved. In this article, we review the naturally occurring monogenic and polygenic obese mouse strains, as well as the large number of transgenic and knockout mouse models currently available for the study of obesity and energy balance.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.34.1.687
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  • 134
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    Digitale Medien
    FUNCTIONS AND MECHANISMS OF RNA EDITING (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 34 (2000), S. 499-531 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract RNA editing can be broadly defined as any site-specific alteration in an RNA sequence that could have been copied from the template, excluding changes due to processes such as RNA splicing and polyadenylation. Changes in gene expression attributed to editing have been described in organisms from unicellular protozoa to man, and can affect the mRNAs, tRNAs, and rRNAs present in all cellular compartments. These sequence revisions, which include both the insertion and deletion of nucleotides, and the conversion of one base to another, involve a wide range of largely unrelated mechanisms. Recent advances in the development of in vitro editing and transgenic systems for these varied modifications have provided a better understanding of similarities and differences between the biochemical strategies, regulatory sequences, and cellular factors responsible for such RNA processing events.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.34.1.499
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  • 135
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    Digitale Medien
    CONSERVATION AND DIVERGENCE IN MOLECULAR MECHANISMS OF AXIS FORMATION (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 407-437 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Genetic screens in Drosophila melanogaster have helped elucidate the process of axis formation during early embryogenesis. Axis formation in the D. melanogaster embryo involves the use of two fundamentally different mechanisms for generating morphogenetic activity: patterning the anteroposterior axis by diffusion of a transcription factor within the syncytial embryo and specification of the dorsoventral axis through a signal transduction cascade. Identification of Drosophila genes involved in axis formation provides a launch-pad for comparative studies that examine the evolution of axis specification in different insects. Additionally, there is similarity between axial patterning mechanisms elucidated genetically in Drosophila and those demonstrated for chordates such as Xenopus. In this review we examine the postfertilization mechanisms underlying axis specification in Drosophila. Comparative data are then used to ask whether aspects of axis formation might be derived or ancestral.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.090832
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  • 136
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    Digitale Medien
    REGULATION OF GENE EXPRESSION BY CELL-TO-CELL COMMUNICATION: Acyl-Homoserine Lactone Quorum Sensing (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 439-468 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Quorum sensing is an example of community behavior prevalent among diverse bacterial species. The term "quorum sensing" describes the ability of a microorganism to perceive and respond to microbial population density, usually relying on the production and subsequent response to diffusible signal molecules. A significant number of gram-negative bacteria produce acylated homoserine lactones (acyl-HSLs) as signal molecules that function in quorum sensing. Bacteria that produce acyl-HSLs can respond to the local concentration of the signaling molecules, and high population densities foster the accumulation of inducing levels of acyl-HSLs. Depending upon the bacterial species, the physiological processes regulated by quorum sensing are extremely diverse, ranging from bioluminescence to swarming motility. Acyl-HSL quorum sensing has become a paradigm for intercellular signaling mechanisms. A flurry of research over the past decade has led to significant understanding of many aspects of quorum sensing including the synthesis of acyl-HSLs, the receptors that recognize the acyl-HSL signal and transduce this information to the level of gene expression, and the interaction of these receptors with the transcriptional machinery. Recent studies have begun to integrate acyl-HSL quorum sensing into global regulatory networks and establish its role in developing and maintaining the structure of bacterial communities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.090913
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  • 137
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    Digitale Medien
    BIOLOGY OF MAMMALIAN L1 RETROTRANSPOSONS (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 501-538 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract L1 retrotransposons comprise 17% of the human genome. Although most L1s are inactive, some elements remain capable of retrotransposition. L1 elements have a long evolutionary history dating to the beginnings of eukaryotic existence. Although many aspects of their retrotransposition mechanism remain poorly understood, they likely integrate into genomic DNA by a process called target primed reverse transcription. L1s have shaped mammalian genomes through a number of mechanisms. First, they have greatly expanded the genome both by their own retrotransposition and by providing the machinery necessary for the retrotransposition of other mobile elements, such as Alus. Second, they have shuffled non-L1 sequence throughout the genome by a process termed transduction. Third, they have affected gene expression by a number of mechanisms. For instance, they occasionally insert into genes and cause disease both in humans and in mice. L1 elements have proven useful as phylogenetic markers and may find other practical applications in gene discovery following insertional mutagenesis in mice and in the delivery of therapeutic genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.091032
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  • 138
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    Digitale Medien
    DOES NONNEUTRAL EVOLUTION SHAPE OBSERVED PATTERNS OF DNA VARIATION IN ANIMAL MITOCHONDRIAL GENOMES? (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 35 (2001), S. 539-566 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Early studies of animal mitochondrial DNA (mtDNA) assumed that nucleotide sequence variation was neutral. Recent analyses of sequences from a variety of taxa have brought the validity of this assumption into question. Here we review analytical methods used to test for neutrality and evidence for nonneutral evolution of animal mtDNA. Evaluations of mitochondrial haplotypes in different nuclear backgrounds identified differences in performance, typically favoring coevolved mitochondrial and nuclear genomes. Experimental manipulations also indicated that certain haplotypes have an advantage over others; however, biotic and historical effects and cyto-nuclear interactions make it difficult to assess the relative importance of nonneutral factors. Statistical analyses of sequences have been used to argue for nonneutrality of mtDNA; however, rejection of neutral patterns in the published literature is common but not predominant. Patterns of replacement and synonymous substitutions within and between species identified a trend toward an excess of replacement mutations within species. This pattern has been viewed as support for the existence of mildly deleterious mutations within species; however, other alternative explanations that can produce similar patterns cannot be eliminated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.35.102401.091106
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  • 139
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    Digitale Medien
    GENETICS OF CRYPTOCOCCUS NEOFORMANS (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 36 (2002), S. 557-615 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Cryptococcus neoformans is a pathogenic fungus that primarily afflicts immunocompromised patients, infecting the central nervous system to cause meningoencephalitis that is uniformly fatal if untreated. C. neoformans is a basidiomycetous fungus with a defined sexual cycle that has been linked to differentiation and virulence. Recent advances in classical and molecular genetic approaches have allowed molecular descriptions of the pathways that control cell type and virulence. An ongoing genome sequencing project promises to reveal much about the evolution of this human fungal pathogen into three distinct varieties or species. C. neoformans shares features with both model ascomycetous yeasts (Saccharomyces cerevisiae, Schizosaccharomyces pombe) and basidiomycetous pathogens and mushrooms (Ustilago maydis, Coprinus cinereus, Schizophyllum commune), yet ongoing studies reveal unique features associated with virulence and the arrangement of the mating type locus. These advances have catapulted C. neoformans to center stage as a model of both fungal pathogenesis and the interesting approaches to life that the kingdom of fungi has adopted.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.36.052402.152652
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  • 140
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    Digitale Medien
    CLOSING MITOSIS: The Functions of the Cdc14 Phosphatase and Its Regulation (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 38 (2004), S. 203-232 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Completion of the cell cycle requires the temporal and spatial coordination of chromosome segregation with mitotic spindle disassembly and cytokinesis. In budding yeast, the protein phosphatase Cdc14 is a key regulator of these late mitotic events. Here, we review the functions of Cdc14 and how this phosphatase is regulated to accomplish the coupling of mitotic processes. We also discuss the function and regulation of Cdc14 in other eukaryotes, emphasizing conserved features.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.38.072902.093051
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  • 141
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    Digitale Medien
    COMPARATIVE GENOMIC STRUCTURE OF PROKARYOTES (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 38 (2004), S. 771-791 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Recent advances in DNA-sequencing technologies have made available an enormous resource of data for the study of bacterial genomes. The broad sample of complete genomes currently available allows us to look at variation in the gross features and characteristics of genomes while the detail of the sequences reveal some of the mechanisms by which these genomes evolve. This review aims to describe bacterial genome structures according to current knowledge and proposed hypotheses. We also describe examples where mechanisms of genome evolution have acted in the adaptation of bacterial species to particular niches.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.38.072902.094318
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  • 142
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    Digitale Medien
    rRNA TRANSCRIPTION IN ESCHERICHIA COLI (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 38 (2004), S. 749-770 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Ribosomal RNA transcription is the rate-limiting step in ribosome synthesis in bacteria and has been investigated intensely for over half a century. Multiple mechanisms ensure that rRNA synthesis rates are appropriate for the cell's particular growth condition. Recently, important advances have been made in our understanding of rRNA transcription initiation in Escherichia coli. These include (a) a model at the atomic level of the network of protein-DNA and protein-protein interactions that recruit RNA polymerase to rRNA promoters, accounting for their extraordinary strength; (b) discovery of the nonredundant roles of two small molecule effectors, ppGpp and the initiating NTP, in regulation of rRNA transcription initiation; and (c) identification of a new component of the transcription machinery, DksA, that is absolutely required for regulation of rRNA promoter activity. Together, these advances provide clues important for our molecular understanding not only of rRNA transcription, but also of transcription in general.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.38.072902.091347
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  • 143
    Digitale Medien
    Digitale Medien
    TRANSVECTION EFFECTS IN DROSOPHILA (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 36 (2002), S. 521-556 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract An unusual feature of the Diptera is that homologous chromosomes are intimately synapsed in somatic cells. At a number of loci in Drosophila, this pairing can significantly influence gene expression. Such influences were first detected within the bithorax complex (BX-C) by E.B. Lewis, who coined the term transvection to describe them. Most cases of transvection involve the action of enhancers in trans. At several loci deletion of the promoter greatly increases this action in trans, suggesting that enhancers are normally tethered in cis by the promoter region. Transvection can also occur by the action of silencers in trans or by the spreading of position effect variegation from rearrangements having heterochromatic breakpoints to paired unrearranged chromosomes. Although not demonstrated, other cases of transvection may involve the production of joint RNAs by trans-splicing. Several cases of transvection require Zeste, a DNA-binding protein that is thought to facilitate homolog interactions by self-aggregation. Genes showing transvection can differ greatly in their response to pairing disruption. In several cases, transvection appears to require intimate synapsis of homologs. However, in at least one case (transvection of the iab-5,6,7 region of the BX-C), transvection is independent of synapsis within and surrounding the interacting gene. The latter example suggests that transvection could well occur in organisms that lack somatic pairing. In support of this, transvection-like phenomena have been described in a number of different organisms, including plants, fungi, and mammals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.36.060402.100441
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  • 144
    Digitale Medien
    Digitale Medien
    TOWARD MAINTAINING THE GENOME: DNA Damage and Replication Checkpoints (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 36 (2002), S. 617-656 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract DNA checkpoints play a significant role in cancer pathology, perhaps most notably in maintaining genome stability. This review summarizes the genetic and molecular mechanisms of checkpoint activation in response to DNA damage. The major checkpoint proteins common to all eukaryotes are identified and discussed, together with how the checkpoint proteins interact to induce arrest within each cell cycle phase. Also discussed are the molecular signals that activate checkpoint responses, including single-strand DNA, double-strand breaks, and aberrant replication forks. We address the connection between checkpoint proteins and damage repair mechanisms, how cells recover from an arrest response, and additional roles that checkpoint proteins play in DNA metabolism. Finally, the connection between checkpoint gene mutation and genomic instability is considered.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.36.060402.113540
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  • 145
    Digitale Medien
    Digitale Medien
    MECHANISMS OF PATTERN FORMATION IN PLANT EMBRYOGENESIS (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 38 (2004), S. 587-614 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Many of the patterning mechanisms in plants were discovered while studying postembryonic processes and resemble mechanisms operating during animal development. The emergent role of the plant hormone auxin, however, seems to represent a plant-specific solution to multicellular patterning. This review summarizes our knowledge on how diverse mechanisms that were first dissected at the postembryonic level are now beginning to provide an understanding of plant embryogenesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.38.072902.092231
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  • 146
    Digitale Medien
    Digitale Medien
    GENETIC APPROACHES TO MOLECULAR AND CELLULAR COGNITION: A Focus on LTP and Learning and Memory (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 36 (2002), S. 687-720 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract Long-term potentiation (LTP) is the predominant experimental model for the synaptic plasticity mechanisms thought to underlie learning and memory. This review is focused on the contributions of genetics to the understanding of the role of LTP in learning and memory. These studies have used a combination of genetics, molecular biology, neurophysiology, and psychology to demonstrate that molecular mechanisms of synaptic plasticity are critical for learning and memory. Because of the large scope of this literature, we focus primarily on genetic studies of hippocampal-dependent learning. Altogether, these findings not only demonstrate a role for plasticity in learning, they also lay down the foundations for the new field of molecular and cellular cognition.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.36.062802.091007
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  • 147
    Digitale Medien
    Digitale Medien
    THE FELINE GENOME PROJECT1 (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 36 (2002), S. 657-686 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract The compilation of a dense gene map and eventually a whole genome sequence (WGS) of the domestic cat holds considerable value for human genome annotation, for veterinary medicine, and for insight into the evolution of genome organization among mammals. Human association and veterinary studies of the cat, its domestic breeds, and its charismatic wild relatives of the family Felidae have rendered the species a powerful model for human hereditary diseases, for infectious disease agents, for adaptive evolutionary divergence, for conservation genetics, and for forensic applications. Here we review the advantages, rationale, and present strategy of a feline genome project, and we describe the disease models, comparative genomics, and biological applications posed by the full resolution of the cat's genome.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.36.060602.145553
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  • 148
    Digitale Medien
    Digitale Medien
    ESTIMATING F-STATISTICS (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 36 (2002), S. 721-750 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract A moment estimator of theta, the coancestry coefficient for alleles within a population, was described by Weir & Cockerham in 1984 (100) and is still widely cited. The estimate is used by population geneticists to characterize population structure, by ecologists to estimate migration rates, by animal breeders to describe genetic variation, and by forensic scientists to quantify the strength of matching DNA profiles. This review extends the work of Weir & Cockerham by allowing different levels of coancestry for different populations, and by allowing non-zero coancestries between pairs of populations. All estimates are relative to the average value of theta between pairs of populations. Moment estimates for within- and between-population theta values are likely to have large sampling variances, although these may be reduced by combining information over loci. Variances also decrease with the numbers of alleles at a locus, and with the numbers of populations sampled. This review also extends the work of Weir & Cockerham by employing maximum likelihood methods under the assumption that allele frequencies follow the normal distribution over populations. For the case of equal theta values within populations and zero theta values between populations, the maximum likelihood estimate is the same as that given by Robertson & Hill in 1984 (70). The review concludes by relating functions of theta values to times of population divergence under a pure drift model.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.36.050802.093940
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  • 149
    Digitale Medien
    Digitale Medien
    GENOMIC IMPRINTING AND KINSHIP: How Good is the Evidence? (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 38 (2004), S. 553-585 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: The kinship theory of genomic imprinting proposes that parent-specific gene expression evolves at a locus because a gene's level of expression in one individual has fitness effects on other individuals who have different probabilities of carrying the maternal and paternal alleles of the individual in which the gene is expressed. Therefore, natural selection favors different levels of expression depending on an allele's sex-of-origin in the previous generation. This review considers the strength of evidence in support of this hypothesis for imprinted genes in four "clusters," associated with the imprinted loci Igf2, Igf2r, callipyge, and Gnas. The clusters associated with Igf2 and Igf2r both contain paternally expressed transcripts that act as enhancers of prenatal growth and maternally expressed transcripts that act as inhibitors of prenatal growth. This is consistent with predictions of the kinship theory. However, the clusters also contain imprinted genes whose phenotypes as yet remain unexplained by the theory. The principal effects of imprinted genes in the callipyge and Gnas clusters appear to involve lipid and energy metabolism. The kinship theory predicts that maternally expressed transcripts will favor higher levels of nonshivering thermogenesis (NST) in brown adipose tissue (BAT) of animals that huddle for warmth as offspring. The phenotypes of reciprocal heterozygotes for Gnas knockouts provide provisional support for this hypothesis, as does some evidence from other imprinted genes (albeit more tentatively). The diverse effects of imprinted genes on the development of white adipose tissue (WAT) have so far defied a unifying hypothesis in terms of the kinship theory.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.37.110801.142741
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  • 150
    Digitale Medien
    Digitale Medien
    SPECIES SPECIFICITY IN POLLEN-PISTIL INTERACTIONS (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 38 (2004), S. 793-818 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: For pollination to succeed, pollen must carry sperm through a variety of different floral tissues to access the ovules within the pistil. The pistil provides everything the pollen requires for success in this endeavor including distinct guidance cues and essential nutrients that allow the pollen tube to traverse enormous distances along a complex path to the unfertilized ovule. Although the pistil is a great facilitator of pollen function, it can also be viewed as an elaborate barrier that shields ovules from access from inappropriate pollen, such as pollen from other species. Each discrete step taken by pollen tubes en route to the ovules is a potential barrier point to ovule access and waste by inappropriate mates. In this review, we survey the current molecular understanding of how pollination proceeds, and ask to what extent is each step important for mate discrimination. As this field progresses, this synthesis of functional biology and evolutionary studies will provide insight into the molecular basis of the species barriers that maintain the enormous diversity seen in flowering plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.38.072902.092356
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  • 151
    Digitale Medien
    Digitale Medien
    INTEGRATION OF ADENO-ASSOCIATED VIRUS (AAV) AND RECOMBINANT AAV VECTORS (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 38 (2004), S. 819-845 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: The driving interest in adeno-associated virus (AAV) has been its potential as a gene delivery vector. The early observation that AAV can establish a latent infection by integrating into the host chromosome has been central to this interest. However, chromosomal integration is a two-edged sword, imparting on one hand the ability to maintain the therapeutic gene in progeny cells, and on the other hand, the risk of mutations that are deleterious to the host. A clearer understanding of the mechanism and efficiency of AAV integration, in terms of contributing viral and host-cell factors and circumstances, will provide a context in which to evaluate these potential benefits and risks. Research to date suggests that AAV integration in any context is inefficient, and that the persistence of AAV gene delivery vectors in tissues is largely attributable to episomal genomes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.37.110801.143717
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  • 152
    Digitale Medien
    Digitale Medien
    LIGHT SIGNAL TRANSDUCTION IN HIGHER PLANTS (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 38 (2004), S. 87-117 
    Details
    ISSN: 0066-4197
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Plants utilize several families of photoreceptors to fine-tune growth and development over a large range of environmental conditions. The UV-A/blue light sensing phototropins mediate several light responses enabling optimization of photosynthetic yields. The initial event occurring upon photon capture is a conformational change of the photoreceptor that activates its protein kinase activity. The UV-A/blue light sensing cryptochromes and the red/far-red sensing phytochromes coordinately control seedling establishment, entrainment of the circadian clock, and the transition from vegetative to reproductive growth. In addition, the phytochromes control seed germination and shade-avoidance responses. The molecular mechanisms involved include light-regulated subcellular localization of the photoreceptors, a large reorganization of the transcriptional program, and light-regulated proteolytic degradation of several photoreceptors and signaling components.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.genet.38.072902.092259
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  • 153
    Digitale Medien
    Digitale Medien
    ELECTROKINETICALLY CONTROLLED MICROFLUIDIC ANALYSIS SYSTEMS (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 29 (2000), S. 155-181 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract Electrokinetic forces are emerging as a powerful means to drive microfluidic systems with flow channel cross-sectional dimensions in the tens of micrometers and flow rates in the nanoliter per second range. These systems provide many advantages such as improved analysis speed, improved reproducibility, greatly reduced reagent consumption, and the ability to perform multiple operations in an integrated fashion. Planar microfabrication methods are used to make these analysis chips in materials such as glass or polymers. Many applications of this technology have been demonstrated, such as DNA separations, enzyme assays, immunoassays, and PCR amplification integrated with microfluidic assays. Further development of this technology is expected to yield higher levels of functionality of sample throughput on a single microfluidic analysis chip.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.29.1.155
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  • 154
    Digitale Medien
    Digitale Medien
    STRUCTURAL SYMMETRY AND PROTEIN FUNCTION (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 29 (2000), S. 105-153 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract The majority of soluble and membrane-bound proteins in modern cells are symmetrical oligomeric complexes with two or more subunits. The evolutionary selection of symmetrical oligomeric complexes is driven by functional, genetic, and physicochemical needs. Large proteins are selected for specific morphological functions, such as formation of rings, containers, and filaments, and for cooperative functions, such as allosteric regulation and multivalent binding. Large proteins are also more stable against denaturation and have a reduced surface area exposed to solvent when compared with many individual, smaller proteins. Large proteins are constructed as oligomers for reasons of error control in synthesis, coding efficiency, and regulation of assembly. Symmetrical oligomers are favored because of stability and finite control of assembly. Several functions limit symmetry, such as interaction with DNA or membranes, and directional motion. Symmetry is broken or modified in many forms: quasisymmetry, in which identical subunits adopt similar but different conformations; pleomorphism, in which identical subunits form different complexes; pseudosymmetry, in which different molecules form approximately symmetrical complexes; and symmetry mismatch, in which oligomers of different symmetries interact along their respective symmetry axes. Asymmetry is also observed at several levels. Nearly all complexes show local asymmetry at the level of side chain conformation. Several complexes have reciprocating mechanisms in which the complex is asymmetric, but, over time, all subunits cycle through the same set of conformations. Global asymmetry is only rarely observed. Evolution of oligomeric complexes may favor the formation of dimers over complexes with higher cyclic symmetry, through a mechanism of prepositioned pairs of interacting residues. However, examples have been found for all of the crystallographic point groups, demonstrating that functional need can drive the evolution of any symmetry.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.29.1.105
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  • 155
    Digitale Medien
    Digitale Medien
    QUANTITATIVE CHEMICAL ANALYSIS OF SINGLE CELLS1 (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 29 (2000), S. 239-263 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract A fundamental perspective can be achieved by targeting single cells for analysis with the goal of deconvoluting complex biological functions. However, single-cell studies have their own difficulties, such as minute volumes and sample amounts. Quantitative chemical analysis of single cells has emerged as a powerful new area in recent years due to several technological advancements. The development of microelectrodes has allowed the measurement of redox-active species as a function of cellular dynamics. This miniaturization trend is also evident in the separation sciences with the application of small column separations to single cells. Desorption ionization methods with mass spectrometric detection have shown single-cell capability owing to numerous technological developments. Finally, fluorescence imaging has also progressed to the point where single-cell dynamics can be probed by native fluorescence utilizing either single or multiple photon excitation. The results of these studies are reviewed with an emphasis on the quantitation of single-cell dynamics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.29.1.239
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  • 156
    Digitale Medien
    Digitale Medien
    THE STRUCTURAL BIOLOGY OF MOLECULAR RECOGNITION BY VANCOMYCIN (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 29 (2000), S. 265-289 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract Vancomycin is the archetype among naturally occurring compounds known as glycopeptide antibiotics. Because it is a vital therapeutic agent used worldwide for the treatment of infections with gram-positive bacteria, emerging bacterial resistance to vancomycin is a major public health threat. Recent investigations into the mechanisms of action of glycopeptide antibiotics are driven by a need to understand their detailed mechanism of action so that new agents can be developed to overcome resistance. These investigations have revealed that glycopeptide antibiotics exhibit a rich array of complex cooperative phenomena when they bind target ligands, making them valuable model systems for the study of molecular recognition.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.29.1.265
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  • 157
    Digitale Medien
    Digitale Medien
    COMPARATIVE PROTEIN STRUCTURE MODELING OF GENES AND GENOMES (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 29 (2000), S. 291-325 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract Comparative modeling predicts the three-dimensional structure of a given protein sequence (target) based primarily on its alignment to one or more proteins of known structure (templates). The prediction process consists of fold assignment, target-template alignment, model building, and model evaluation. The number of protein sequences that can be modeled and the accuracy of the predictions are increasing steadily because of the growth in the number of known protein structures and because of the improvements in the modeling software. Further advances are necessary in recognizing weak sequence-structure similarities, aligning sequences with structures, modeling of rigid body shifts, distortions, loops and side chains, as well as detecting errors in a model. Despite these problems, it is currently possible to model with useful accuracy significant parts of approximately one third of all known protein sequences. The use of individual comparative models in biology is already rewarding and increasingly widespread. A major new challenge for comparative modeling is the integration of it with the torrents of data from genome sequencing projects as well as from functional and structural genomics. In particular, there is a need to develop an automated, rapid, robust, sensitive, and accurate comparative modeling pipeline applicable to whole genomes. Such large-scale modeling is likely to encourage new kinds of applications for the many resulting models, based on their large number and completeness at the level of the family, organism, or functional network.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.29.1.291
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  • 158
    Digitale Medien
    Digitale Medien
    PROTEIN FOLDING INTERMEDIATES AND PATHWAYS STUDIED BY HYDROGEN EXCHANGE (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 29 (2000), S. 213-238 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract In order to solve the immensely difficult protein-folding problem, it will be necessary to characterize the barriers that slow folding and the intermediate structures that promote it. Although protein-folding intermediates are not accessible to the usual structural studies, hydrogen exchange (HX) methods have been able to detect and characterize intermediates in both kinetic and equilibrium modes-as transient kinetic folding intermediates on a subsecond time scale, as labile equilibrium molten globule intermediates under destabilizing conditions, and as infinitesimally populated intermediates in the high free-energy folding landscape under native conditions. Available results consistently indicate that protein-folding landscapes are dominated by a small number of discrete, metastable, native-like partially unfolded forms (PUFs). The PUFs appear to be produced, one from another, by the unfolding and refolding of the protein's intrinsically cooperative secondary structural elements, which can spontaneously create stepwise unfolding and refolding pathways. Kinetic experiments identify three kinds of barrier processes: (a) an initial intrinsic search-nucleation-collapse process that prepares the chain for intermediate formation by pinning it into a condensed coarsely native-like topology; (b) smaller search-dependent barriers that put the secondary structural units into place; and (c) optional error-dependent misfold-reorganization barriers that can cause slow folding, intermediate accumulation, and folding heterogeneity. These conclusions provide a coherent explanation for the grossly disparate folding behavior of different globular proteins in terms of distinct folding pathways.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.29.1.213
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  • 159
    Digitale Medien
    Digitale Medien
    A STRUCTURAL VIEW OF Cre-loxP SITE-SPECIFIC RECOMBINATION (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 30 (2001), S. 87-104 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract Structural models of site-specific recombinases from the lambda integrase family of enzymes have in the last four years provided an important new perspective on the three-dimensional nature of the recombination pathway. Members of this family, which include the bacteriophage P1 Cre recombinase, bacteriophage lambda integrase, the yeast Flp recombinase, and the bacterial XerCD recombinases, exchange strands between DNA substrates in a stepwise process. One pair of strands is exchanged to form a Holliday junction intermediate, and the second pair of strands is exchanged during resolution of the junction to products. Crystal structures of reaction intermediates in the Cre-loxP site-specific recombination system, together with recent biochemical studies in the field, support a "strand swapping" model for recombination that does not require branch migration of the Holliday junction intermediate in order to test homology between recombining sites.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.30.1.87
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  • 160
    Digitale Medien
    Digitale Medien
    PROBING THE RELATION BETWEEN FORCE-LIFETIME-AND CHEMISTRY IN SINGLE MOLECULAR BONDS (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 30 (2001), S. 105-128 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract On laboratory time scales, the energy landscape of a weak bond along a dissociation pathway is fully explored through Brownian-thermal excitations, and energy barriers become encoded in a dissociation time that varies with applied force. Probed with ramps of force over an enormous range of rates (force/time), this kinetic profile is transformed into a dynamic spectrum of bond rupture force as a function of loading rate. On a logarithmic scale in loading rate, the force spectrum provides an easy-to-read map of the prominent energy barriers traversed along the force-driven pathway and exposes the differences in energy between barriers. In this way, the method of dynamic force spectroscopy (DFS) is being used to probe the complex relation between force-lifetime-and chemistry in single molecular bonds. Most important, DFS probes the inner world of molecular interactions to reveal barriers that are difficult or impossible to detect in assays of near equilibrium dissociation but that determine bond lifetime and strength under rapid detachment. To use an ultrasensitive force probe as a spectroscopic tool, we need to understand the physics of bond dissociation under force, the impact of experimental technique on the measurement of detachment force (bond strength), the consequences of complex interactions in macromolecular bonds, and effects of multiply-bonded attachments.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.30.1.105
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  • 161
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    Digitale Medien
    PULSED AND PARALLEL-POLARIZATION EPR CHARACTERIZATION OF THE PHOTOSYSTEM II OXYGEN-EVOLVING COMPLEX (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 29 (2000), S. 463-495 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract Photosystem II uses visible light to drive the oxidation of water, resulting in bioactivated electrons and protons, with the production of molecular oxygen as a byproduct. This water-splitting reaction is carried out by a manganese cluster/tyrosine radical ensemble, the oxygen-evolving complex. Although conventional continuous-wave, perpendicular-polarization electron paramagnetic resonance (EPR) spectroscopy has significantly advanced our knowledge of the structure and function of the oxygen-evolving complex, significant additional information can be obtained with the application of additional EPR methodologies. Specifically, parallel-polarization EPR spectroscopy can be used to obtain highly resolved EPR spectra of integer spin Mn species, and pulsed EPR spectroscopy with electron spin echo-based sequences, such as electron spin echo envelope modulation and electron spin echo-electron nuclear double resonance, can be used to measure weak interactions obscured in continuous-wave spectroscopy by inhomogeneous broadening.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.29.1.463
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  • 162
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    Digitale Medien
    STRESS-INDUCED STRUCTURAL TRANSITIONS IN DNA AND PROTEINS (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 29 (2000), S. 523-543 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract The ability to manipulate, stretch and twist biomolecules opens the way to an understanding of their structural transitions. We review some of the recently discovered stress-induced structural transitions in DNA as well as the application of single molecule manipulation techniques to DNA unzipping and to the study of protein folding/unfolding transitions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.29.1.523
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  • 163
    Digitale Medien
    Digitale Medien
    ELECTROSTATIC MECHANISMS OF DNA DEFORMATION (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 29 (2000), S. 497-521 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract The genomes of higher cells consist of double-helical DNA, a densely charged polyelectrolyte of immense length. The intrinsic physical properties of DNA, as well as the properties of its complexes with proteins and ions, are therefore of fundamental interest in understanding the functions of DNA as an informational macromolecule. Because individual DNA molecules often exceed 1 cm in length, it is clear that DNA bending, folding, and interaction with nuclear proteins are necessary for packaging genomes in small volumes and for integrating the nucleotide sequence information that guides genetic readout. This review first focuses on recent experiments exploring how the shape of the densely charged DNA polymer and asymmetries in its surrounding counterion distribution mutually influence one another. Attention is then turned to experiments seeking to discover the degree to which asymmetric phosphate neutralization can lead to DNA bending in protein-DNA complexes. It is argued that electrostatic effects play crucial roles in the intrinsic, sequence-dependent shape of DNA and in DNA shapes induced by protein binding.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.29.1.497
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  • 164
    Digitale Medien
    Digitale Medien
    ATOMIC FORCE MICROSCOPY IN THE STUDY OF MACROMOLECULAR CRYSTAL GROWTH (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 29 (2000), S. 361-410 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract Atomic force microscopy (AFM) has been used to study protein, nucleic acid, and virus crystals in situ, in their mother liquors, as they grow. From sequential AFM images taken at brief intervals over many hours, or even days, the mechanisms and kinetics of the growth process can be defined. The appearance of both two- and three-dimensional nuclei on crystal surfaces have been visualized, defect structures of crystals were clearly evident, and defect densities of crystals were also determined. The incorporation of a wide range of impurities, ranging in size from molecules to microns or larger microcrystals, and even foreign particles were visually recorded. From these observations and measurements, a more complex understanding of the detailed character of macromolecular crystals is emerging, one that reveals levels of complexity previously unsuspected. The unique features of these crystals, apparently in AFM images, undoubtedly influence the diffraction properties of the crystals and the quality of the molecular images obtained by X-ray crystallography.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.29.1.361
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  • 165
    Digitale Medien
    Digitale Medien
    MOLECULAR MECHANISMS CONTROLLING ACTIN FILAMENT DYNAMICS IN NONMUSCLE CELLS (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 29 (2000), S. 545-576 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract We review how motile cells regulate actin filament assembly at their leading edge. Activation of cell surface receptors generates signals (including activated Rho family GTPases) that converge on integrating proteins of the WASp family (WASp, N-WASP, and Scar/WAVE). WASP family proteins stimulate Arp2/3 complex to nucleate actin filaments, which grow at a fixed 70o angle from the side of pre-existing actin filaments. These filaments push the membrane forward as they grow at their barbed ends. Arp2/3 complex is incorporated into the network, and new filaments are capped rapidly, so that activated Arp2/3 complex must be supplied continuously to keep the network growing. Hydrolysis of ATP bound to polymerized actin followed by phosphate dissociation marks older filaments for depolymerization by ADF/cofilins. Profilin catalyzes exchange of ADP for ATP, recycling actin back to a pool of unpolymerized monomers bound to profilin and thymosin-beta4 that is poised for rapid elongation of new barbed ends.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.29.1.545
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  • 166
    Digitale Medien
    Digitale Medien
    HYDROGEN BONDING, BASE STACKING, AND STERIC EFFECTS IN DNA REPLICATION (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 30 (2001), S. 1-22 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract Understanding the mechanisms by which genetic information is replicated is important both to basic knowledge of biological organisms and to many useful applications in biomedical research and biotechnology. One of the main functions of a DNA polymerase enzyme is to help DNA recognize itself with high specificity when a strand is being copied. Recent studies have shed new light on the question of what physical forces cause a polymerase enzyme to insert a nucleotide into a strand of DNA and to choose the correct nucleotide over the incorrect ones. This is discussed in the light of three main forces that govern DNA recognition: base stacking, Watson-Crick hydrogen bonding, and steric interactions. These factors are studied with natural and structurally altered DNA nucleosides.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.30.1.1
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  • 167
    Digitale Medien
    Digitale Medien
    UNNATURAL LIGANDS FOR ENGINEERED PROTEINS: New Tools for Chemical Genetics (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 29 (2000), S. 577-606 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract Small molecules that modulate the activity of biological signaling molecules can be powerful probes of signal transduction pathways. Highly specific molecules with high affinity are difficult to identify because of the conserved nature of many protein active sites. A newly developed approach to discovery of such small molecules that relies on protein engineering and chemical synthesis has yielded powerful tools for the study of a wide variety of proteins involved in signal transduction (G-proteins, protein kinases, 7-transmembrane receptors, nuclear hormone receptors, and others). Such chemical genetic tools combine the advantages of traditional genetics and the unparalleled temporal control over protein function afforded by small molecule inhibitors/activators that act at diffusion controlled rates with targets.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.29.1.577
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  • 168
    Digitale Medien
    Digitale Medien
    STRUCTURES AND PROTON-PUMPING STRATEGIES OF MITOCHONDRIAL RESPIRATORY ENZYMES (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 30 (2001), S. 23-65 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract Enzymes of the mitochondrial respiratory chain serve as proton pumps, using the energy made available from electron transfer reactions to transport protons across the inner mitochondrial membrane and create an electrochemical gradient used for the production of ATP. The ATP synthase enzyme is reversible and can also serve as a proton pump by coupling ATP hydrolysis to proton translocation. Each of the respiratory enzymes uses a different strategy for performing proton pumping. In this work, the strategies are described and the structural bases for the action of these proteins are discussed in light of recent crystal structures of several respiratory enzymes. The mechanisms and efficiency of proton translocation are also analyzed in terms of the thermodynamics of the substrate transformations catalyzed by these enzymes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.30.1.23
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  • 169
    Digitale Medien
    Digitale Medien
    MASS SPECTROMETRY AS A TOOL FOR PROTEIN CRYSTALLOGRAPHY (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 30 (2001), S. 67-85 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract Atomic resolution structure determinations of proteins by X-ray crystallography are formidable multidisciplinary undertakings, requiring protein construct design, expression and purification, crystallization trials, phase determination, and model building. Modern mass spectrometric methods can greatly facilitate these obligate tasks. Thus, mass spectrometry can be used to verify that the desired protein construct has been correctly expressed, to define compact domains in the target protein, to assess the components contained within the protein crystals, and to screen for successful incorporation of seleno-methionine and other heavy metal reagents used for phasing. In addition, mass spectrometry can be used to address issues of modeling, topology, and side-chain proximity. Here, we demonstrate how rational use of mass spectrometry assists and expedites high resolution X-ray structure determination through each stage of the process of protein crystallography.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.30.1.67
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  • 170
    Digitale Medien
    Digitale Medien
    PHOTOSYSTEM II: The Solid Structural Era (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 30 (2001), S. 307-328 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract Understanding the precise role of photosystem II as an element of oxygenic photosynthesis requires knowledge of the molecular structure of this membrane protein complex. The past few years have been particularly exciting because the structural era of the plant photosystem II has begun. Although the atomic structure has yet to be determined, the map obtained at 6 A resolution by electron crystallography allows assignment of the key reaction center subunits with their associated pigment molecules. In the following, we first review the structural details that have recently emerged and then discuss the primary and secondary photochemical reaction pathways. Finally, in an attempt to establish the evolutionary link between the oxygenic and the anoxygenic photosynthesis, a framework structure common to all photosynthetic reaction centers has been defined, and the implications have been described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.30.1.307
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  • 171
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    Digitale Medien
    PROTEIN FOLDING THEORY: From Lattice to All-Atom Models (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 30 (2001), S. 361-396 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract This review focuses on recent advances in understanding protein folding kinetics in the context of nucleation theory. We present basic concepts such as nucleation, folding nucleus, and transition state ensemble and then discuss recent advances and challenges in theoretical understanding of several key aspects of protein folding kinetics. We cover recent topology-based approaches as well as evolutionary studies and molecular dynamics approaches to determine protein folding nucleus and analyze other aspects of folding kinetics. Finally, we briefly discuss successful all-atom Monte-Carlo simulations of protein folding and conclude with a brief outlook for the future.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.30.1.361
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  • 172
    Digitale Medien
    Digitale Medien
    THE SEARCH AND ITS OUTCOME: High-Resolution Structures of Ribosomal Particles from Mesophilic, Thermophilic, and Halophilic Bacteria at Various Functional States (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 31 (2002), S. 257-273 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract We determined the high-resolution structures of large and small ribosomal subunits from mesophilic and thermophilic bacteria and compared them with those of the thermophilic ribosome and the halophilic large subunit. We confirmed that the elements involved in intersubunit contacts and in substrate binding are inherently flexible and that a common ribosomal strategy is to utilize this conformational variability for optimizing its functional efficiency and minimizing nonproductive interactions. Under close-to-physiological conditions, these elements maintain well-ordered characteristic conformations. In unbound subunits, the features creating intersubunit bridges within associated ribosomes lie on the interface surface, and the features that bind factors and substrates reach toward the binding site only when conditions are ripe.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.31.082901.134439
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  • 173
    Digitale Medien
    Digitale Medien
    CONFORMATIONAL DYNAMICS OF THE CHROMATIN FIBER IN SOLUTION: Determinants, Mechanisms, and Functions (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 31 (2002), S. 361-392 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract Chromatin fibers are dynamic macromolecular assemblages that are intimately involved in nuclear function. This review focuses on recent advances centered on the molecular mechanisms and determinants of chromatin fiber dynamics in solution. Major points of emphasis are the functions of the core histone tail domains, linker histones, and a new class of proteins that assemble supramolecular chromatin structures. The discussion of important structural issues is set against a background of possible functional significance.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.31.101101.140858
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  • 174
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    Digitale Medien
    PARAMAGNETIC RESONANCE OF BIOLOGICAL METAL CENTERS (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 31 (2002), S. 393-422 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract The review deals with recent advances in magnetic resonance spectroscopy (hf EPR and NMR) of paramagnetic metal centers in biological macromolecules. In the first half of our chapter, we present an overview of recent technical developments in the NMR of paramagnetic bio-macromolecules. These are illustrated by a variety of examples deriving mainly from the spectroscopy of metalloproteins and their complexes. The second half focuses on recent developments in high-frequency EPR spectroscopy and the application of the technique to copper, iron, and manganese proteins. Special attention is given to the work on single crystals of copper proteins.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.31.091701.171000
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  • 175
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    Digitale Medien
    FORCE EXERTION IN FUNGAL INFECTION (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 31 (2002), S. 321-341 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract Fungal pathogens of plants or animals invade their hosts either by secretion of lytic enzymes, exerting force, or by a combination of both. Although many fungi are thought to rely mostly on lysis of the host tissue, some plant pathogenic fungi differentiate complex infection cells that develop enormous turgor pressure, which in turn is translated into force used for invasion. In order to understand mechanisms of fungal infection in detail, methods have been developed that indirectly or directly measure turgor pressure and force. In this article, these methods are described and critically discussed, and their importance in analysis of fungal infection are outlined.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.31.091701.170951
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  • 176
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    Digitale Medien
    COMPUTATIONAL CELL BIOLOGY: Spatiotemporal Simulation of Cellular Events (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 31 (2002), S. 423-441 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract The field of computational cell biology has emerged within the past 5 years because of the need to apply disciplined computational approaches to build and test complex hypotheses on the interacting structural, physical, and chemical features that underlie intracellular processes. To meet this need, newly developed software tools allow cell biologists and biophysicists to build models and generate simulations from them. The construction of general-purpose computational approaches is especially challenging if the spatial complexity of cellular systems is to be explicitly treated. This review surveys some of the existing efforts in this field with special emphasis on a system being developed in the authors' laboratory, Virtual Cell. The theories behind both stochastic and deterministic simulations are discussed. Examples of respective applications to cell biological problems in RNA trafficking and neuronal calcium dynamics are provided to illustrate these ideas.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.31.101101.140930
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  • 177
    Digitale Medien
    Digitale Medien
    THE STRUCTURE OF MAMMALIAN CYCLOOXYGENASES (2003)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 183-206 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract Cyclooxygenases-1 and -2 (COX-1 and COX-2, also known as prostaglandin H2 synthases-1 and -2) catalyze the committed step in prostaglandin synthesis. COX-1 and -2 are of particular interest because they are the major targets of nonsteroidal antiinflammatory drugs (NSAIDs) including aspirin, ibuprofen, and the new COX-2-selective inhibitors. Inhibition of the COXs with NSAIDs acutely reduces inflammation, pain, and fever, and long-term use of these drugs reduces the incidence of fatal thrombotic events, as well as the development of colon cancer and Alzheimer's disease. In this review, we examine how the structures of COXs relate mechanistically to cyclooxygenase and peroxidase catalysis and how alternative fatty acid substrates bind within the COX active site. We further examine how NSAIDs interact with COXs and how differences in the structure of COX-2 result in enhanced selectivity toward COX-2 inhibitors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.32.110601.141906
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  • 178
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    Digitale Medien
    COMPUTER SIMULATIONS OF ENZYME CATALYSIS: Methods, Progress, and Insights (2003)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 425-443 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Abstract Understanding the action of enzymes on an atomistic level is one of the important aims of modern biophysics. This review describes the state of the art in addressing this challenge by simulating enzymatic reactions. It considers different modeling methods including the empirical valence bond (EVB) and more standard molecular orbital quantum mechanics/molecular mechanics (QM/MM) methods. The importance of proper configurational averaging of QM/MM energies is emphasized, pointing out that at present such averages are performed most effectively by the EVB method. It is clarified that all properly conducted simulation studies have identified electrostatic preorganization effects as the source of enzyme catalysis. It is argued that the ability to simulate enzymatic reactions also provides the chance to examine the importance of nonelectrostatic contributions and the validity of the corresponding proposals. In fact, simulation studies have indicated that prominent proposals such as desolvation, steric strain, near attack conformation, entropy traps, and coherent dynamics do not account for a major part of the catalytic power of enzymes. Finally, it is pointed out that although some of the issues are likely to remain controversial for some time, computer modeling approaches can provide a powerful tool for understanding enzyme catalysis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.32.110601.141807
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  • 179
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    Digitale Medien
    FORCE AS A USEFUL VARIABLE IN REACTIONS: Unfolding RNA (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 33 (2004), S. 363-385 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: The effect of force on the thermodynamics and kinetics of reactions is described. The key parameters are the difference in end-to-end distance between reactant and product for thermodynamics, and the distance to the transition state for kinetics. I focus the review on experimental results on force unfolding of RNA. Methods to measure Gibbs free energies and kinetics for reversible and irreversible reactions are described. The use of the worm-like-chain model to calculate the effects of force on thermodynamics and kinetics is illustrated with simple models. The main purpose of the review is to describe the simple experiments that have been done so far, and to encourage more people to enter a field that is new and full of opportunities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.33.110502.140418
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  • 180
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    Digitale Medien
    MOLECULES OF THE BACTERIAL CYTOSKELETON (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 33 (2004), S. 177-198 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: The structural elucidation of clear but distant homologs of actin and tubulin in bacteria and GFP labeling of these proteins promises to reinvigorate the field of prokaryotic cell biology. FtsZ (the tubulin homolog) and MreB/ParM (the actin homologs) are indispensable for cellular tasks that require the cell to accurately position molecules, similar to the function of the eukaryotic cytoskeleton. FtsZ is the organizing molecule of bacterial cell division and forms a filamentous ring around the middle of the cell. Many molecules, including MinCDE, SulA, ZipA, and FtsA, assist with this process directly. Recently, genes much more similar to tubulin than to FtsZ have been identified in Verrucomicrobia. MreB forms helices underneath the inner membrane and probably defines the shape of the cell by positioning transmembrane and periplasmic cell wall-synthesizing enzymes. Currently, no interacting proteins are known for MreB and its relatives that help these proteins polymerize or depolymerize at certain times and places inside the cell. It is anticipated that MreB-interacting proteins exist in analogy to the large number of actin binding proteins in eukaryotes. ParM (a plasmid-borne actin homolog) is directly involved in pushing certain single-copy plasmids to the opposite poles by ParR/parC-assisted polymerization into double-helical filaments, much like the filaments formed by actin, F-actin. Mollicutes seem to have developed special systems for cell shape determination and motility, such as the fibril protein in Spiroplasma.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.33.110502.132647
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  • 181
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    Digitale Medien
    STRUCTURE, DYNAMICS, AND CATALYTIC FUNCTION OF DIHYDROFOLATE REDUCTASE (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 33 (2004), S. 119-140 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Molecular motions are widely regarded as contributing factors in many aspects of protein function. The enzyme dihydrofolate reductase (DHFR), and particularly that from Escherichia coli, has become an important system for investigating the linkage between protein dynamics and catalytic function, both because of the location and timescales of the motions observed and because of the availability of a large amount of structural and mechanistic data that provides a detailed context within which the motions can be interpreted. Changes in protein dynamics in response to ligand binding, conformational change, and mutagenesis have been probed using numerous experimental and theoretical approaches, including X-ray crystallography, fluorescence, nuclear magnetic resonance (NMR), molecular dynamics simulations, and hybrid quantum/classical dynamics methods. These studies provide a detailed map of changes in conformation and dynamics throughout the catalytic cycle of DHFR and give new insights into the role of protein motions in the catalytic activity of this enzyme.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.33.110502.133613
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  • 182
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    Digitale Medien
    TETHERING: Fragment-Based Drug Discovery (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 33 (2004), S. 199-223 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: The genomics revolution has provided a deluge of new targets for drug discovery. To facilitate the drug discovery process, many researchers are turning to fragment-based approaches to find lead molecules more efficiently. One such method, Tethering1, allows for the identification of small-molecule fragments that bind to specific regions of a protein target. These fragments can then be elaborated, combined with other molecules, or combined with one another to provide high-affinity drug leads. In this review we describe the background and theory behind Tethering and discuss its use in identifying novel inhibitors for protein targets including interleukin-2 (IL-2), thymidylate synthase (TS), protein tyrosine phosphatase 1B (PTP-1B), and caspases.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.33.110502.140409
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  • 183
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    Digitale Medien
    TAKING X-RAY DIFFRACTION TO THE LIMIT: Macromolecular Structures from Femtosecond X-Ray Pulses and Diffraction Microscopy of Cells with Synchrotron Radiation* (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 33 (2004), S. 157-176 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Recent work is extending the methodology of X-ray crystallography to the structure determination of noncrystalline specimens. The phase problem is solved using the oversampling method, which takes advantage of "continuous" diffraction patterns from noncrystalline specimens. Here we review the principle of this newly developed technique and discuss the ongoing experiments of imaging nonperiodic objects, such as cells and cellular structures, using coherent and bright X rays produced by third-generation synchrotron sources. In the longer run, the technique may be applicable to image single biomolecules using anticipated X-ray free electron lasers. Here, computer simulations have so far demonstrated two important steps: (a) by using an extremely intense femtosecond X-ray pulse, a diffraction pattern can be recorded from a macromolecule before radiation damage manifests itself; and (b) the phase information can be retrieved in an ab initio fashion from a set of calculated noisy diffraction patterns of single protein molecules.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.33.110502.140405
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  • 184
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    Digitale Medien
    STRUCTURE, MOLECULAR MECHANISMS, AND EVOLUTIONARY RELATIONSHIPS IN DNA TOPOISOMERASES (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 33 (2004), S. 95-118 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Topoisomerases are enzymes that use DNA strand scission, manipulation, and rejoining activities to directly modulate DNA topology. These actions provide a powerful means to effect changes in DNA supercoiling levels, and allow some topoisomerases to both unknot and decatenate chromosomes. Since their initial discovery over three decades ago, researchers have amassed a rich store of information on the cellular roles and regulation of topoisomerases, and have delineated general models for their chemical and physical mechanisms. Topoisomerases are now known to be necessary for the survival of cellular organisms and many viruses and are rich clinical targets for anticancer and antimicrobial treatments. In recent years, crystal structures have been obtained for each of the four types of topoisomerases in a number of distinct conformational and substrate-bound states. In addition, sophisticated biophysical methods have been utilized to study details of topoisomerase reaction dynamics and enzymology. A synthesis of these approaches has provided researchers with new physical insights into how topoisomerases employ chemistry and allostery to direct the large-scale molecular motions needed to pass DNA strands through each other.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.33.110502.140357
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  • 185
    Digitale Medien
    Digitale Medien
    THREE-DIMENSIONAL ELECTRON MICROSCOPY AT MOLECULAR RESOLUTION* (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 33 (2004), S. 141-155 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Emerging methods in cryo-electron microscopy allow determination of the three-dimensional architectures of objects ranging in size from small proteins to large eukaryotic cells, spanning a size range of more than 12 orders of magnitude. Advances in determining structures by "single particle" microscopy and by "electron tomography" provide exciting opportunities to describe the structures of subcellular assemblies that are either too large or too heterogeneous to be investigated by conventional crystallographic methods. Here, we review selected aspects of progress in structure determination by cryo-electron microscopy at molecular resolution, with a particular emphasis on topics at the interface of single particle and tomographic approaches. The rapid pace of development in this field suggests that comprehensive descriptions of the structures of whole cells and organelles in terms of the spatial arrangements of their molecular components may soon become routine.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.33.110502.140339
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  • 186
    Digitale Medien
    Digitale Medien
    ROTATION OF F1-ATPASE: How an ATP-Driven Molecular Machine May Work (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 33 (2004), S. 245-268 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: F1-ATPase is a rotary motor made of a single protein molecule. Its rotation is driven by free energy obtained by ATP hydrolysis. In vivo, another motor, Fo, presumably rotates the F1 motor in the reverse direction, reversing also the chemical reaction in F1 to let it synthesize ATP. Here we attempt to answer two related questions, How is free energy obtained by ATP hydrolysis converted to the mechanical work of rotation, and how is mechanical work done on F1 converted to free energy to produce ATP? After summarizing single-molecule observations of F1 rotation, we introduce a toy model and discuss its free-energy diagrams to possibly answer the above questions. We also discuss the efficiency of molecular motors in general.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.33.110502.132716
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  • 187
    Digitale Medien
    Digitale Medien
    MASS SPECTRAL ANALYSIS IN PROTEOMICS (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 33 (2004), S. 297-316 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Mass spectrometry provides key tools for the analysis of proteins. New types of mass spectrometers that provide enhanced capability to discover protein identities and perform improved proteomic experiments are discussed. Handling the complex mixtures of peptides and proteins generated from protein complexes and whole cells requires multidimensional separations; several forms of separation are discussed. Applications of mass spectrometry-based approaches for contemporary proteomic analyses are described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.33.111502.082538
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  • 188
    Digitale Medien
    Digitale Medien
    INFORMATION CONTENT AND COMPLEXITY IN THE HIGH-ORDER ORGANIZATION OF DNA (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 33 (2004), S. 317-342 
    Details
    ISSN: 1056-8700
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Physik
    Notizen: Nucleic acids are characterized by a vast structural variability. Secondary structural conformations include the main polymorphs A, B, and Z, cruciforms, intrinsic curvature, and multistranded motifs. DNA secondary motifs are stabilized and regulated by the primary base sequence, contextual effects, environmental factors, as well as by high-order DNA packaging modes. The high-order modes are, in turn, affected by secondary structures and by the environment. This review is concerned with the flow of structural information among the hierarchical structural levels of DNA molecules, the intricate interplay between the various factors that affect these levels, and the regulation and physiological significance of DNA high-order structures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.biophys.33.110502.133328
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  • 189
    Digitale Medien
    Digitale Medien
    ETHYLENE: A Gaseous Signal Molecule in Plants (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Cell and Developmental Biology 16 (2000), S. 1-18 
    Details
    ISSN: 1081-0706
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Medizin
    Notizen: Abstract Ethylene regulates a multitude of plant processes, ranging from seed germination to organ senescence. Of particular economic importance is the role of ethylene as an inducer of fruit ripening. Ethylene is synthesized from S-adenosyl-L-methionine via 1-aminocyclopropane-1-carboxylic acid (ACC). The enzymes catalyzing the two reactions in this pathway are ACC synthase and ACC oxidase. Environmental and endogenous signals regulate ethylene biosynthesis primarily through differential expression of ACC synthase genes. Components of the ethylene signal transduction pathway have been identified by characterization of ethylene-response mutants in Arabidopsis thaliana. One class of mutations, exemplified by etr1, led to the identification of the ethylene receptors, which turned out to be related to bacterial two-component signaling systems. Mutations that eliminate ethylene binding to the receptor yield a dominant, ethylene-insensitive phenotype. CTR1 encodes a Raf-like Ser/Thr protein kinase that acts downstream from the ethylene receptor and may be part of a MAP kinase cascade. Mutants in CTR1 exhibit a constitutive ethylene-response phenotype. Both the ethylene receptors and CTR1 are negative regulators of ethylene responses. EIN2 and EIN3 are epistatic to CTR1, and mutations in either gene lead to ethylene insensitivity. Whereas the function of EIN2 in ethylene transduction is not known, EIN3 is a putative transcription factor involved in regulating expression of ethylene-responsive genes. Biotechnological modifications of ethylene synthesis and of sensitivity to ethylene are promising methods to prevent spoilage of agricultural products such as fruits, whose ripening is induced by ethylene.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.cellbio.16.1.1
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  • 190
    Digitale Medien
    Digitale Medien
    MECHANISMS OF SYNAPTIC VESICLE EXOCYTOSIS (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Cell and Developmental Biology 16 (2000), S. 19-49 
    Details
    ISSN: 1081-0706
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Medizin
    Notizen: Abstract Chemical synaptic transmission serves as the main form of cell to cell communication in the nervous system. Neurotransmitter release occurs through the process of regulated exocytosis, in which a synaptic vesicle releases its contents in response to an increase in calcium. The use of genetic, biochemical, structural, and functional studies has led to the identification of factors important in the synaptic vesicle life cycle. Here we focus on the prominent role of SNARE (soluble NSF attachment protein receptor) proteins during membrane fusion and the regulation of SNARE function by Rab3a, nSec1, and NSF. Many of the proteins important for transmitter release have homologs involved in intracellular vesicle transport, and all forms of vesicle trafficking share common basic principles. Finally, modifications to the synaptic exocytosis pathway are very likely to underlie certain forms of synaptic plasticity and therefore contribute to learning and memory.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.cellbio.16.1.19
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  • 191
    Digitale Medien
    Digitale Medien
    ERM-MERLIN AND EBP50 PROTEIN FAMILIES IN PLASMA MEMBRANE ORGANIZATION AND FUNCTION (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Cell and Developmental Biology 16 (2000), S. 113-143 
    Details
    ISSN: 1081-0706
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Medizin
    Notizen: Abstract The ezrin-radixin-moesin (ERM) family of proteins have emerged as key regulatory molecules in linking F-actin to specific membrane proteins, especially in cell surface structures. Merlin, the product of the NF2 tumor suppressor gene, has sequence similarity to ERM proteins and binds to some of the same membrane proteins, but lacks a C-terminal F-actin binding site. In this review we discuss how ERM proteins and merlin are negatively regulated by an intramolecular association between their N- and C-terminal domains. Activation of at least ERM proteins can be accomplished by C-terminal phosphorylation in the presence of PIP2. We also discuss membrane proteins to which ERM and merlin bind, including those making an indirect linkage through the PDZ-containing adaptor molecules EBP50 and E3KARP. Finally, the function of these proteins in cortical structure, endocytic traffic, signal transduction, and growth control is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.cellbio.16.1.113
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  • 192
    Digitale Medien
    Digitale Medien
    MOLECULAR REGULATION OF ADIPOGENESIS (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Cell and Developmental Biology 16 (2000), S. 145-171 
    Details
    ISSN: 1081-0706
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Medizin
    Notizen: Abstract Adipogenesis, or the development of fat cells from preadipocytes, has been one of the most intensely studied models of cellular differentiation. In part this has been because of the availability of in vitro models that faithfully recapitulate most of the critical aspects of fat cell formation in vivo. More recently, studies of adipogenesis have proceeded with the hope that manipulation of this process in humans might one day lead to a reduction in the burden of obesity and diabetes. This review explores some of the highlights of a large and burgeoning literature devoted to understanding adipogenesis at the molecular level. The hormonal and transcriptional control of adipogenesis is reviewed, as well as studies on a less well known type of fat cell, the brown adipocyte. Emphasis is placed, where possible, on in vivo studies with the hope that the results discussed may one day shed light on basic questions of cellular growth and differentiation in addition to possible benefits in human health.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.cellbio.16.1.145
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  • 193
    Digitale Medien
    Digitale Medien
    GUT FEELINGS: Enteropathogenic E. coli (EPEC) Interactions with the Host (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Cell and Developmental Biology 16 (2000), S. 173-189 
    Details
    ISSN: 1081-0706
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Medizin
    Notizen: Abstract Enteropathogenic Escherichia coli (EPEC) is a gram-negative bacterial pathogen that adheres to human intestinal epithelial cells, resulting in watery, persistent diarrhea. It subverts the host cell cytoskeleton, causing a rearrangement of cytoskeletal components into a characteristic pedestal structure underneath adherent bacteria. In contrast to other intracellular pathogens that affect the actin cytoskeleton from inside the host cytoplasm, EPEC remains extracellular and transmits signals through the host cell plasma membrane via direct injection of virulence factors by a "molecular syringe," the bacterial type III secretion system. One injected factor is Tir, which functions as the plasma membrane receptor for EPEC adherence. Tir directly links extracellular EPEC through the epithelial membrane and firmly anchors it to the host cell actin cytoskeleton, thereby initiating pedestal formation. In addition to stimulating actin nucleation and polymerization in the host cell, EPEC activates several other signaling pathways that lead to tight junction disruption, inhibition of phagocytosis, altered ion secretion, and immune responses. This review summarizes recent developments in our understanding of EPEC pathogenesis and discusses similarities and differences between EPEC pedestals, focal contacts, and Listeria monocytogenes actin tails.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.cellbio.16.1.173
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  • 194
    Digitale Medien
    Digitale Medien
    BONE DEVELOPMENT (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Cell and Developmental Biology 16 (2000), S. 191-220 
    Details
    ISSN: 1081-0706
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Medizin
    Notizen: Abstract Early development of the vertebrate skeleton depends on genes that pattern the distribution and proliferation of cells from cranial neural crest, sclerotomes, and lateral plate mesoderm into mesenchymal condensations at sites of future skeletal elements. Within these condensations, cells differentiate to chondrocytes or osteoblasts and form cartilages and bones under the control of various transcription factors. In most of the skeleton, organogenesis results in cartilage models of future bones; in these models cartilage is replaced by bone by the process of endochondral ossification. Lastly, through a controlled process of bone growth and remodeling the final skeleton is shaped and molded. Significant and exciting insights into all aspects of vertebrate skeletal development have been obtained through molecular and genetic studies of animal models and humans with inherited disorders of skeletal morphogenesis, organogenesis, and growth.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.cellbio.16.1.191
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  • 195
    Digitale Medien
    Digitale Medien
    CELLULAR SIGNALING AND VOLUME CONTROL IN STOMATAL MOVEMENTS IN PLANTS (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Cell and Developmental Biology 16 (2000), S. 221-241 
    Details
    ISSN: 1081-0706
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Medizin
    Notizen: Abstract Stomatal guard cells are unique as a plant cell model and, because of the depth of present knowledge on ion transport and its regulation, offer a first look at signal integration in higher plants. A large body of data indicates that Ca2+ and H+ act independently, integrating with protein kinases and phosphatases, to control the gating of the K+ and Cl- channels that mediate solute flux for stomatal movements. Oscillations in the cytosolic-free concentration of Ca2+ contribute to a signaling cassette, integrated within these events through an unusual coupling with membrane voltage for solute homeostasis. Similar cassettes are anticipated to include control pathways linked to cytosolic pH. Additional developments during the last two years point to events in membrane traffic that play equally important roles in stomatal control. Research in these areas is now adding entirely new dimensions to our understanding of guard cell signaling.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.cellbio.16.1.221
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  • 196
    Digitale Medien
    Digitale Medien
    THE DEVELOPMENTAL AND MOLECULAR BIOLOGY OF GENES THAT SUBDIVIDE THE BODY OF DROSOPHILA (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Cell and Developmental Biology 16 (2000), S. 243-271 
    Details
    ISSN: 1081-0706
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Medizin
    Notizen: Abstract During the past decade, much progress has been made in understanding how the adult fly is built. Some old concepts such as those of compartments and selector genes have been revitalized. In addition, recent work suggests the existence of genes involved in the regionalization of the adult that do not have all the features of selector genes. Nevertheless, they generate morphological distinctions within the body plan. Here we re-examine some of the defining criteria of selector genes and suggest that these newly characterized genes fulfill many, but not all, of these criteria. Further, we propose that these genes can be classified according to the domains in which they function. Finally, we discuss experiments that address the molecular mechanisms by which selector and selector-like gene products function in the fly.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.cellbio.16.1.243
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  • 197
    Digitale Medien
    Digitale Medien
    CAJAL BODIES: The First 100 Years (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Cell and Developmental Biology 16 (2000), S. 273-300 
    Details
    ISSN: 1081-0706
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Medizin
    Notizen: Abstract Cajal bodies are small nuclear organelles first described nearly 100 years ago by Ramon y Cajal in vertebrate neural tissues. They have since been found in a variety of animal and plant nuclei, suggesting that they are involved in basic cellular processes. Cajal bodies contain a marker protein of unknown function, p80-coilin, and many components involved in transcription and processing of nuclear RNAs. Among these are the three eukaryotic RNA polymerases and factors required for transcribing and processing their respective nuclear transcripts: mRNA, rRNA, and pol III transcripts. A model is discussed in which Cajal bodies are the sites for preassembly of transcriptosomes, unitary particles involved in transcription and processing of RNA. A parallel is drawn to the nucleolus and the preassembly of ribosomes, which are unitary particles involved in translation of proteins.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.cellbio.16.1.273
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  • 198
    Digitale Medien
    Digitale Medien
    EPITHELIAL M CELLS: Differentiation and Function (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Cell and Developmental Biology 16 (2000), S. 301-332 
    Details
    ISSN: 1081-0706
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Medizin
    Notizen: Abstract M cells are distinctive epithelial cells that occur only in the follicle-associated epithelia that overlie organized mucosa-associated lymphoid tissues. They are structurally and functionally specialized for transepithelial transport, delivering foreign antigens and microorganisms to organized lymphoid tissues within the mucosae of the small and large intestines, tonsils and adenoids, and airways. M cell transport is a double-edged sword: Certain pathogens exploit the features of M cells that are intended to promote uptake for the purpose of immunological sampling. Eludication of the molecular architecture of M cell apical surfaces is important for understanding the strategies that pathogens use to exploit this pathway and for utilizing M cell transport for delivery of vaccines to the mucosal immune system. This article reviews the functional and biochemical features that distinguish M cells from other intestinal cell types. In addition it synthesizes the available information on development and differentiation of organized lymphoid tissues and the specialized epithelium associated with these immune inductive sites.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.cellbio.16.1.301
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  • 199
    Digitale Medien
    Digitale Medien
    DYNAMIN AND ITS ROLE IN MEMBRANE FISSION1 (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Cell and Developmental Biology 16 (2000), S. 483-519 
    Details
    ISSN: 1081-0706
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Medizin
    Notizen: Abstract Dynamin, a 100-kDa GTPase, is an essential component of vesicle formation in receptor-mediated endocytosis, synaptic vesicle recycling, caveolae internalization, and possibly vesicle trafficking in and out of the Golgi. In addition to the GTPase domain, dynamin also contains a pleckstrin homology domain (PH) implicated in membrane binding, a GTPase effector domain (GED) shown to be essential for self-assembly and stimulated GTPase activity, and a C-terminal proline-rich domain (PRD), which contains several SH3-binding sites. Dynamin partners bind to the PRD and may either stimulate dynamin's GTPase activity or target dynamin to the plasma membrane. Purified dynamin readily self-assembles into rings or spirals. This striking structural property supports the hypothesis that dynamin wraps around the necks of budding vesicles where it plays a key role in membrane fission. The focus of this review is on the relationship between the GTPase and self-assembly properties of dynamin and its cellular function.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.cellbio.16.1.483
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  • 200
    Digitale Medien
    Digitale Medien
    THE ROLE OF ORPHAN NUCLEAR RECEPTORS IN THE REGULATION OF CHOLESTEROL HOMEOSTASIS (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Cell and Developmental Biology 16 (2000), S. 459-481 
    Details
    ISSN: 1081-0706
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie , Medizin
    Notizen: Abstract Cholesterol balance is maintained by a series of regulatory pathways that control the acquisition of cholesterol from endogenous and exogenous sources and the elimination of cholesterol, facilitated by its conversion to bile acids. Over the past decade, investigators have discovered that a family of membrane-bound transcription factors, sterol regulatory element-binding proteins (SREBPs), mediate the end-product repression of key enzymes of cholesterol biosynthesis. Recently orphan members of another family of transcription factors, the nuclear hormone receptors, have been found to regulate key pathways in bile acid metabolism, thereby controlling cholesterol elimination. The study of these orphan nuclear receptors suggests their potential as targets for new drug therapies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.cellbio.16.1.459
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