Flight mechanism of insect is different from that of our familiar system of aircraft, machinery, or bird. Recent studies quantitatively indicated that many features of insect flight mechanism, such as thin airfoil, high beating frequency, or continuous beating motion, well conform to the fluiddynamic condition given to the insect.
Binding of plasma apolipoproteins to surface membrane of lipid particles causes the strong positive curvature stain. Although apolipoproteins can hardly bind to egg phosphatidylcholine planar surface in bilayers, many apolipoproteins bind to the emulsion surface with significantly higher capacity compared to bilayers. This marked difference in apolipoprotein binding between bilayers and emulsions can be explained by the difference in mechanisms by which the apolipoprotein-induced membrane curvature stress is relaxed. The binding capacity of apolipoprotein A-I increases with increasing spontaneous negative curvature in bilayers, whereas in emulsions, the contribution of core lipids to the relief of curvature stress appears to be the key event for apolipoprotein binding.
It has increasingly become evident that the plant cell wall not only provides a structural scaffold to support plant bodies but also plays crucial roles in regulation of a number of intracellular activities. Based on recent findings obtained in an aquatic monocot Vallisneria gigantea, a possible occurrence of structural and/or functional homologues of focal contact in plant cells, the site of animal cells for signal transduction from the exterior as well as for cell-substrate adhesion, is discussed.
The heat shock response is a universally conserved mechanism protecting cells from external stress. Here we present an overall picture of the heat shock response of E. coli. Under steady state conditions, the DnaK chaperone system downregulates the activity, synthesis and stability of the heat shock transcription factor σ32, which plays a central role in the synthesis of heat shock proteins. Upon heat shock, the downregulation by the DnaK system is overcome and σ32 is induced, leading to rapid and transient induction of heat shock proteins. Degradation of σ32 is mainly achieved by the membrane-bound ATP-dependent protease FtsH.
The thermodynamics of the interaction of the c-Myb DNA-binding domain(R2R3) and its target DNA have been analyzed using isothermal titration calorimetry(ITC) and protein engineering. The observed thermodynamic parameters gave several new insights into the DNA recognition mechanism, such as the electrostatic contributions, the local folding in the linker region between R2 and R3, and the thermodynamic differences between specific and nonspecific protein-DNA interactions.
It is assumed that positional information within a developing organism is represented by a morphogen gradient. However, it is not yet understood how positional information is organized in a size invariant manner. To achieve such size invariance, it is necessary for an organism to organize the polarity of positional information in advance. We focus on tactic behavior of the Physarum plasmodium and propose a model that describes the organization of size invariant positional information, in which the direction of the phase wave represents the polarity. We would like to point out that self-referential dynamics exist in our model, and their implementation is discussed. Our mode may be applied to other developmental systems.