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991.
Gordon R 《The International journal of developmental biology》2006,50(2-3):245-253
Mechanics is shown to be an important, perhaps central component to the differentiation and development of embryos. Mechanics of the nucleus may also be involved in determining which genes are expressed in a given cell. There are two major approaches at present to the mechanics of differentiation in embryos: morphomechanics and differentiation waves. These are compared in detail, to provide a starting point for future experimental work to bring them into one conceptual framework. This may rationalize the present cookbookery of stem cell production by placing it in the context of differentiation waves and the differentiation code. Embryonics, the realization of concepts from embryology in computer hardware and software, might be considerably enhanced by incorporating mechanical concepts of embryogenesis. Segmented robots, modular robotics, cellular microrobotics, flexible electronics, wearable computers, diatom nanotechnology and waves in active media point to a synthesis that we could call embryonic robotics. 相似文献
992.
Lev V Beloussov Richard Gordon 《The International journal of developmental biology》2006,50(2-3):79-80
We, the Guest Editors of this Special Issue of The International Journal of Developmental Biology, are two older embryologists, who are trying to bridge the current chasm between Entwicklungsmechanic, the developmental mechanics of our embryogenesis forefathers, and the modern movement of molecular developmental biology. Our rallying cry is that of Wilhelm His: "To think that heredity will build organic beings without mechanical means is a piece of unscientific mysticism" (His, 1888). Until recently, this claim appeared to us to fall on the somewhat deaf ears of molecular developmental biologists. Yet, the world is still one, and both physics and chemistry obviously have their place in embryogenesis. Indeed, at the molecular level, membrane proteins which are mechanoreceptors and motor molecules may begin to point the way. Here, we and our colleagues will make the case for a more equitable consideration of molecules and mechanics. 相似文献
993.
Gingras AR Vogel KP Steinhoff HJ Ziegler WH Patel B Emsley J Critchley DR Roberts GC Barsukov IL 《Biochemistry》2006,45(6):1805-1817
Talin is a key protein involved in linking integrins to the actin cytoskeleton. The long flexible talin rod domain contains a number of binding sites for vinculin, a cytoskeletal protein important in stabilizing integrin-mediated cell-matrix junctions. Here we report the solution structure of a talin rod polypeptide (residues 1843-1973) which contains a single vinculin binding site (VBS; residues 1944-1969). Like other talin rod polypeptides, it consists of a helical bundle, in this case a four-helix bundle with a right-handed topology. The residues in the VBS important for vinculin binding were identified by studying the binding of a series of VBS-related peptides to the vinculin Vd1 domain. The key binding determinants are buried in the interior of the helical bundle, suggesting that a substantial structural change in the talin polypeptide is required for vinculin binding. Direct evidence for this was obtained by NMR and EPR spectroscopy. [1H,15N]-HSQC spectra of the talin fragment indicate that vinculin binding caused approximately two-thirds of the protein to adopt a flexible random coil. For EPR spectroscopy, nitroxide spin labels were attached to the talin polypeptide via appropriately located cysteine residues. Measurements of inter-nitroxide distances in doubly spin-labeled protein showed clearly that the helical bundle is disrupted and the mobility of the helices, except for the VBS helix, is markedly increased. Binding of vinculin to talin is thus a clear example of the unusual phenomenon of protein unfolding being required for protein/protein interaction. 相似文献
994.
995.
996.
Stawski CY Grigg GC Booth DT Beard LA 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2006,143(2):173-183
We investigated the capacity of two reptiles, an agamid lizard Pogona barbata and a chelid turtle Emydura signata, to compensate for the effects of temperature by making changes in their whole blood respiratory properties. This was accomplished by measuring the P50 (at 10, 20 and 30 degrees C), hematocrit (Hct), haemoglobin concentration ([Hb]) and mean cell haemoglobin concentration (MCHC) in field acclimatised and laboratory acclimated individuals. The acute effect of temperature on P50 in P. barbata, expressed as heat of oxygenation (deltaH), ranged from -16.8+/-1.84 to -28.5+/-2.73 kJ/mole. P50 of field acclimatised P. barbata increased significantly from early spring to summer at the test temperatures of 20 degrees C (43.1+/-1.2 to 48.8+/-2.1 mmHg) and 30 degrees C (54.7+/-1.2 to 65.2+/-2.3 mmHg), but showed no acclimation under laboratory conditions. For E. signata, deltaH ranged from -31.1+/-6.32 to -48.2+/-3.59 kJ/mole. Field acclimatisation and laboratory acclimation of P50 did not occur. However, in E. signata, there was a significant increase in [Hb] and MCHC from early spring to summer in turtles collected from the wild (1.0+/-0.1 to 1.7+/-0.2 mmol/L and 4.0+/-0.3 to 6.7+/-0.7 mmol/L, respectively). 相似文献
997.
Brown GD 《Nature reviews. Immunology》2006,6(1):33-43
Dectin-1 is a natural killer (NK)-cell-receptor-like C-type lectin that is thought to be involved in innate immune responses to fungal pathogens. This transmembrane signalling receptor mediates various cellular functions, from fungal binding, uptake and killing, to inducing the production of cytokines and chemokines. These activities could influence the resultant immune response and can, in certain circumstances, lead to autoimmunity and disease. As I discuss here, understanding the molecular mechanisms behind these functions has revealed new concepts, including collaborative signalling with the Toll-like receptors (TLRs) and the use of spleen tyrosine kinase (SYK), that have implications for the role of other non-TLR pattern-recognition receptors in immunity. 相似文献
998.
999.
Borthwick AD Exall AM Haley TM Jackson DL Mason AM Weingarten GG 《Bioorganic & medicinal chemistry letters》2002,12(13):1719-1722
Mechanism-based inhibitors of HCMV protease, which are stable to human plasma (> or = 20 h) and have single-figure potency in the microM range against HCMV protease, have been developed based on the dansylproline alpha-methyl pyrrolidine-5,5-trans-lactam nucleus. 相似文献
1000.
Mukhopadhyay S Muimo R Campbell FM Gordon MJ Monaghan AS Dutta-Roy AK 《Prostaglandins, leukotrienes, and essential fatty acids》2000,62(6):341-348
We investigated the fatty acid distribution in guinea pig alveolar apical membranes at different developmental stages. Fatty acid composition of the purified membranes isolated from guinea pig fetuses (at 65 day, term=68 day), neonates (day 1) and adult males was determined. The levels of arachidonic acid (AA) and docosahexaenoic acid (DHA) were higher in the adult guinea pig alveolar apical membrane phosphatidylethanolamine (PE) fraction (9. 3+/-2.2 and 2.9+/-1.0%, respectively) while in other phospholipids (PL) fractions their levels were low or absent (P<0.01). Furthermore, levels of AA and DHA in the PE fraction of apical membrane increased significantly from fetal (6.6+/-3.0 and 0.8+/-0.4%, respectively) to neonatal life (10.3+/-1.5 and 3.0+/-0.8%, respectively). Increase in the level of DHA (almost four-fold) was much more pronounced than that of AA (P<0.05). As for guinea pig alveolar membranes, EPA and AA were mostly present in the PE fraction in pulmonary adenocarcinoma derived cells (A549 cells), a parallel model of type II pneumocytes, with the levels of AA around three-fold greater than that of EPA, Binding of radiolabelled fatty acids to A549 cells showed no significant differences between the maximum uptake achieved for different fatty acids (AA, 1.7+/-0.2, EPA, 2.3+/-0.3, LA, 1.7+/-0.2, OA, 2.0+/-0.2nmol/mg protein, P>0.5). Once the fatty acids were taken up by these cells AA was mostly identifiable in the monoacylglycerol (MAG) fraction, whereas EPA was equally distributed between the MAG and PL fractions. Oleic acid was mainly present in the triglyceride (TAG) fraction whereas LA was evenly distributed between the TAG, MAG, and PL fractions. Our data demonstrate a preferential distribution of AA and DHA in PE fractions of alveolar apical membranes during development. 相似文献