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11.
Many external signals influence growth cone motility, pathfinding, and the formation of synapses that lead to the final map formation of the retinotectal system. Chick temporal retinal ganglion cell axons (RGCs) collapse and retract after encountering posterior tectal cells in vitro. During this process lateral extensions appear along the RGC axonal shaft. Lateral extensions appear as nascent interstitial axonal branches and also as defasciculating growth cones that are trailing along the pioneer axon. RGC branching controlled by repellent tectal cues has recently been shown to be the critical event in retinotectal map development. The intracellular mechanism underlying this phenomenon, however, is not understood. Inhibiting RhoA with either C3 toxin or inhibiting p160Rock kinase, an effector of RhoA, with Y27632 inhibited collapse, retraction, and the number of axons that showed lateral extensions. Lateral extension length increased significantly. Inhibiting Rac1A and cdc42 with cell permeable peptide inhibitors did not inhibit collapse of growth cones, but did inhibit axon retraction. In addition, the number of axons that showed lateral extensions and lateral extension length were significantly reduced. A dynamic cytoskeleton is necessary to react to incoming guidance information. This study addresses the problems of how growth cone motility and branching or defasciculation are affected by Rho-GTPases as extracellular signals are transmitted to the cytoskeleton. 相似文献
12.
Brouard S Berberat PO Tobiasch E Seldon MP Bach FH Soares MP 《The Journal of biological chemistry》2002,277(20):17950-17961
13.
Edda Siegl Barbara Nebe Heidrun Blunk Joachim Rychly 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》1998,119(4):2047
Flow cytometric analysis of the forward/side light scatter (FSC/SSC) of density gradient-separated head kidney cells of the rainbow trout revealed three distinctly separated populations, which we defined as population 1, 2 and 3. In spleen cells, populations 1 and 2 were also found, whereas population 3 was not detected. Further characterization regarding the surface Ig (sIg) revealed that population 2 of the head kidney and spleen contained 37.4 and 34.4% sIg+-cells, respectively. Incubation of the head kidney and spleen cells with different concentrations of concanavalin A (ConA), phytohemagglutinin (PHA) and [PWM] induced a pronounced intracellular calcium increase only in cells of population 2. This reaction was concentration dependent and caused by a release of intracellular Ca2+-stores. FMLP, a chemotactic peptide, had no effect on intracellular calcium response in all three populations. Similarly, the stimulation with PMA had no effect. This indicates that population 2 of the head kidney as well as the spleen is characterized by a high forward and low side light scatter and contains both subpopulation of lymphocytes, B- and T-cells. We demonstrated that the analysis of intracellular calcium increase due to mitogens is a suitable approach to identify lymphocytes in fish and enables further functional studies in these cells. 相似文献
14.
Peter Müller Karl-Rudolf Erlemann Karin Müller Juan J. Calvete Edda Töpfer-Petersen Kathleen Marienfeld A. Herrmann 《European biophysics journal : EBJ》1998,27(1):33-41
PDC-109 is the major protein of bovine seminal plasma. It binds to the bovine sperm surface at ejaculation and modulates
sperm capacitation. PDC-109 displays phosphorylcholine- and heparin-binding activities which are thought to account for its
sperm surface coating and glycosaminoglycan-induced sperm capacitating activities, respectively. We have characterized the
interaction of isolated PDC-109 with membranes of phospholipid vesicles using a biophysical approach. Our results show that
PDC-109 interacts not only with the solvent-exposed phosphorylcholine head group but also with the hydrophobic core of liposomes.
Binding of PDC-109 to membranes is a very rapid, biphasic process with half times of less than one second. Maximal binding
of PDC-109 to small unilamellar vesicles was achieved with a stoichiometric ratio of 10–11 phosphatidylcholine molecules/PDC-109
molecule. Incorporation of phosphatidylethanolamine or phosphatidylserine into phosphatidylcholine vesicles reduced the binding
of PDC-109, suggesting that both the density of phosphorylcholine groups and the surface charge determine the interaction
of the seminal plasma protein with the surface of the membrane. Electron spin resonance measurements showed that binding of
PDC-109 to phosphatidylcholine vesicles caused a rigidification of the membrane. The relevance of the data for describing
the role of PDC-109 in the modulation of sperm capacitation is discussed.
Received: 16 June 1997 / Accepted: 10 September 1997 相似文献
15.
Jingjing Zang Jennifer Keim Edda Kastenhuber Matthias Gesemann Stephan C. F. Neuhauss 《Open biology》2015,5(8)
The neuronal Ca2+-binding protein Recoverin has been shown to regulate phototransduction termination in mammalian rods. Here we identify four recoverin genes in the zebrafish genome, rcv1a, rcv1b, rcv2a and rcv2b, and investigate their role in modulating the cone phototransduction cascade. While Recoverin-1b is only found in the adult retina, the other Recoverins are expressed throughout development in all four cone types, except Recoverin-1a, which is expressed only in rods and UV cones. Applying a double flash electroretinogram (ERG) paradigm, downregulation of Recoverin-2a or 2b accelerates cone photoresponse recovery, albeit at different light intensities. Exclusive recording from UV cones via spectral ERG reveals that knockdown of Recoverin-1a alone has no effect, but Recoverin-1a/2a double-knockdowns showed an even shorter recovery time than Recoverin-2a-deficient larvae. We also showed that UV cone photoresponse kinetics depend on Recoverin-2a function via cone-specific kinase Grk7a. This is the first in vivo study demonstrating that cone opsin deactivation kinetics determine overall photoresponse shut off kinetics. 相似文献
16.
17.
Tannert A Kurz A Erlemann KR Müller K Herrmann A Schiller J Töpfer-Petersen E Manjunath P Müller P 《European biophysics journal : EBJ》2007,36(4-5):461-475
The bovine seminal plasma protein PDC-109 modulates the maturation of bull sperm cells by removing lipids, mainly phosphatidylcholine
and cholesterol, from their cellular membrane. Here, we have characterized the process of extraction of endogenous phospholipids
and of their respective analogues. By measuring the PDC-109-mediated release of fluorescent phospholipid analogues from lipid
vesicles and from biological membranes (human erythrocytes, bovine epididymal sperm cells), we showed that PDC-109 extracts
phospholipids with a phosphorylcholine headgroup mainly from the outer leaflet of these membranes. The ability of PDC-109
to extract endogenous phospholipids from epididymal sperm cells was followed by mass spectrometry, which allowed us to characterize
the fatty acid pattern of the released lipids. From these cells, PDC-109 extracted phosphatidylcholine and sphingomyelin that
contained an enrichment of mono- and di-unsaturated fatty acids as well as short-chain and lyso-phosphatidylcholine species.
Based on the results, a model explaining the phospholipid specificity of PDC-109-mediated lipid release is presented.
Astrid Tannert and Anke Kurz have contributed equally to this work.
Dedicated to Prof. K. Arnold on the occasion of his 65th birthday. 相似文献
18.
Sciutto E Rosas G Cruz-Revilla C Toledo A Cervantes J Hernández M Hernándezt B Goldbaum FA de Aluja AS Fragoso G Larralde C 《The Journal of parasitology》2007,93(4):824-831
Review of experimental and observational evidence about various cestode infections of mammalian hosts revives hope for the development of an effective vaccine against adult intestinal tapeworms, the central protagonists in their transmission dynamics. As for Taenia solium, there are abundant immunological data regarding cysticercosis in humans and pigs, but information about human taeniasis is scarce. A single publication reporting protection against T. solium taeniasis by experimental primo infection and by vaccination of an experimental foster host, the immunocompetent female hamster, kindles the hope of a vaccine against the tapeworm to be used in humans, its only natural definitive host. 相似文献
19.