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The brain of Antarctic fish of the perciform suborder Notothenioidea was analysed with lightand electronmicroscopical methods. The overall organization and ultrastructure of the optic tectum is very similar to that of fish from temperate climates. However, unusual structures were observed in neurons and glial cells, sometimes in high frequencies. The structures are ovoid or elongated, about 200-600 nm in diameter and surrounded by two layers of membranes in a uniform distance of about 30 nm. The enclosed inter-membrane space is similar to extracellular space, both in size and in cytochemical calcium precipitation, while the interior of the structures resembles cytoplasm. These structures are sometimes connected to neuronal processes, so that they seem to originate by a sort of budding process, but most of them are isolated as can be concluded from thick sections of up to 800 nm thickness, analysed with energy-filtering transmission electron microscopy (EFTEM). These unusual objects are present in high abundance in members of the white-blooded Antarctic fish family Channichthyidae. These so-called icefish lack haemoglobin and exhibit the highest degree of cold adaptation. The red-blooded notothenoid fish had smaller amounts of these structures and they were observed even in fish from temperate climates (trout, carp, cichlid fish). In fish from temperate climates the unusual substructures were more abundant during adaptation to cold water temperatures (winter) than to warm conditions (summer). Therefore, the findings may indicate a general phenomenon of cold adaptation with unusual interactions of neurons and glial cells, but the precise function is not yet understood. 相似文献
54.
Marcia L. Moss Dmitriy Minond Toshie Yoneyama Hinrich P. Hansen Nikola Vujanovic Fred H. Rasmussen 《Analytical biochemistry》2016
A fluorescent resonance energy transfer substrate with improved sensitivity for ADAM17, −10, and −9 (where ADAM represents a disintegrin and metalloproteinase) has been designed. The new substrate, Dabcyl-Pro-Arg-Ala-Ala-Ala-Homophe-Thr-Ser-Pro-Lys(FAM)-NH2, has specificity constants of 6.3 (±0.3) × 104 M−1 s−1 and 2.4 (±0.3) × 103 M−1 s−1 for ADAM17 and ADAM10, respectively. The substrate is more sensitive than widely used peptides based on the precursor tumor necrosis factor-alpha (TNF-alpha) cleavage site, PEPDAB010 or Dabcyl-Ser-Pro-Leu-Ala-Gln-Ala-Val-Arg-Ser-Ser-Lys(FAM)-NH2 and Mca-Pro-Leu-Ala-Gln-Ala-Val-Dpa-Arg-Ser-Ser-Arg-NH2. ADAM9 also processes the new peptide more than 18-fold better than the TNF-alpha-based substrates. The new substrate has a unique selectivity profile because it is processed less efficiently by ADAM8 and MMP1, −2, −3, −8, −9, −12, and −14. This substrate provides a unique tool in which to assess ADAM17, −10, and −9 activities. 相似文献
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Summary Correlative histological, histochemical and biochemical investigations on laminar compartments from four different areas of fetal human neopallium at 28 weeks of gestation revealed discrete distribution of gangliosides in the cerebral wall. Highest level of total ganglioside concentration was found in the layers of cortical anlage (cortical plate and subplate layer) which are concomittantly characterized by highest activity of acetylcholinesterase (AChE) and which are known to be involved in intensive synaptogenesis at this stage of cortical development. In three of four areas the proportion of GD1a — ganglioside from total ganglioside amount tended to increase and that of GT1b to decrease from inside (ventricle) to outside (cortical anlage) throughout the cerebral wall. 相似文献
56.
G B?ssler R Hilbig H Rahmann 《Comparative biochemistry and physiology. A, Comparative physiology》1983,76(1):85-93
The influence of electrical stimulation ("attack"-frequency of 40 Hz, 2 V, 2 days) and of social and electrical deprivation on the metabolism of gangliosides of various brain structures and the electric organ of the weakly electric tapirfish (Gnathonemus petersi, Mormyridae) was investigated. After stimulation the daily average discharges of the electric organ increased from 9.4 to 11.1 Hz, whereas after deprivation they decreased to 7.9 Hz as compared with controls. There were significant and structure specific differences in some ganglioside-fractions (GM1, GD3, GD1a, GD1b and GP1) in concentration and in specific radioactive NeuAc-labelling between stimulated and deprived animals respectively, compared with controls. 相似文献
57.
The effect of a negatively charged mono-sialoglyco-sphingolipid (GM1-ganglioside) on the molecular organization and on physiochemical properties of lipid/peptide (valinomycin) systems was investigated in monolayers at the air/water interface. At a high molar fraction of GM1, the surface pressure/area isotherms of the two-component films of the system GM1/valinomycin and the isotherm of the pure ganglioside monolayer are identical concerning the space requirement of the molecules and thereby the packing of the monolayer. Using space-filling molecular models, a simple calculation gives the theoretical amount of 4.5 ganglioside molecules associated with one molecule of the depsipeptide valinomycin. The average surface potential indicates, that valinomycin, interacting with the polar head group of GM1, becomes partly embedded within the lipid interface. For GM1/eicosanol and valinomycin/eicosanol mixtures, the agreement between theory and experimental data strongly supports the model of ideal mixing without any molecular interactions between the different components. The results suggest the formation of a ganglioside/valinomycin complex with simultaneous alteration of the surface potential and molecular structure of the single components. 相似文献
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The effect of K+, Mg2+ and serotonin on the interaction between Ca2+ and different phospholipids as well as glycosphingolipids (gangliosides) was studied by equilibrium dialysis using 45Ca as tracer. The highly polar phosphatidylinositol-4,5-bisphosphate (TPI) was found to bind more Ca2+ per lipid molecule than all other lipids tested and Ca2+ could not be released as easily as in the other lipids by K+, Mg2+ and serotonin. Ca2+ is released from all lipid-Ca2+ complexes most effectively by Mg2+, serotonin is less effective but enhances K+ in its capacity to displace Ca2+ from the respective binding sites. A remarkable dissociating influence of serotonin on ganglioside-Ca2+ and phosphatidylserine-Ca2+ complexes is observed. This effect is less pronounced with phosphatidylinositol-Ca2+ complexes under comparable comparable conditions. The possible functional role of phospholipids and gangliosides in vivo is discussed with regard to the specific Ca2+-binding properties of these lipids. 相似文献
59.
Hinrich Peters 《Histochemistry and cell biology》1964,4(4):345-347
Zusammenfassend läßt sich sagen, daß die angegebene Methode im Gegensatz zu der herkömmlichen Eindeckweise eine dauerhafte Konservierung der bei fermenthistochemischen Reaktionen entstehenden Azofarbstoffe und damit einen exakten und reproduzierbaren Vergleich verschiedener, zeitlich weit auseinander liegender Beobachtungen ermöglicht. Wir glauben, daß sich dieses Verfahren mit dem gleichen Erfolg auch auf andere als die angegebene Azofarbstoffmethode anwenden läßt.Herrn Prof. Dr.E. Uehlinger zum 65. Geburtstag. 相似文献
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