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11.
Rat sciatic nerve cytosol contains a phosphodiesterase of the phospholipase C type that catalyzes the hydrolysis of inositol phospholipids, with preferences of phosphatidylinositol 4'-phosphate (PIP) greater than phosphatidylinositol (PI) much greater than phosphatidylinositol 4',5'-bisphosphate (PIP2), at a pH optimum of 5.5-6.0 and at maximum rates of 55, 13, and 0.7 nmol/min/mg protein, respectively. Analysis of reaction products by TLC and formate exchange chromatography shows that inositol 1,2-cyclic phosphate (83%) and diacylglycerol are the major products of PI hydrolysis. [32P]-PIP hydrolysis yields inositol bisphosphate, inositol phosphate, and inorganic phosphate, indicating the presence of phosphodiesterase, phosphomonoesterase, and/or inositol phosphate phosphatase activities in nerve cytosol. Phosphodiesterase activity is Ca2+-dependent and completely inhibited by EGTA, but phosphomonoesterase activity is independent of divalent cations or chelating agents. Phosphatidylcholine (PC) and lysophosphatidylcholine (lysoPC) inhibit PI hydrolysis. They stimulate PIP and PIP2 hydrolysis up to equimolar concentrations, but are inhibitory at higher concentrations. Both diacylglycerols and free fatty acids stimulate PI hydrolysis and counteract its inhibition by PC and lysoPC. PIP2 is a poor substrate for the cytosolic phospholipase C and strongly inhibits hydrolysis of PI. However, it enhances PIP hydrolysis up to an equimolar concentration. 相似文献
12.
Harald Tichy 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1987,160(1):43-53
Summary Simultaneous recordings were made from 3 sensory units in an easily identifiable sensillum on the 12th antennal segment ofCarausius morosus. Impulse frequency (F) of one unit rose sharply when either the temperature (T) or the partial pressure of water vapor (Pw) was suddenly lowered. F of another rose sharply either when T was suddenly lowered or Pw was raised. F of the third was hardly affected by sudden changes in T but rose abruptly when Pw fell (Fig. 1). The reactions of the first may be explained by enthalpic cooling and is considered a cold cell. Those of the second may be attributed to changes in relative humidity (Hr) and is thus termed a moist cell. The third is taken to be the latter's antagonist, a dry cell.A 90%-probability that a single moist cell of average differential sensitivity will correctly discriminate between two humidity levels is not reached until the difference between the two is 38% Hr. The dry cell requires a difference of only 7.5% (Table 1). The basis for discrimination is a single presentation of each level.The power to discriminate Hr steps is better in both cell types. For a single moist cell of average differential sensitivity the difference required between the steps for a 90%-probability of correct discrimination is only 6.3% Hr; for the dry cell, 3.5% Hr. Basis for discrimination: a single presentation of each step. Step range: 5% to 55% Hr.Abbreviations
F
impulse frequency in impulses per second (imp/s)
-
Hr orHR
relative humidity in %
-
Ps
saturation pressure of water vapor in torr
-
Pw
partial pressure of water vapor in torr
-
r
correlation coefficient
-
T
temperature in °C
Dedicated to Prof. Dr. F. Schaller on the occasion of his 65th birthday 相似文献
13.
Harald Wolf Keir G. Pearson 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1987,161(1):103-114
Summary In the locust,Locusta migratoria, the pairs of connectives between the three thoracic ganglia and in the neck were transected in all possible combinations. Each of these preparations was tested for the production of rhythmic flight motor activity, with sensory input from the wing receptors intact and after deafferentation. The motor activity elicited in these preparations was characterized by intracellular recordings from motoneurons and electromyographic analyses.The motor patterns observed in locusts with either the neck or the pro-mesothoracic connectives severed (Figs. 2, 3, and 4) were very similar to the flight motor pattern produced by animals with intact connectives. The activity recorded in mesothoracic flight motoneurons of locusts with either only the meso-metathoracic connectives cut or both the meso-metathoracic and the neck connectives transected were similar to each other. Rhythmic motor activity could be observed in these preparations only as long as sensory feedback from the wing receptors was intact. These patterns were significantly different from the intact motor pattern (Figs. 5, 6, and 7). Similar results were obtained when the mesothoracic ganglion was isolated from the other two thoracic ganglia, although the oscillations produced under these conditions were weak (Fig. 8 upper). In the isolated metathorax no rhythmic flight motor activity could be recorded (Fig. 8 lower), even when wing afferents were intact.Considering the differences between the motor patterns observed in the various preparations these results suggest that the ganglia of the locust ventral nerve cord do not contain segmental, homologous flight oscillators which are coupled to produce the intact flight rhythm. Instead they support the idea that the functional flight oscillator network is distributed throughout the thoracic ganglia (Robertson and Pearson 1984). The results also provide further evidence that sensory feedback from the wing sense organs is necessary for establishing the correct motor pattern in the intact animal (Wendler 1974, 1983; Pearson 1985; Wolf and Pearson 1987 a).Abbreviations
CPG
central pattern generator
-
EMG
electromyogram 相似文献
14.
15.
Walter A. Heidmann Annegret Büthe Martin Beyerbach Reinhard Löhmer und Harald A. Rüssel-Sinn 《Journal of Ornithology》1989,130(3):311-320
Zusammenfassung Rückstände chlorierter Kohlenwasserstoffe in Eiern und Lebern von im Binnenland Niedersachsens brütenden Vogelarten — Feldsperling, Mehlschwalbe, Weißstorch, Graureiher, Saatkrähe, Stockente und andere Arten — werden angegeben und deren Abhängigkeit von Brutort, Nahrung und Zugverhalten diskutiert.
Chlorinated hydrocarbons of some bird species breeding in the inland of Lower Saxony (FRG)
Summary Residues of chlorinated hydrocarbons in eggs and livers of some bird species — Tree Sparrow, House Martin, White Stork, Heron, Rook, Mallard, and further species — are presented. The dependence on place of breeding, food web, and migration is discussed.相似文献
16.
Harald Sverdrup Salim Belyazid Bengt Nihlg?rd Lars Ericson 《Plant Growth Regulation》1991,10(2):173-174
Book Review
Plant protoplasts and genetic engineering IIY.P.S. Bajaj (Ed.), (Biotechnology in Agriculture and Forestry, Vol. 9). Berlin: Springer-Verlag, 1989. 510 pages. DM398.00. ISBN 3-540-50789-2 相似文献17.
Peter Heimann Stephan Laage Harald Jockusch 《Differentiation; research in biological diversity》1991,47(2):77-83
In the wobbler (WR) mouse, a neuromuscular mutant characterized by a motoneuron degeneration and male infertility, the cellular basis of the defect in spermiogenesis was studied by light and electron microscopy as well as by lectin binding. Spermatozoa of the wobbler mutant had rounded heads, and their motility was reduced. In histological sections of WR testes, spermatogenesis appeared normal up to the stage of round spermatids, but the elongation and flattening of the nucleus during late spermiogenesis did not occur. Numbers of spermatid nuclei in WR testes were reduced to 70%-80% of controls. The acrosomal marker glycoprotein, peanut agglutinin receptor, was synthesized, but the acrosomal membrane did not attach to the nucleus. The disturbance in spermiogenesis of the wobbler mouse is not due to impaired descent of the testis, nor to a lack of testosterone, and is distinct from that observed in other mouse mutants (quaking, QK; Purkinje cell degeneration, PCD) with combined neurological and spermiogenesis defects. 相似文献
18.
Harald Fuge 《Chromosoma》1985,91(3-4):322-328
Microtubules of amphitelically oriented sex univalent chromosome fibres were traced in longitudinal serial sections. The investigated chromosomes were from four different cells representing consecutive stages of anaphase segregation. A correlation was found between chromosome movement and a characteristic distribution of free microtubules (fMTs) oriented obliquely with respect to the kinetochore microtubules. During chromosome segregation the proportion of these skew fMTs (the proportion of skew fMTs is a measure of the degree of disorder in the fibre) is higher in the fibre pointing in the direction of movement than in the trailing fibre. The results are discussed in relation to spindle forces. Although the anaphase of amphitelic sex chromosomes is different in several respects (orientation of chromosome fibres, mutual connexion of chromosomes via kinetochore microtubules, spindle elongation occurring simultaneously), the observations on the distribution of fMTs in the chromosome fibres is, in principle, compatible with those previously made on syntelic autosomes. 相似文献
19.
Koen Martens 《Hydrobiologia》1985,124(1):81-83
Salinity tolerance, and the effects of temperature upon it, of the Australian ostracod Mytilocypris henricae (Chapman) was determined in direct transfer experiments using adults. Animals were subjected to a combination of 11 salinities (ranging between 0.0 g · 1–1 and 45.0 g · 1–1) and 4 temperatures (10, 15, 20 and 25 °C). Survival was analysed using two statistical techniques: the logit linear model and the proportional hazards model. Results show that both salinity and temperature have a significant effect on survival, but there is no significant interaction between temperature and salinity. 相似文献
20.
Zusammenfassung Regionale und artliche Unterschiede der Rückstände von Quecksilber in Eiern von sieben Brutvogelarten der deutschen Nordseeküste wurden untersucht. Bei vier Arten stellten wir deutliche geographische Unterschiede in der Kontamination fest (Abb. 1). Höchstgehalte fanden wir in Eiern von der Elbmündung (Region V). Austernfischer- und Flußseeschwalbeneier von der inneren Deutschen Bucht (Region VI) enthielten größere Mengen als solche von Nordfriesland (Region VII). Der gesetzliche Richtwert für Eier (0,03 mg/kg) wurde von 353 der 355 untersuchten Eier überschritten. Fluß- und Brandseeschwalbe waren am stärksten, Brandgans, Austernfischer und Lachmöwe am wenigsten mit Quecksilber kontaminiert (Abb. 2, 4.2.). Mit Ausnahme von Brandgans und Silbermöwe erreichten die Rückstände in vielen Eiern der anderen Arten, an der Elbe sogar in allen Eiern, eine den Bruterfolg gefährdende Größenordnung, insbesondere bei der Flußseeschwalbe.
Pollutants in eggs of birds breeding at the German North Sea Coast. II. Mercury
Summary Regional and interspecific differences of mercury residues were investigated in the eggs of seven species breeding at the German North Sea Coast (Tadorna tadorna, Haematopus ostralegus, Charadrius hiaticula, Larus argentatus, L. ridibundus, Sterna hirundo, S. sandvicensis). We found distinct geographical differences in contamination (Fig. 1): In eggs from the Elbe Eastuary (region V) maximum residues of mercury were ascertained. Eggs of Oystercatcher and Common Tern from the Bay of Helgoland (region VI) contained larger quantities than eggs from Northern Frisia (region VII). 353 from 355 eggs examined showed a value exceeding the legal standard value for eggs which is 0,03 mg/kg in Germany. Common Tern and Sandwich Tern eggs had the highest, Shelduck, Oystercatcher and Blackheaded Gull eggs the lowest mercury contamination (Fig. 2, 4.2.). With the exception of Shelduck and Herring Gull, residues in many eggs of the other species — at the river Elbe in all eggs — came up to a range endangering breeding success, especially in Common Terns.相似文献