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971.
G van Dessel M de Wolf A Lagrou H J Hilderson W Dierick 《Biochimica et biophysica acta》1986,878(3):346-352
The presence of a dolichol binding system is demonstrated in human serum. The dolichol binding exhibits normal saturation kinetics with an apparent affinity constant Kd of 6.9 X 10(-6) M. Optimal binding is obtained at pH 7.4 and 5 degrees C. After binding the [3H]dolichol cannot be chased by unlabelled dolichol. The selectivity is examined by competition studies showing that only dolichyl derivatives equally compete for binding sites. From buoyant density centrifugation and gel filtration it is deduced that the dolichol binding is due to a serum protein fraction, displaying the characteristics of VLDL. 相似文献
972.
973.
Rainer Wolf 《Development genes and evolution》1980,188(1):65-73
Summary In the eggs ofWachtliella persicariae the cleavage nuclei move relative to the surrounding ooplasm. This active migration is caused by an organelle whose ultrastructure was studied throughout the mitotic cycle. It consists of a greatly enlarged polar cytaster derived from the mitotic apparatus, linked to the nucleus by 100 Å filaments. The microtubules of the cytaster were found only during periods of active nuclear migration, i.e., from the onset of anaphase to the early prophase of the next mitotic cycle. They are always solitary and follow the course of the astral rays, which are known to temporarily adhere to peripheral structures of the egg cell and to exert tractive forces. In contrast to the cytaster microtubules, the microtubules in the spindle are bundled and persist from early metaphase through late telophase.During ontogenesis the first migration cytaster is built up between 3 and 12 min after oviposition near the anterior egg pole, in the vicinity of the sperm nucleus. In non-inseminated eggs time lapse films show a migration cytaster to develop autonomously in a region free from nuclei, but it does not follow the normal path of the male pronucleus. In several cases the female pronucleus, which remains without a cytaster of its own, was observed to move to the cytaster generated in the absence of the male pronucleus. Whether or not it is adhering to a nucleus, the cytaster divides into two at the correct time, i.e, corresponding to the first cleavage division in fertilized eggs. In some non-inseminated eggs this type of pseudocleavage has been observed to occur repeatedly, giving rise to an increasing number of anucleate cytasters. 相似文献
974.
975.
Extraoocytäre Komponenten des Eiwachstums beiApis Mellifica 总被引:1,自引:0,他引:1
Wolf Engels 《Insectes Sociaux》1968,15(3):271-288
976.
Wolf H. Fahrenbach 《Cell and tissue research》1968,93(4):451-483
Summary The Limulus ommatidium consists of 4 to 20 retinula cells surrounding the dendrite of the eccentric cell. Adjoining membranes are differentiated into the microvillous rhabdome in the central area of the ommatidium. Three types of pigment cells envelop the sensory cells. The distal pigment cells cover the periphery of the distal half of the ommatidium; proximal pigment cells (beneath the base of the ommatidium) and intraommatidial pigment cells provide glial wrapping for the sensory cells, the partitions between them, and the peripheral loose framework. Processes of the overlying cone cells penetrate into the ommatidium and lie at the edges of the rhabdomal fins. Numerous neurosecretory axons terminate at all levels of the ommatidium on pigment cells, conveyed there either by enveloping pigment cells or by separate neuroglial cells. Tight junctions in the ommatidium are confined to the contacts between rhabdomal miorovilli. The periphery of the rhabdome is surrounded by continuous adhering junctions except at the tip and exit of the eccentric cell dendrite. The discussion centers on possible correlations between known neurophysiological characteristics of ommatidial cells and significant morphological aspects of the ommatidium, such as distribution of supporting cells, extracellular space, and junctional specializations.This study constitutes publication No. 329 from the Oregon Regional Primate Research Center, supported by Grants FR00163 and NB07717-01 from the National Institutes of Health and by a Bob Hope Fight-for-Sight Grant-in-Aid of the National Council to Combat Blindness, Inc.The author wishes to thank Mrs. Audrey Griffin for patient and excellent technical assistance, Mr. Joel Ito for the execution of the drawing, and Dr. C. J. Russell for constructive criticism. 相似文献
977.
978.
Wolf H. Fahrenbach 《Cell and tissue research》1968,87(2):278-291
Summary The dioptric apparatus of the Limulus compound eye is composed of the corneal cuticle with its internally projecting cuticular cones and the specialized underlying epidermis. The latter is composed of three distinct cell types. The guanophores, located between cuticular cones, contain guanine as a reflecting pigment. The distal pigment cells, which clothe the sides of the cuticular cones and form a sheath around the underlying ommatidium, contain massive bundles of microtubules, abundant pigment droplets and a large Golgi system. The cone cells are positioned between the flattened tip of the cuticular cone and the apex of the ommatidium. They serve to anchor the retinula cells to the cuticle and, by virtue of long processes along the periphery of the rhabdome, perform a glial function with respect to the interaction of adjacent retinula cells. The geometry and fine structure of the dioptric apparatus provide supporting evidence for the wide angle of acceptance and lack of polarized light perception by the ommatidia.This study constitutes publication No. 288 from the Oregon Regional Primate Research Center, supported in part by Grants FR 00163 and NB 07717-01 from the National Institutes of Health and in part by a Bob Hope Fight For Sight Grant-in-Aid of the National Council to Combat Blindness, Inc. The author wishes to thank Mrs. Audrey Griffin for patient and excellent technical assistance. 相似文献
979.
Summary A family is described wherein a G-chromosome carrying a structural anomaly within the short arm region, is transferred from each of both parents. In the mother, this chromosome has a secondary constriction on the enlarged short arm and in addition normal satellites (Gp+h); this maker chromosome is also found in the maternal grandfather. In the father, the aberrant G-chromosome presents giant satellites (Gs+). At least one of both marker chromosomes is transferred to all four children. Three of these are healthy, the fourth is retarded mentally and statically, and has a number of congenital anomalies. It is discussed whether these small chromosome aberrations range under normal variability or may be responsible for the developmental disorders exhibited in the proband.
Wesentliche Teile der vorliegenden Arbeit wurden von H. Lohmann als Dissertation der Medizinischen Fakultät der Universität Freiburg i. Br. vorgelegt. 相似文献
Wesentliche Teile der vorliegenden Arbeit wurden von H. Lohmann als Dissertation der Medizinischen Fakultät der Universität Freiburg i. Br. vorgelegt. 相似文献
980.
Wolf Dietrich Jeschke 《Planta》1972,103(2):164-180
Summary The light-dependent influxes of K+ and Cl- in detached leaves of Elodea densa were measured using 36Cl- and 42K+ or 86Rb+ as tracers.The K+ and Cl- influxes were enhanced by light and also in the dark after a preillumination. The rate of influx decayed in the dark according to a first order reaction with a half-time of 25 or 27 sec.DCMU inhibits the light-dependent K+ influx more severely in the presence of CO2 than in its absence in an atmosphere of N2 containing a trace of oxygen. This is similar to the effect of DCMU on the Cl- influx. CCCP1, atebrin (quinacrine) and Dio-9 all affect the influx of K+ and Cl- in a comparable way. CCCP exerts the strongest effect at low light intensities; atebrin and Dio-9 inhibit strongly even at high intensities when the ion influxes are light-saturated. The influence of these two inhibitors in attributed to an effect at the cellular membranes in addition to an effect on photophosphorylation. The effect of CCCP is ascribed to uncoupling of photophosphorylation, as photosynthesis is inhibited by about the same concentration as is ion influx.In far-red light the relative quantum yields of K+ and Cl- influx drop to a similar degree as does the quantum yield of photosynthesis. Estimated values of the quantum requirement of ion influx are given. The quantum requirement in air is higher than in an atmosphere of N2. It is a function of ion concentration and is lower at higher external concentrations.The results indicate that the K+ and Cl- influxes are partially coupled. The linkage of the ion influxes with the energy sources in the light and a possible contribution of a pseudocyclic photophosphorylation are discussed. 相似文献