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151.
Organization of hindbrain segments in the zebrafish embryo   总被引:17,自引:0,他引:17  
B Trevarrow  D L Marks  C B Kimmel 《Neuron》1990,4(5):669-679
To learn how neural segments are structured in a simple vertebrate, we have characterized the embryonic zebrafish hindbrain with a library of monoclonal antibodies. Two regions repeat in an alternating pattern along a series of seven segments. One, the neuromere centers, contains the first basal plate neurons to develop and the first neuropil. The other region, surrounding the segment boundaries, contains the first neurons to develop in the alar plate. The projection patterns of these neurons differ: those in the segment centers have descending axons, while those in the border regions form ventral commissures. A row of glial fiber bundles forms a curtain-like structure between each center and border region. Specific features of the individual hindbrain segments in the series arise within this general framework. We suggest that a cryptic simplicity underlies the eventual complex structure that develops from this region of the CNS.  相似文献   
152.
Summary Prolactin (PRL) binds to the testis of mice and rats where it increases the number of luteinizing hormone receptors, increases the binding of human chorionic gonadotropin (hCG) to LH receptors, and enhances testosterone synthesis and secretion. PRL also binds to the prostate and seminal vesicles of rats and humans where it increases organ weight and stimulates growth and uptake of testosterone. PRL binds to the epididymis of rats but the effect of PRL on this organ is unknown. In the present study, a standard immunoperoxidase (PAP) technique was used to detect the binding of endogenous and exogenous PRL or PRL-like peptides to the epididymis of the mature mouse. Throughout the epididymal duct, a positive reaction for peroxidase, suggesting PRL or PRL-like binding, occurred in the Golgi area of principal cells. In segment 1, positive reactions were also visualized in the perinuclear area and in the region located between the Golgi area and the apical surface of the principal cells (supra-Golgi area). In the corpus and cauda epididymidis, scattered entire principal cells were also positive. Throughout the epididymal duct, the reactions indicating the binding of exogenous PRL were slightly stronger than those testing for binding of endogenous peptides. The significance of such binding to the epididymis is uncertain but PRL may perform the same functions in epididymal principal cells as it does in the testis, prostate, and seminal vesicles.  相似文献   
153.
Summary The accumulation of mansonones E and F was investigated in Ulmus americana L. seedlings 5 weeks after inoculation with three aggressive and three non-aggressive isolates of Ophiostoma ulmi (Buism.) Nannf. The three non-aggressive isolates stimulated significantly more mansonone E and F accumulation than the three aggressive isolates of O. ulmi. Mansonone induction also varied within both the aggressive and the non-aggressive groups. Aggressive and non-aggressive isolates were recovered in equal frequencies from the inoculation wounds, whereas the aggressive isolates were recovered more frequently than the non-aggressive isolates 15 cm and 25 cm up the seedlings' stem. Vascular browning in the outer xylem of the seedlings correlated with mansonone E and F accumulation. Mansonone accumulation in U. americana seedlings is therefore associated with vascular browning and a reduction in fungal spread.  相似文献   
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A phase I trial of interleukin-2 and interferon gamma combination treatment in patients with advanced malignancies was performed based on preclinical in vitro and in vivo data which demonstrated synergistic antitumor effect. The toxicities, immune parameters, and tumor responses are described. The clinical and biologic maximal tolerated doses were extrapolated from these data.  相似文献   
157.
When rat cerebral-cortex membranes were labelled with [3H]propylbenzilylcholine mustard ([3H]PrBCM), a single protein of Mr 68,000 was found to carry the atropine-sensitive covalent label. After trypsinolysis of the receptors solubilized in 0.075% SDS, the resulting fragments were submitted to size analysis in combination with wheat-germ agglutinin (WGA)-Sepharose and organomercurial-agarose chromatography. Peptides of Mr 75,000, 50,000, 30,000, 18,000 and 8000 were specifically released from the receptor. All fragments above Mr 8000 were able to bind WGA-Sepharose and therefore the peptide of Mr 18,000 was taken as the upper limit of the distance between the antagonist and the glycan moieties. The limit fragment of Mr 8000 carried chemical groups which were modified by N-ethylmaleimide and reacted with an immobilized organomercurial. About 65-80% of the labelled receptors were adsorbed on concanavalin A-Sepharose with low affinity, generating two further components after sequential application to WGA-Sepharose. About 50% of the receptors were susceptible to neuraminidase treatment, with a concomitant slight modification of the SDS/polyacrylamide-gel-electrophoretic pattern.  相似文献   
158.
A new variant rat myogenic cell line, ts485, was isolated by subcloning the cell line ts3b2 (H. T. Nguyen, R. M. Medford, and B. Nadal-Ginard, Cell 34:281-293, 1983). Unlike the progenitor cell line, ts485 was thermosensitive for differentiation. Experiments with conditioned medium suggested that diffusible extracellular factors were not involved in dictating the differential phenotypes of ts485 cells cultured at the permissive and nonpermissive temperatures. Temperature shift experiments performed on cultures of ts485 cells indicated that the temperature-sensitive lesion was in a factor active during the growth phase and required to trigger a cascade of events leading to terminal differentiation.  相似文献   
159.
The primary purpose of this investigation was to study the eccentric and concentric torque-velocity characteristics of the quadriceps femoris in man using a recently developed combined isometric, concentric and eccentric controlled velocity dynamometer (the SPARK System). A secondary purpose was to compare the method error associated with maximal voluntary concentric and eccentric torque output over a range of testing velocities. 21 males (21-32 years) performed on two separate days maximal voluntary isometric, concentric and eccentric contractions of the quadriceps femoris at 4 isokinetic lever arm velocities of 0 degree.s-1 (isometric), 30 degrees.s-1, 120 degrees.s-1 and 270 degrees.s-1. Eccentric peak torque and angle-specific torques (measured every 10 degrees from 30 degrees to 70 degrees) did not significantly change from 0 degrees.s-1 to 270 degrees.s-1 (p greater than 0.005) with the exception of angle-specific 40 degrees torque, which significantly increased; p less than 0.05). The mean method error was significantly higher for the eccentric tests (10.6% +/- 1.6%) than for the concentric tests (8.1% +/- 1.7%) (p less than 0.05). The mean method error decreased slightly with increasing concentric velocity (p greater than 0.05), and increased slightly with increasing eccentric velocity (p greater than 0.05). A tension restricting neural mechanism, if active during maximal eccentric contractions, could possibly account for the large difference seen between the present eccentric torque-velocity results and the classic results obtained from isolated animal muscle.  相似文献   
160.
The isolated liver from 24 h fasted rats was perfused in a non-recirculating manner in the ortho- and retrograde direction with erythrocyte-containing (20% v/v) media to provide adequate oxygenation of the liver. Glucose and/or gluconeogenic precursors were added as substrates. Glycogen formation was determined biochemically and demonstrated histochemically. With glucose as the sole exogenous substrate glycogen was deposited in the perivenous area, with gluconeogenic precursors it was formed in the periportal zone during ortho- and retrograde flow. When glucose and gluconeogenic compounds were offered together, glycogen was deposited in both zones. The results corroborate the model of metabolic zonation predicting that periportal glycogen is synthesized indirectly from gluconeogenic precursors while perivenous glycogen is formed directly from glucose.  相似文献   
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