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91.
Previous studies from this laboratory have shown that the phosphorylation of the S6 protein of the ribosomes is catalyzed by at least two different and separable kinase activities in PC12 cells. One of these activities is increased by treatment of the cells with nerve growth factor, the other by treatment of the cells with epidermal growth factor. The present work shows that these two factors stimulate the phosphorylation of S6 with quite different kinetics, and that both the number of phosphates incorporated into S6 and the phosphopeptide pattern of S6 are different in cells treated with nerve growth factor than in cells treated with epidermal growth factor. The characteristics of the nerve growth factor-sensitive S6 kinase and of the epidermal growth factor-sensitive kinase were also clearly different. Substrate specificity and inhibitor studies indicated that neither was identical to cyclic AMP-dependent kinase, kinase C, or the calcium/calmodulin-dependent kinases. However, two major phosphopeptides produced by S6 phosphorylation in nerve growth factor-treated cells were also seen on phosphorylation of S6 by cyclic AMP-dependent kinase in vitro. In addition, when rat liver 40S ribosomal subunits were pretreated with cyclic AMP-dependent kinase in vitro, the action of the nerve growth factor-sensitive S6 kinase was increased about twofold. 相似文献
92.
S Urieli-Shoval R L Meek R H Hanson M Ferguson D Gordon E P Benditt 《The journal of histochemistry and cytochemistry》1992,40(12):1879-1885
Tissues fixed with organic solvent fixatives such as Carnoy's solution are known to give poor and erratic results with in situ hybridization, whereas those fixed with paraformaldehyde produce more consistent results. To understand this difference and to improve the utility of Carnoy's-fixed tissue for in situ hybridization, we explored several parameters of RNA integrity and preservation. Carnoy's-fixed, paraffin-embedded livers and paraformaldehyde-fixed, paraffin-embedded livers of mice were compared for RNA extractability, degradation, and hybridizability. In addition, retention of RNA in tissue sections after sequential in situ hybridization treatments was compared. RNA was found to be easily extractable from Carnoy's-fixed liver and was well preserved, with only slight degradation of high molecular weight RNA. Conversely, only a small percentage of the RNA was extractable from paraformaldehyde-fixed liver unless the tissue was digested with protease. The extracted RNA was well preserved, without detectable degradation. Sections of tissue fixed in Carnoy's solution subjected to in situ hybridization retained only about 10% of their original RNA content and gave correspondingly weak in situ hybridization signals. Formaldehyde-fixed tissues retained much more of the RNA (about 45%) and produced strong in situ hybridization signals. Treatment of Carnoy's-fixed tissue sections with vaporous formaldehyde increased retention of RNA and provided in situ hybridization signals comparable with those of paraformaldehyde-fixed tissues. 相似文献
93.
D S Gordon V A Bochkarev G N Stepanova 《Arkhiv anatomii, gistologii i émbriologii》1991,101(9-10):81-84
Contents of histamine, 5-hydroxytryptamine, functional state of heparinic proteoglycan have been studied in the rat peritoneal mast cells during various seasons of the year (January-February, May-June, July). In winter the mast cells have a high content of histamine and 5-hydroxytryptamine, heparinic proteoglycan of their granules is stained with both alcian blue and safranin. In summer (July) content of histamine in the mast cells is sharply decreased in comparison with that of 5-hydroxytryptamine and in May-June the content of both amines is decreased nearly to background values. Both during spring and summer periods heparinic proteoglycan of the mast cell granules is stained only with alcian blue and does not take safranin. A suggestion is made on independence of the seasonal changes of annual rhythmical pattern of histamine and 5-hydroxytryptamine contents in the mast cells. A conclusion is made concerning possible participation of the mast cell system of organs and tissues in the seasonal changes of biogenic amine levels in them. 相似文献
94.
Macrophage dependence of peripheral sensory nerve regeneration: possible involvement of nerve growth factor. 总被引:12,自引:0,他引:12
The levels of NGF and NGF receptor mRNA, the degree of macrophage recruitment, and the ability of sensory and motor axons to regenerate were measured in C57BL/Ola mice, in which Wallerian degeneration following a nerve lesion is very slow. Results were compared with those from C57BL/6J and BALB/c mice, in which degeneration is normal. We found that in C57BL/Ola mice, apart from the actual lesion site, recruitment of macrophages was much lower, levels of mRNA for both NGF and its receptor were raised only slightly above normal, and sensory axon regeneration was much impaired. Motor axons regenerated quite well. These results provide in vivo evidence that macrophage recruitment is an important component of NGF synthesis and of sensory (but not motor) axon maintenance and regrowth. 相似文献
95.
Brian K. Lathrop W. Richard Burack Rodney L. Biltonen Gordon S. Rulet 《Protein expression and purification》1992,3(6)
A synthetic gene encoding the Group 11 phospholipase A2 (PLA2) from the venom of Agkistrodon piscivorus piscivorus has been constructed and expressed with high efficiency in Escherichia coli. No enzymatic activity was recovered when the polypeptide contained the initiator Met residue. Replacement of an Asn residue penultimate to the initiator Met with Ser or Gly permitted removal of the initiator Met by the endogenous methionine aminopeptidase. The amino-terminal serine (N-Ser) and amino-terminal glycine PLA2's were isolated from intracellular inclusion bodies and were renatured with 25% recovery. Automated Edman degradation confirmed the removal of the initiator Met and confirmed the sequence of the first 40 residues of N-Ser PLA2. The recombinant proteins were purified to apparent homogeneity and showed the same specific activity as the wild-type protein. N-Ser PLA2 demonstrated the same kinetics of activation as the wild type enzyme on large vesicles of zwitterionic lipid. 相似文献
96.
Hugh A. Gilmore 《American journal of physical anthropology》1981,56(4):387-392
The formation of the American Association of Physical Anthropologists some 50 years ago marked the official recognition of physical anthropology as a legitimate subfield of anthropology. Since then, with the growth of individual and institutional participation in the Association, and with the development of new research paradigms, a number of subspecializations have come to be accepted within the field. Perhaps none of these specializations, however, has grown as rapidly, or spectacularly, as has the subfield of primatology. This article details some of the rise of primatology as an accepted subdiscipline of physical anthropology and discusses the theoretical orientations which guided the first anthropological forays into the study of nonhuman primates. 相似文献
97.
Stephanie Gordon Phillips Shiu-Lan Lui David M. Phillips 《In vitro cellular & developmental biology. Plant》1982,18(8):727-738
Summary Epithelial cells may relate to their basement membrane substrates via lectin-like interactions. In a model system for study
of this type of interaction, lectin-coated bacteriological plastic petri dishes were presented as substrates for epithelial
cell adhesion. Of 21 lectins tested by mixed agglutination against two epithelial cell types, Madin-Darby canine kidney (MDCK),
and human embryonic kidney cells (HEK), nine gave less than 5% rosettes and 12 gave 5 to 50% rosettes. Wheat germ agglutinin
(WGA) andGeodia cydonium lectin gave the highest percentage of rosettes. Wheat germ agglutinin was readily adsorbed to plastic surfaces and maintained
specificity in binding interactions. Both MDCK and HEK cells attached as well to WGA coated petri dishes as to conventional
tissue culture dishes. Furthermore, both spread over the lectin-coated surfaces. The MDCK cells grew to confluence and could
be subcultured and maintained indefinitely on such surfaces, although WGA in solution was toxic to the cells in concentrations
as low as 0.1 to 1.0 μg/ml. Cell attachment to WGA coated dishes was blocked by cycloheximide only if the cells had been preincubated
with the inhibitor for several hours. Cell attachment was not inhibited by pretreatment of cells with neuraminidase. Precoating
cells with WGA blocked binding to both WGA-coated surfaces and untreated tissue culture dishes. Cells attached to WGA-coated
dishes could not be readily dislodged by trypsin-EDTA for the first 2 h after subculture. By 4 h, attachment was again trypsin
sensitive, suggesting that the cells synthesized a trypsin-sensitive material that was laid down between the cell surface
and the WGA-coated dish. Regeneration of trypsin sensitivity was not blocked by cycloheximide.
This work was supported by Research Grant AG01986 from the National Institutes of Health, Bethesda, Maryland. 相似文献
98.
A mathematical model of body fluid volume and osmolality regulation was developed which incorporated the major nonlinearities of fluid assimilation, exchange, distribution and excretion. The non-linear differential equations define compartmental material balances for water, urea, sodium, protein and antidiuretic hormone (ADH). The parameters of these equations were calculated using analytical solutions and available steady-state experimental data. The model was used to simulate the renal response to five input forcings: (1) intraesophageal water infusion; (2) water ingestion; (3) intravenous ADH injection; (4) intravenous water infusion; and (5) intermittent water loading. The model yielded continuous simulation curves which agreed reasonably well with the available transient and steady-state experimental data. The model predicted that stimulating volume receptors via changes in left atrial pressure accounts for only 15–20% of changes in ADH secretion rate, whereas stimulation of the osmotic receptors via changes in plasma osmolality accounts for the remaining 80–85% of changes. Thus, it appears that regulation of ADH secretion is largely dependent upon plasma osmolality during forcings which do not appreciably alter the cardiovascular blood volume. 相似文献
99.
The Receptor-Mediated Activation of Tyrosine Hydroxylation in the Superior Cervical Ganglion of the Rat 总被引:10,自引:5,他引:5
Takeyuki Ikeno Geneva Dickens Tom Lloyd Gordon Guroff 《Journal of neurochemistry》1981,36(5):1632-1640
The addition of carbachol to superior cervical ganglia causes a rapid increase in tyrosine hydroxylation in situ. The increase occurs in ganglia from both newborn and adult animals, and in ganglia from animals pretreated with reserpine. The increase is not due to increased transport of the substrate. The increase is dependent upon the presence of calcium, and is additive to the stimulation produced by dibutyryl cyclic AMP. The stimulation seems specific for tyrosine hydroxylation; dopamine beta-hydroxylation is not increased. Preincubation experiments suggest that the carbachol-induced stimulation is due to a change in the availability of, or the affinity of the enzyme for, reduced pterin cofactor. The stimulation is inhibited by atropine and also by low concentrations of phenoxybenzamine or haloperidol, which suggests that it is caused by an action of carbachol on the interneurons in the ganglia. 相似文献
100.
Summary Using techniques for enhanced microtubular preservation, including albumin pretreatment (Gray, 1975), occipital cortex of rats was studied electron microscopically at various ages of development. A close structural relationship was seen between microtubules, sacs of SER and the postsynaptic thickening in primordial spines and with the dense plate material of spine apparatuses. Stereoscopic preparations in addition show a more complicated substructure than previously described for the plate. Microtubules may contribute to the formation of the plate of the spine apparatus which in turn is associated with the postsynaptic thickening of the mature spine. Possible functional correlates are discussed.Dr. L.E. Westrum is an affiliate of the CDMRC at the University of Washington and a recipient of a Burroughs-Wellcome (USA) — Wellcome Trust (U.K.) Research Travel Grant. The research was also supported in part by NIH Grants NS 09678, NS 04053 (NINCDS) and DE 04942 (NIDR), DHHS 相似文献