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1.
The specific synthesis of F mRNA directed by the F gene carried on the specialized transducing bacteriophage F, performed , is described with the use of an S180 extract from a strain carrying R?. Synthesis of F mRNA is biphasic at approximately 7 minutes. The regulation of F mRNA synthesis by the specific arginine holorepressor present in an S180 extract prepared from a strain carrying the R+ allele is described. 相似文献
2.
E.A. Hosein M. Lapalme E.B. Vadas 《Biochemical and biophysical research communications》1977,78(1):194-201
Differential scanning calorimetry of crude brain mitochondrial lipids obtained from control and morphine treated rats was carried out and the lipid phase transition measured. Morphine treatment resulted in a significant decrease in the temperature range and enthalpy of the phase transition. This effect was found to be dose dependent and reversible both and by naloxone. Studies with levorphanol and dextrorphan demonstrated stereospecificity. Furthermore, the ether precipitable fraction of total lipid extracts was shown to mediate the opiate response. 相似文献
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Guanylate cyclase from crude homogenates of vegetative has been characterized. It has a pH optimum of 8.0, temperature optimum of 25°C and requires 1 mM dithiothreitol for optimal activity. It strongly prefers Mn++ to Mg++ as divalent cation, requires Mn++ in excess of GTP for detectable activity, and is inhibited by high Mn++ concentrations. It has an apparent Km for GTP of approximately 517 μM at 1 mM excess Mn++.The specific activity of guanylate cyclase in vegetative homogenates is 50–80 pmoles cGMP formed/min/mg protein. Most of the vegetative activity is found in the supernatant of a 100,000 x g spin (S100). The enzyme is relatively unstable. It loses 40% of its activity after 3 hours storage on ice. Enzyme activity was measured from cells that had been shaken in phosphate buffer for various times. It was found that the specific activity changed little for at least 8 hours. Cyclic AMP at 10?4 M did not affect the guanylate cyclase activity from crude homogenates of vegetative or 6 hour phosphate-shaken cells. 相似文献
6.
Uterine stage embryos collected from the hamster (8-cell) and cow (morula, early blastocyst) were monitored for development (embryo culture) and (embryo transfer) following premature removal of the zona pellucida.Removal of the zona pellucida did not significantly affect development to the blastocyst stage of (1) 8-cell hamster embryos (zonae removed by a combined enzymic-mechanical procedure), (2) bovine morulae (zonae removed by mechanical means only) (3) early bovine blastocysts (zonae removed by the enzymic-mechanical technique).Zona-free hamster embryos formed significantly fewer viable fetuses than did zona-intact embryos. The lower incidence of fetal development observed following transfer of zona-free 8-cell hamster embryos may have resulted in part from the formation of chimeras by fusion of these embryos . Such fusion was observed to occur between zona-free embryos placed in close proximity. The proportion of pregnancies resulting from transfer of bovine blastocysts cultured from zona-free morulae was similar to that of zona-intact embryos.In this study we have demonstrated that (1) enzymic and mechanical procedures used to remove zonae pellucidae from uterine-stage hamster and bovine embryos do not adversely affect subsequent development of these embryos and and (2) zonae pellucidae are not required for normal development of these embryos. These findings have implications for microsurgery of mammalian embryos and for embryo transfer. 相似文献
7.
Kazuo Yoshida Michio Hagiya Naohiko Yanagishima 《Biochemical and biophysical research communications》1976,71(4):1085-1094
The substance responsible for the sexual agglutinability was successfully solubilized by a newly established autoclaving method from the surface of mating type cells of and purified by DEAE cellulose chromatography, gel filtration, affinity chromatography and electrophoresis. The substance was found to consist of at least two different glycoprotein subunits. The molecular weight of the substance was estimated to be about 23,000 daltons by gel filtration. The substance was univalent in its biological activity and specifically masked the sexual agglutinability of the mating type α cells. The substance formed a complementary complex with the agglutination substance from α cells in vitro. 相似文献
8.
OKY-1581 is an effective inhibitor of thromboxane synthesis and . The generation of thromboxane B2 (TxB2), prostaglandin E (PGE) and prostaglandin F (PGF) was measured following clotting and during platelet aggregation induced by collagen. The presence of OKY 1581 either or caused a reduction in TxB2 generation during clotting and platelet aggregation with a concomitant increase in PGE and PGF. The effect could be observed two hours after oral or subcutaneous administration of 5 to 100 mg per rabbit and lasted for 24 to 48 hours. The reduction in TxB2 was not accompanied by an inhibition of clotting or platelet aggregation. OKY-1581 appears to be a suitable agent for studying the role of TxB2 in atherosclerosis. 相似文献
9.
The ability of various prostaglandins (PGs) to affect the anamnestic immune response of keyhole limpet hemocyanin (KLH)-primed rabbit popliteal lymph node cells was investigated. Of the four PGs studied (PGA1, PGE2 and PGF2α), PGE1 was found to have a stimulatory effect, whereas PGA1, PGE2 and PGF2α were ineffective in stimulating or inhibiting the anamnestic response. Under the conditions studied, a 3.5-fold increase in antibody production was obtained in PGE1-treated, KLH-stimulated cultures. Maximum enhancement was obtained when 0.2 μg of PGE1 were added at the time of culture initiation and were allowed to remain in contact with the lymph node cells for 24 hours. 相似文献
10.
John W. Wilks Kristi K. Forbes Jerome F. Norland 《Prostaglandins & other lipid mediators》1973,3(4):427-437
Prostaglandin F2α (PGF2α) did not alter the biosynthesis of progesterone by slices of luteinized rat ovaries when used in concentrations from 1 to 10,000 ng/ml of incubation medium; likewise, PGF2α did not affect the incorporation of acetate-1-14C into progestins. PGF1α, 15-keto PGF2α, and PGE1 did not alter the biosynthesis of progesterone by luteinized rat ovaries; PGE2 inhibited the production of progesterone when used at a concentration of 10 μg/ml, but not at lower doses. PGF2α in combination with luteinizing hormone (LH) enhanced the metabolism of progesterone to 20α-hydroxypregn-4-en-3-one in luteinized rat ovaries. Interestingly, PGF2α, at a high concentration of 10 μg/ml, did stimulate progesterone biosynthesis by slices of ovarian tissue from immature rats hormonally primed to simulate “pseudopregnancy,” suggesting a steroidogenic action of prostaglandins on the ovarian follicular or interstitial cell. PGF2α (10 μg/ml) did not stimulate the biosynthesis of progesterone or 20α-hydroxypregn-4-en-3-one by slices of rabbit corpora lutea or rabbit ovarian interstitial tissue. It is concluded that prostaglandins do not stimulate progestin biosynthesis in rat luteal tissue. 相似文献
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Ronald M. Hamelik Mead M. McCabe 《Biochemical and biophysical research communications》1982,106(3):875-880
An inhibitor of , endodextranase was detected in proteins prepared from batch cultures of , strains representing serotypes through . Affinity chromatography of strain 6715-49 proteins, which apparently were free of endodextranase activity, yielded an active endodextranase and, in a separate peak, the endodextranase inhibitor. The presence of the inhibitor in culture fluids accounts for the absence of endodextranase activity in batch-grown cultures of , known to produce this enzyme. 相似文献
12.
R.M. Sharpe D.G. Doogan I. Cooper 《Biochemical and biophysical research communications》1982,106(4):1210-1217
Injection of a luteinizing hormone-releasing hormone (LHRH) agonist into 55-day-old male rats which had been hypophysectomized 3 days earlier resulted in a 10- to 30-fold increase in the levels of testosterone in serum and testicular interstitial fluid (IF) in the 4h following injection. The levels achieved were within or above the normal range for intact untreated rats of this age. In similar animals, injection of LHRH agonist also enhanced the serum testosterone response to injected hCG at , but not at later times after injection, and by 24h reduced IF levels of testosterone suggested that LHRH agonist had begun to inhibit stimulation by hCG. , dispersed Leydig cells from untreated hypophysectomized rats showed a 2-fold increase in testosterone responsiveness to LHRH agonist when compared to cells from intact rats, and this change was associated with an 80% increase in the number of Leydig cell LHRH-receptors. 相似文献
13.
Nikolai Nikolaev Virginia Folsom David Schlessinger 《Biochemical and biophysical research communications》1976,70(3):920-924
Strain S296, isolated by screening 2000 colonies after nitrosoguanidine mutagenesis, yields extracts with less than 1% of wild-type RNase activity against (3H) poly(U). Unlike other strains, S296 grows with a doubling time of about 2 hr., both in nutrient broth and in minimal medium, and at 30°, 37° and 42°. The strain retains 10 to 20% of wild-type exonuclease activity against (3H) rRNA or T4 phage-specific mRNA; but two further mutants, made by screening mutagenized colonies of strain S296, are reduced to 3% of wild-type activity against those substrates as well. 相似文献
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Edward W. Voss James E. Babb Peyton Metzel Jeffrey L. Winkelhake 《Biochemical and biophysical research communications》1973,50(3):950-956
Rabbit anti-fluorescyl antibody producing lymphoid cells incubated with LSD do not secrete the 7S form of immunoglobulin. The low molecular weight extracellular labeled material shows no measurable anti-fluorescyl antibody activity. Results indicate that during a short incubation period LSD interferes with tryptophan incorporation into antibody protein. 相似文献
15.
Frederick Chu Paul Caldwell Mark Samuels Herbert Weissbach Nathan Brot 《Biochemical and biophysical research communications》1977,76(2):593-601
The synthesis of ribosomal protein L10 has been demonstrated using λrifd18 DNA as template. The L10 synthesized forms a complex with ribosomal protein L12 and the L10 in this complex can be immunoprecipitated with L12 antiserum. 相似文献
16.
Prostaglandin synthesis in rat embryo tissue: The effect of non-steroidal anti-inflammatory drug and
Kenneth L. Klein Kenneth E. Clark William J. Scott 《Prostaglandins & other lipid mediators》1984,27(5):659-672
Aspirin and salicylate are well-known but poorly understood teratogens in laboratory animals. Because aspirin inhibits PG synthesis, we systematically examined PG synthesis in rat embryo homogenates, the inhibition of PG synthesis and by various non-steroidal anti-inflammatory drugs, and tested the hypothesis that the inhibition of PG synthesis is responsible for aspirin-induced limb defects in rats. We report that embryonic rat homogenates synthesis 6-keto-PGF1α, PGE, and PGF in large amounts from endogenous substrate, that aspirin and other non-steroidal anti-inflammatory drugs inhibit PG synthesis but not necessarily , and that contrary to our original hypothesis, the inhibition of PG synthesis is likely not responsible for aspirin-induced limb defects in rats. 相似文献
17.
Yuji Kamiya Akira Sakurai Nobutaka Takahashi 《Biochemical and biophysical research communications》1980,94(3):855-860
Rhodotorucine which induces mating tube formation of cells in is metabolized rapidly by cells. By use of labeled rhodotorucine , the degradation was found to be proteolytic. Two peptide fragments Tyr-Pro-Glu-Ile-Ser-Trp-Thr-Arg and Asn-Gly-Cys(S-farnesyl) were identified as the metabolites. Proteolysis of the pheromone mainly occurred on the cell surface. Culture filtrate of cells at log phase did not metabolize rhodotorucine . 相似文献
18.
Robert D. Koos Martin R. Clark Per O. Janson Kurt E.B. Ahrén William J. LeMaire 《Prostaglandins & other lipid mediators》1983,25(5):715-724
Prostaglandin (PG) levels in follicular fluid from preovulatory follicles of rabbit ovaries perfused were measured in order to compare PG changes in this model system with those that occur and in isolated, LH-treated follicles . One ovary from each rabbit was perfused without further treatment (control). The other ovary was exposed to LH (0.1 or 1 ug/ml) beginning 1 hour (h) after initiation of perfusion. Samples of perfusion medium were taken at frequent intervals for measurement of PGE, PGF, progesterone and estradiol 17β. The perfusions were terminated when the first ovulation occurred or appeared imminent as judged by changes in the size and shape of the follicles. Follicular fluid was then rapidly aspirated from all large follicles on both ovaries for PGE and PGF measurement.Ovulations occurred only in the LH-treated ovaries. Progesterone and estradiol levels were significantly elevated in the perfusion medium within 1 h of LH treatment in comparison to controls. PG levels in perfusion medium from the control and LH-treated ovaries were not different throughout perfusion and increased in both groups. In contrast, PG levels measured in follicular fluid from LH-treated ovaries were 4- to 5-fold greater than in fluid from control ovaries. It is concluded that ovulation induced by LH in this experimental model is accompanied by an increase in follicular PG levels similar to that seen in other and models. This difference in follicular PG levels between the LH-treated and control ovaries is, however, not reflected in the perfusion medium. 相似文献
19.
Evelyn A. Devine Mary C. Moran Peter J. Jederlinic Anthony J. Mazaitis Henry J. Vogel 《Biochemical and biophysical research communications》1975,67(4):1589-1593
The transducing phage λd, carrying a portion of the chromosome including , is derived from the heat-inducible, lysis-defective strain λy199, which has the and deletions. Cleavage of λy199 DNA by RI endonuclease, followed by agarose slab gel electrophoresis, results in bands corresponding to the known C, D, E, and F segments of λ, and a segment A′ (A plus B minus minus , the cleavage site between A and B being eliminated). Cleavage of λd DNA by RI yields the expected D, E, and F segments of λ and four other segments, termed 14-1 through 14-4, whose length is 17.5, 6.2, 3.0, and 2.0 kilobases, respectively, as determined by electron microscopy and corroborated by electrophoretic mobility. Heteroduplex analysis shows that the cluster is on the 14-1 segment. 相似文献
20.
Claude Benicourt Anne-Lise Haenni 《Biochemical and biophysical research communications》1978,84(4):831-839
Total TYMV RNA was incubated in a reticulocyte lysate, and the initiation peptides of the main proteins synthesized (195 K, 150 K and 20 K daltons) analyzed after tryptic digestion. The 195 K and the 150 K dalton proteins present analogous patterns, different from the one obtained with the 20 K dalton protein (coat protein), suggesting that only one initiation site exists on the genomic RNA for the synthesis of the two high molecular proteins. The results of competition experiments between genomic and coat protein mRNA indicate that the ribosomes have a much greater affinity for the coat protein mRNA. This may represent a regulatory mechanism for the preferential amplification of coat protein synthesis in the infected cells. 相似文献