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31.
Lidia Sautebin Hans Kindahl Maria Kumlin Elisabeth Granstrm 《Prostaglandins & other lipid mediators》1985,30(3):435-456
Conjugates of prostaglandins and thromboxanes with tritium labeled amino acids were prepared and employed as labeled ligands in porstaglandin and thromboxane radioimmunoassays. Assays for PGF2α, 15-keto-13, 14-dihydro-PGF2α, TXB2 and 15-keto-13, 14-dihydro-TXB2 were evaluated in comparative studies using either these heterologous ligands or the corresponding homologus tritiated eicosanoid as tracers. Binding properties for the respective antibodies were found to be similar using either tracer.Three biological studies were also conducted, viz. study of the release of TXB2 during collagen induced platelet aggregation, of 15-keto-13, 14-dihydro-TXB2 during guinea pig pulmonary anaphylaxis, and of PGF2α (measured as 15-keto-13, 14-dihydro-PGF2α in peripheral plasma) during bovine luteolysis. The analyses gave comparable results using either the heterologous or the homologous assay.Thus, this type of labeled prostanoid conjugates may serve as a convenient alternative to homologous tracers in radioimmunoassay. Heterologous tracers may even in certain cases provide the only simple solution to the problem of preparing a labeled ligand of high specific activity. 相似文献
32.
B. Cesca M. C. Manca de Nadra A. M. Strasser de Saad A. Pesce de Ruiz Holgado G. Oliver 《Folia microbiologica》1984,29(4):288-294
The activity of β-D-galactosidase was studied in 13 strains of lactobacilli (groupsStreptobacterium, Thermobacterium andBetabacterium). Using 2-nitrophenyl galactopyranoside as substrate, the enzyme activity varied with the strain. The values found in theThermobacterium group were superior to those in theStreptobacterium group. The optimum pH for the species belonging to theThermobacterium group was uniform, in contrast to the ph for those from theStreptobacterium which varied according to the species. The optimum temperature was quite uniform within each group and higher in theStreptobacterium. Lactose acted as a competitive inhibitor. MgCl2 protected the enzyme from thermal denaturation. The calcium ions inhibited the activity in all cases. The behaviour of the
protectors of the SH groups varied according to the strain. 6-Phospho-β-D-galactosidase activity was also determined, levels lower than β-D-galactosidase were found, except inLactobacillus plantarum ATCC 8014 and 14917. 相似文献
33.
Promotion, termination, and anti-termination in the rpsU-dnaG-rpoD macromolecular synthesis operon of E. coli K-12 总被引:18,自引:0,他引:18
Summary The regulatory regions for the rpsU-dnaG-rpoD macromolecular synthesis operon have been fused to a structural gene whose product is readily assayed (the Cmr structural gene coding for chloramphenicol acetyl transferase, CAT). The promoters (P1, P2, P3, Pa, Pb, Phs) for the macromolecular synthesis operon have different strengths as shown by their relative abilities to drive expression of the CAT gene. Promoter occlusion by P1 can be demonstrated within this operon. Regions 5kb upstream have a profound effect on operon gene expression. There is a thermoinducible promoter located within the dnaG structural gene. One of the macromolecular synthesis operon promoters is under lexA control. Although the operon structure allows coordinate expression of rpsU, dnaG and rpoD these additional features suggest that expression of individual genes can be independently regulated in response to altered growth conditions.Abbreviations Apr
ampicillin resistance
- CAT
chloramphenicol acetyl transferase
- Cmr
chloramphenicol resistance
- kb
kilobase pair
- orf
open reading frame
- P
promoter
- T
terminator
- Tcr
tetracycline resistance 相似文献
34.
35.
The presence of reactive spleen cells to sheep red blood cells (SRBC) in nonimmunized BALB/c mice injected with histoplasmin, the culture filtrate of Histoplasma capsulatum, was monitored for 21 days following inoculation. Polyclonal activation, as evidenced by a sharp increase in the number of anti-SRBC rosetteforming cells (RFC), as well as an enhanced response to heterologous non-cross-reactive erythrocytes from other species, was found in the spleens of these rodents on Days 11 to 13. Elimination of B-cell-derived RFC by the addition of complement indicated that the erythrocyte-binding cells consisted of both T- and B-lymphocytes. An immunosuppressive effect was detected if histoplasmin was injected 2 days before the antigen (SRBC), but could be reversed by injecting the filtrate 30 min prior to the antigen, as is found with polyclonal activators displaying immunosuppressive activity. Histoplasmin also had a mitogenic effect on lymphocyte obtained from the spleen, bone marrow, and thymus similar in magnitude to that produced by lipopolysaccharide (LPS) and concanaval in A. The biological significance of these findings is discussed. 相似文献
36.
C M Ruiz de Galarreta L F Fanjul R Meidan A J Hsueh 《The Journal of biological chemistry》1983,258(18):10988-10996
delta 5-3 beta-Hydroxysteroid dehydrogenase is a key enzyme for testicular androgen biosynthesis and a marker for the Leydig cells. The hormonal regulation of this enzyme was studied in cultured rat testicular cells. Human chorionic gonadotropin (hCG) increased testosterone production in vitro while time course studies indicated a biphasic action of the gonadotropin on 3 beta-hydroxysteroid dehydrogenase activity. An initial stimulation (51%) of the enzyme was detected between 3 and 12 h of culture when medium testosterone was low. This is followed by an inhibition of 3 beta-hydroxysteroid dehydrogenase activity on days 2 and 3 of culture when medium testosterone was elevated. Concomitant treatment with a synthetic androgen (R1881) inhibited 3 beta-hydroxysteroid dehydrogenase activity and testosterone production in hCG-treated cultures while an anti-androgen (cyproterone acetate) increased 3 beta-hydroxysteroid dehydrogenase activity and testosterone biosynthesis. Addition of 10(-5) M spironolactone, an inhibitor of 17 alpha-hydroxylase, blocked the hCG stimulation of testosterone production but increased medium progesterone. In the absence of the secreted androgen, hCG stimulated 3 beta-hydroxysteroid dehydrogenase activity in a time- and dose-related manner. Furthermore, hCG stimulation of 3 beta-hydroxysteroid dehydrogenase activity and progesterone accumulation in spironolactone-supplemented cultures was decreased by concomitant treatment with R1881 but was not affected by cyproterone acetate. The inhibitory effect of R1881 was blocked by the anti-androgen. In the absence of hCG, treatment with testosterone, dihydrotestosterone, or R1881, but not promegestone, alone also inhibited 3 beta-hydroxysteroid dehydrogenase activity while the inhibitory effect of testosterone was blocked by cyproterone acetate. Thus, hCG stimulates 3 beta-hydroxysteroid dehydrogenase activity in cultured testicular cells. The androgenic steroidogenic end products, in turn, inhibit this enzyme. The hormonal regulation of 3 beta-hydroxysteroid dehydrogenase activity may be important in the ultrashort loop autoregulation of androgen biosynthesis. 相似文献
37.
The immune response to sheep red blood cells (SRBC) in mice and hamsters injected with an extract of entamoeba histolytica was studied. Both the primary and secondary immune response, measured by anti-SRBC antibody titers, were unaltered in the mouse, while a significant depression of the primary, but not the secondary, response was observed in the hamster. The effect was greatest when the amebic extract (AE) and SRBC were injected on the same day. The number of anti-SRBC rosettes formed in the spleen cells of hamsters treated with both AE and SRBC on day 0 was measured from days 1-16. The response peaked on day 13, while cells from animals injected with SRBC alone gave a maximal response on day 5. The formation of anti-SRBC rosettes in T-lymphocyte-enriched spleen cells treated with anti-gamma globulin serum and complement was almost abolished for the duration of the experiment. It is suggested that the mechanism responsible for this immunosuppressive phenomenon could involve early interference in the afferent limb of the immune response. 相似文献
38.
39.
Cesare de Martino Lidia Accini Giuseppe A. cAndres Italo Archetti 《Cell and tissue research》1969,97(4):502-511
Summary Round bodies, tubular profiles and crystalline images have been studied by electron microscopy in the endothelium of seven normal young Rhesus monkeys and in the renal glomerular endothelium of two nephritic human patients. The crystalline images are most frequently formed by aggregation of round bodies, 200–240 Å in diameter. In Rhesus monkeys a variety of crystalline images are seen. On the contrary, in nephritic patients round bodies and tubular profiles are rare and less organized. In the glomerular endothelium of two normal men they were not found.The results obtained suggest that the round bodies, the tubular profiles and the crystalline images result from sectioning of a system of undulating tubules associated with the smooth endoplasmic reticulum. In nephritic patients the formation of such a tubular system could represent a change taking place within the affected cells as a pathologic response to the disease.This work was supported by U.S. Public Health Service (N.H.I.), Grant AI-04527-03-04, and by the Consiglio Nazionale delle Ricerche (C.N.R.), Contributo 115/0815/0-1365. The Authors are greatly indebted to Miss Hermina Spiele for skilful technical assistance. 相似文献
40.
Summary In a study of the yeasts associated with insect frass underneath the bark ofTsuga heterophylla (the Pacific Coast hemlock) four new species of yeast were found. These were described asSporobolomyces singularis, Bullera tsugae, Cryptococcus skinneri andCandida oregonensis. Sporobolomyces singularis is a non-pigmented species, which required an amendment of the genus definition. Ballistospore formation of the new species
ofSporobolomyces and ofBullera was absent on malt agar and on potato glucose agar, but positive on corn meal agar. An unusual case of quantitative transgalactosylation
by growing cells ofSporobolomyces singularis on lactose has been described. It has been proposed to establish a “Candida parapsilosis Group” of species to whichC. oregonensis was assigned.
Supported by a fellowship of the Calouste Gulbenkian Foundation, Lisbon, Portugal. 相似文献