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931.
Immortalization of antigen specific, helper T cell lines by transformation with the radiation leukemia virus (RadLV) 总被引:1,自引:0,他引:1
E Yefenof Y Azar P Eidelsztein S Z Ben-Sasson 《Journal of immunology (Baltimore, Md. : 1950)》1982,128(2):625-628
Antigen-specific immune T lymphocytes of male C57BL/6 mice were enriched in vitro on monolayers of antigen-pulsed syngeneic macrophages. The cells were treated in vitro with RadLV and inoculated intrathymically into irradiated female C56BL/6 animals. Thymomas arising in the inoculated recipients were characterized as donor- (male) type according to their karyotype. In vivo and in vitro cell lines were established from the primary lymphomas, two of which (designated ROT/6.1 and ROT/6.2) were capable of providing antigen- (carrier) specific help in normal or preimmunized mice. None of the lymphomas could induce antigen-specific DTH reaction. Five months after their establishment, ROT/6.2 alone retained its carrier specificity. ROT/6.2 consisted mainly of Lyt-1+ cells, whereas the ROT/6.1 population was more heterogeneous and contained Lyt-1+, Lyt-2+, and Lyt-3+ cells. The carrier specificity of the latter may have been lost due to selection against the specific helper cells during prolonged passages. 相似文献
932.
Summary Seedlings of two mangrove species, Avicennia marina and Aegiceras corniculatum, were grown in a range of salinities and humidities in controlled environment chambers, and Phaseolus vulgaris plants were grown in the glasshouse. The fractionation of carbon isotopes in the three species was correlated with the ratio of intercellular and ambient partial pressures of CO2. The results are consistent with fractionation being due both to diffusion in air and to carboxylation in the leaf. It was concluded that the latter process discriminates against 13CO2 relative to 12CO2 by about 27. 相似文献
933.
Chick embryonic RNA was fractionated by affinity chromatography on oligo(dT)-cellulose and poly(U)-Sepharose into three classes: poly(A)+RNA containing poly(A) segments of 100 and more residues, poly(A)-oligo(A)+RNA containing oligo(A) segments of about 25 residues, and poly(A)-oligo(A)-RNA which bound to neither of the beds used and which contained double-stranded segments of 300 and more base pairs. These three classes of RNA were found in cytoplasmic as well as in heterogeneous nuclear RNA. Double-stranded segments in hnRNA, unlike those in cytoplasmic RNA, were intermolecular in nature; this may explain the occurrence of "giant" molecules in hnRNA. 相似文献
934.
ACTH release under the effect of median eminence extract (ME) was studied in both incubation and superfusion experiments. ACTH content of the incubation medium was measured by radioimmunoassay or by the corticosterone production of trypsinisolated adrenocortical cells. Dopamine at low concentration led to a slight increase of basal ACTH secretion, while at higher concentration failed to influence ACTH release. The dopamine agonist CB-154 produced a significant rise of ACTH secretion and augmented the ME extract-induced increase of pituitary ACTH release. Chlorpromazine and haloperidol suppressed basal ACTH secretion and inhibited the ME extract-induced release. The simultaneous administration of CB-154 and haloperidol into the incubation medium prevented the haloperidol-induced inhibition of ACTH release. The observations indicate that dopaminergic receptors play a role in the activation of CRF-induced ACTH secretion under in vitro experimental conditions. 相似文献
935.
Previous data showed that after bilateral pallidal lesion (GPL) the weight loss of animals is higher in males than females. Data in the literature have called attention to the possible involvement of thyroid hormones. The sex dependence of weight loss was prevented by neonatal castration. In the present experiments, plasma triiodothyronine level was determined in neonatally castrated and non-castrated male and female rats on the 4th day after GPL. Body weight changes in food and water deprived male and female rats were compared after 4 days of T3 administration. A positive correlation between weight loss and T3 levels was found but there was no difference in mean T3 values between male and females. In the non-castrated group, T3 levels were higher in lesioned than in food and water deprived animals. In neonatally castrated animals no such difference was found. T3 administration caused a uniform weight loss in both sexes. It seems that while they play a role in the mechanism of weight loss after GPL, the sex-dependence is not due to changes in factors involved in regulation of the thyroid hormone level. 相似文献
936.
937.
An intracellular α-glucosidase (α-glu1) of Aspergillus niger was purified and its properties were compared to those of a secreted α-glucosidase (α-gluE). The estimated molecular weight of α-gluI was 95,000 by gel filtration (α-gluE = 63,000); it is a glycoprotein possessing 29 mol of mannose, 6 mol of glucosamine, and 14 mol of glucose (α-gluE has 5–6 and 2 mol of mannose and glucosamine, respectively). The Km′s of α-glu1 for p-nitrophenyl-α-d-glucopyranoside and maltose were 1.49 and 1.04, respectively, slightly lower than those of α-gluE. In addition, at 65 °C α-gluI enzymatic activity decayed fivefold faster than that of α-gluE, and anti-α-gluE antibody did not recognize α-gluI. While some of these distinctions between the enzymes could be ascribed to conformational differences, the great dissimilarity in molecular weight (approximately 32,000) and lack of reactivity with anti-α-gluE argue against α-gluI being related to α-gluE. The antibody covalently coupled to horseradish peroxidase (Ab-Px) was used as a probe to determine the cellular location of α-gluE by electron microscopic immunocytology. It was found on both sides of the plasma membrane (pm) and in the outer of the two layers of the cell wall. This may mean that α-gluE is synthesized at the inner surface of the pm, is extruded through the pm, becomes associated with the outer layer of the cell wall (perhaps as enzyme—substrate complex), and is eventually released into the growth medium. 相似文献
938.
The relationship between Ir genes and Ia antigens was studied in the T-cell proliferative responses to two synthetic polypeptides poly(glu40ala60) (GA) and poly(glu51lys34tyr15) (GLT15). The response to GA was found to be controlled by an Ir gene in the I-A subregion, whereas the anti-GLT15 response was shown to be under dual control, one Ir gene mapping probably in the I-A subregion, and the other in the I-E subregion. We obtained two different lines of evidence suggesting identity of Ir and Ia genes. First, the presence of certain serologically identified allelic forms of the I-A-encoded A molecule correlated with the responder status to GA both in inbred strains and in B10.W lines, the latter carrying wild-derived H-2 haplotypes. Thus the Ir and Ia phenotypes were not separable in strains of independent origin. Second, the anti-GA response was completely inhibited by monoclonal antibodies against determinants on the A molecule (Ia.8, 15, and 19), but not by a monoclonal antibody against a determinant on the E molecule (Ia.7). In contrast, the anti-GLT15 response was only inhibited by a monoclonal antibody against the E molecule, but not by antibodies against the A molecule. Our data support the hypothesis that Ia antigens, as restriction elements for T-cell recognition, may in fact be the phenotypic manifestation of Ir genes. 相似文献
939.
Antibody inhibition of radiolabelled stimulator membrane vesicle binding by T blasts activated in the mixed lymphocyte reaction (MLR) was used to identify responder-cell determinants involved in the binding phenomenon. Antisera or monoclonal antibodies against Thy-1, Lyt-1, Lyt-2 and Ly-6 antigens were not inhibitory. However, antibodies against heavy-chain V region (VH) determinants strongly inhibited vesicle binding by both primary and long-term MLR blasts. Anti-Ia (both alloantisera and monoclonal reagents) caused inhibition of antigen binding by primary MLR blasts only. T blasts from long-term MLR lines were neither Ia-positive, nor susceptible to blocking of antigen binding with anti-Ia. However, these cells were capable of specifically absorbing soluble syngeneic Ia material, with the concomitant appearance of vesicle-binding inhibition with anti-Ia sera. Acquisition of syngeneic Ia by T blasts was effectivelly blocked with the anti-VH reagent. Passively bound self-Ia did not interfere with vesicle binding in the absence of anti-Ia. These results strongly suggest the existance of specific self-Ia acceptor sites closely linked to the receptors for stimulator alloantigens on T cells proliferating in MLR. A receptor model based on these findings is briefly discussed. 相似文献
940.
Summary The possibility that adenosine 3,5 monophosphate exerts an effect on citric acid production by Aspergillus niger by influencing pellet morphology has been investigated. The effect of pH and inoculum size on pellet formation, citric acid production, and intracellular and extracellular cAMP levels were studied. High levels of intracellular and extracellular cAMP in the later stages of the fermentation, the period of maximum citric acid formation, were associated with those treatments which gave pellets of intermediate size. The highest cAMP levels were associated with those treatments which gave the highest citric acid titre. It was concluded that high cAMP levels are principally associated with an optimum physiological state for citric acid production and that cAMP levels do not vary directly with pellet size. 相似文献