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The phosphorylation of proteins in intact mouse spleen lymphocytes was monitored following mitogenic activation. Little change in the autoradiographic patterns of phosphorylated protein fractionated by polyacrylamide gel electrophoresis occurred during the first 8 h after Concanavalin A (conA) treatment. The intensity of 32P incorporation into two proteins of 135 000 and 150 000 mol. wt began to increase, relative to control cells, 10 h after conA treatment and was maximal at 50 h. This increased phosphorylation followed the rise in RNA synthesis but preceded the onset of DNA synthesis. In addition to this temporal link between enhanced phosphorylation of these proteins and the initiation of DNA synthesis, various agents which inhibited the onset of S phase also blocked the phosphorylation of both proteins. Such treatments included the displacement of conA from its surface receptors by α-methyl-mannoside (αMM), the omission of serum from the culture medium, and the presence of indomethacin. The similar time courses of phosphorylation and responses to various proliferation inhibitors supports the idea that the 135 000 and 150 000 mol. wt proteins have a common physiological function. These proteins may be involved in the progression of stimulated lymphocytes toward S phase, and their phosphorylation may be an important regulatory event in this sequence. 相似文献
3.
The in vitro synthesis of interferon (IFN) by human lymphocytes stimulated in mixed-lymphocyte culture (MLC) was examined. The production of IFN in MLC was restricted to T lymphocytes and maximum levels of IFN were detected in supernatants from cells incubated for 5 to 7 days. The IFN produced was identified as IFN-gamma by antibody neutralization. To identify the T cell responsible for IFN production, purified T lymphocytes were separated into subpopulations after incubation in 5 mM theophylline. Theophylline-resistant (T-res) T cells retain the ability to form sheep erythrocyte (SRBC) rosettes and are depleted in IgG Fc receptor-positive T cells (T gamma cells). Theophylline-sensitive (T-sens) T cells fail to form rosettes after theophylline treatment and are enriched in T gamma cells. In addition, analyses using monoclonal antibodies showed that T-sens cells were enriched in OKM1-, HNK-1-, and 7.2-positive cells and T-res cells contained increased numbers of 9.6- and OKT4-positive cells. Following MLC stimulation, equivalent levels of IFN-gamma were produced by T-res and T-sens cells and both subpopulations maintained natural killer (NK)-like cytotoxicity against K562 target cells. Addition of partially purified IFN-gamma to unstimulated T-res and T-sens cells resulted in the maintenance of NK-like cytotoxicity in a manner analogous to that observed after MLC. Additional experiments indicated that peripheral blood lymphocytes depleted of 9.6- or OKM1-positive cells by complement-mediated lysis were devoid of cytotoxicity against K562 cells. Furthermore, MLC stimulation of 9.6- or OKM1-depleted cells failed to restore cytotoxic activity. In summary, these experiments demonstrate that the maintenance of NK-like cytotoxicity by MLC-stimulated T cells is associated with the synthesis of IFN-gamma, that MLC stimulated T-res and T-sens T-cell subsets produce equivalent amounts of IFN, and that 9.6- or OKM1-positive cells are required for the maintenance of NK-like cytotoxicity in MLC. 相似文献
4.
The relative rates of synthesis of actin and tubulin during mouse preimplantation development have been investigated utilizing O'Farrell's two-dimensional polyacrylamide gel system and internal protein markers. During mouse preimplantation development, rates of protein synthesis remain low and are little changed until the 8-cell stage when a rapid increase is evident. From the 8-cell stage on, a much higher rate of synthesis is maintained. The rate of synthesis of actin remains also at a steady low level in the unfertilized and fertilized ovum. However, by the 8-cell stage actin synthesis has increased 10-fold. Our measurements include the blastocyst, at that point in development actin synthetic rates are almost 90-fold higher than in the unfertilized ovum. While this precipitous increase is proceeding, incorporation of [3H]leucine into total protein increases only 7-fold. Synthesis of actin in the blastocyst represents 5.7% of total protein synthesis. The rate of tubulin synthesis, unlike actin, more closely parallels the increments in total protein synthetic rates. At the blastocyst stage it has increased 14-fold and its synthesis represents almost 2% of total protein synthesis. These results are discussed with reference to some of the physiological changes taking place during preimplantation development. 相似文献
5.
A murine model for Transfer Factor (TF) was used in an attempt to identify the nature of its antigen-specific component. TF was prepared from lymph node cells of CBA/Ca/T6 mice sensitized 30 days previously with 2,4-dinitrofluorobenzene (DNFB). To assay for the specific component of TF, 2 × 107 lymphocyte equivalents were injected intravenously into normal syngeneic recipients. Lymph node cells obtained 18–24 hr later gave a positive response in the macrophage migration inhibition (MMI) test in the presence of the soluble analog of DNFB (sodium 2,4-dinitrobenzenesulfonate). The activity of TF was abrogated by absorption with anti-Ia sera including both an Ia alloantiserum (A.TH anti-A.TL) and a xenogeneic rabbit anti-serum which exclusively recognizes carbohydrate-defined Ia antigens. Analysis by paper chromatography using the technique for purification of carbohydrate-defined Ia antigens revealed that MIF production was obtained exclusively with those fractions known to contain Ia antigenic activity. In addition, pretreatment of TF with insoluble conconavalin A (Con A) which has an affinity for carbohydrate-defined Ia antigens resulted in removal of its activity. Taken together these findings pointed to the presence in TF of I-region gene products. Absorption with antibody directed against the dinitrophenyl determinant abolished the capacity of TF to stimulate macrophage inhibition factor production suggesting that it might also contain antigen fragments possibly in association with Ia. No evidence was, however, obtained for H-2 restriction of the action of TF in vivo since it was found to exert an effect in a variety of strain combinations including A.TH and Balb/c which share no known common I-region specificities. Parallel experiments were carried out with the lymphocyte transformation assay since this is known to be a measure of the nonspecific components in TF. Pretreatment with mouse allo-anti-Iak serum directed against both protein-and carbohydrate-defined Ia antigens caused a partial reduction in the proliferative response. In contrast no change in response was observed when the TF was absorbed with insoluble Con A or anti-DNP serum. Furthermore, lymphocyte transformation was obtained with only one of the three paper chromatography fractions positive in the MMI assay as well as two other different fractions. Taken together, these findings permitted a distinction to be made between specific and nonspecific components of TF and indicated that the specificity of TF could be explained in terms of the presence of I-region gene coded products possibly in association with antigen fragments. 相似文献
6.
Guinea pig peritoneal macrophages were activated in vitro by culturing with MAF (macrophage activating factor)-containing fractions from stimulated lymphocytes. These macrophage preparations demonstrate a 60% increase in the production of prostaglandins of the E series (PGE) when compared with macrophages cultured with fractions from unstimulated lymphocytes. PGE accumulation in macrophage cultures is maximal after 24 hr with MAF; tumor cytotoxicity is also maximal at this time. The final PGE concentration in cultures of activated macrophages averaged 3 × 10?8M. 相似文献
7.
Actin and tubulin synthesis in murine blastocyst outgrowths 总被引:1,自引:0,他引:1
The actin and tubulin contents of blastocysts grown in vitro for 72 h were estimated by densitometric analysis of Coomasie-blue stained SDS-gels. Actin represents 7% and tubulin 13% of total blastocyst outgrowth protein. The relative synthesis of these two proteins was measured by two-dimensional electrophoresis utilizing unlabeled and isotopically labeled actin and tubulin internal markers. Actin synthesis constituted 6.3% and tubulin synthesis 1.5% of the total protein synthesis. These values are not significantly different from those we have reported previously for mouse preimplantation blastocysts recovered from uteri. It appears then that the relative proportion of synthesis does not change significantly during the developmental period that encompasses the blastocyst stage and early implantation as represented by the in vitro hatching, attachment and outgrowth of the blastocyst. Data on the characteristics of growth and culture of the outgrowths is also presented. 相似文献
8.
L4-PHA (L4) and E4-PHA (E4) lectins isolated from Phaseolus vulgaris have different mitogenic properties. The mechanisms of the differences in mitogenic behavior were sought in the interaction of lectin, lymphocyte subsets, and T-cell growt factor (TCGF) also known as interleukin 2 (IL-2). TCGF activity in culture supernatants ( L4S ; E4S ) from L4- and E4-stimulated, freshly isolated lymphocytes was assayed as stimulation of DNA synthesis in TCGF-dependent continuous T-cell cultures (CTC). E4S contained less TCGF than did L4S . Addition of partially purified TCGF does not increase the stimulation of fresh lymphocytes by L4 or E4. L4 and E4 equally stimulate both helper (OKT4+) and suppressor (OKT8+) cells. The ability of L4 to further stimulate CTC is slowly lost (15 greater than 30 greater than 45 days). It is concluded that production of TCGF is not rate limiting in E4 and L4 stimulation of lymphocytes. The growth of CTC, which requires the presence of TCGF, remains sensitive to, but not dependent on, L4 for at least 30 days. 相似文献
9.
α-Aminoisobutyrate (AIB) serves as a transportable, nonmetabolizable alanine analog in the purple sulfur bacterium Chromatium vinosum. AIB transport in C. vinosum appears to be catalyzed by an electrogenic Na+-alanine (AIB) symport without any direct participation of ATP-driven or H+-symport systems. In addition to Na+ being cotransported with AIB via the symport, a transmembrane Na+ gradient appears to increase the affinity of the symport of AIB. It appears that these two effects of Na+ involve different Na+-binding sites. 相似文献
10.
Site and timing of synthesis of tubulin and other proteins during oogenesis in Drosophila melanogaster 总被引:4,自引:0,他引:4
Protein synthetic patterns during oogenesis in Drosophila melanogaster were examined; in particular the site, time, and rate of tubulin synthesis and accumulation during oogenesis were determined. Ovarian proteins were labeled with [35S]methionine in vivo or in organ culure in vitro, and the proteins synthesized in egg chambers of specific developmental stages displayed by two-dimensional gel electrophoresis. A dissection technique was devised to examine proteins synthesized in each of the three cell types present in stage 10B egg chambers. The majority of proteins which were resolved by two-dimensional gel electrophoresis, including tubulin and actin, were synthesized throughout oogenesis and, at least to some extent, in each of the stage 10B cell types. Protein synthesis specific to developmental stage and/or cell type was also observed; for example, two nonchorion proteins were synthesized only in follicle cells and primarily at stage 10. A sensitive and specific radioimmune assay was developed in order to quantitate tubulin accumulation. Synthesis of several α-tubulin subunits and one β-tubulin subunit was observed. The tubulin content per egg chamber increased from 3 ng in stage 9 to 17 ng in stage 14, a period of about 13 hr. An accumulation rate of 1 ng/hr suggests that tubulin mRNA can account for about 4% of the total, nonmitochondrial, poly(A)+ RNA of the egg. Analysis of separated cell types at stage 10B revealed that both the follicle and nurse cells synthesize and accumulate appreciable amounts of tubulin. The stage 10B oocyte contains relatively little tubulin but actively synthesizes it. These two complementary analyses demonstrate that the tubulin present in the egg is synthesized within the oocyte-nurse cell syncytium, first in the nurse cells and later in the oocyte. 相似文献
11.
Studies were undertaken to identify cell surface markers specific for different phases of the cell cycle. Antisera were prepared in rabbits against membrane protein preparations from synchronized BW 5147 cells, an AKR mouse T-lymphoma cell line, in the G1, S, G2 or M phases of the cell cycle. These antisera were used to precipitate radioiodinated surface proteins from synchronized cells in the different phases. The immunoprecipitates were quantitatively analyzed by sodiumdodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Cells in S phase had significantly higher concentrations of proteins weighing 70 × 103 and 165 × 103 D than cells in G1 or G2 phase. The other major labeled surface components did not vary. These results were confirmed by quantitative absorption of the antisera with synchronized cells. Comparative analysis of the antisera showed that the 165 × 103 D peak contained at least two antigens, one recognized by both a-G1 and a-S and the other by a-G1 only. Though cells in S phase had large quantities of the 70 × 103 D protein, intact and SDS-solubilized membrane preparations from S phase could not elicit in rabbits any antibody against that protein. These antisera did, however, have good antibody titers to the other major protein peaks and the antisera developed against cells in G1, G2 or M had good anti-70 × 103 activity. The results suggest a qualitative molecular change in the 70 × 103 protein during S phase. 相似文献
12.
Cleavage of head and tail proteins during bacteriophage T5 assembly: selective host involvement in the cleavage of a tail protein 总被引:31,自引:0,他引:31
Electrophoresis studies showed that at least three phage-specified proteins undergo proteolytic cleavage during the development of bacteriophage T5. One of these proteins has a molecular weight of about 135,000 and the product of this cleavage reaction is a minor component of the T5 tail, having a molecular weight of about 128,000. All of the tail-defective T5 mutants studied in this report failed to induce this cleavage reaction under restrictive conditions. This reaction also failed to occur in Escherichia coli groEA639 and groEA36 infected with wild type T5. Examination of lysates of infected groE cells in the electron microscope revealed the presence of filled and empty heads as well as tubular head structures, but no tails were detected. The filled heads were able to combine with separately prepared T5 tails in vitro to form infectious phage particles. Therefore, propagation of T5 in these groE mutants is prevented primarily by a specific block in tail assembly. A T5 mutant, T5?6, was isolated, which has the capacity to propagate in these groE hosts. The gene locus in T5?6 was mapped.The second T5 protein which is cleaved has a molecular weight of 50,000 and is related to head morphogenesis. Treatment of infected cells with l-canavanine (50 μg/ml) inhibited cleavage of this polypeptide. Only small quantities of the major head protein (32,000 mol. wt) were produced in these treated cells. Treatment with canavanine lead to production of tubular heads. The major protein component of partially purified tubular heads has a molecular weight of 50,000. Cells infected with T5 amber H30b, a mutant defective in head gene D20, does not produce the 50,000 and 32,000 molecular weight proteins. These findings suggest that the 50,000 molecular weight protein undergoes cleavage to form the major head polypeptide. A third T5 protein is cleaved to form a minor head component with a molecular weight of 43,000 and its cleavage is linked to that involving the major head protein. 相似文献
13.
Guido Damiani Elisabetta Cosulich Antonio Bargellesi 《Experimental cell research》1979,118(2):295-303
A mutant of the MPC-11 mouse myeloma cell line which grows as a monolayer has been used to study the synthesis and secretion of IgG in relation to the cell cycle. The mitotic detachment method has been used to obtain a pure population of mitotic cells which were then allowed to progress through the G1, S, and G2 phases of the cell cycle. The synthesis and the rate of secretion of IgG have been studied in each phase of the cycle by incubation of cells with 14C-amino acids, followed by immunoprecipitation and quantitation of synthesized and secreted IgG2b. The data are consistent with the idea that synthesis and secretion of Ig are not a cell cycle dependent event in myeloma cells. 相似文献
14.
The determination of purine levels in human and mouse plasma 总被引:2,自引:0,他引:2
Variable levels of acetic anhydride have been recommended for addition to one of two reagents used in the glyoxylic acid method for the determination of tryptophan. For use of this reagent immediately after preparation it was shown that a minimum of 16% (v/v) of acetic anhydride should be included in the formulation to obtain near-maximum sensitivity. It was further demonstrated that reagent formulations with and without acetic anhydride changed with exposure to light. The observed changes are manifest as changes in the relative sensitivities of the assay. Several modifications are recommended to improve the sensitivity and stability of the acetic anhydride-containing reagent in this assay. 相似文献
15.
Synaptonemal complexes in a tetraploid mouse spermatocyte 总被引:1,自引:0,他引:1
Quadrivalents, represented by unique synaptonemal complex configurations, together with normal bivalents are observed for the first time in a mammalian tetraploid pachytene spermatocyte prepared by microspreading. The chromosomal axes (lateral elements) clearly demonstrate the switching of partners in the quadrivalents as predicted from classical cytogenetic theory. Tetraploid formation, possibly by nuclear fusion, must have occurred prior to meiotic prophase. 相似文献
16.
The percental participation of exogenous cytidine in liver RNA synthesis was determined after application of 3H-cytidine to rats. The amount of exogenous cytidine was varied by a factor of 5 × 105, between 0.000 02 and 10.0 μg/g rat. With the 3H-cytidine doses and specific activities most frequently reported in the literature, the percental participation of the exogenous precursor is only about 0.1%, with 99.9% of the cytidylic acid incorporated into RNA under these conditions being of endogenous origin.The results show that the upper limit of the tracer dose of exogenous cytidine is about 1.0 μg/g rat. Within this tracer region 1.8% of 3H-activity—and therefore 1.8% of the amount of exogenous cytidine—is incorporated into liver RNA. The dependence of the percental participation on the duration of the experiments is examined.It is shown that autoradiographic grain density and specific activity of RNA can only be regarded as direct measures for the rate of RNA synthesis in different cells and animals if the percental participation of exogenous cytidine in RNA synthesis is generally of equal value.Comparable situations exist in the incorporation of 3H-thymidine into DNA as shown by earlier experimental work. 相似文献
17.
Aqueous extracts of various lymphoid tissues, but not of non-lymphoid tissues, contain a species-non-specific but cell-specific inhibitor of the transformation and DNA synthesis of PHA-stimulated human lymphocytes which is apparently not cytotoxic and is reversible. This activity is found in similar molecular weight fractions from pure lymphocytes obtained in culture and hence appears to be endogenous to the lymphocyte itself. This specific and endogenous mitotic inhibitor does not appear to be a result of competitive lectin-binding, thymidine pool size dilution, phosphorylation, destruction of thymidine, or the direct immunosuppressive effects of thymidine upon the lymphocytes themselves. Rather, it appears to be a result of the effects of a protein contained in the crude ultrafiltrate from lymphoid tissues whose properties correspond to those originally described by Bullough & Laurence for a ‘chalone’. The chalone activity from thymus appears to be specific for T cells rather than B cells. 相似文献
18.
Correlated light scatter and fluorescence flow cytometric analysis of human peripheral blood lymphocytes showed that the expression of the T4 antigen was higher in the larger lymphocytes than in the smaller lymphocytes. A similar expression pattern was observed for HLA Class I antigens but not for T3 and T8, whose expression was independent of cell size. Results with lymphocytes from spleen, lymph node, and tonsil were comparable to those of peripheral blood. Thymocytes, however, were smaller and expressed less T4 and T8 than peripheral lymphocytes. In studies of lymphocytes stimulated in vitro with allogeneic cells or pokeweed mitogen, two populations of T4-positive cells were observed: one of large cells expressing high amounts of T4 and one of small cells expressing low amounts of T4. Similar patterns were seen with T8, although less consistently. In contrast, the expression of T3 was the same in both large and small cells. The large cells expressing high amounts of T4 were not restricted to cells engaged in DNA synthesis or mitosis. This was established by selectively analyzing cells in the G0G1 phases of the cell cycle and by studying stimulated lymphocytes no longer undergoing proliferation. Taken together, these results suggest that immature T lymphocytes are small and express low amounts of T4 and T8. We postulate that as they differentiate, cell size and T4 expression increase proportionally, both parameters increasing even further after antigenic or mitogenic stimulation. The quantitative expression of T4, and probably of T8 but not of T3, is therefore intimately related to maturation and activation of lymphocytes, a fact that may conceivably be related to a functional role of these surface molecules. 相似文献
19.
Late morulae and early blastocysts consist of two main cell subpopulations which occupy different positions within the embryos. The cells of the outer layer have a polar surface phenotype. The outward-facing surface of this cell type has a discrete dense pole of short microvilli, whilst the inward-facing surface has a relatively sparse distribution of longer, thick microvilli. The inner cells lack short, dense microvilli but exhibit thick microvilli of variable density. After short-term isolation in medium low in Ca2+, the individual polar and apolar cells remain distinguishable. The expanded blastocyst also has two major cell subpopulations, but within each of these, heterogeneity is observed. The mural trophectodermal cells have a larger, more regular outward-facing area of sparse, short microvilli than do polar trophectodermal cells. The ICM consists of some cells that show extensive blebbing in medium low in Ca2+ and others that do not. 相似文献
20.
A large body of data has accumulated in recent years supporting the view that orotate phosphoribosyltransferase and orotidylate decarboxylase exist as a bifunctional enzyme complex in adult mammalian tissues. This paper presents evidence that such a complex also occurs in mouse liver and brain, regardless of the developmental stage of the animal. Orotate phosphoribosyltransferase and orotidylate decarboxylase activities remained coordinate in fetal, neonatal, immature and adult liver and brain. In addition, these two enzymes routinely cosedimented during centrifugation of cell-free extracts in sucrose gradients. The sedimentation coefficient of the enzyme complex did not change significantly during mouse development. However, the liver complex exhibited a sedimentation coefficient (5.0 ± 0.2) that differed from that of the brain complex (4.3 ± 0.1) 相似文献