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1.
Adhesive contacts between developing germ cells and Sertoli cells may play an important role in mammalian spermatogenesis. Adhesion between isolated spermatogenic cells (pachytene spermatocytes and round spermatids) and Sertoli cells was studied. The attachment of single mouse germ cells to mouse Sertoli cell layers was weak, but the rate of attachment was stimulated by Concanavalin A (conA; 5 μg/ml). ConA-induced attachment was largely stable during a subsequent incubation for 30 min in the presence of 20 mM α-methyl-
-mannoside (an inhibitor of conA). The cellular specificity of the stable attachment of germ cells to Sertoli cells was inferred from the observations that a comparable inhibitor-resistant attachment could not be obtained between germ cells and kidney cells, and between mouse myeloma cells and Sertoli cells. Juxtaposition of male germ cells and Sertoli cells through conA bridges may lead to the subsequent formation of strong and specific cell-cell adhesive bonds. 相似文献
2.
The aim of our experiments was to study the influence of genistein [tyrosine kinase (TK) inhibitor with estrogenic activity] and lavendustin A (TK inhibitor without estrogenic activity) on female reproductive processes in domestic animals in vitro. It was found that genistein (0.001–1 μg/ml) increased IGF-I release by cultured bovine and porcine granulosa cells, but decreased its secretion by rabbit granulosa cells (0.01–10 μg/ml). Genistein stimulated progesterone secretion by bovine and rabbit granulosa cells (at 0.01–10 μg/ml), estradiol output by rabbit granulosa cells (at 1 μg/ml) and porcine ovarian follicles (at 10 μg/ml), as well as cAMP production by bovine (at 0.001–1 μg/ml) and rabbit (at 1 μg/ml) granulosa cells. No effects of genistein (at 10 μg/ml) on PGF-2 alpha and progesterone release by porcine ovarian follicles were observed. Genistein significantly (P < 0.05) stimulated the reinitiation and completion of nuclear maturation of porcine oocytes (at 5 μg/ml), as well as the preimplantation development of rabbit zygotes (at 1 μg/ml). Lavendustin A (0.001–1 μg/ml) increased IGF-I release by bovine (but not by porcine) granulosa cells, cAMP release by bovine granulosa cells, and PGF-2 alpha output by porcine ovarian follicles (at 10 μg/ml). Lavendustin (at 1 μg/ml) had no significant effect on IGF-I release by porcine granulosa cells, on estradiol and cAMP output by rabbit granulosa cells, or on progesterone secretion by porcine follicles (at 10 μg/ml). Inhibitory actions of lavendustin (at 10 μg/ml) on estradiol secretion by porcine follicles were also found. Furthermore, lavendustin, like genistein, promoted the reinitiation and completion of meiosis in porcine oocytes. The present study demonstrates a predominantly stimulatory effect of TK inhibition on endocrine and generative processes in domestic animals. The majority of these effects are similar for both compounds, indirectly suggesting that their action is due to tyrosine kinase inhibition and protein kinase A-stimulation, rather than estrogenic activity. 相似文献
3.
Influences of steroid hormone additions or of their binding by specific antisera on nuclear maturation and subsequent fertilization and cleavage of bovine oocytes were studied in vitro. It was found that progesterone in doses of 50 ng/ml, 250 ng/ml, 1 μg/ml or 5 μg/ml stimulates reinitiation and in doses of 1 or 5 μg/ml stimulates further development of meiosis. Antiserum to progesterone had opposite effects on nuclear maturation, but has no influence on the ability of matured oocytes to subsequent fertilization and cleavage. Testosterone additions (10 ng, 100 ng, 1 μg or 5 μg/ml) did not influence nuclear maturation, but antiserum to this hormone inhibited both meiosis reinitiation and completion, as well as lowered the rate of oocytes fertilized and embryos obtained. Estradiol (5, 50, 100 or 500 ng or 5 μg/ml) treatment stimulated reinitiation, but not nuclear maturation. Antiserum to estradiol activated both reinitiation, development and completion of meiosis, but the cells matured by estradiol deficit were as a rule uncapable of fertilization and further cleavage. Estradiol addition (1 μg/ml) to maturation medium together with FSH (10 μg/ml) (but not of FSH alone) lead to a significantly higher rate of fertilization and cleavage of matured cells. Results obtained suggest (1) relative independence of reinitiation, further development of nuclear maturation and cytoplasmic maturation regulation in bovine oocytes as well as (2) the involvement of steroid hormones in these three processes. 相似文献
4.
The effect of bromodeoxyuridine (BrdU)-substituted DNA template and thymidine (dT) pool on excess sister-chromatid exchanges (SCEs) was studied in Bloom syndrome (BS) cells and an ataxia telangiectasia (AT)-derived mutant cell line (AsHa). When BS endomitotic cells were labeled with low and high (or high and low) BrdU concentrations during S 1 and S 2, only the BrdU concentration during S 1 phase affected the observed SCE. In BS cells about a 10-fold increase in SCEs occurs during or following replication on a BrdU-substituted template (high-high and high-low BrdU labeling) relative to the normal DNA template. SCEs decreased to about half in AsHa cells labeled with various BrdU doses (40, 60, 80 and 100 μg/ml) during only S 1, compared with those labeled during S 1 and S 2. Co-cultivation of AsHa and BS cells resulted in a significant reduction in SCE level from 70 to 13–17 in BS cells, lowered the BrdU concentrations necessary for sister-chromatid differential (SCD) staining from 40 to 10 μg/ml with normal SCE level and resulted in decreased level of SCEs at high BrdU concentrations (80–100 μg/ml) 12–14 SCE) in AsHa cells, compared with the originally increased SCE level (36.65 SCE at 100 μg/ml) without co-culture. However, co-cultivation between AsHa and normal cells lowered the BrdU dose necessary for SCD staining from 40 to 30 μg/ml; the dT pool possibly balanced at this level, which is clearly higher than that at co-cultivation between AsHa and BS cells. The reason for the very high BrdU doses needed to achieve SCD would seem to be that AsHa cells have high levels of thymidylate (TMP) synthetase, which maintain a large endogenous thymidine pool. This has been confirmed by direct measurement. These findings strongly support that excess and decreased dT pools are closely related to the condition necessary for high SCE induction. 相似文献
5.
Melissa officinalis L. (Lamiaceae) has been used in a variety of practical applications in medical science. Our objective in the current study was to determine the effects of the volatile oil components of M. officinalis on Herpes simplex virus type 2 (HSV-2) replication in HEp-2 cells. Four different concentrations (25, 50, 100, 150 and 200 μg/ml) of volatile oils were examined. Experiments were carried out using HEp-2 cells. M. officinalis volatile oil was found to be non-toxic to HEp-2 cells up to a concentration of 100 μg/ml. It was, however, found to be slightly toxic at a concentration over of 100 μg/ml. The antiviral activity of non-toxic concentrations against HSV-2 was tested. The replication of HSV-2 was inhibited, indicating that the M. officinalis L. extract contains an anti-HSV-2 substance. 相似文献
6.
Three types of Giemsa differential staining of sister chromatids were observed in HeLa cells when they were exposed continuously to 5-bromodeoxyuridine (BrdUrd) for three replication cycles. In type-1, about a half set of chromosome complements were composed of pairs of darkly-stained and intermediately-stained chromatids; the other half consisted of pairs of intermediately-stained and lightly-stained chromatids. In type-2, one fourth of chromatids was stained darkly and the remaining ones were stained lightly. In type-3, about a half set of chromosomes consisted of the pairs of darkly-stained and lightly-stained chromatids and the rest of pairs of intermediately-stained and lightly-stained chromatids. Cells showing each differentiation pattern at the third mitotic phase were dependent on the stages of the first DNA synthetic (S) phase at which BrdUrd treatments were initiated. Type-1 cells were observed, when BrdUrd treatment was initiated anywhere from G1 to early S phase, type-2 when treatments were begun in middle S stage, and type-3 when treatments were initiated in the late stages of the first S phase. The appearance of the three types seems to be caused by a different amount of BrdUrd incorporated into DNA between the first (S1) and the second S period (S2). The amount of BrdUrd incorporated is as follows: in type-1 S1>S2, in type-2 S1 S2 and in type-3 S2>S1.By analysing type-1 cells, all of the sister chromatid exchanges (SCEs) occurring during each replication cycle can be accurately counted and distinguished from one another. In cells exposed to BrdUrd above 5 μg/ml, the frequencies of SCEs occurring during S1, S2, and S3 are higher than those detected at lower BrdUrd concentrations. On the other hand, at lower concentrations (0.1–1.0 μg/ml) they occurred at the same frequency during S1, S2, and S3. Thus, SCEs detected at low concentrations are free from the incremental effect of BrdUrd incorporated, and enable us to estimate the spontaneous level of SCE frequency. 相似文献
7.
Novel bacterial resistance genes were cloned and expressed as dominant selection markers in mammalian cells. Escherichia coli genes coding for resistance to the aminocyclitol antibiotics hygromycin B (Hm) and G418 were cloned into the eukaryotic expression plasmid pSV5GPT [Mulligan and Berg, Proc. Natl. Acad. Sci. USA 78 (1981) 2072–2076]. Mouse cells normally sensitive to 100 μg/ml Hm were transformed with these plasmids and selected in 200 μg/ml Hm. Transformants resistant to as much as l mg/ml Hm and 500 μg/ml G418 were isolated. Cell extracts contained an acetyltransferase activity capable of acetylating G418 and an Hm amino-cyclitol phosphotransferase activity. Plasmid DNA sequences were identified by Southern blot analysis of high Mr DNA isolated from transformed cells. 相似文献
8.
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
9.
An isocratic liquid chromatographic method employing one extraction step and a 150 mm × 4.6 mm I.D. Spherisorb ODS2, 3-μm HPLC column using UV-absorbance detection at 210 nm has been developed for the quantitation of felbamate and three felbamate metabolites in 0.100-ml aliquots of rat and dog plasmas. The linear quantitation range in rat plasma is 0.195–200 μg/ml for felbamate; 1.563–200 μg/ml for the p-hydroxy metabolite; 0.391–200 μg/ml for the 2-hydroxy metabolite; and 0.098–200 μg/ml for the monocarbamate metabolite. The linear quantitation range in dog plasma is 0.195–200 μg/ml for felbamate; 0.781–200 μg/ml for the p-hydroxy metabolite; 0.195–200 μg/ml for the 2-hydroxy metabolite; and 0.098–200 μg/ml for the monocarbamate metabolite. 相似文献
10.
In confluent primary mouse-kidney cell cultures, abortive infection with SV40 has been demonstrated to cause an increase in the bulk of cellular RNA (mainly rRNA). However, the increase in the rate of rRNA synthesis is not involved in the initiation of the virus-induced cellular DNA replication since after actinomycin D treatment (0.05 μg/ml, from 6 to 9 h p.i.) the onset of cellular DNA replication takes place at a time when the rate of rRNA synthesis is still depressed. 相似文献
11.
Actively cycling human lymphocytes were treated with mitomycin C for 1 h (1.4 μg/ml) and then grown in medium containing 10 μg/ml bromodeoxyuridine. Serial 5-h colcemid accumulation samples were taken up to 35 h and the air-dried methaphase spreads stained for replication banding. A complete cell-cycle subphasing analysis was made, and classified cells scored for all categories of chromatid-type aberrations and their location. Inspite of the high dose which produced massive delay and cycle perturbation, there was no evidence for selectively lethality of early-S cells, in fact such cells were in excess. Extreme localization of aberrations to late-replicating (mostly centromeric) regions was found at all subphases and in pre-S cells. This rules out ‘localization by default’ as an explanation for the observed preferential occurence of ‘break points’ in these regions. The frequency of incomplete intrachanges, low in late S, rises dramaticallyin early S to become maximal in pre-S cells. 相似文献
12.
A sulphated polysaccharide (SP-2a) from the brown alga Sargassum patens (Kütz.) Agardh (Sargassaceae) was found to significantly inhibit the in vitro replication of both the acyclovir (ACV)-sensitive and -resistant strains of Herpes simplex virus type 1 (HSV-1), in dose-dependent manners, with 50% inhibitions occurring with 1.5–5.3 μg/ml of the polysaccharide. SP-2a exhibited extracellular virucidal activity only against the ACV-sensitive strains, but not the resistant strain, at the concentration of 100 μg/ml. The strongest antiviral activities against the different strains of HSV-1 were observed when this polysaccharide was present during and after adsorption of the virus to host cells. The inhibitory effect of SP-2a on virus adsorption occurred dose-dependently in all the HSV-1 strains tested, and the adsorption of the ACV-resistant DM2.1 strain was reduced by 81.9% (relative to control) with 4 μg/ml of the polysaccharide. This study clearly demonstrated that the antiviral mode of action of SP-2a is mediated mainly by inhibiting virus attachment to host cells, and this sulphated polysaccharide might have different modes of action against the ACV-sensitive and -resistant strains of HSV-1. 相似文献
13.
From the dichloromethane extract of the flowers of Helichrysum gymnocomum (Asteraceae) two known flavonoids, 4 and 5, and a known acylphloroglucinol, 3B, were isolated. In addition to 1 and 2, the 4′,6′-dibenzyloxy-2′-hydroxy derivative of 2′,4′,6′-trihydroxychalcone and 5,7-dibenzyloxy derivative of pinocembrin, respectively, are reported in Nature for the first time. A compound 3A, related to 3B has the structure 2-methyl-1-[2,4,6-trihydroxy-3-(2-hydroxy-3-methyl-3-butenyl)phenyl]-1-propanone. Compounds 1, 2, 3A, 3B, 4 and 5 have MIC values below 64 μg/ml against a selection of pathogens, with 3B having the highest sensitivity (6.3–45 μg/ml) for eight of the ten pathogens tested, including Staphylococcus aureus (6.3 μg/ml) and methicillin and gentamycin resistant strain of S. aureus (7.8 μg/ml). With the exception of 2, the other compounds had notable activity (45–63 μg/ml) towards Pseudomonas aeruginosa. 相似文献
14.
The effect of tannic acid (TA), gallic acid (GA), propyl gallate (PA) and ellagic acid (EA) on DNA damage in human lymphocytes induced by food mutagens [3-amino-1-methyl-5 H-pyrido (4,3- b) indole (Trp-P-2) and 2-amino-1-methyl-6-phenylimadazo (4,5- b) pyridine (PhIP) or H 2O 2 was evaluated by using single-cell electrophoresis (comet assay). The toxicity of these tested compounds (0.1–100 μg/ml) on lymphocytes was not found. These compounds did not cause DNA strand breaks at lower concentrations of 0.1–10 μg/ml. At a concentration of 100 μg/ml, TA and GA exhibited slight DNA damage, whereas PA and EA showed no DNA strand breaks. TA and its related compounds decreased the DNA strand breaks induced by Trp-P-2, PhIP or H 2O 2 at concentrations of 0.1–10 μg/ml. DNA repair enzymes endonuclease III (Endo III) and formamidopyrimidine-DNA glycoslase (FPG)] were used to examine the levels of oxidised pyrimidines and purines in human lymphocytes induced by H 2O 2. All the compounds at 10 μg/ml can reduce the level of FPG sensitive sites. However, only EA inhibited the formation of EndoIII sensitive sites. The results indicated that these compounds can enhance lymphocytes resistance towards DNA strand breaks induced by food mutagens or H 2O 2 in vitro. 相似文献
15.
Summary Maximal liquid-holding recovery (LHR) of the DEB-treated rad3 mutant occurs at 30° C in buffer supplemented with glucose. Addition of cycloheximide (CHX) to the buffer, the increase in cell density above 2 × 10 7/ml as well as lowering of temperature during liquid holding (LH) below 27° C decrease considerably the cell capacity for recovery. LHR does not take place at 5° C. No measurable DNA synthesis or degradation occurs in cells held in buffer alone, while addition of 0.02% glucose results in incorporation of radioactivity into DNA both of DEB-treated and control cells. Similarly, protein synthesis was observed only in cultures held in buffer supplemented with glucose. Cells transfered to growth medium directly after treatment complete one round of DNA replication and at least one division cycle, but further DNA replication and cell division are inhibited. Cells placed in growth medium after 5 days LH show an increased rate of DNA replication and cell division. Completion of the first posttreatment round of DNA replication in growth medium abolishes ishes the cell capacity for LHR. DEB treatment results in abnormal cell division of the rad3 mutant, giving colonies consisting of several cells, usually abnormal in shape, held together by common cell walls. 相似文献
16.
We investigated the influence of transforming growth factor-beta (TGF-beta) on DNA synthesis in human fetal fibroblasts, as measured by the incorporation of [3H]thymidine and cell replication. In serum-free medium, without additional peptide growth factors, TGF-beta had no action on thymidine incorporation. However, in the presence of 0.1% v/v fetal calf serum, TGF-beta exhibited a bi-functional action on the cells. A dose-dependent stimulation of [3H]thymidine incorporation, and an increase in cell number, occurred with fibroblasts established from fetuses under 50 g body weight, with a maximum stimulation seen at 1.25 ng/ml. For fibroblasts from fetuses of 100 g or greater body weight, TGF-beta caused a dose-related decrease in thymidine uptake with a maximal inhibition at 2.5 ng/ml, and a small decrease in cell number. When DNA synthesis was stimulated by the addition of somatomedin-C/insulin-like growth factor I, epidermal growth factor, or platelet-derived growth factor, their actions were potentiated by the presence of TGF-beta on cells derived from fetuses under 50 g body weight, but inhibited on cells obtained from the larger fetuses weighing more than 100 g. Similar results were found for changes in cell number in response to TGF-beta when stimulated by SM-C/IGF I. The ability of TGF-beta to modulate [3H] thymidine incorporation did not involve a change in the time required for growth-restricted cells to enter the S phase of the replication cycle. These data suggest that TGF-beta may exert either a growth-promoting or growth-inhibiting action on human fetal connective tissues in the presence of other peptide growth factors, which is dependent on fetal age and development. 相似文献
18.
Esenbeckia febrifuga (Rutaceae) is a plant traditionally used to treat malaria in the Brazilian Amazon region. Ethanol extract of stems displayed a good antiplasmodial activity against Plasmodium falciparum strains W-2 (IC 50 15.5±0.71 μg/ml) and 3 D7 (IC 50 21.0±1.4 μg/ml). Two coumarins (bergaptene 1 and isopimpinellin 2), five alkaloids (flindersiamine 3, kokusaginine 4, skimmiamine 5, γ-fagarine 6 and 1-hydroxy-3-methoxy- N-methylacridone, 7), besides a limonoid (rutaevine 8), have been isolated for the first time from this species. Antiplasmodial activity of compounds 3, 5–8 has been evaluated in vitro against P. falciparum strains (W-2 and 3D7) and the furoquinolines 5 and 6 were the most potent displaying IC 50 values <50 μg/ml; flindersiamine (3) showed a weak activity while alkaloid 7 and rutaevine (8) were inactive (IC 50>100 μg/ml). 相似文献
19.
Neuropeptide Y (NPY) was tested for an ability to directly influence the release of insulin using an in vitro isolated rat pancreatic islet system. NPY, at doses ranging from 100 pg/ml to 1 μg/ml, had no significant effect on the basal release (5.5 mM glucose) of insulin. However, NPY treatment resulted in a significant, dose-dependent (1 ng/ml to 1 μg/ml) inhibition of glucose-stimulated (11 mM) insulin release. When tested in a perfused rat pancreas preparation in situ, NPY administration led to a marked inhibition of both basal and stimulated insulin release followed by a postinhibitory rebound which exceeded the control insulin levels by 3-fold. In contrast, the intracerebroventricular (ICV) microinjection of NPY (5 μg) produced a significant but delayed (30 min) elevation of circulating insulin. It is therefore suggested that the direct action of NPY on insulin release is inhibitory while the central action of NPY indirectly results in an increase in plasma insulin. Thus, NPY may be added to the growing list of peptidergic agents which may affect the endocrine pancreas by acting as neurotransmitters and/or neuromodulators. 相似文献
20.
Sulfinpyrazone, a potent uricosuric drug, was tested in vitro for its scavenging action against oxygen free radicals. In this study, sulfinpyrazone was able to scavenge 1,1-diphenyl-2-picrylhydrazyl radical with IC 50 value of 29.82 μg/ml compared to butylated hydroxytoluene (BHT, IC 50 value=20.15 μg/ml) and Trolox (IC 50 value=16.01 μg/ml). It was able to scavenge superoxide anion with IC 50 value of 27.72 μg/ml compared to Trolox (IC 50 value=22.08 μg/ml) and ascorbic acid (IC 50 value=14.65 μg/ml). The hydroxyl radical scavenging activity of sulfinpyrazone is in a concentration-dependent fashion. In the range of concentrations used, sulfinpyrazone was not a scavenger toward H 2 O 2 . However, the intracellular H 2 O 2 -induced 2',7'-dichlorofluorescin diacetate (DCF-DA) fluorescence in HL-60 cells was significantly reduced by sulfinpyrazone during 30-60 min of incubation. Finally, phorbol-12-myristate-13-acetate induced-lucigenin chemiluminescence in whole blood was markedly inhibited by sulfinpyrazone. Our results suggest a new direction for the pharmacological actions of sulfinpyrazone in free radical scavenging properties. 相似文献
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