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111.
Neonatal mouse heart fragments were grafted under the ear skin of adult recipients. Cardiac allograft survival was evaluated by visual observation of pulsation, electrocardiography, and histology. Employing a series of congenic resistant strains differing from C57BL/10Sn at theH-1, H-3,H-4, H-7, H-8, H-9, H-10, H-11, andH-12 loci, the median survival times of the heart grafts to and from C57BL/10Sn were obtained. The various interallelic combinations resulted in a wide variation of graft survival. Reciprocal transplants frequently showed different survival times.H-1
c
grafts were rejected by B10.129(5M)/nSn female mice with a median survival time of 90 days.H-1
b
grafts were not rejected by C57BL/10Sn mice for the experiment's duration of 200 days. The weaker the histocompatibility barrier, the more variable the survival times and the smaller the ratio of rejected to total grafted heart fragments. Female recipients were observed to reject their grafts more rapidly and to reject a higher proportion than males of the same strain. Although the strength of the different non-H-2 barriers generally paralleled that determined by skin transplants, the rankings of the strongest minor barriers were not the same for both tissues. 相似文献
112.
Radhey S. Gupta David Y. H. Chan Louis Siminovitch 《Journal of cellular physiology》1978,97(3):461-467
The hypothesis of functional hemizygosity has been examined for the α-amanitin resistant (AmaR, a codominant marker) locus in a series of Chinese hamster cell lines. AmaR mutants were obtained from different cell lines, e.g., CHO, CHW, M3-1 and CHO-Kl, at similar frequencies. After fractionation of different RNA polymerase activities in the extracts by chromatographic procedures, the sensitivity of the mutant RNA polymerase II towards α-amanitin was determined. While all of the RNA polymerase II activity in mutant CHO and CHO-Kl lines became resistant to α-amanitin inhibition, only about 50% of the activity is highly resistant in AmaR mutants of CHW and M3-1 cell lines. The remaining activity in the latter cell lines shows α-amanitin sensitivity similar to that seen with the wild-type enzyme. This behaviour is similar to that observed with a 1:1 mixture of resistant and sensitive enzymes from CHO cells. These results, therefore, strongly indicate that while only one functional copy of the gene affected by α-amanitin is present in CHO and CHO-Kl cells, two copies of this gene are functional in the CHW and M3-1 cell lines. 相似文献
113.
114.
The hypothesis of functional hemizygosity at the emetine-resistant (Emtr, a non-X-linked recessive marker) locus in Chinese hamster ovary (CHO) cells has been examined by segregation analysis. The frequencies and the rates of segregation of the Emtr and Thgr (thioguanine-resistant, an X-linked recessive mutation) markers were determined from hybrids constructed between an Emtr-Thgr CHO cell line and various other Chinese hamster lines (V79, M3-1, CHO, GM7S, CHW and CHL). Thgr segregants were obtained at similar frequencies (10?2–10?3) from all the hybrids. The frequency of segregation of the Emtr marker, however, was similar to that of Thgr only in the CHO × CHO hybrids and was much lower (10?4–10?6) than the CHO × other Chinese hamster hybrids. Similar results were obtained when the segregation rates for the two markers from various hybrids were determined. These results are consistent with the hypothesis that in CHO cells, the gene responsible for Emtr is present in a single (functional) copy, whereas two copies of this gene are present in other Chinese hamster lines examined. 相似文献
115.
Muramyl dipeptide (MDP), a synthetic adjuvant, increased the primary response of CBA mice to sheep red blood cells (SRBC). In reconstituted irradiated recipients, cooperation between T and B lymphocytes was required for the expression of adjuvant activity and MDP increased the efficiency of SRBC-educated T cells. The role of T-derived lymphocytes in mediating the MDP adjuvant activity was also demonstrated in irradiated mice and in mice reconstituted with various splenic cellular types of donors which had received SRBC and MDP 24 hr earlier. In our experiments, the macrophage did not seem to be involved, since MDP did not increase the phagocytic capacity of peritoneal exudate cells and MDP- and SRBC-pretreated macrophages had no increased ability to induce an anti-SRBC immune response. These results demonstrate the importance of T lymphocytes as mediators of the adjuvant activity of MDP. 相似文献
116.
117.
Inactivation of Glutamine Synthetase by Ammonia Shock in the Gram-Positive Bacterium Streptomyces cattleya 总被引:1,自引:0,他引:1
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In cultures of the gram-positive bacterium Streptomyces cattleya, a rapid inactivation of glutamine synthetase was seen after ammonia shock. pH activity curves for ammonia-shocked and control cultures are shown. A peak of glutamine synthetase activity was seen during fermentation for production of the antibiotic thienamycin. 相似文献
118.
Nicole Dousset Lydia Lapchine Jean-Claude Dousset Louis Douste-Blazy 《生物化学与生物物理学报:生物膜》1982,692(2):223-230
The effect of dicarboxylic phosphatidylcholines (glutarylphosphatidylcholine) on the structural changes of phosphatidylcholine liposomes is examined by using multilamellar liposomes prepared with egg phosphatidylcholine or dipalmitoylphosphatidylcholine and by varying the surface charge by addition of dicetyl phosphate. Investigations are performed by gel chromatography and electron microscopy. Glutarylphosphatidylcholine is in micellar form (rod-like micelles or globular micelles). The structures obtained depend on the fatty acid saturation of liposomes and on the charge of liposome (addition or not of dicetyl phosphate). With egg phosphatidylcholine/glutarylphosphatidylcholine dispersions, an aspect more similar to myelinic figures than liposomes is observed, while in the presence of dicetyl phosphate, liposomes similar to control egg phosphatidylcholine liposomes are obtained. Gel chromatography on Sepharose 4B and turbidity measurements prove that dicetyl phosphate increases the stability of egg phosphatidylcholine/glutarylphosphatidylcholine mixtures. On the other hand, in dipalmitoylphosphatidylcholine/glutarylphosphatidylcholine dispersions, incorporation of dicetyl phosphate destabilizes bilayer structure and the formation of mixed micelles occurs. Viscosity measurement shows, in the presence of dicetyl phosphate, an increased fluidity for dipalmitoylphosphatidylcholine/glutarylphosphatidylcholine dispersions, in agreement with the micellar organization. These data confirm that the disorganization of liposomal membranes by dicarboxylic phosphatidylcholine depends on the fatty acid composition of phosphatidylcholine and on the presence of dicetyl phosphate. 相似文献
119.
A study was conducted to measure the blood plasma concentrations of prostaglandin F2α (PGF2α), 13,14-dihydro-15-keto-prostaglandin F (PGFM), 6-keto-prostaglandin F1α (6-keto), prostaglandin E2 (PGE2), and thromboxane B2 (TBX2) in the ovarian vein, uterine artery, uterine vein, umbilical artery and umbilical vein in 24 cows from days 80 to 260 of pregnancy. Blood was collected during surgery and all prostaglandins were measured using specific radioimmunoassay procedures. Results indicate that PGF2α blood levels are higher in the umbilical vessels and uterine vein than in the ovarian vein and uterine artery. PGFM and PGE2 showed a trend towards higher values in the umbilical than in the maternal vessels, but the levels of 6-keto and TBX2 were not different among the vessels studied. No differences across time couls be observed in any of the prostaglandins measured, partly due to the great variability in blood levels among animals during the same stage of pregnancy. 相似文献
120.
S Cassanelli P Guillaud J Louis D Seigneurin 《The journal of histochemistry and cytochemistry》1991,39(12):1713-1718
Progesterone receptors (PR) appear to be distributed in a heterogeneous way in mammary tumor cells. The study presented here was designed to examine if heterogeneity of PR expression is cell-cycle dependent. Immunofluorescence techniques were used to label PR on the MCF-7 human breast cancer cell line and image cytometry was used to analyze the PR expression during G0 (Ki-67 antigen-negative cells), G1, S, and G2/M cell-cycle phases. A second PR, BrdU, and DNA analysis was performed to study PR expression in the S-phase (BrdU-positive cells). Our results show that PR synthesis occurs preferentially during the G0-G1 transition and that PR levels are constant during the G1-G2 transition. The PR expression appears to be cell-cycle related and may therefore explain the heterogeneity of PR expression. However, the possibility that PR heterogeneity may be linked to the existence of PR-negative subclones cannot be ruled out. 相似文献