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91.
M.Carmen Aragón Cecilio Giménez Federico Mayor Juan G. Marvizón Fernando Valdivieso 《生物化学与生物物理学报:生物膜》1981,646(3):465-470
Tyrosine uptake by membrane vesicles derived from rat brain has been investigated. The uptake is dependent on an Na+ gradient ([). The uptake is transport into an osmotically active space and not a binding artifact as indicated by the effect of increasing the medium osmolarity. The process is stimulated by a membrane potential (negative inside) as demonstrated by the effect of the ionophores valinomycin and carbonyl cyanide and anions with different permeabilities. Kinetic data show that tyrosine is accumulated by two systems with different affinities. Tyrosine uptake is inhibited by the presence of phenylalanine and tryptophan. 相似文献
92.
93.
Summary The majority of lymphocytes separated from tumor cell suspensions were T cells. Conjugates of T lymphocytes and tumor cells were often seen. Variable numbers of T cells exhibited signs of activation such as the ability to form stable E rosettes and attachment to normal and malignant cells (a phenomenon designated natural attachment: NA). A proportion of T cells activated in vitro by allogeneic stimulation regularly exhibit these properties. The T cell-tumor conjugates in the suspensions may represent the NA phenomenon, but they could also be the product of T cells that adhere on the basis of specific recognition of cell surface antigens.Abbreviations BBS
balanced salt solution
- E rosettes
rosettes formed with sheep erythrocytes
- EA rosettes
rosettes formed with ox erythrocytes coated with anti-ox IgG
- FCS
fetal calf serum
- MLC
mixed lymphocyte cultures
- NA
natural attachment
- PBL
peripheral blood lymphocytes
- SRBC
sheep erythrocytes
- T lymphocytes
thymusderived lymphocytes 相似文献
94.
95.
Carmen Attolini Giorgio Mazza Adriana Fortunato Giovanni Ciarrocchi Giorgio Mastromei Silvano Riva Arturo Falaschi 《Molecular & general genetics : MGG》1976,148(1):9-17
Summary The dnaP strains of Bacillus subtilis are altered in the initiation of DNA replication at high temperature (Riva et al., 1975). Fine mapping of the gene shows that it is located very close to the dnaF gene, described by Karamata and Gross (1970) and mapped by Love et al. (1976) in the polC region. The phenotype of both mutants is indistinguishable: the DNA synthesis stops at non permissive temperature after synthesizing an amount of DNA equivalent to the completion of the rounds of replication already initiated; at permissive temperature they are abnormally sensitive to MMS and are reduced in the ability to be transformed. Both mutants are to be considered as belonging to the dnaF locus.The dnaF gene is very close to the polC gene, which specifies the DNA polymerase III of B. subtilis. The DNA polymerase III of the dnaF mutants is not temperature sensitive in vitro, however, the level of this enzyme is lower by a factor of 4 or 5 in the dnaF mutants, at the permissive temperature. Following shift of dnaF cultures to the non permissive temperature, the level of DNA polymerase III activity specifically decreases further by a factor of at least 10 in the mutant, whereas the DNA polymerase I level is unaffected.The possible roles of the dnaF gene in the control of the cellular level of the DNA polymerase III, and the possibility of a regulatory role of DNA polymerase III in the initiation of DNA replication in bacteria are discussed.Abbreviations and symbols HPUra
6-(p-hydroxyphenylazo)-uracil; mic, minimum inhibitory concentration
- MMS
methyl-methanesufonate
- Pol I
Pol II and Pol III: DNA polymerase I, II and III respectively
- PCMB
parachloro-mercuri-benzoate 相似文献
96.
Summary The dryness-induced ultrastructural changes of both myco- and phycobiont of three lichen species (R. geographicum, P. conspersa, andU. pustulata) have been studied over three months and half, period of time. During this time other ecological factors, such as rock substratum, temperature, light and gas interchange were unaltered compared to the natural conditions. A large number of ultrastructural changes were observed in the mycobiont as well as in the phycobiont (Trebouxia) and often, cells showed a highly disorganized morphology. The most important ultrastructural modifications were: 1. pyrenoglobuli of the algae were peripheral, 2. new and unknown structures were observed in the phycobionts of bothR. geographicum andU. pustulata as well as in the mycobiont of the latter species. 相似文献
97.
Carol M. Warner Ruth M. Graves Carla M. Tollefson Mary Jo F. Schmerr Thomas J. Stephens Carmen F. Merryman Paul H. Maurer 《Immunogenetics》1976,3(1):337-348
The immune response of allophenic mice of type C57BL/6(A × SJL) F1 to GL administered in complete Freund's adjuvant was tested. Control mice of the three strains C57BL/6, A, and SJL are all nonresponders to this antigen. However, the F1 generations of C57BL/6 × A, C57BL/6 × SJL, and A × SJL were all responders to the antigen, so that the complementarity of at least two genes is confirmed. The allophenic mice showed no further complementation beyond the F1 generation, a result which may argue against the possibility that more than two genes control the response to GL in these mouse strains. Characterization of the allophenic mice over several months showed that they exhibit chimeric drift, both in their coat color and in peripheral white blood cell population. There is no apparent correlation of coat color to the lymphocyte composition of the mice at any one time. The mice are true chimeras, since killing of the two populations of white blood cells with two different anti-H-2 sera produced a 100 percent killing. The immune response of individual allophenic mice to GL showed a good correlation to the number of A × SJL lympho-cytes in the animal.Abbreviations used in this paper are GL
an amino acid polymer of 57 %l-glutamic acid, 38%l-lysine, and 5%l-phenylalanine
- GLT15
an amino acid polymer ofl-glutamic acid,l-lysine, and 15 %l-tyrosine
- (T,G)-A-L
an amino acid polymer having a polylysine backbone with side chains of polyd-l-alanine, terminating in short sequences of tyrosine and glutamic acid
- GAT10
an amino acid polymer of 60%l-glutamic acid, 30%l-alanine, and 10%l-tyrosine
- GLA5
an amino acid polymer of 57%l-glutamic acid, 38%l-lysine, and 5%l-alanine
- DNP
2,4 dinitrophenyl
- BGG
bovine gamma globulin
- FCS
fetal calf serum
- PWBC
peripheral white blood cell
- SWBC
spleen white blood cell
- T cell
thymus-derived lymphocyte
- B cell
bone marrow-derived lymphocyte 相似文献
98.
David S. Auld Ikuo Atsuya Carmen Campino Pablo Valenzuela 《Biochemical and biophysical research communications》1976,69(2):548-554
Microwave excitation spectrometry and metal binding inhibition studies show that zinc is a catlytically essential component of the highly purified RNA polymerase I from yeast, the first eukaryotic RNA polymerase I available in quantities sufficient for such studies. It contains 2.4 g-atom of zinc based on a molecular weight of 6.5 × 105 (8). Copper, iron, manganese and magnesium are absent, i.e., below the limits of detection, 10?13 to 10?14 g-atoms. A number of derivatives of 1,10-phenanthroline reversibly inhibit the polymerase catalyzed reaction, apparently by forming a ternary polymerase·Zn·OP complex while the nonchelating isomer, 1,7-phenanthroline, is ineffective. 相似文献
99.
100.