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Expression of nodule-specific uricase in soybean callus tissue is regulated by oxygen 总被引:1,自引:0,他引:1 下载免费PDF全文
In soybean root nodules the enzyme uricase is expressed concomitantly with nodule development. The initial expression of this protein does not depend on active nitrogen fixation, as demonstrated by analysis of uricase activity in effective and ineffective root nodules. However, the maximal level of uricase activity is determined by the infecting Rhizobium japonicum strain. Sterile root cultures and callus tissue, devoid of the microsymbiont, were incubated at varying oxygen concentrations and analyzed for uricase activity. The specific activity of uricase was increased by lowering the oxygen concentration, with the highest activity obtained around 4−5% oxygen. The increase in uricase activity was due to increased uricase synthesis, as demonstrated by in vivo labelling of callus culture followed by immunoprecipitation with antibodies raised against highly purified nodule uricase. 相似文献
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P Valentin-Hansen J E Larsen P H?jrup S A Short C S Barbier 《Nucleic acids research》1986,14(5):2215-2228
We have determined the nucleotide sequence of the cytR gene, which codes for the Cyt repressor (CytR). The coding region consists of 1023 or 1029 bp. The subunits of CytR are thus predicted to consist of 341 or 343 residues. It is shown that the N-terminal segment of the polypeptide is structurally similar to the DNA-binding region of known DNA-binding proteins. In addition, there exists an exceptionally high amino acid sequence homology between CytR and the Gal repressor, indicating a common origin of evolution. 相似文献
44.
The relationship of filipin-sterol complexes to tight and gap junctions during their formation, maturation, internalization, and degradation was studied in separate cell lines. Filipin-sterol complexes tended to be excluded from mature junctions in tight junction forming COLO 316 cells and gap junction forming SW-13 cells. Once internalized, unlabeled junctional membrane appeared to fuse with heavily labeled vesicles, presumably lysosomes. Although the absence of filipin-sterol complexes from junctional membrane does not necessarily reflect the absolute sterol content of this membrane, the fact that filipin-sterol complexes are largely excluded from these areas indicates that this membrane is different from surrounding membrane. The absence of filipin-sterol complexes also permits the visualization of 'mixing' of this specialized unlabeled membrane domain with other filipin labeled membrane systems. 相似文献
45.
Characterization by human autoantibody of a nuclear antigen related to the cell cycle 总被引:4,自引:0,他引:4 下载免费PDF全文
Using a serum from a patient with an autoimmune disease, we have recently described a novel 55 000-dalton antigen (p55) in the nucleus of several animal cells including human ones. This antigen, designated PSL, was not related to the previously defined antigens recognized by sera from patients with systemic rheumatic diseases (Sm, n-RNP, SS-B, Scl-70). We have now found that p55 is associated with chromatin structures as it is released from the nucleus of mink cell fibroblasts by saline + DNase treatments. Analysis by sucrose gradient centrifugation of the nuclear material released in these conditions indicated that p55 co-migrated with core histones. Meanwhile, p55 was absent from the residual nuclear matrices (achromatinic nuclei). Localization of p55 in synchronized cells was performed by indirect immunofluorescence and immunoprecipitation. P55 appeared to accumulate in the nucleus during the S phase. Finally, it was not recognized by an anti-SV40 tumor serum that specifically precipitated the protein p53, which has been recently related to cell proliferation. Thus, PSL an p53, although apparently not antigenically related, appear to be implicated in the same step of the cell cycle. 相似文献
46.
Identity of the two 8S RNA components of the mouse sarcoma virus (Moloney) 总被引:1,自引:0,他引:1 下载免费PDF全文
Larsen CJ Ravicovitch RE Hampe A Mauchauffe M Bazilier M Robert-Robin J 《Nucleic acids research》1974,1(7):849-854
The two 8S A and B RNAs of the Mouse Sarcoma Virus (Moloney) can be converted by heating into a homogeneous population. After digestion with T1 RNAse, they give identical fingerprints. It is concluded that these two molecules represent conformational isomers of the same molecular species. 相似文献
47.
Mucous cysts of the fingers 总被引:1,自引:0,他引:1
E Constant J R Royer R J Pollard R D Larsen J L Posch 《Plastic and reconstructive surgery》1969,43(3):241-246
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Alterations in the longevity and fecundity of adult Trichinella pseudospiralis related to method of isolation of infective larvae 总被引:1,自引:0,他引:1
The infectivity of Trichinella pseudospiralis infective larvae was reduced significantly following exposure to low pH or a combination of 1% pepsin at low pH compared to that for larvae isolated in phosphate-buffered saline (PBS) at pH 7.0. Reduction of host gastric pH by administration to mice of sodium bicarbonate solution in PBS was accompanied by an increase in the infectivity of larvae isolated in 1% pepsin/HCl (P/HCl) compared to that for worms inoculated into hosts given PBS alone. Fewer adult worms developing from larvae isolated in P/HCl became established in the host small bowel than was seen with larvae isolated in PBS; moreover, the fecundity in vitro of adult worms developing from P/HCl-isolated larvae was reduced below that for adults developing from larvae isolated from host muscle in PBS. More adult worms were recovered following infection of immune hosts with PBS-isolated larvae than were recovered from immune mice challenged with larvae isolated in P/HCl. Similar findings were observed in mice immunized by infection with Trichinella spiralis and challenged with T. pseudospiralis larvae isolated in either P/HCl or PBS. Immunization of mice with T. pseudospiralis larvae isolated by either method and challenged with larvae of T. spiralis resulted in recovery of similar percentages of the challenge inoculum. 相似文献