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71.
Silvio De Flora Francesco D'Agostini Alberto Izzotti Roumen Balansky 《Mutation research》1991,250(1-2):87-93
The daily i.t. administration of benzo[a]pyrene (BP) to Sprague-Dawley rats, for 3 consecutive days, did not cause any toxicity or clastogenicity in bone marrow cells, as evaluated by monitoring the ratio of polychromatic to normochromatic erythrocytes and the frequency of micronucleated polychromatic erythrocytes. However, BP produced a considerable enhancement of binucleated and micronucleated pulmonary alveolar macrophages, as well as a significant increase in polymorphonucleates recovered by bronchoalveolar lavage. These effects were prevented by administering the thiol N-acetylcysteine (NAC) by gavage 5 h before each BP instillation. In addition, the i.t. treatment with BP resulted in the formation of BP diolepoxide (BPDE)-DNA adducts in lungs and liver, as assessed by synchronous fluorescence spectrophotometry, with fluorescence peaks of similar magnitude in the 2 tissues. Pretreatment with NAC by gavage completely prevented BPDE adducts to liver DNA and significantly decreased those to lung DNA. 相似文献
72.
Rosa Sorrentino Carlo Iannicola Sandro Costanzi Alberto Chersi Roberto Tosi 《Immunogenetics》1991,33(2):118-123
DNA molecules derived from three alleles of the HLA-DRB3 locus and differing from each other at several nucleotide sites were denatured and cross-hybridized. Each allelic combination was found to generate a pair of heteroduplexes of different mobility. Their retardation as compared to homoduplexes was proportional to the number of mismatches. In each heteroduplexes pair the component possessing the highest number of Pyr-Pyr oppositions was the most retarded. The results are those predicted by a theoretical model implying a correlation between base-pair opening and bending of the DNA double helix. These observations introduce a new HLA typing method at the genomic level and indicate an experimental approach to the analysis of the superhelical DNA conformation as related to different types of base oppositions. 相似文献
73.
Gerardo Argüello Enrique García-Hernández Mireya Sánchez Patricio Gariglio Luis Herrera-Estrella June Simpson 《The Plant journal : for cell and molecular biology》1992,2(3):301-309
Two protein factors binding to the regulatory region of the pea chlorophyl a/b binding protein gene AB80 have been identified. One of these factors is found only in green tissue but not in etiolated or root tissue. The second factor (denominated ABF-2) binds to a DNA sequence element that contains a direct heptamer repeat TCTCAAA. It was found that presence of both of the repeats is essential for binding. ABF-2 is present in both green and etiolated tissue and in roots and factors analogous to ABF-2 are present in several plant species. Computer analysis showed that the TCTCAAA motif is present in the regulatory region of several plant genes. 相似文献
74.
Summary Previous studies examining the regulation of the synthesis of G6PDH and 6PGDH in rat liver and adipose tissue have focused on the induction of these enzymes by different diets and some hormones. In rat liver these enzymatic activities seem to be regulated by a mechanism involving changes in the NADPH requirements. In this paper we have studied the effect of changes in the flux through different NADPH-consuming pathways on G6PDH and 6PGDH levels in adipose tissue and on the NADPH/NADP ratio. The results show that: I) an increase in the consumption of NADPH, caused by the activation of either fatty acid synthesis or detoxification systems which consume NADPH, is paralleled by an increase in the levels of these enzymes; II) when the increase in consumption of NADPH is prevented, the G6PDH and 6PGDH levels do not change.Abbreviations G6PDH
Glucose-6-Phosphate Dehydrogenase
- 6PGDH
6-Phosphogluconate Dehydrogenase
- GR
Glutathione Reductase
- ME
Malic Enzyme
- tBHP
t-Butyl Hydroperoxide
- NF
Nitrofurantoin
- CumOOH
Cumene Hydroperoxide 相似文献
75.
Luigi D. Notarangelo Ornella Parolini Fulvio Porta Franco Locatelli Arnalda Lanfranchi Massimo Marconi Luigi Nespoli Alberto Albertini Ian W. Craig Alberto G. Ugazio 《Human genetics》1991,88(2):237-241
Summary We report on a thrombocytopenic female belonging to a pedigree with the Wiskott-Aldrich syndrome (WAS). Restriction fragment length polymorphism (RFLP) analysis with probe M27, closely linked to the WAS gene, demonstrated that she is a carrier of WAS. Both small-sized and normal-sized platelets were present, suggesting that, unlike the vast majority of WAS carriers, she does not manifest nonrandom X-chromosome inactivation in the thrombopoietic cell lineage. Study of X-chromosome inactivation by means of RFLP and methylation analysis demonstrated that the pattern of X-chromosome inactivation was nonrandom in T lymphocytes, but random in granulocytes. While this is the first complete report on the occurrence of thrombocytopenia in a carrier female of WAS as the result of atypical lyonization, it also suggests that expression of the WAS gene occurs at (or extends up to) a later stage than the multipotent stem cell along the hematopoietic differentiation pathway. 相似文献
76.
Quantitative Immunologic Analysis of the Methanogenic Flora of Digestors Reveals a Considerable Diversity 总被引:9,自引:8,他引:1
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To determine which methanogens occur in digestors, we performed a quantitative immunologic analysis of a variety of samples. A comprehensive panel of calibrated polyclonal antibody probes of predefined specificity spectra was used. This allowed precise identification of bacteria by antigenic fingerprinting. A considerable diversity of methanogens was uncovered, much larger than previously reported, encompassing at least 14 strains of 11 species. Strategies were developed to measure the load of any given methanogen in a sample and to compare samples quantitatively. Two methanogens were found to predominate which were antigenically closely related with either Methanobacterium formicicum MF or Methanobrevibacter arboriphilus AZ. Fundamental data, probes, and methods are now available to monitor methanogenic subpopulations during digestor operation and thus learn about their respective roles and predictive significance. 相似文献
77.
Alberto J. Solari 《Genetica》1988,77(2):149-158
A sample of 90 XY pairs from men with normal karyotypes has been analyzed by measuring their morphological features in electron micrographs of microspread spermatocytes. The classification of human XY types (Solari, 1980) has been given stricter definitions. Stepwise splitting of the axes is seen in types 1 and 2. The development of axial branches and lenhthening of the X axis is seen in type 3. In the two subtypes a and b of type 4 the net-like filamentous array grows in length to a maximum (average=59.7 m) in subtype b. The location of the putative Y kinetochore defines a short arm that measures 22.34% of Y axis length, and the kinetochore of the X axis defines a short arm of 38.15% of the axial length. The average number of excrescences in the X axis is 19.9 and in the Y is 4.3. The frequency of a non-homologous, distal end-joining grows steadily from type 0 to type 3. The average length of the synaptonemal complex (SC) in 51 XY pairs of types 1 and 2 is 1.33 m (SD=0.65) and it corresponds to 25.54% of the Y axis length. Thus, the average SC covers the short arm of the Y and the pericentromeric region. Maximum lengths of this SC may reach up to 81.8% of the Y axis, 30 recombination nodules (RNs) were located in 26 XY pairs, and 90% of the nodules are located in the distal half of the short arm of the Y axis. Thus, RNs are restricted to a segment much shorter than the length of the average SC. A gradient of decreasing probability of recombination may reach up to the centromeric region of the Y chromosome. Some possible consequences of these facts are discussed. 相似文献
78.
79.
Elizabeth R. Fielding David B. Archer Everly Conway de Macario Alberto J. L. Macario 《Applied microbiology》1988,54(3):835-836
Methanogenic bacteria were isolated from landfill sites in the United Kingdom. Strains of Methanobacterium formicicum, Methanosarcina barkeri, several different immunotypes of Methanobacterium bryantii, and a coccoid methanogen distinct from the reference immunotypes were identified. 相似文献
80.
The components of magnesium efflux in squid axons have been studied under internal dialysis and voltage clamp conditions. The present report rules out the existence of an ATP-dependent, Na0- and Mg0-independent Mg2+ efflux (ATP-dependent Mg2+ pump) leaving the Mg2+---Na+ exchange system as the only mechanism for Mg2+ extrusion. The main features of the Mg2+ efflux are: (1) The efflux is completely dependent on ATP. (2) The efflux can be activated either by external Na+ (forward Mg2+---Na+ exchange) or external Mg2+ (Mg2+---Mg2+ exchange). (3) The mobility of the Mg2+ exchanger in the Na0+-loaded form is greater than that in the Mg2+-loaded one. (4) In variance with the Na+---Ca2+ exchange mechanism, Mg2+---Mg2+ exchange is not activated by external monovalent cations. (5) ATPγS replaces ATP in activating Mg2+---Na+ exchange suggesting that a phosphorylation/dephosphorylation process regulates this transport mechanism. 相似文献