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61.
Two newly established inbred strains derived from Mus musculus musculus, designated PWD/Ph (F29) and PWK/Ph (F33), were examined for their alleles at 37 biochemical loci located on 12 different chromosomes. The allelic pattern showed characteristic differences from those observed in common inbred strains. The genetic distance D between PWK/Ph and PWD/Ph was 0.027, whereas the corresponding values for the genetic distances between PWK/Ph and C57BL/6J, DBA/2J, BALB/cJ and SWR/J were 0.777, 0.721, 0.721 and 0.838 respectively. New allozymes are described as being controlled by the loci Es-23, Pre-2 and Tam-1. The genetic relationship to M.m.molossinus is indicated by identical alleles at six other loci (Es-2, Es-9, Es-10, Es-11, Es-18 and Es-22). 相似文献
62.
8 antioxidants were tested in the SOS chromotest for induction of SOS function and for modulation of benzo[a]pyrene-induced SOS function. None of the antioxidants leads to increased beta-galactosidase activity by itself. Butylated hydroxytoluene at concentrations between 10(-5) M and 3 X 10(-4) M enhances benzo[a]pyrene-induced SOS function at benzo[a]pyrene concentrations between 10(-6) M and 3 X 10(-5) M. Butylated hydroxyanisole, ethoxyquin, propyl gallate and octyl gallate also slightly enhance benzo[a]pyrene-induced SOS function at concentrations up to 3 X 10(-4) M though to a lesser degree than butylated hydroxytoluene. Dodecyl gallate, vitamin C and alpha-tocopherol do not increase benzo[a]pyrene action. In concentrations exceeding 3 X 10(-4) M all synthetic antioxidants tested but not vitamin C and alpha-tocopherol decrease beta-galactosidase activity both in the absence and, more extensively, in the presence of benzo[a]pyrene. Preliminary data suggest that the apparent suppression of benzo[a]pyrene-induced SOS function is not due to an effect on the formation of benzo[a]pyrene metabolites by the metabolizing system used. 相似文献
63.
Carbon and nitrogen partitioning in young nodulated pea (wild type and nitrate reductase-deficient mutant) plants exposed to NH4 NO3 总被引:1,自引:0,他引:1
David C. Taylor Barry J. Shelp Louise M. Nelson Bernard Grodzinski 《Physiologia plantarum》1988,74(4):593-601
Carbon and nitrogen partitioning was examined in a wild-type and a nitrate reductase-deficient mutant (A317) of Pisum sativum L. (ev. Juneau), effectively inoculated with two strains of Rhizobium leguminosarum (128C23 and 128C54) and grown hydroponically in medium without nitrogen for 21 days, followed by a further 7 days in medium without and with 5 mM NH4 NO3 . In wild-type symbioses the application of NH4 NO3 significantly reduced nodule growth, nitrogenase (EC 1.7.99.2) activity, nodule carbohydrates (soluble sugars and starch) and allocation of [14 C]-labelled (NO3 − , NH4 + , amino acids) in roots. In nodules, there was a decline in amino acids together with an increase in inorganic nitrogen concentration. In contrast, symbioses involving A317 exhibited no change in nitrogenase activity or nodule carbohydrates, and the concentrations of all nitrogenous solutes measured (including asparagine) in roots and nodules were enhanced. Photosynthate allocation to the nodule was reduced in the 128C23 symbiosis. Nitrite accumulation was not detected in any case. These data cannot be wholly explained by either the carbohydrate deprivation hypothesis or the nitrite hypothesis for the inhibition of symbiotic nitrogen fixation by combined nitrogen. Our result with A317 also provided evidence against the hypothesis that NO3 − and NH4 + or its assimilation products exert a direct effect on nitrogenase activity. It is concluded that more than one legume host and Rhizobium strain must be studied before generalizations about Rhizobium /legume interactions are made. 相似文献
64.
J Nakagawa D von der Ahe D Pearson B A Hemmings S Shibahara Y Nagamine 《The Journal of biological chemistry》1988,263(5):2460-2468
65.
A J Marcus L B Safier H L Ullman N Islam M J Broekman J R Falck S Fischer C von Schacky 《The Journal of biological chemistry》1988,263(5):2223-2229
In the course of a cell-cell interaction, 12-HETE (12-hydroxy-5,8,10,14-eicosatetraenoic acid), the arachidonic acid lipoxygenase product released from stimulated platelets, is metabolized by a cytochrome P-450 enzyme system in unstimulated neutrophils to 12,20-DiHETE (12,20-dihydroxy-5,8,10,14-eicosatetraenoic acid). This report describes time-dependent formation of a new eicosanoid by unstimulated neutrophils exposed to 12-HETE, which is more polar than 12,20-DiHETE (reversed-phase high performance liquid chromatography). Time course studies indicated that the precursor compound of this new eicosanoid was 12,20-DiHETE. This was determined by incubation of purified 12,20-DiHETE with neutrophils, which resulted in a progressive decrease in 12,20-DiHETE as formation of the polar metabolite increased. In the absence of neutrophils, 12,20-DiHETE was quantitatively unchanged. The new metabolite of 12,20-DiHETE was identified as 12-hydroxyeicosatetraen-1,20-dioic acid, based upon its UV spectrum, co-chromatography with a chemically synthesized standard in both high performance liquid chromatography and thin layer chromatography systems, and gas chromatography-mass spectrometry. Formation of 12-HETE-1,20-dioic acid was partially inhibited by 20-hydroxy-LTB4. This indicated that the neutrophil dehydrogenase responsible for further metabolism of 12,20-DiHETE may also be involved in conversion of 20-hydroxy-LTB4 to 20-carboxy-LTB4. The 12,20-DiHETE dehydrogenase enzyme system specifically requires NAD as cofactor and has subcellular components in both cytosolic and microsomal fractions which are synergistic in their activity. These results provide additional evidence for the occurrence of multicellular metabolic events during hemostasis, thrombosis, and the inflammatory response. 相似文献
66.
Richard M. Napier Michael A. Venis Michael A. Bolton Louise I. Richardson Goeffrey W. Butcher 《Planta》1988,176(4):519-526
Binding proteins, thought to be auxin receptors, can be solubilised from maize (Zea mays L.) membranes after acetone treatment. From these crude extracts, receptor preparations of over 50% purity can be obtained by a reliable, straight-forward procedure involving three chromatographic steps — anion exchange, gel filtration and high-resolution anion exchange. Such preparations have been used to immunise rats for subsequent production of monoclonal antibodies. By the further step of native polyacrylamide gel electrophoresis the semi-purified preparations yield homogeneous, dimeric (22-kilodalton, kDa) auxin-binding protein, which has been used to produce a polyclonal rabbit antiserum. The preliminary characterisation of this antiserum and of the five monoclonal antibodies is presented. Two of the monoclonal antibodies specifically recognise the major 22-kDa-binding protein polypeptide whilst the other three recognise, in addition, a minor 21-kDa species. All the monoclonal antibodies recognise the polypeptide rather than the glycan side chain and the polyclonal antiserum also recognises deglycosylated binding protein. The antibodies have been used to quantify the abundance of auxinbinding protein in a number of tissues of etiolated maize seedlings. Root membranes contain 20-fold less binding protein than coleoptile membranes.Abbreviations ABP
auxin-binding protein
- DEAE
diethylaminoethyl
- Ig
immunoglobulin
- kDa
kilodalton
- NAA
naphthalene-1-acetic acid
- Mr
relative molecular mass
- PAGE
polyacrylamide gel electrophoresis
- SDS
sodium dodecyl sulfate 相似文献
67.
Mechanism of neutrophil activation by NAF, a novel monocyte-derived peptide agonist 总被引:27,自引:0,他引:27
The rise in cytosolic free Ca2+, shape change, superoxide formation, and granule exocytosis induced in human neutrophils by N-formyl-Met-Leu-Phe (fMLP) and by a newly discovered activating peptide, neutrophil-activating factor, termed NAF, were compared. NAF was effective in the concentration range of 0.1-10 nM and was 10- to 100-fold more potent than fMLP. In qualitative terms, the single responses to either stimulus were remarkably similar: they showed virtually identical onset and initial kinetics, and were all inhibited by pretreatment of the neutrophils with Bordetella pertussis toxin. In addition, the respiratory burst elicited by either stimulus was inhibited by 17-hydroxywortmannin and staurosporine. Two conclusions are drawn from these results: 1) neutrophil activation by NAF (as by fMLP) is dependent on a GTP-binding protein and on protein kinase C; 2) a similar, or even identical, mechanism of signal transduction must be assumed on stimulation of human neutrophils with NAF, fMLP, and other chemotactic agonists. Human monocytes, lymphocytes, and platelets did not show cytosolic free Ca2+ changes when exposed to NAF, which suggests that NAF is selective for the neutrophils. 相似文献
68.
Selection of DNA binding sites by regulatory proteins 总被引:15,自引:0,他引:15
69.
P Kolkhof D Teichmann B Kisters-Woike B von Wilcken-Bergmann B Müller-Hill 《The EMBO journal》1992,11(8):3031-3038
Lac repressor, lambda cro protein and their operator complexes are structurally, biochemically and genetically well analysed. Both proteins contain a helix-turn-helix (HTH) motif which they use to bind specifically to their operators. The DNA sequences 5'-GTGA-3' and 5'-TCAC-3' recognized in palindromic lac operator are the same as in lambda operator but their order is inverted form head to head to tail to tail. Different modes of aggregation of the monomers of the two proteins determine the different arrangements of the HTH motifs. Here we show that the HTH motif of lambda cro protein can replace the HTH motif of Lac repressor without changing its specificity. Such hybrid Lac repressor is unstable. It binds in vitro more weakly than Lac repressor but with the same specificity to ideal lac operator. It does not bind to consensus lambda operator. 相似文献
70.
The translocation (6;9), associated with a specific subtype of acute myeloid leukemia, results in the fusion of two genes, dek and can, and the expression of a chimeric, leukemia-specific dek-can mRNA. 总被引:14,自引:0,他引:14
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M von Lindern M Fornerod S van Baal M Jaegle T de Wit A Buijs G Grosveld 《Molecular and cellular biology》1992,12(4):1687-1697