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61.
Fractionation and Estimation of Particle-Attached and Unattached Bradyrhizobium japonicum Strains in Soils 总被引:2,自引:2,他引:0 下载免费PDF全文
Rhizobial cells attached or unattached to soil particles were estimated. Nonsterile soils into which antibiotic-resistant mutants of Bradyrhizobium japonicum had been introduced were fractionated by a centrifugation technique into two fractions: A, which contained mainly rhizobial cells attached to soil particles, and F, which contained mainly rhizobial cells unattached to them. Rhizobial counts decreased in both fractions during incubation of the soil at 30°C, with a concomitant decrease in the proportion of the count of fraction F to that of fraction A. Sonication of fraction A of the soil incubated for more than 3 weeks caused an increase in the rhizobial count. The ratio of the count of fraction A estimated by the plant infection method to that estimated by the dilution plate method increased after 5 days of soil incubation. More than 90% of the indigenous rhizobia in an agricultural field existed in fraction A. These results suggest that the majority of rhizobial cells are attached to soil particles. 相似文献
62.
Y Kawano K Taniguchi A Toshitani K Nomoto 《Journal of immunology (Baltimore, Md. : 1950)》1986,136(12):4729-4734
H-2+ and H-2- cells of B16 melanoma were established by repeated fluorescence-activated cell sorting. The H-2- line formed no metastasis in untreated C57BL/6 mice, whereas the H-2+ cells showed evidence of metastatic development. This difference was ascribed mainly to the increased susceptibility of H-2- cells to attack by natural effector mechanisms, particularly asialo GM1+ NK cells. After treatment with both anti-asialo GM1 serum and whole body irradiation (400 rad), numerous colonies of H-2- cells formed in the lung, whereas the metastasis was only marginally enhanced by irradiation and moderately by treatment with anti-asialo GM1 serum. With the H-2+ cells, treatment with each modality significantly increased the number of metastatic colonies. Therefore collaboration of asialo GM1+ NK cells and radiosensitive natural effectors seems to be the main mechanism involved in the synergistic effects on defense against H-2- cell metastasis, and to a lesser extent against H-2+ cell metastasis. Irradiation (1000 rad) to the right lung to abrogate the organ-associated defense increased the colonies, particularly in the H-2+ cells. On the other hand, treatment with anti-asialo GM1 serum increased colonization in the early phase of metastasis with H-2- cells and may have abolished asialo GM1+ NK cells capable of recognizing the reduced expression of H-2 antigens and eliminating H-2- cells in the blood-born phase. Natural defense mechanisms probably exert suppressive effects on the metastasis of H-2+ cells, mainly in the organ-associated phase after extravasation. 相似文献
63.
Quantitation of the Myelin-Associated Glycoprotein in Human Nervous Tissue from Controls and Multiple Sclerosis Patients 总被引:3,自引:2,他引:1
David Johnson Shuzo Sato Richard H. Quarles Takashi Inuzuka Roscoe O. Brady Wallace W. Tourtellotte 《Journal of neurochemistry》1986,46(4):1086-1093
Myelin-associated glycoprotein (MAG) was measured by radioimmunoassay in the human CNS and peripheral nervous system (PNS). The level of MAG, expressed as ng/microgram of total protein, was approximately 20-fold higher in whole homogenates of cerebral white matter (4.7 +/- 0.60) than of peripheral nerve (0.12-0.28). MAG concentrations were only slightly higher in the isolated myelin fractions from these tissues: CNS myelin, 5.6 ng/microgram; PNS myelin, 0.37 ng/microgram. The levels of MAG were measured in nine plaques, periplaque regions, and areas of macroscopically normal-appearing white matter (NAWM) from six separate multiple sclerosis brains and compared with the levels of other myelin proteins in the same samples. MAG and other myelin proteins were reduced to very low levels in plaques. The levels of MAG and basic protein (BP) and the activity of 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) in periplaque areas were significantly lower than those in control white matter, and MAG and BP levels were also significantly reduced in NAWM. In a periplaque region and NAWM from the most rapidly progressing case of multiple sclerosis examined, the MAG content was between 30 and 35% of the control level, whereas BP and PLP levels and CNP activity were between 50 and 85% of control values. The reduction of MAG content in periplaque regions from all nine multiple sclerosis plaques examined was significantly greater than the reductions of BP level and CNP activity. In NAWM samples, the mean reduction of MAG content was also greater than the reductions of BP level and CNP activity, but the difference was only statistically significant in comparison to CNP.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
64.
Growth and Aspartate Kinase Activity in Wheat Cell Suspension Culture: Effects of Lysine Analogs and Aspartate-Derived Amino Acids 总被引:1,自引:0,他引:1
Yamada Yasuyuki; Kumpaisal Rosarin; Hashimoto Takashi; Sugimoto Yukihiro; Suzuki Akinori 《Plant & cell physiology》1986,27(4):607-617
The effects of lysine analogs and aspartate-derived amino acidson the growth of wheat cell suspension culture were studied.S-(2-Aminoethyl)-L-cysteine (AEC), -hydroxylysine (DHL) andtrans-lysene caused complete growth inhibition at 1.0 mM. Thegrowth inhibition of lysine analogs were, in the order of decreasingeffectiveness; AECDHL, trans-lysene>oxalysine, homolysineand lysyne. cis-Lysene and methyllysine were not inhibitoryeven at concentrations of 10 mM. Lysine effectively relievedgrowth inhibition induced by the lysine analogs. Lysine plusthreonine showed concerted inhibition, which was relieved bythe addition of methionine. Activity of aspartate kinase extracted from wheat cell suspensionculture was strongly inhibited by L-lysine; 0.75 to 1 mM oflysine was required for half-maximal inhibition. Threonine andmethionine, individually or in combination with lysine, showedno inhibitory effect on the enzyme activity. S-Adenosylmethionine,when added with lysine in equimolar concentrations, enhancedthe feedback inhibition by lysine, lowering the concentrationof lysine for half-maximal inhibition to 0.13 mM. The aspartatekinase isolated from the cells cultured in the presence of 5mM lysine did not differ in regulatory properties from the enzymefrom the cells cultured without lysine. AEC at 5 mM inhibitedthe enzyme activity by 50%. Other lysine analogs were not inhibitoryto the enzyme activity even at 10 mM. Growth inhibition of wheat suspension culture by aspartate-derivedamino acids and lysine analogs were discussed in relation totheir inhibitory effects on aspartate kinase activity. (Received October 25, 1985; Accepted February 26, 1986) 相似文献
65.
Biochemical Characterization of α-Adrenergic Receptors in Human Brain and Changes in Alzheimer-Type Dementia 总被引:2,自引:2,他引:0
Shun Shimohama Takashi Taniguchi Motohatsu Fujiwara Masakuni Kameyama 《Journal of neurochemistry》1986,47(4):1294-1301
Abstract Using ligand binding techniques, we studied α-adrenergic receptors in brains obtained at autopsy from seven histologically normal controls and seven patients with histopathologically verified Alzheimer-type dementia (ATD). Binding of the α-adrenergic antagonists [3H]prazosin and [3H]yohimbine to membranes of human brains exhibited characteristics compatible with α1- and α2-adrenergic receptors, respectively. Binding of both ligands was saturable and reversible, with dissociation constants of 0.15 nM for [3H]prazosin and 5.5 nM for [3H]yohimbine. [3H]Prazosin binding was highest in the hippocampus and frontal cortex and lowest in the caudate and putamen in the control brains. [3H]Yohimbine binding was highest in the nucleus basalis of Meynert (NbM) and frontal cortex and lowest in the caudate and cerebellar hemisphere in the control brains. Compared with values for the controls, [3H]prazosin binding sites were significantly reduced in number in the hippocampus and cerebellar hemisphere, and [3H]yohimbine binding sites were significantly reduced in number in the NbM in the ATD brains. These results suggest that α1 and α2-adrenergic receptors are present in the human brain and that there are significant changes in numbers of both receptors in selected regions in patients with ATD. 相似文献
66.
(6R)-Tetrahydrobiopterin Increases the Activity of Tryptophan Hydroxylase in Rat Raphe Slices 总被引:2,自引:2,他引:0
Makoto Sawada Takashi Sugimoto Sadao Matsuura Toshiharu Nagatsu† 《Journal of neurochemistry》1986,47(5):1544-1547
The effects of (6R)- and (6S)-tetrahydrobiopterin (BPH4), tetrahydroneopterin, and 6-methyltetrahydropterin on the activity of tryptophan hydroxylase were investigated in rat raphe slices. The activity of tryptophan hydroxylase was estimated by measurement of 5-hydroxytryptophan (5-HTP) formation under inhibition of aromatic L-amino acid decarboxylase with use of HPLC-fluorometric detection. (6R)-BPH4 (the naturally occurring form) at 42 microM, tetrahydroneopterin at 50 microM, and 6-methyltetrahydropterin at 100 microM increased tryptophan hydroxylase activity to 350, 145, and 146% of control values, respectively. (6S)-BPH4, however, had no significant effects on tryptophan hydroxylase activity. These results suggest that tryptophan hydroxylase is subsaturating in vivo for the naturally occurring cofactor, (6R)-BPH4, and that the concentration of (6R)-BPH4 may play an important role for the regulation of tryptophan hydroxylase activity in vivo. 相似文献
67.
An oxygen-evolving complex has been highly purified from the thermophilic cyanobacterium Synechococcus sp. The complex, which reproducibly showed 5 major polypeptide bands of 47, 40, 35, 30 and 9 kDa on SDS-polyacrylamide gel electrophoresis and contained 3.2 Mn per QA, had an oxygen-evolving activity of 300–400 μmol/mg chl per h in the presence of 5 mM MnCl2; or CaCl2. The complex most likely represents a minimum functional unit of the photosynthetic oxygen evolution. 相似文献
68.
GM3 ganglioside, added exogenously to a promyelocytic leukemia cell line (HL-60 cells) in serum-free synthetic medium, induced differentiation into macrophage-like cells. Macrophagic morphology and function of differentiation-induced cells were determined by cell growth behavior, May-GriJnwald-Giemsa staining, activities of nonspecific esterase, phagocytosis and nitroblue tetrazolium (NBT) reduction. GM3 ganglioside may play a role in triggering differentiation of HL-60 cells into macrophage-like cells. 相似文献
69.
Takashi Momoi Tatsuko Furuya Yoshiyuki Suzuki Hiroko Sato Nubuo Yamaguchi 《Bioscience reports》1985,5(3):267-273
The permanent human cell lines preserving defects of lysosomal enzymes, GM1-1019-SV and SA-1077-SV, were established from the respective fibroblasts from patients with GMl-gangliosidosis and Sandhoff disease by transfection with replication origin-minus simian virus 40 DNA. These ceils grow rapidly without entering senescence during more than 120 population doublings. The activity of -galactosidase in GM1-1019-SV and of B-N-acetylhexosaminidase in SA-1077-SV was respectively 40- and 180-fold lower than that of normal fibroblasts. 相似文献
70.
Susumu Wakabayashi Yumi Magae Yutaka Kashiwagi Takashi Sasaki 《Applied microbiology and biotechnology》1985,21(5):328-330
Summary When purified protoplasts of Pleurotus cornucopiae IFO9614 were incubated with a mixture of cell wall lytic enzymes, they were found to increase their size. Their average diameter increased from 4.3 m to 31 m after 65 h incubation at 24° C. The presence of cellulase ONOZUKARS in the enzyme mixture had a significant effect on the formation of giant protoplasts. Regeneration frequency of giant protoplasts in a medium containing 0.5 M sucrose was 3.5%, approximately six times that of normal protoplasts. 相似文献