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41.
Abstract Nif− mutants of Rhodobacter capsulatus carrying mutations either in the nifR4 regulatory gene or in the nifH structural gene both outgrew the wild-type strain B10 in mixed chemostat cultures under conditions favouring nitrogenase-mediated H2 production by the wild-type (ammonia as limiting nutrient, inert argon atmosphere, light as energy source), whereas under aerobic conditions in the dark, or in batch culture, the growth of Nif− mutants was not favoured. Nitrogenase-mediated H2 production therefore appears to be detrimental to the growth of R. capsulatus in nitrogen-limited continuous culture, as may also be the case for other nitrogen fixers. 相似文献
42.
Seven different hosts,Panicum maximum, Chrysopogon fulvis, Themeda triandra, Chloris gayana, Brachiaria brizantha, Paspalum scrobiculatum andEleusine coracana were screened in order to select a better host for mass multiplication ofGlomus fasciculatum inoculum. Of these,Chloris gayana (Rhodes grass) was found to be the best host on the basis of root colonization and spore production and of the infective
propagules of the potball. 相似文献
43.
Production of gibberellins and indole-3-acetic acid by Rhizobium phaseoli in relation to nodulation of Phaseolus vulgaris roots 总被引:2,自引:0,他引:2
Similar ranges of gibberellins (GAs) were detected by high-performance liquid chromatography (HPLC)-immunoassay procedures in ten cultures of wild-type and mutant strains of Rhizobium phaseoli. The major GAs excreted into the culture medium were GA1 and GA4. These identifications were confirmed by combined gas chromatographymass spectrometry. The HPLC-immunoassays also detected smaller amounts of GA9- as well as GA20-like compounds, the latter being present in some but not all cultures. In addition to GAs, all strains excreted indole-3-acetic acid (IAA) but there was no obvious relationship between the amounts of GA and IAA that accumulated. The Rhizobium strains studied included nod
– and fix
– mutants, making it unlikely that the IAA- and GA-biosynthesis genes are closely linked to the genes for nodulation and nitrogen fixation.The HPLC-immunoassay analyses showed also that nodules and non-nodulated roots of Phaseolus vulgaris L. contained similar spectra of GAs to R. phaseoli culture media. The GA pools in roots and nodules were of similar size, indicating that Rhizobium does not make a major contribution to the GA content of the infected tissue.Abbreviations EIA
enzyme immunoassay
- GAn
gibberellin An
- GC-MS
gas chromatography-mass spectrometry
- HPLC
high-performance liquid chromatography
- IAA
indole-3-acetic acid
- Me
methyl ester
- RIA
radioimmunoassay
- TLC
thin-layer chromatography 相似文献
44.
Merten OW 《Cytotechnology》1988,1(2):113-121
Batch cultures of mouse-mouse hybridoma cell lines were carried out and their growth and production kinetics investigated. Three main cell specific production patterns (expressed as pg IgG/cell x hour) were found, which can be used as a classification system for hybridoma cell lines (groups I–III). Cells showing the highest IgG-production at the beginning of the batch culture (during the lag and the onset of the log-phase) were classified as either group I and II. The difference was that cell lines of group II showed a second high cell specific production at the onset of the stationary and death phases. Cell lines of group III had a quite constant production of antibodies during their growth; but IgG secretion completely stopped after the beginning of the stationary phase. The implications of these three production patterns on the design of a production process are discussed. 相似文献
45.
Mycelium ofBeauveria bassiana can be grown in liquid culture, filtered, and the mycelium dried. After rehydration the mycelium sporulates.
Two carbohydrate sources (sucrose and maltose), and one nitrogen/vitamin source (yeast extract) were tested for mycelium growth
and subsequent conidial production. Maximum mycelium growth (12.31 mg/ml), in liquid culture, was in the sucrose (3.5%)/yeast
extract (3.5%) medium, but mycelium from a maltose (2%)/yeast extract (0.75%) medium produced the maximum of 4.62×106 conidia/mg dry mycelium after incubation in moist Petri dishes.
Using the data on mycelium yield (in liquid culture) and conidial production (by dry mycelium) it is calculated that the sucrose
(3.5%)/yeast extract (3.5%) and the maltose (2%)/yeast extract (0.75%) media produce most conidia per media volume (an equivalent
of 3.52–3.72×107 conidia/ml).
相似文献
46.
The correlation between manganese deficiency, loss of mitochondrial respiratory chain NADH: ubiquinone oxidoreductase (complex I) activity and citric acid overproduction in the Aspergillus niger strain B 60 was analysed. With increasing manganese-supplementation of the production medium the loss of complex I activity and the production of citric acid was reduced. Addition of manganese during growth stopped further loss of complex I activity and further increase of citric acid production. A possible causality between complex I deficiency and citric acid overproduction is discussed. 相似文献
47.
Marie A. Salmeron Tatsuo Morita Hidetoshi Seki Chris D. Platsoucas Kyogo Itoh 《Cancer immunology, immunotherapy : CII》1992,35(3):211-217
Summary Lymphokine production by human melanoma tumor-infiltrating lymphocytes (TIL) was studied. Uncultured TIL produced interferon (IFN), but not interleukin-2 (IL-2) or IL-4, in response to anti-CD3 mAb or IL-2. In bulk cultures, IL-2-activated TIL displaying autologous tumor-specific cytotoxicity (CTL-TIL) produced IFN in culture with medium alone, whereas IL-2-activated noncytotoxic TIL did not. Addition of anti-CD3 mAb or autologous tumor cells up-regulated IFN production in IL-2-activated TIL from 10 of 12 or 6 of 12 cases respectively. Those from 4 of 12 cases (2 CTL-TIL and 2 noncytotoxic TIL) produced IL-2 in culture with medium alone. At the clonal level, 5 (4 CD4+ and 1 CD8+) of 7 autologous tumor-specific CTL clones derived from TIL and 3 (2 CD4+ and 1 CD8+) of 7 noncytotoxic TIL clones produced IFN in culture with medium alone, which was up-regulated by adding anti-CD3 mAb. Two IFN-producing CTL clones tested produced IL-2 in 4 ×-concentrated supernatants from a 3.5-h culture with medium alone. Furthermore, 2 IFN-producing CTL clones tested expressed mRNA for both IFN and IL-2. IL-2 production and its mRNA expression were up- or down-regulated, respectively, by adding anti-CD3 mAb or autologous tumor cells. IL-4 production was not observed in culture either with medium alone or with IL-2 in any of the cells described above. Anti-CD3 mAb was required for IL-4 production in 3 of 12 IL-2-activated TIL, 2 of 6 CTL clones, and none of 5 noncytotoxic TIL clones. In summary, IFN production was characteristic of melanoma TIL. Some autologous tumor-specific CTL in TIL are suggested to be productive of IL-2 and IFN under unstimulated conditions, both being required for self-activation in an autocrine loop.This work was supported in part by grant CA-47891 from the National Cancer Institute 相似文献
48.
Metabolism of nitric oxide and nitrous oxide during nitrification and denitrification in soil at different incubation conditions 总被引:1,自引:0,他引:1
Abstract NO production and consumption rates as well as N2 O accumulation rates were measured in a loamy cambisol which was incubated under different conditions (i.e. soil moisture content, addition of nitrogen fertilizer and/or glucose, aerobic or anaerobic gas phase). Inhibition of nitrification with acetylene allowed us to distinguish between nitrification and denitrification as sources of NO and N2 O. Under aerobic conditions untreated soil showed very low release of NO and N2 O but high consumption of NO. Fertilization with NH4 + or urea stimulated both NO and N2 O production by nitrification. Addition of glucose at high soil moisture contents led to increased N2 and N2 O production by denitrification, but not to increased NO production rates. Anaerobic conditions, however, stimulated both NO and N2 O production by denitrification. The production of NO and N2 O was further stimulated at low moisture contents and after addition of glucose or NO3 − . Anaerobic consumption of NO by denitrification followed Michaelis-Menten kinetics and was stimulated by addition of glucose and NO3 − . Aerobic consumption of NO followed first-order kinetics up to mixing ratios of at least 14 ppmv NO, was inhibited by autoclaving but not by acetylene, and decreased with increasing soil moisture content. The high NO-consumption activity and the effects of soil moisture on the apparent rates of anaerobic and aerobic production and consumption of NO suggest that diffusional constraints have an important influence on the release of NO, and may be a reason for the different behaviour of NO release vs N2 O release. 相似文献
49.
Summary High yields of protoplasts were obtained from leaves of aseptically grown plants and calli originated from different explants, in several cultivars of Cajanus cajan L. The protoplasts divided to form cell clusters in modified KM 8p medium and developed to protocolonies after dilution with liquid Caboche's medium within three to four weeks of culture. The protocolonies proliferated to form green calli on solid Caboche's medium. No shoots or plants were obtained.Abbreviations BAP
6-benzylaminopurine
- NAA
-napthaleneacetic acid
- 2,4-D
2,4-dichlorophenoxyacetic acid
- Kin
kinetin
- Zea
zeatin
- Adn S
adenine sulphate
- GA 3
gibberellic acid 相似文献
50.
Kenji Kato Su-wan Oh Hiroyuki Yamamoto Takayuki Hanazato Ikuko Yasuda Akira Otuki Masayuki Takahashi 《Ecological Research》1992,7(3):267-276
In order to understand the control mechanisms of a large, stable bacterial standing stock, enclosure experiments were conducted
in a eutrophic lake, where both bacterial productivity and grazing pressure were very high. Total bacterial number in the
different enclosures ranged from 1.2 to 2.7×107 cells mL−1 throughout the experiment. The average bacterial cell production rate estimated from a grazer eliminating experiment was
6.3×105 cells mL−1 h−1. Difference in the bacterial cell production rate between shaded and unshaded enclosures was not apparent. Bacteria showed
a reduction in standing stock of only about 25–30% even after the supply of light was cut to 1%. Bacteria in the shaded enclosures
then recovered their production rate in the first 12 days of perturbation. Grazing pressure in the shaded enclosures was not
less than that for the control. Thus, it was considered a control mechanism of bacterial stable standing stock that the bacteria
shifted their organic substrate from extracellular dissolved organic carbon freshly released from phytoplankton to that already
stocked in the water column, though it is not known whether the dominant bacteria were the same. 相似文献