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11.
cAMP in Anabaena cylindrica: Rapid Changes in Cellular Levels in Response to Changes in Extracellular Environments 总被引:2,自引:0,他引:2
The cellular level of cyclic 3',5'-AMP (cAMP) in the cyanobacteriumAnabaena cylindrica changed transiently in response to changesin extracellular environments. When the cells were transferedfrom dark to light, or anaerobic to aerobic conditions in thedark, the cAMP level rapidly decreased within one min and thengradually recovered. Addition of carbonyl cyanide m-chlorophenylhydrazone(CCCP) which inhibits ATP synthesis caused an increase in cAMPlevel in the light but not in the dark. The level of cAMP increasedseveral fold by lowering the pH from 8 to 6. On the contrary,a rise of pH from 6 to 8 caused a decrease in the cAMP level.It is suggested that the change in membrane electrochemicalpotential is involved in the regulation of cellular cAMP concentration. (Received January 27, 1989; Accepted June 19, 1989) 相似文献
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Twelve polyether compounds originating from dinoflagellates were tested for growth-inhibiting activities againstAspergillus niger, Penicillium funiculosum, Candida rugosa, Escherichia coli, Bacillus megaterium andStaphylococcus aureus by a paper disc method. These polyethers represent six groups of different skeletons and originate from three species;Prorocentrum lima, Dinophysis fortii andGambierdiscus toxicus. Potent antifungal activities were observed with okadaic acid and its two congeners, desulfated yessotoxin, and ciguatoxin but not with okadaic acid esters, prorocentrolide, pectenotoxin-1, yessotoxin, maitotoxin, and desulphated maitotoxin. The antifungal activities and mouse lethalities of the polyethers were markedly affected by slight modification of their structures. Antibacterial potency of the tested compounds was not significant. 相似文献
14.
Nobuo Kato Sumiko Mizuno Yukio Imada Masayuki Shimao Chikahiro Sakazawa 《Applied microbiology and biotechnology》1988,27(5-6):567-571
Summary Formaldehyde dismutase was greatly stabilized by immobilization in a urethane prepolymer (PU-6). The immobilized enzyme exhibited stochiometrical dismutation of formaldehyde to methanol and formate in several repeated reactions. Conversion of methanol to formate occurred in a reaction with an immobilized enzyme system consisting of alcohol oxidase, catalase and formaldehyde dismutase, and with an intact cell-mixture of Hansenula polymorpha and Pseudomonas putida. Furthermore, the stability of the cell-mixture during repeated reactions was greatly improved by the immobilization, the 600 mM methanol added periodically being converted to formate in a 75% yield in 12 h. The immobilized cellsystem was also effective for the conversion of several aliphatic alcohols, C1 to C4, to the corresponding acids. 相似文献
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Chika Kawashima Koji Terayama Masayuki II Shogo Oka Toshisuke Kawasaki 《Glycoconjugate journal》1992,9(6):307-314
The properties of a rat brain glucuronyltransferase, which is presumed to be associated with the biosynthesis of the HNK-1 epitope on sulfoglucuronyl glycolipids, are described. The enzyme required divalent cations for reaction, with maximal activity at 10mm Mn2+, and exhibited a dual optimum at pH 4–5 and pH 6 depending upon the buffer used, with the highest activity at pH 4.5 in MES buffer. This enzyme strictly recognized the Gal1-4GlcNAc terminal structure, and was highly specific for neolacto (type 2) glycolipids as acceptor. The enzyme was localized specifically in the brain, and was barely detected in other issues, including the thymus, spleen, liver, kidney, lung, and sciatic nerve fibres. Phosphatidylinositol and phosphatidylserine increased the enzymatic reaction 4.4- and 2.3-fold, respectively, whereas phosphatidylcholine slightly decreased the rate.Abbreviations GlcA
glucuronic acid
- Lc-PA14
lactotetraose-phenyl-C14H29
- nLc-PA14
neolactotetraose-phenyl-C14H29
- nLcOse4-Cer
neolactotetraosylceramide
- NP-40
Nonidet P-40
- PC
phosphatidylcholine
- PE
phosphatidylethanolamine
- PI
phosphatidylinositol
- PS
phosphatidylserine
- SGGL
sulfoglucuronyl glycolipid 相似文献
17.
Masayuki Nishida Hirotaka Nishijima Kazuya Yonezawa Isao Sato Teisuke Anzai Kohichi Okita Hisakazu Yasuda 《European journal of applied physiology and occupational physiology》1992,64(6):528-533
To assess exercise energy metabolism of forearm flexor muscles in rowers, six male student rowers and six control subjects matched for age and sex were studied using phosphorus-31 magnetic resonance spectroscopy (31P-MRS). Firstly, to adjust for the effect of differences in cross-sectional muscle area, the maximal cross-sectional area (CSAmax) of the forearm flexor muscles was estimated in each individual using magnetic resonance imaging. Multistage exercise was then carried out with an initial energy production of 1 J.cm-2 CSAmax for 1 min and an increment of 1 J.cm-2 CSAmax every minute to the point of muscle exhaustion. A series of measurements of 31P-MRS were performed every minute. The CSAmax was significantly greater in the student rowers than in the control subjects [19.8 (SD 2.2) vs 17.1 (SD 1.2) cm2, P less than 0.05]. The absolute maximal exercise intensity (J.min-1) was greater in the rowers than in the control subjects. However, the maximal exercise intensity per unit of muscle cross sectional area (J.min-1.cm-2) was not significantly different between the two groups. During mild to moderate exercise intensities, a decrease in phosphocreatine and an increase in inorganic phosphate before the onset of acidosis were significantly less in the rowers, indicating a requirement of less adenosine 5'-diphosphate to drive adenosine 5'-triphosphate production. The onset of acidosis was also significantly delayed in the rowers. No difference was observed in forearm blood flow between the two groups at the same exercise intensity (J.min-1.cm-2).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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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