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11.
Characterisation of Non-Uniform Photosynthesis Induced by Abscisic Acid in Leaves Having Different Mesophyll Anatomies 总被引:29,自引:0,他引:29
Terashima Ichiro; Wong Suan-Chin; Osmond C. Barry; Farquhar Graham D. 《Plant & cell physiology》1988,29(3):385-394
The effects of abscisic acid (ABA) on photosynthesis in leavesof Helianthus annuus L. were compared with those in leaves ofVicia faba L. After the ABA treatment, the response of photosyntheticCO2 assimilation rate, A, to calculated intercellular partialpressure of CO2, Pi, (A(pi) relationship) was markedly depressedin H. annuus. A less marked depression was also observed inV.faba. However, when the abaxial epidermes were removed fromthese leaves, neither the maximum rate nor the CO2 responseof photosynthetic oxygen evolution was affected by the applicationof ABA. Starch-iodine tests revealed that photosynthesis was not uniformover the leaves of H. annuus treated with ABA. The starch contentwas diffferent in each bundle sheath extension compartment (thesmallest subdivision of mesophyll by veins with bundle sheathextensions, having an area of ca. 0.25 mm2 and ca. 50 stomata).In some compartments, no starch was detected. The distributionof open stomata, examined using the silicone rubber impressiontechniques, was similar to the pattern of starch accumulation.In V.faba leaves, which lack bundle sheath extensions, distributionof starch was more homogeneous. These results indicate that the apparent non-stomatal inhibitionof photosynthesis by ABA deduced from the depression of A(pi)relationship is an artifact which can be attributed to the non-uniformdistribution of transpiration and photosynthesis over the leaf.Intercellular gaseous environment in the ABA-treated leavesis discussed in relation to mesophyll anatomy.
1 Present address: Department of Botany, Duke University, Durham,NC 27706, U.S.A. (Received September 30, 1987; Accepted January 13, 1988) 相似文献
12.
Kenji Kanaji Minoru Okuma Fumitaka Ushikubi Haruto Uchino 《Prostaglandins, leukotrienes, and essential fatty acids》1988,31(3):155-161
Lipoxygenase activities were estimated in washed platelets (intact platelets) and their subcellular fractions obtained from 7 patients with deficient platelet lipoxygenase activities and 9 normal subjects. From sonicated platelet preparations, 12,000 g supernatant (F-I), cytosol (F-II) and microsomal fractions (F-III) were prepared by differential centrifugation. When 12-hydroxyeicosatetraenoic acid (12-HETE) produced by the incubation of arachidonic acid with intact platelets or each of their subcellular fractions from normal subjects was measured by reversed-phase high-performance liquid chromatography analysis, the lipoxygenase activities of F-I, F-II and F-III were 87%, 31% and 17%, respectively, of the enzyme activity of intact platelets. One of the patients showed no detectable lipoxygenase activity in any preparation, while the other patients showed reduced enzyme activities in all preparations. The addition of CaCl2 significantly increased 12-HETE synthesis solely by F-I from these patients. In most of these patients, contrary to normal subjects, it appeared that the lipoxygenase activity was not fully expressed in intact platelets, since the F-I produced more 12-HETE than the intact platelets. 相似文献
13.
Terashima Ichiro; Sonoike Kintake; Kawazu Tamotsu; Katoh Sakae 《Plant & cell physiology》1991,32(8):1275-1283
To examine the effects of chilling of leaves of cucumber (Cucumissativus L.) in moderate light on the coupling state of thylakoidsin situ, changes in fluorescence, changes in light scatteringand flash-induced changes in absorbance at 518 nm were examinedin intact leaves. After chilling of leaves at 5?C in the lightfor 5 h, the non-photochemical quenching of fluorescence, ameasure of energisation of thylakoids, was largely suppressed.The treatment also caused a suppression of light-induced changesin the light scattering by leaves, which depends on the formationof a pH gradient across thylakoid membranes. When thylakoidswere prepared by very gentle methods from the leaves chilledin the light, through a step of preparation of intact chloro-plasts,the transport of electrons from H2O to ferricyanide was uncoupled,being insensitive to an uncoupler, methylamine. These data provide consistent evidence that the thylakoids areuncoupled in situ by the chilling of leaves in the light and,as a consequence of the uncoupling, the energisation of themembranes is suppressed. However, the decay of the flash-inducedchange in absorbance at 518 nm in leaves was not markedly acceleratedby the treatment. The thylakoids isolated from leaves chilledin the light, which were in the uncoupled state, also did notshow a rapid decay, unless an efficient uncoupler such as gramicidinwas added. These results suggest that even a considerable uncouplingof thylakoids, brought about by chilling of leaves in the light,is not sufficient to cause a marked acceleration of the decayof the flash-induced change in absorbance at 518 nm. Therefore,analysis at 518 nm is not always a sensitive method for assessingthe coupling state of thylakoids. (Received July 1, 1991; Accepted October 4, 1991) 相似文献
14.
Carbon isotope ratios (13C) for bubble CH4 in a submerged paddy soil were studied in Yokohama, Japan, throughout a growing period, and its variation was found. Bubble CH4 collected from other 33 paddy fields in Japan was also measured for its 13C and the results agreed with Yokohama. Furthermore, the variation occurred irrespective of the amount and the type of supplied organic substances to the fields (whole rice straw, rice stubble, or compost). The 13C value (average value of -55.9 ± 4.24) from these paddy fields was higher than those of the CH4 emitted from African and North American paddies. The higher value was little affected by their difference in the supplied organic substances. CH4 oxidation likely occurs for bubble CH4 in the shallow paddy fields. A rough estimate of the total CH4 production, using isotope mass balance, showed that 17 to 22% of organic carbon supplied to Japanese paddies transforms to CH4. 相似文献
15.
A leptomycin B resistance gene of Schizosaccharomyces pombe encodes a protein similar to the mammalian P-glycoproteins 总被引:4,自引:0,他引:4
Kazunori Nishi Minoru Yoshida Marie Nishimura Mitsuo Nishikawa Makoto Nishiyama Sueharu Horinouchi Teruhiko Beppu 《Molecular microbiology》1992,6(6):761-769
Screening for leptomycin B (LMB)-resistant transformants in a gene library constructed in Schizosaccharomyces pombe with the chromosomal DNA of an LMB-resistant mutant of S. pombe and with multicopy plasmid pDB248' as the vector led to the isolation of a gene, named pmd1+, encoding a 1362-amino-acid protein. This protein showed great similarity in amino acid sequence to the mammalian P-glycoprotein encoded by the multidrug resistance gene, mdr, and the Saccharomyces cerevisiae a-factor transporter encoded by STE6. In addition, computer analyses predicted that the protein encoded by pmd1+ formed an intramolecular duplicated structure and each of the halves contained six transmembrane regions as well as two ATP-binding domains, as observed with the P-glycoproteins and the STE6 product. Consistent with this was that S. pombe cells containing the pmd1+ gene on a multicopy plasmid showed resistance not only to LMB but also to several cytotoxic agents. The pmd1 null mutants derived by gene disruption were viable and hypersensitive to these agents. All these data suggest that the pmd1+ gene encodes a protein that is a structural and functional counterpart of mammalian mdr proteins. 相似文献
16.
Sada E Katoh S Terashima M Yamana S Ueyama N Nagaya M 《Biotechnology and bioengineering》1986,28(1):1-6
Permeabilities of several solutes through the composite membranes containing phospholipids have been measured. They were inversely proportional to the content of the phospholipids in the membrane. Both the permeability of solutes and the degree of permeability change around the phase transition temperature of the phospholipids for the hydrophobic solutes such as n-butanol and salicylamide were larger than those for the hydrophilic solutes such as amino acids and pyridoxine. These results suggest thatthe permeation path of hydrophobic solutes is different from that of hydrophilic ones. The addition of phosphatidyl ethanolamine, phosphatidyl serine, or phosphatidic acid to the composite membrane influenced the solute permeability due to the introduced negative charge and/or the change in the molecular packing of phospholipid. 相似文献
17.
Adult frog (Xenopus laevis) hepatocytes were found to proliferate in a culture medium containing adult homologous serum. Insulin and dexamethasone were required for a net proliferation of hepatocytes. Dose-response analysis showed that a low concentration of serum (greater than or equal to 0.5%) was enough to induce DNA synthesis and mitosis, but a higher concentration (5%) caused certain necrotic changes. Under optimal conditions, there was a two- to threefold increase in nuclei per culture 10 days after serum treatment. Heterologous sera (fetal bovine, calf and chick) showed less proliferative activity. Based on our results, hepatocyte-proliferating activity in adult frog serum is considered to be heat-unstable and acidic protein(s). Thus, adult frog serum may contain hepatopoietin possibly different from well-known growth factors. 相似文献
18.
Molecular Genetic Analysis of Myelin-Deficient Mice: Shiverer Mutant Mice Show Deletion in Gene(s) Coding for Myelin Basic Protein 总被引:17,自引:6,他引:11
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