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1.
The photosynthetic action spectrum of the bean plant leaf, Phaseolus vulgaris L. (variety Red Kidney), has been determined with a diffraction grating illuminated by a 6500-watt xenon arc. An infrared CO2 analyzer was used to determine the gross photosynthetic rate of the terminal leaflet of the first trifoliate leaf. The rate was measured as a function of the light intensity at steps of 12.5 nanometers which approximates the length of the leaflet used. Twenty-five curves between 400 and 700 nanometers were used to establish the action spectrum. All light curves were some linear function of the incident intensity, and all were extrapolated to zero. The action spectrum shows the following features. (a) there are two peaks (i.e., at about 670 and 630 nanometers) and a shoulder between 600 and 612 nanometers in the red region where the highest rate of photosynthesis is found. Lower peaks in descending order are found in the blue (at about 437 nanometers) and the green (at about 500 nanometers) regions. (b) There are two small minima at about 650 nanometers and between 470 and 480 nanometers, and a broad minimum is found between 540 and 530 nanometers. (c) The photosynthetic rate declines rapidly above 680 nanometers, reaching the lowest value at 700 nanometers. (d) At wave lengths below the blue maximum, the rate decreases progressively to 400 nanometers. 相似文献
2.
The peridinin-chlorophyll a-protein (PCP) from dinoflagellates is a soluble light harvesting antenna which gathers incoming photons mainly by the carotenoid peridinin. In PCPs reconstituted with different chlorophylls, the peridinin to chlorophyll energy transfer rates are well predicted by a Förster-like theory, but only if the pigment arrangements are identical in all PCPs. We have determined the X-ray structures of PCPs reconstituted with Chlorophyll-b (Chl-b), Chlorophyll-d (Chl-d) and Bacteriochlorophyll-a (BChl-a) to resolutions ?2 Å. In all three cases the pigment arrangements are essentially the same as in native PCP. Hydrogen bonding is not responsible for preferential incorporation of “non-native” chlorophylls over Chl-a. 相似文献
3.
Relationship between Chloroplast Development and ent-Kaurene Biosynthesis in Peas 总被引:3,自引:3,他引:0
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Treatment of etiolated pea (Pisum sativum (L. cv. Alaska) seedlings with 2′-isopropyl-4′-(trimethylammonium chloride)-5′-methylphenyl piperidine-1-carboxylate (Amo-1618) prior to irradiation with white light inhibits photomorphogenesis and formation and stacking of thylakoid membranes in the chloroplasts, as well as (−)-kaur-16-ene (ent-kaurene)biosynthesis. Exogenous gibberellic acid also inhibits greening. A crudely determined action spectrum for the photoinduction of ent-kaurene biosynthesis shows two peaks, one in the blue region at 458 to 490 nanometers and another in the red region at 606 to 678 nanometers. The possible participation of phytochrome in the photoinduction of ent-kaurene biosynthesis is indicated by comparative effects of red, far red, and alternating red/far red irradiations on enhancement of enzyme activity. The activity of blue light as well as red shows a similarity of the photoinduction of ent-kaurene synthesis activity to the high irradiance responses, and indicates probable participation of a second photoreceptor. From these observations, it is concluded that photoinduction of ent-kaurene biosynthesis and chloroplast development in shoots are closely linked processes. 相似文献
4.
Ross O. Meyers Joshua D. Lambert Nicole Hajicek Alan Pourpak John A. Kalaitzis Robert T. Dorr 《Bioorganic & medicinal chemistry letters》2009,19(16):4752-4755
Synthesis of seven semi-synthetic analogs of NDGA is described. An approach to NDGA derivatization is described in which the ortho-phenolic groups are tethered together by one atom, forming a 5-membered heterocyclic ring. The analogs were evaluated for cytotoxicity in four cancer cell lines and compared to NDGA and tetra-O-methyl-NDGA (M4N) (1a). NDGA bis-cyclic sulfate (2a), NDGA bis-cyclic carbonate (2b), and methylenedioxyphenyl-NDGA (2d) and NDGA tetra acetate (1b) showed anti-cancer activity in vitro. Two compounds, (1b) and (2b), were evaluated for anticancer activity in a mouse xenograft model of human melanoma and showed dose-dependent activity. 相似文献
5.
Keith R. Solomon Stephen B. Bowlus Robert L. Metcalf John A. Katzenellenbogen 《Life sciences》1973,13(6):733-742
The effects of synergists on the morphogenetic activity of farnesyl methyl ether (a), 10,11-episulphido farnesyl methyl ether (b), 10,11-epoxyfarnesyl methyl ether (c), farnesyl methyl sulphide (d), farnesyl methyl sulphoxide (e) and ethyl 10,11-episulphido farnesoate (f) were determined. Both synergists showed very low juvenilizing activity. All compounds except f were more active in T. molitor. a < b < c showed increasing order of basal activity and of synergism. d had low activity in both insects and was not affected by piperonyl butoxide (PB). In O. fasciatus, e had low activity which was slightly increased by PB. However, in T. molitor e showed moderate activity that was decreased by PB, suggesting an activation reaction, possibly to the sulphone. f showed high activity which was little affected by synergists. 相似文献
6.
Electroretinogram Characteristics and the Spectral Mechanisms of the Median Ocellus and the Lateral Eye in Limulus polyphemus 总被引:5,自引:5,他引:0
Electrical responses (ERG) to light flashes of various wavelengths and energies were obtained from the dorsal median ocellus and lateral compound eye of Limulus under dark and chromatic light adaptation. Spectral mechanisms were studied by analyzing (a) response waveforms, e.g. response area, rise, and fall times as functions of amplitude, (b) slopes of amplitude-energy functions, and (c) spectral sensitivity functions obtained by the criterion amplitude method. The data for a single spectral mechanism in the lateral eye are (a) response waveforms independent of wavelength, (b) same slope for response-energy functions at all wavelengths, (c) a spectral sensitivity function with a single maximum near 520 mµ, and (d) spectral sensitivity invariance in chromatic adaptation experiments. The data for two spectral mechanisms in the median ocellus are (a) two waveform characteristics depending on wavelength, (b) slopes of response-energy functions steeper for short than for long wavelengths, (c) two spectral sensitivity peaks (360 and 530–535 mµ) when dark-adapted, and (d) selective depression of either spectral sensitivity peak by appropriate chromatic adaptation. The ocellus is 200–320 times more sensitive to UV than to visible light. Both UV and green spectral sensitivity curves agree with Dartnall's nomogram. The hypothesis is favored that the ocellus contains two visual pigments each in a different type of receptor, rather than (a) various absorption bands of a single visual pigment, (b) single visual pigment and a chromatic mask, or (c) fluorescence. With long duration light stimuli a steady-state level followed the transient peak in the ERG from both types of eyes. 相似文献
7.
《Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism》1995,1254(1):73-76
Major incubation products in feeding experiments with the sodium salt of 7-(5-butyl-furan-2-yl)heptanoic acid (3) on suspension cultures of Saccharum spec. are the unusual F-acids (4a) and (4b). They possess in contrast to natural monomethyl substituted F-acids a methyl substituent in the 4-position of the furan ring. Unexpectedly, the dimethyl substituted F-acids (4c) and (4d) were found only in very small amounts. The detection and structure elucidation of the methylation products (4a)–(4d) was achieved predominantly by GC-MS analysis of the corresponding tetrahydrofuran derivatives (5a)–(5d). 相似文献
8.
Shrikanth Ulloora Ramakrishna Shabaraya Syed Aamir Airody Vasudeva Adhikari 《Bioorganic & medicinal chemistry letters》2013,23(5):1502-1506
Five new series of imidazo[1,2-a]pyridines carrying biologically active pyrazoline (4a–e), cyanopyridone (5a, b), cyanopyridine (6a–f), 2-aminopyrimidine (7a–f) and pyrimidine-2-thione (8a–d) systems were designed and synthesized as prominent anticonvulsant agents. The target compounds were screened for their in vivo anticonvulsant activity following maximal electroshock (MES) and subcutaneous pentylene tetrazole (scPTZ) methods at a small test dose of 10 mg/kg. Further, Rotarod toxicity method was used to study the toxicity profile of selected compounds. Compounds 4b, 5a, 5b, 6a, 7e and 8d possessing 4-fluorophenyl substituent at 2nd position of imidazo[1,2-a]pyridine ring displayed potent anticonvulsant activity without displaying any toxicity. Enhanced activity profile was observed for new compounds in PTZ method over MES method. 相似文献
9.
Ferdinand Mouafo Talontsi Md. Tofazzal Islam Petrea Facey Clovis Douanla-Meli Andreas von Tiedemann Hartmut Laatsch 《Phytochemistry letters》2012,5(3):657-664
In our search for secondary metabolites regulating the motility behavior of zoospores of the grapevine downy mildew pathogen Plasmopara viticola, we found that extracts from an endophytic fungus Phomopsis sp. CAFT69 and its host plant Endodesmia calophylloides remarkably impaired motility of zoospores followed by lysis. The active principles in the extracts were isolated and identified as two new compounds, namely excelsional (1a) and 9-hydroxyphomopsidin (2a), together with excelsione (1b), phomopsidin (2b), alternariol (3a), alternariol-5-O-methyl ether (3b), the hitherto undescribed 5′-hydroxyalternariol (3c), altenusin (4) from the fungus, xanthochymol (5) and 1,5-dihydroxy-3-methoxyxanthone (mesuaxanthone, 6) from the plant. Bioassays revealed that compounds 1a/b, 2a/b, and 3a–6 displayed motility inhibition and lytic activities against zoospores of the grapevine downy mildew pathogen P. viticola in a dose- and time-dependent manner from 1 to 10 μg/mL. Their structures were elucidated by extensive spectroscopic analyses including 2D NMR techniques. This is the first report of an endophyte and its natural products from E. calophylloides and the first isolation of compounds 5 and 6 from this plant. 相似文献
10.
Rashmi Singh S. Maurya R. S. Upadhyay 《Archives Of Phytopathology And Plant Protection》2013,46(16):1579-1588
Antagonistic capability of Trichoderma harzianum was improved through UV-irradiation. Four different type of mutants, T. harzianum - Ma (Th-Ma), T. harzianum - Mb(Th-Mb), T. harzianum - Mc (Th-Mc), T. harzianum - Md (Th-Md) of T. harzianum and the parent strain (Th-P) were selected for further studies. Th-Ma and Th-Mb showed more antagonistic capability against Macrophomina phaseolina than its parent strain Th-P in dual culture. Biochemical analysis of these four mutants and the parent strain showed that Th-Ma releases higher level of two lytic enzymes i.e. chitinases and cellulases and Th-Mb produces more β-1,3-glucanase activity than the parent strain. Culture filtrate of Th-Ma also showed antifungal properties. Study of the competitive saprophytic ability (CSA) of these four mutants and the parent strain were also made. Th-Ma exhibited higher CSA than the parental isolate while Th-Md had less CSA than all other mutants and the parent strain of T. harzianum. 相似文献
11.
Toshie Fujishima Takato Nozaki Tsutomu Suenaga 《Bioorganic & medicinal chemistry》2013,21(17):5209-5217
Four structurally novel stereoisomeric analogues of 1,25-dihydroxyvitamin D3 (3a–d) bearing a spiro-oxetane fused at the C2 position of the A-ring have been designed and synthesised in a convergent manner. The requisite A-ring enyne precursors (13a,b) for the vitamin D analogues (3a,b) and (3c,d), respectively, were synthesised from pentaerythritol according to an eleven-step procedure. Preliminary biological evaluation of the analogues using the bovine thymus vitamin D receptor (VDR) suggested that the incorporation of the spiro-oxetane moiety instead of a gem-dimethyl group at the C2 position had a beneficial effect on the VDR affinity. 相似文献
12.
Tanabe G Otani T Cong W Minematsu T Ninomiya K Yoshikawa M Muraoka O 《Bioorganic & medicinal chemistry letters》2011,21(10):3159-3162
Four analogs with 3′-O-alkyl groups (9a: CH3, 9b: C2H5, 9c: C13H27 or 9d: CH2Ph) instead of the 3′-O-sulfate anion in salacinol (1), a naturally occurring potent α-glucosidase inhibitor, were synthesized by the coupling reaction of 1,4-dideoxy-1,4-epithio-d-arabinitols (18a and 18b) with appropriate epoxides (10a-10d). These analogs showed equal or considerably higher inhibitory activity against rat small intestinal α-glucosidases than the original sulfate (1), and one of them (9d) was found more potent than currently used α-glucosidase inhibitors as antidiabetics. Thus, introduction of a hydrophobic moiety at the C3′ position of this new class of inhibitor was found beneficial for onset of stronger inhibition against these enzymes. 相似文献
13.
Chloroplast membrane carboxyl groups were modified by carbodiimide activation followed by glycine methyl ester substitution, leaving the derivatized group uncharged. This charge alteration induced a number of effects similar to addition of salts to control chloroplasts suspended in a low salt medium. These include: (a) restacking or multiple membrane association in low salt-treated chloroplasts that lack grana stacks, (b) protection against polycation inhibition of photosystem I electron transfer, (c) reduction of the amount of polycations bound to the membranes, and (d) increased 90° light scattering due to membrane conformational changes. Carboxyl modification also altered acid-induced conformational changes. 相似文献
14.
Francisco García González Manuel Gómez Guillén Juan A. Galbis Pérez Emilio Román Galán 《Carbohydrate research》1980,78(1):17-23
The reaction between 2-amino-2-deoxyaldoses and β-dicarbonyl compounds yields polyhydroxyalkylpyrroles. Thus, 6,6-dimethyl-2-(D-galacto-pentitol-1-yl)-4,5,6,7-tetrahydroindol-4-one (4a), 6,6-dimethyl-2-(D-gluco-pentitol-1-yl)-4,5,6,7-tetrahydroindol-4-one (4b), and 6,6-dimethyl-2-(D-manno-pentitol-1-yl)-4,5,6,7-tetrahydroindol-4-one (4c) have been obtained from 5,5-dimethylcyclohexane-1,3-dione (2) and 2-amino-2-deoxyheptoses having D-glycero-L-gluco (1a), D-glycero-D-ido (1b), and D-glycero-D-talo (1c) configurations, respectively. 2-Amino-2-deoxy-D-glycero-L-manno-heptose (1d), the epimer of 1a, also reacts with 2, to yield 4a. In a similar way, 1a, 1b, and 1c react with cyclohexane-1,3-dione (3), to give 2-(D-galacto-pentitol-1-yl)-4,5,6,7-tetrahydroindol-4-one (5a), 2-D-gluco-pentitol-1-yl)-4,5,6,7-tetrahydroindol-4-one (5b), and 2-(D-manno-pentitol-1-yl)-4,5,6,7-tetrahydroindol-4-one (5c), respectively. 相似文献
15.
Anand R. Saundane Katkar Vijaykumar A. Verma Vaijinath 《Bioorganic & medicinal chemistry letters》2013,23(7):1978-1984
As a part of systematic investigation of synthesis and biological activities of indole analogues linked to various heterocyclic systems, we have synthesized new compounds viz., 2-amino-4-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-6-aryl-4H-pyran-3-carbonitriles (2a–i), 4,5-diamino-6-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-8-aryl-2-oxo-2,6-dihydrodipyrano [2,3-b:3,2-e]pyridine-3-carbonitriles (3a–i), 4-amino-5-(5′-substituted 2′-phenyl-1H-indol-3-yl)-7-aryl-1H-pyrano[2,3-d]pyrimidin-2(5H)-ones (4a–i), 4-amino-5-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-7-aryl-1H-pyrano[2,3-d]pyrimidin-2(5H)-thiones (5a–i), 4-(5′-subtituted 2′-phenyl-1H-indol-3′-yl)-6-aryl-1,4-dihydropyrano[2,3-c]pyrazol-3-amines (6a–i) and 5-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-7-aryl-3H-pyrano[2,3-d]pyrimidin-4(5H)-ones (7a–i). Antibacterial activity results revealed that, compound 6a showed promising activity versus Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae. Compound 6d exhibited good activity against S. aureus, K. pneumoniae and Pseudomonas aeruginosa. Antifungal activity results indicated that, compound 4d exhibited maximum zone of inhibition against Aspergillus oryzae and Aspergillus flavus. In case of antioxidant activity, compound 4a showed promising radical scavenging activity, ferric ions (Fe3+) reducing antioxidant power (FRAP) and metal chelating activity. 相似文献
16.
Evidence for a Block between Plastoquinone and Cytochrome f in a Photosynthetic Mutant of Lemna with Abnormal Flowering Behavior 总被引:3,自引:2,他引:1
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Mutant strain 1073 of Lemna perpusilla is concluded to be blocked between plastoquinone and cytochrome f in the photosynthetic electron transport system. The location of the block is based on the following observations of activities in chloroplasts isolated from the mutant and wild-type plants. (a) Relative to wild type, electron flow rates from water to ferricyanide, 2,6-dichlorophenol indophenol or NADP were very low in the mutant, but rates of photosystem I-dependent electron flow and cyclic phosphorylation were high. (b) Chlorophyll a fluorescence induction curves for mutant and wild type were similar. (c) Silicomolybdate and lipophilic acceptors in the mutant were photoreduced at rates comparable to wild type. (d) Cytochrome f of the mutant chloroplasts was not reduced by red light, but was oxidized by red or far red light. (e) Reduction of the primary electron acceptor of photosystem II (Q) by ATP-driven reverse electron flow was not observed in the mutant. 相似文献
17.
An Action Spectrum for Light-induced Primordium Formation in a Basidiomycete, Favolus arcularius (Fr) Ames 总被引:1,自引:0,他引:1
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The action spectrum for the initiation of fruiting (primordium formation) in Favolus arcularius was determined on the equal response basis. The detectable effect of light was observed in the region between 350 to 560 nanometers, showing six distinct peaks at 374, 398, 424, 446, 480, and 514 nanometers. The half maximum response is reached with 1.8 × 108 ergs per cm2 at the most effective wavelength, 398 nanometers. Since the inhibitors, diphenylamine and quinacrine, had no consistent effect on the primordium formation, it is suggested that the possible photoreceptor pigment(s) may be neither carotenoid nor flavinoid. 相似文献
18.
The molecular structures of water-soluble and -insoluble hemicelluloses of bamboo leaf, and of a hemicellulosic xylan from the former, have been examined. It is concluded that all the materials have the same structural features on their main xylan chain, namely, the side-chains or residues (a) l-arabinofuranose, (b) O-galactopyranosyl-(1→5)-l-arabinofuranose, (c) O-galactopyranosyl-(1→4)-O-d-xylopyranosyl-(1→2)-l-arabinofuranose, (d) O-d-xylopyranosyl-(1→2)-O-l-arabinofuranosyl-(1→2)-l-arabinofuranose, (e) O-(d-glucopyranosyluronic acid)-(1→4)-O-d-xylopyranosyl-(1→4)-galactopyranose, and (f) d-glucopyranuronic acid and its 4-methyl ether. Feature (d) is proposed for the first time, but it may have been present in xylans studied by others. The main xylose chain in the soluble, insoluble, and xylan materials have, respectively, 1 in every 2.8, 4.0, and 7.6 xylan residues substituted by side residues or chains (a)–(e). It is concluded that the polysaccharide product recovered after methylation of the three hemicellulosic materials does not fully represent the quantitative composition of the materials subjected to methylation, although structural features (a), (d), and (e) are not much altered. When the soluble material was treated with dilute acid under mild conditions, most of (a) was removed, while (d) and other substituents, including those with l-arabinofuranose residues, were not removed to the same extent. 相似文献
19.
Blue-light control of sporangiophore initiation in Phycomyces 总被引:1,自引:0,他引:1
K. Bergman 《Planta》1972,107(1):53-67
Summary Many fungi produce spores or spore-bearing structures under the control of blue light. Sporangiophores of Phycomyces blakesleeanus are produced continuously along racing tube cultures grown in constant darkness or constant light. However, if a dark-grown culture is exposed to light for a short time on one day a narrow, dense band of sporangiophores is observed the next day at that point of the tube occupied by the mycelial tips during the light pulse. A periodic program with short days (e.g., 4 h light; 20 h dark), leads to periodic bands of sporangiophores spaced at intervals corresponding to one period-length (in this case 24 h) of mycelial growth. Sporangiophore initiation is inhibited by a light to dark transition and is stimulated by a dark to light transition. A partial action spectrum of the initiation response, covering the critical 480–540 nm region, strongly suggests that the same photoreceptor pigment is involved as in the phototropic response and light growth response of sporangiophores. Mutants with altered light control of sporangiophore initiation have been found among those selected for altered phototropism. This joint elimination of these two responses to blue light by a single mutation is evidence for a common early transduction system. 相似文献
20.
Nida N. Farshori Mudasir R. Banday Anis Ahmad Asad U. Khan Abdul Rauf 《Bioorganic & medicinal chemistry letters》2010,20(6):1933-1938
The long-chain alkenoic acid hydrazides (1a–d) on reaction with phenylisocyanate and phenylthiocyanate gave their corresponding semicarbazides (2a–d) and thiosemicarbazides (4a–d), which on further refluxing with POCl3 and Ac2O yielded corresponding 1,3,4-oxadiazoles (3a–d) and thiadiazoles (5a–d), respectively.The structure elucidation of synthesized compounds is based on the elemental analysis and spectral data (IR, 1H NMR, 13C NMR and MS). The synthesized oxadiazoles and thiadiazoles have been screened for antibacterial and antifungal activities. The investigation of antimicrobial screening revealed that compounds 3c, 3d, 5c, 5d and compounds 3b, 5b, showed good antibacterial and antifungal activities, respectively. 相似文献