摘要:

The photosynthetic action spectrum of the bean plant leaf,Phaseolus vulgarisL. (variety Red Kidney), has been determined with a diffraction grating illuminated by a 6500-watt xenon arc. An infrared CO2analyzer 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.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

The nuclear DNAs from a number of angiosperm species were tested for hybridization to the RNAs contained in 70 S (chloroplastic) and 80 S (cytoplasmic) ribosomes. All of the DNAs contained regions complementary to RNAs from chloroplastic as well as cytoplasmic ribosomes. DNAs from closely related plants varied widely in their proportion of coding for these RNAs. About 0.15% of the DNAs from a number of different species ofNicotianawere found to be complementary to the RNAs of each kind of ribosome; however, DNAs from some other members of this genus had more than three times this proportion of coding for ribosomal RNAs. These and other data suggest that hybridization percentage for ribosomal RNA is not a familial or generic characteristic.DNAs with high amounts of coding for ribosomal RNAs have thus far been found to contain satellite DNAs of base composition more like ribosomal RNA than the main DNA component. The satellite DNA from pumpkin has been isolated and shown to contain cistrons for both chloroplastic and cytoplasmic ribosomal RNAs.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

Redox changes of the flavoproteins of mung bean (Phaseolus aureus) mitochondria were measured by differential absorbance at 468 to 493 nanometers and by fluorescence emission above 500 nanometers excited at 436 nanometers. Four flavoproteins are distinguishable by the ratio of their fluorescence to absorbance changes, and by their requirement, or lack of it, for energy-linked reverse electron transport for reduction by succinate. Two flavoproteins are reduced by succinate in fully depleted mitochondria which lack the capacity for reverse electron transport. These are designated Fphaand Fphfand have fluorescence to absorbance ratios of 0 and 1.4, respectively. The two flavoproteins have the same half-time for oxidation, but Fphfis reduced more slowly than Fphaby substrate in the presence of cyanide. One flavoprotein with a fluorescence to absorbance ratio of 0 is not reduced by succinate in anaerobic, fully depleted mitochondria, but is rapidly reduced on subsequent addition of malate; it is designated Fpm. The fourth distinguishable flavoprotein component is reducible by succinate in an energy-linked reaction, even in partially depleted mitochondria. This component has a fluorescence to absorbance ratio of 3.8 and is designated Fp1f. In addition to these four flavoproteins reducible by substrates, there is a highly fluorescent flavin-containing component in or associated with these mitochondria, which is rapidly reduced by dithionite.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

The effects of phenylethylbiguanidide, decamethylenediguanidide, and octylguanidine have been studied with mung bean hypocotyl mitochondria (Phaseolus aureusvar. Jumbo) supplied with malate, reduced nicotinamide adenine dinucleotide, succinate, or ascorbate-tetramethyl-p-phenylenediamine as substrates. The guanidines act as energy transfer inhibitors, all three inhibiting all three phosphorylation sites. Phenylethylbiguanidide causes only partial inhibition even at relatively high concentrations. Decamethylenediguanidide inhibits about 70% of the malate respiration, 55% of the succinate respiration, and 35% of the ascorbate-tetramethyl-p-phenylenediamine respiration.Octylguanidine inhibits all three phosphorylation sites and the cyanide-insensitive respiration, but to differing extents and at different concentrations. Both states 3 and 4 are inhibited by octylguanidine. Inhibition of state 4 is preceded by an uncoupling action at lower concentrations of inhibitor, while inhibition of state 3 is influenced by the state of the mitochondria when the inhibitor is added. Application of the guanidine to state 4 mitochondria is more effective than application to mitochondria already in state 3.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

Osmotic shock was found to be better than freezing and thawing, a French press, or sonic oscillation for the preparation of submitochondrial particles from mung bean (Phaseolus aureus) hypocotyl mitochondria. Particles prepared by osmotic shock rapidly oxidize reduced nicotinamide adenine dinucleotide and succinate, but they oxidize malate slowly. NADH oxidation was slightly stimulated by cytochromec, ATP, and ADP; succinate oxidation was markedly increased by ATP, slightly by ADP and cytochromec; and malate oxidation required the addition of NAD+NADH oxidation is inhibited weakly by amytal, completely by antimycin A and KCN, but not by rotenone. Chlorsuccinate, malonate, antimycin A, and KCN inhibit succinate oxidation. The action of antimycin A and KCN is incomplete, while chlorsuccinate and malonate were competitive inhibitors. Antimycin A combined stoichiometrically with particle protein in the ratio of 0.23 millimicromole per milligram of protein.Oligomycin and bis(hexafluoroacetonitryl) acetone, a potent uncoupler of oxidative phosphorylation, were without effect on oxygen uptake but did influence the ATP-stimulated onset of respiration when succinate was substrate. Fresh particles were markedly inhibited by oxtylguanidine, indicating energy conservation, but this inhibition decreased on storage of the particles.Spectra show the presence of cytochrome components the same as those of the intact mung bean mitochondrion, but present at higher concentrations. The molar concentrations of the particle cytochromes were two to three times those of the intact mitochondrion and the molar ratios were calculated as 0.9:1.0:1.0:2.8 for cytochromesa:b:c:flavoprotein, respectively.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

Submitochondrial particles from mung bean mitochondria (Phaseolus aureus) are able to catalyze an energy-linked reduced nicotinamide adenine dinucleotide-nicotinamide adenine dinucleotide phosphate transhydrogenase reaction supported by ATP or by aerobically generated high energy intermediates. The energy transfer pathway appears to differ from that utilized for oxidative phosphorylation.Mung bean submitochondrial particles will also reduce nicotinamide adenine dinucleotide by reversed electron transport from succinate or ascorbate tetramethyl-p-phenylenediamine. The energy requirement can be met by ATP or by aerobically generated high energy intermediates.A scheme for the energy transduction pathway in mung beans is postulated from the effects of inhibitors and uncouplers of energy transfer on transhydrogenase and reversed electron transfer reactions.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

A critical evaluation was made of the hypothesis that the primary mode of action of ethylene in inducing physiological responses is by changing the permeability of cell organelles. The parameter investigated was the evaluation of the influence of ethylene and other gases on mitochondrial oxidation and swelling. Spectrometric evidence demonstrated that mitochondria prepared with good respiratory control can be induced to swell more rapidly with ethylene and other aliphatic gases (ethane, propene, propane, I-butene) in test solutions of 0.125mKCl. The fact that saturated as well as unsaturated hydrocarbon gases elicited similar changes provides evidence that ethylene does not directly alter membrane permeability as its mechanism of action.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

Mitochondria isolated from cotyledons of germinating wax beans (Phaseolus vulgarisL.) showed fairly good respiratory control on days 1 and 2 after planting. The respiratory control was completely lost from days 3 to 5. During this period mitochondria were shown to be very leaky, losing about 88% of their total nicotinamide adenine dinucleotide to the suspending medium in a short time. The respiratory control was partially recovered by day 7, after which it completely disappeared again. By the use of differential centrifugation, the mitochondria were divided into subfractions by sequential centrifugation: 10,000gfor 5 minutes, 25,000gfor 5 minutes, and 40,000gfor 5 minutes. The 10,000gsubfraction was responsible for the recovery of mitochondrial activity (respiratory control value, adenosine diphosphate to oxygen ratio, and rate of oxygen utilization), on day 7. Activities of succinate dehydrogenase, cytochrome oxidase, pyruvate dehydrogenase, and isocitrate dehydrogenase from different mitochondrial subfractions of aging cotyledons were determined. In general, the enzyme activities, adenosine diphosphate to oxygen ratios, and the ability of mitochondria to swell and contract followed the same pattern as for respiratory control.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

The host-specific toxin ofHelminthosporium carbonumUllstrup has a molecular formula approximating C32H50N6O10. The compound has been crystallized and a crystalline hydrochloride derivative has been produced. The molecular weight, as determined by chromatography on Sephadex G-10, is slightly less than 700. The toxin appears to be a cyclic peptide, since, although it does not react with ninhydrin or dinitrofluorobenzene, it yields, on hydrolysis, compounds which react to these reagents. It is unstable in dilute acids, yielding ninhydrin-reacting products. Complete acid hydrolysis yields alanine, proline, and three other ninhydrin-reacting components. The infrared spectrum of the toxin reveals an ester band in addition to amide absorption. Its ultraviolet spectrum reveals the presence of unsaturation in the molecule. The toxin is relatively unstable and loses its specific toxicity. This loss of activity appears to be associated with loss of nitrogen and with decreased solubility in water.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

Magnesium-28 was applied to specific leaves of bean (Phaseolus vulgaris) and barley (Hordeum vulgare) plants. After 24 hours, as much as 7% of the absorbed Mg was exported from the treated bean leaves and 11% was transported basipetally from the treated zone of the barley leaves. Transport of Mg did not occur past a heat-killed section of the treated leaf, thereby indicating that translocation took place via the phloem. Mg movement in the phloem was also evident in autoradiograms of bean stem segments in which the xylem was separated from the phloem by a thin sheet of plastic.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB