Urethane as an inhibitor of the firefly light reaction

Effects of three diphenylether herbicides [2,4-dichlorophenyl-p-nitrophenyl ether (nitrofen); 2,4,6-trichlorophenyl-4′-nitrophenyl ether (hereinafter referred to as MC-1478); and 2,4′-dinitro-4-trifluoromethyl-diphenylether (hereinafter referred to as C-6989)] were measured on phosphorylation and electron transport in spinach(Spinacia oleraceaL.) chloroplasts, and mung bean(Phaseolus aureusL., var. Jumbo) and white potato tuber(Solarium tuberosumL.) mitochondria. All of the diphenylethers acted primarily as inhibitors of chloroplast noncyclic electron transport, and the coupled photophosphorylation. The compounds ranked in the following decreasing order of inhibitory effectiveness: MC-1478 ≥ C-6989 >> nitrofen. A site of action close to light reaction II was suggested. At high molar concentrations, marginal interference with cyclic electron transport or phosphorylation was obtained. In mitochondria, MC-1478 and nitrofen acted primarily as electron transport inhibitors with malate, NADH, and succinate as substrates. MC-1478 was a slightly stronger inhibitor than nitrofen. Only slight stimulation of ADP-limited oxygen uptake was obtained during the oxidation of NADH and succinate; whereas, strong inhibition of oxygen uptake was obtained with malate. C-6989 also weakly stimulated ADP-limited oxygen uptake with NADH and succinate but differed from the two chlorinated diphenylethers in that electron transport was not inhibited when ADP was present in excess. Interference with ATP generation could be one of the mechanisms through which the phytotoxicity of diphenylether herbicides is expressed.

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Transcriptome profiling of developing leaf and shoot apices to reveal the molecular mechanism and co-expression genes responsible for the wheat heading date

BMC Genomics ◽

10.1186/s12864-021-07797-7 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Yuxin Yang ◽

Xueying Zhang ◽

Lifen Wu ◽

Lichao Zhang ◽

Guoxiang Liu ◽

...

Keyword(s):

Transcription Factor ◽

Flowering Time ◽

Heading Date ◽

Yield Component ◽

Potential Candidate ◽

Rna Seq ◽

Nucleotide Synthesis ◽

Light Reaction ◽

Grain Number Per Spike ◽

Double Ridge

Abstract Background Wheat is one of the most widely planted crops worldwide. The heading date is important for wheat environmental adaptability, as it not only controls flowering time but also determines the yield component in terms of grain number per spike. Results In this research, homozygous genotypes with early and late heading dates derived from backcrossed progeny were selected to conduct RNA-Seq analysis at the double ridge stage (W2.0) and androgynous primordium differentiation stage (W3.5) of the leaf and apical meristem, respectively. In total, 18,352 differentially expressed genes (DEGs) were identified, many of which are strongly associated with wheat heading date genes. Gene Ontology (GO) enrichment analysis revealed that carbohydrate metabolism, trehalose metabolic process, photosynthesis, and light reaction are closely related to the flowering time regulation pathway. Based on MapMan metabolic analysis, the DEGs are mainly involved in the light reaction, hormone signaling, lipid metabolism, secondary metabolism, and nucleotide synthesis. In addition, 1,225 DEGs were annotated to 45 transcription factor gene families, including LFY, SBP, and MADS-box transcription factors closely related to flowering time. Weighted gene co-expression network analysis (WGCNA) showed that 16, 336, 446, and 124 DEGs have biological connections with Vrn1-5 A, Vrn3-7B, Ppd-1D, and WSOC1, respectively. Furthermore, TraesCS2D02G181400 encodes a MADS-MIKC transcription factor and is co-expressed with Vrn1-5 A, which indicates that this gene may be related to flowering time. Conclusions RNA-Seq analysis provided transcriptome data for the wheat heading date at key flower development stages of double ridge (W2.0) and androgynous primordium differentiation (W3.5). Based on the DEGs identified, co-expression networks of key flowering time genes in Vrn1-5 A, Vrn3-7B, WSOC1, and Ppd-1D were established. Moreover, we discovered a potential candidate flowering time gene, TraesCS2D02G181400. Taken together, these results serve as a foundation for further study on the regulatory mechanism of the wheat heading date.

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Superoxide-and Ethane-Formation in Subchloroplast Particles: Catalysis by Pyridinium Derivatives

Zeitschrift für Naturforschung C ◽

10.1515/znc-1980-9-1019 ◽

1980 ◽

Vol 35 (9-10) ◽

pp. 770-775 ◽

Cited By ~ 11

Author(s):

E. F. Elstner ◽

H. P. Fischer ◽

W. Osswald ◽

G. Kwiatkowski

Keyword(s):

Electron Transport ◽

Photosystem I ◽

Photosynthetic Electron Transport ◽

Redox Potentials ◽

Light Reaction ◽

Pyridinium Bromide ◽

Superoxide Formation ◽

Fatty Acid Peroxidation ◽

Chlorophyll Bleaching ◽

Ethane Formation

Abstract Oxygen reduction by chloroplast lamellae is catalyzed by low potential redox dyes with E′0 values between -0 .3 8 V and -0 .6 V. Compounds of E′0 values of -0 .6 7 V and lower are inactive. In subchloroplast particles with an active photosystem I but devoid of photosynthetic electron transport between the two photosystems, the active redox compounds enhance chlorophyll bleaching, superoxide formation and ethane production independent on exogenous substrates or electron donors. The activities of these compounds decrease with decreasing redox potential, with one exception: 1-methyl-4,4′-bipyridini urn bromide with an E′0 value of lower -1 V (and thus no electron acceptor of photosystem I in chloroplast lamellae with intact electron transport) stimulates light dependent superoxide formation and unsaturated fatty acid peroxidation in sub chloroplast particles, maximal rates appearing after almost complete chlorophyll bleaching. Since this activity is not visible with compounds with redox potentials below -0 .6 V lacking the nitrogen atom at the 1-position of the pyridinium substituent, we assume that 1 -methyl-4,4′-bi-pyridinium bromide is “activated” by a yet unknown light reaction.

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PERSISTENT LIGHT REACTION WITH JADIT

The Medical Journal of Australia ◽

10.5694/j.1326-5377.1973.tb110963.x ◽

1973 ◽

Vol 1 (22) ◽

pp. 1119-1119 ◽

Cited By ~ 3

Keyword(s):

Light Reaction

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Influence of High Temperature on Photosynthesis, Antioxidative Capacity of Chloroplast, and Carbon Assimilation among Heat-tolerant and Heat-susceptible Genotypes of Nonheading Chinese Cabbage

HortScience ◽

10.21273/hortsci12259-17 ◽

2017 ◽

Vol 52 (11) ◽

pp. 1464-1470 ◽

Cited By ~ 4

Author(s):

Lingyun Yuan ◽

Yujie Yuan ◽

Shan Liu ◽

Jie Wang ◽

Shidong Zhu ◽

...

Keyword(s):

High Temperature ◽

Chinese Cabbage ◽

Photosynthetic Capacity ◽

Photochemical Efficiency ◽

Membrane Integrity ◽

Photosynthetic Apparatus ◽

Carbon Assimilation ◽

Light Reaction ◽

Chlorophyll Contents ◽

Heat Tolerant

High temperature (HT) is a major environmental stress limiting oversummer production of nonheading Chinese cabbage (NHCC, Brassica campestris ssp. chinensis Makino). In the present study, the effects of HT on photosynthetic capacity, including light reaction and carbon assimilation, were completely investigated in two NHCC, ‘xd’ (heat-tolerant), and ‘sym’ (heat-susceptible). The two genotypes showed significant differences in plant morphology, photosynthetic capacity, and photosynthate metabolism (carboassimilation). HT caused a decrease in photosynthesis, chlorophyll contents, and photochemical activity in NHCC. However, these main photosynthetic-related parameters, including net photosynthetic rate (PN), maximal photochemical efficiency of PSII (Fv/Fm), and total chlorophyll content in ‘xd’, were significantly higher than those of ‘sym’ plants. The antioxidant contents and antioxidative enzyme activities of ascorbic acid-reduced glutathione cycle in the chloroplast of ‘xd’ were significantly higher than those of ‘sym’. Microscopic analyses revealed that HT affected the structure of photosynthetic apparatus and membrane integrity to a different extent, whereas ‘xd’ could maintain a better integrated chloroplast shape and thylakoid. Inhibited light reaction also hampered carbon assimilation, resulting in a decline of carboxylation efficiency and imbalance of carbohydrate metabolism. However, larger declined extents in these data were presented in ‘sym’ (heat-susceptible) than ‘xd’ (heat-tolerant). The heat-tolerant genotype ‘xd’ had a better capacity for self-protection by improved light reaction and carbon assimilation responding to HT stress.

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Direct Action of Light in Naturally Pigmented Muscle Fibers

The Journal of General Physiology ◽

10.1085/jgp.46.2.333 ◽

1962 ◽

Vol 46 (2) ◽

pp. 333-342 ◽

Cited By ~ 24

Author(s):

Howard H. Seliger

Keyword(s):

Visual Pigment ◽

Absorption Maximum ◽

Pupil Diameter ◽

Direct Action ◽

Pigment Epithelium ◽

Action Spectrum ◽

Square Root ◽

Light Reaction ◽

First Order ◽

Iris Sphincter

Contraction due to light in excised eel irises appears to follow a simple first order law. The action spectrum for contraction has a maximum which agrees with the eel rhodopsin absorption maximum. Inasmuch as rhodopsin is the rod pigment-opsin complex and the iris sphincter pupillae evolves from the pigment epithelium of the retina in the region of the iris, the muscle pigment might be the same as the visual pigment. In the human eye the contraction of the iris sphincter is activated only by light incident on the retina and the pupil diameter varies inversely with the square root of the light intensity. The inverse first power relation observed in the present experiments suggests a more primitive origin for the light reaction in eel irises. Relaxation is a much slower process and can be approximated as the sum of two first order processes.

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