• Journal of Plant Biology
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• v.36 no.3
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• pp.293-296
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• 1993

Effects of dark treatment and N1-dichlorophenyl-N3-dimethylurea (DCMU) on the desaturation of galactolipids of Dunaliella salina were investigated to see whether light-driven photosynthetic electron transport is involved in in vivo desaturation of galactolipids. The incorporation of radioactive fatty acid precursors ([14C]lauric acid) into galactolipids, mainly composed of prokaryotic molecular species, was most affected among different polar lipid classes by both treatments. The analysis of specific radioactivities of individual galactolipid molecular species revealed that their synthesis was greatly inhibited by the treatments except for eukaryotic molecular species, 18 : 3/ 18 : 3 digalactosyldiacylglycerol, whose desaturation occurs in endoplasmic reticulum.

• Journal of Plant Biology
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• v.31 no.3
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• pp.205-215
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• 1988

The effects of simetryne on light induced electron transport and phosphorylation in isolated spinach (Spinacia oleracea L.) chloroplasts were investigated in comparison with sencor and DCMU. Simetryne, like sencor and DCMU, completely, inhibited PSII electron transport and phosphoryltion with 10-6 M treatment but did not inhibit PSI electron transport. Interference with the electron transport pathway was evidenced by the greater sensitivity of oxygen evolution and uptake than phosphorylation. The following order of decreasing inhibitory effectiveness was exihibited; DCMU>simetryne>sencor. The photoacoustic technique was also used to monitor the relative photosynthetic activity in the leaves treated with the herbicides (simetryne, sencor or DCMU) in vivo and in vitro. Photoacoustic measurements on intact leaves provide quantitative information on two related aspects of the photosynthetic process, namely, photochemical energy storage and oxygen evolution. The relative photoacoustic signal of leaves treated with the herbicides showed low level in 21 Hz, but high level in 380 Hz and on isolated chloroplasts (both 21 Hz and 380 Hz) in comparison with that of the untreated leaves. These results suggest that some of photochemical energy is converted into the heat owing to the inhibition of electorn transport pathway by the herbicides.

• Journal of Plant Biotechnology
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• v.4 no.4
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• pp.171-178
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• 2002

Chlorophyll (Chl) fluorescence imaging was used to investigate the effectiveness of in vivo incorporation methods for two chemicals, 3-(3',4'-dichlorophenyl)-1,1-dimethylurea (DCMU) and methyl viologen (MV) in rice, a monocot, and cucumber, a dicot, leaves. four different methods (vacuum infiltration, floating, transpiration-aided incorporation through petiole and spraying) were compared, and $F_i$ and $F_v$/$F_m$ were chosen for the imaging of the DCMU- and MV-treated leaves, respectively. The effects of the chemicals in plants were generally heterogeneous over the whole leaf area. Moreover, the effectiveness of the treatment of a chemical in plant leaves was dependent on chemical species, plant species, concentration of the chemical, the treatment method, the duration of the treatment, the existence of light and detergent, etc. In conclusion, we suggest that to achieve the proposed effects of chemicals in plants for an actual experiment, these factors must be considered before the chemical treatment, and the best method for the treatment of the chemicals tested was floating and vacuum infiltration in the dicot and the monocot leaves, respectively, as drawn from Chl fluorescence imaging analysis.

• Korean Journal of Microbiology
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• v.32 no.1
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• pp.65-69
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• 1994

Light appears to be needed in the early and late function of the cyanophage of Synechococcus sp. and dark treatment during the first 2 hr of the replication cycle increased the virus yield to 200%. The burst size of the cyanophage multiplied in Synechococcus sp. in dark was 11% of that of control. The viral multiplication was reduced 2% in the presence of photosynthetic inhibitor, DCMU of $10^{-6}$ M, and nearly blocked in $10^{-4}$ M CCCP. These data suggested that the photosynthetic dependence of the cyanophage is greater than those of LPP-1 and AS-1, and smaller than SM-1.

• BMB Reports
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• v.29 no.1
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• pp.58-62
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• 1996

The structural changes in the electron donor side of the PSII reaction center have been monitored since heat treatment ($45^{\circ}C$ for 5 min) of thylakoids is known to decrease the oxygen evolving activity. In heat-treated spinach chloroplast thylakoids, the inhibitory effect of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) on the electron transport activity of the PSII reaction center from diphenyl carbazide to dichlorophenolindophenol became reduced approximately 3.8 times and [$^{14}C$]-labeled DCMU binding on the D1 polypeptide decreased to 25~30% that of intact thylakoid membranes, implying that the conformational changes of the DCMU binding pocket, residing on the D1 polypeptide, occur by heat treatment. The accessibility of trypsin to the $NH_2$-terminus of the cytochrome b-559 ${\alpha}$-subunit, assayed with Western blot using an antibody generated against the synthetic peptide (Arg-68 to Arg-80) of the COOH-terminal domain, was also increased, indicating that heat-treatment caused changes in the structural environments near the stromal side of the cytochrome b-559 ${\alpha}$-subunit, allowing trypsin more easily to cleave the $NH_2$-terminal domain. Therefore, the structural changes in the electron donor side of the PSII reaction center complexes could be one of the reasons why the oxygen evolving activity of the heat-treated thylakoid membranes decreased.

• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.64.2-64.2
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• 2008

• Journal of Plant Biotechnology
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• v.35 no.2
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• pp.141-145
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• 2008

In this study, glucose-inducible intergenic sequences were used to generate bioreporters of the cyanobacterium Synechocystis sp. PCC 6803 that could monitor environmental pollutants. Luciferase genes LuxAB from the marine bacterium Vibrio fischeri under the control of glucose-inducible intergenic seqeucens of eight genes (atpI, ndbA, ctaD1, tkt, pgi, pdh, ppc, and cydA) were successfully expressed in the cyano-bacterial transformants, showing 5-25 fold increases in biolumeniscence upon exposure to glucose. In addition, glucose-inducible cyanobacterial bioreporters were very sensitive to various chemicals such as heavy metals ($Hg^{2+}$, $Cu^{2+}$, $Zn^{2+}$), electron transport inhibitors (DCMU, DBMIB, $CN^-$), and antibiotics (chloramphenicol and rifampicin). These glucose-inducible cyanobacterial bioreporters would be useful to develop biosensors for rapid screening of environmental samples.

• Journal of Ginseng Research
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• v.16 no.2
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• pp.124-128
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• 1992

Vsing the phosphorylated thylakoid membrane induced by 5-35kLux of light intensities, we investigated the chlorophyll nuorescence quenching of PSII and the phosphorylation of LHCPII i in relation to the chlorophyll-bleaching of Panax ginseng C.A. Meyer. In the Presence of DCMU, both of the fluorescence yield of non-phosphorylated thylakoid and the rate of fluorescence quencing dependent on the Phosphorylation were high p. ginseng more then Glyine max L. And at the high light F intensity (above 25 kLux) the fluorescence quenching rate of p. ginseng compared with that of G. max reached nearly to 2 times. The LHCPII of P. ginseng was composed of 3 major Polypeptides (24.5, 26 and 27kD) and 3 minor polypeptides (24, 25.3 and 28.3kD) in the region of 24-29kD and differed, from G. max in both of the number and quantity of polypeptides. Among these polypeptides, the phosphorylated polypeptide dependent on the light intensity was 24kD in P. ginseng.

• Proceedings of the Botanical Society of Korea Conference
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• 1999.07a
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• pp.63-67
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• 1999

We have isolated more than a dozen cDNA clones corresponding to genes that were expressed in Arabidopsis leaves when they were kept in the dark. The nucleotide sequence analysis showed that some of the clones encoded proteins with significant homology to $\beta$-glucosidase (din2), branched-chain $\alpha$-keto acid dehydrogenase subunit E1$\beta$(din3), and another subunit E2 (din4), yeast RAD23 (din5), asparagine synthetase (din6), pre-mRNA splicing factor SRp35 (din7), phosphomannose isomerase (din9), seed imbibition protein (din10), and 2-oxoacid-dependent oxidase (din11). Accumulation of transcripts from din3,4,6 and 10 occurred rapidly after the plants were transferred to darkness. Transcripts from din2,9, and 11 could be detected only after 24 h of dark treatment. Inhibition of photo-synthesis by DCMU strongly induced the accumulation of transcripts from those genes, and application of sucrose to detached leaves suppressed the accumulation both in the dark and by DCMU. These observations indicate that expression of the genes is caused by sugar starvation resulted from the cessation of photosynthesis. We further showed that din2-encoded protein also accumulated in senescing leaves. Given these results, possible roles of din genes in leaves in the dark and senescing leaves are discussed.

• Journal of Photoscience
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• v.9 no.2
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• pp.373-375
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• 2002

Lhcb genes encoding light-harvesting chlorophyll-a/b binding (LHC) proteins of photosystem (PS) II were comprehensively characterized using the expressed sequence tag (EST) databases in the green alga, Chlamydomonas reinhardtii. The gene family was composed of eight Lhcb genes including four new genes, which were isolated and sequenced. The effects of light intensity on the levels of mRNAs accumulation of multiple Lhcb genes were studied under various conditions. The results indicate that Lhcb genes are coordinately regulated in response to light conditions, and repressed when the input light energy exceeded the requirement for $CO_2$ assimilation. The effects of high light on the expression of the Lhcb genes observed in the presence of an electron transport inhibitor, DCMU, and in mutants deficient in photosynthetic reaction centers suggest the presence of two alternative mechanisms for regulating the genes expression under high-light conditions.