The Experts below are selected from a list of 147 Experts worldwide ranked by ideXlab platform
Alex Sivan - One of the best experts on this subject based on the ideXlab platform.
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Characterization of mutants of the red microalga Porphyridium aerugineum (Rhodophyceae) resistant to DCMU and atrazine
Phycologia, 1997Co-Authors: Sigalit Boura-halfon, Shoshana Arad, Moshe Rise, Alex SivanAbstract:Abstract In an attempt to obtain genetic markers in the red microalga Porphyridium aerugineum Geitler, two stable spontaneous mutants were isolated that were resistant to the herbicides diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) (designated D9)] and atrazine [2-chloro-4-ethylamino-(isopropylamino)-1,3,5-triazine (designated A10)]. The mutant resistant to DCMU was also found to be resistant to atrazine, whereas the atrazine-resistant mutant proved sensitive to DCMU. When the wild-type P. aerugineum was grown in the presence of the herbicides, the cellular contents of chlorophyll a, phycocyanin, zeaxanthin, and protein were higher, but the amounts of β-carotene and of cell wall polysaccharide were lower as compared to cells grown in herbicide-free medium. In the mutants, the herbicides did not have a significant effect on these cellular features.
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A mutant of the red microalga Porphyridium sp. (Rhodophyceae) resistant to DCMU and atrazine
Phycologia, 1995Co-Authors: Alex Sivan, Shoshana AradAbstract:Abstract A mutant (DC-2) of the unicellular red alga Porphyridium sp. (UTEX 637) resistant to the herbicide diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea, DCMU] was isolated after induced mutagenesis with N-methyl-N′-nitro-N-nitrosoguanidine (NNG) at a frequency of 2.1 × 10−5. The minimal concentration of DCMU that completely inhibited growth of the wild type was fiftyfold lower than that required for complete inhibition of the mutant's growth. The mutant was found to be stable over several consecutive growth cycles in the absence of DCMU. When the wild type was exposed to a sub-lethal concentration of DCMU (0.2 μM),its photosynthesis was reduced by up to 72%, while the mutant was not affected by this concentration. In the presence of up to 5.0 μM DCMU the Pmax of the mutant was slightly reduced. However, these concentrations completely inhibited photosynthesis in the wild type. DCMU at a concentration of 0.2 μM decreased the cellular level of phycobiliproteins (phycoerythrin and phycocyanin) but not of...
Shoshana Arad - One of the best experts on this subject based on the ideXlab platform.
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Characterization of mutants of the red microalga Porphyridium aerugineum (Rhodophyceae) resistant to DCMU and atrazine
Phycologia, 1997Co-Authors: Sigalit Boura-halfon, Shoshana Arad, Moshe Rise, Alex SivanAbstract:Abstract In an attempt to obtain genetic markers in the red microalga Porphyridium aerugineum Geitler, two stable spontaneous mutants were isolated that were resistant to the herbicides diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) (designated D9)] and atrazine [2-chloro-4-ethylamino-(isopropylamino)-1,3,5-triazine (designated A10)]. The mutant resistant to DCMU was also found to be resistant to atrazine, whereas the atrazine-resistant mutant proved sensitive to DCMU. When the wild-type P. aerugineum was grown in the presence of the herbicides, the cellular contents of chlorophyll a, phycocyanin, zeaxanthin, and protein were higher, but the amounts of β-carotene and of cell wall polysaccharide were lower as compared to cells grown in herbicide-free medium. In the mutants, the herbicides did not have a significant effect on these cellular features.
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A mutant of the red microalga Porphyridium sp. (Rhodophyceae) resistant to DCMU and atrazine
Phycologia, 1995Co-Authors: Alex Sivan, Shoshana AradAbstract:Abstract A mutant (DC-2) of the unicellular red alga Porphyridium sp. (UTEX 637) resistant to the herbicide diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea, DCMU] was isolated after induced mutagenesis with N-methyl-N′-nitro-N-nitrosoguanidine (NNG) at a frequency of 2.1 × 10−5. The minimal concentration of DCMU that completely inhibited growth of the wild type was fiftyfold lower than that required for complete inhibition of the mutant's growth. The mutant was found to be stable over several consecutive growth cycles in the absence of DCMU. When the wild type was exposed to a sub-lethal concentration of DCMU (0.2 μM),its photosynthesis was reduced by up to 72%, while the mutant was not affected by this concentration. In the presence of up to 5.0 μM DCMU the Pmax of the mutant was slightly reduced. However, these concentrations completely inhibited photosynthesis in the wild type. DCMU at a concentration of 0.2 μM decreased the cellular level of phycobiliproteins (phycoerythrin and phycocyanin) but not of...
Assaf Sukenik - One of the best experts on this subject based on the ideXlab platform.
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Selective effect of the herbicide DCMU on unicellular algae — a potential tool to maintain monoalgal mass culture of Nannochloropsis
Journal of Applied Phycology, 1996Co-Authors: Y. Gonen-zurgil, Y. Carmeli-schwartz, Assaf SukenikAbstract:The selective effect of DCMU on photosynthetic activity and growth rate was examined in several marine unicellular algae:Nannochloropsis sp. (Eustigmatohyceae),Dunaliella salina (Chlorophyceae)Isochrysis galbana (Prymnesiophyceae) andChaetoceros sp. (Bacillariophyceae). DCMU at 10−7 M caused an immediate decrease in the photosynthetic rate ofDunaliella andIsochrysis (about 50% inhibition), whereas 10−6 M imposed 80% inhibition in the photosynthetic rate ofChaetoceros. InNannochloropsis the rate was affected only when DCMU concentration exceeded 10−6M. Cellular growth rate of all studied algae was affected by DCMU in a similar manner to photosynthesis. The differential effect of DCMU was further examined in mixed cultures in whichNannochloropsis was cultivated together with an additional species simulating a contamination situation of aNannochloropsis culture. When DCMU was added at concentrations higher than 10−7 M, the growth of the competing algae significantly decreased, whileNannochloropsis maintained a relatively high growth rate. Consequently, after a growth period of 4 to 7 days a clear domination ofNannochloropsis was observed. These results demonstrate that DCMU and probably other herbicides of similar characteristics can be used effectively as a selective tool to suppress contaminating unicellular algae in open ponds in order to maintain a monoculture ofNannochloropsis.
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selective effect of the herbicide DCMU on unicellular algae a potential tool to maintain monoalgal mass culture of nannochloropsis
Journal of Applied Phycology, 1996Co-Authors: Y Gonenzurgil, Y Carmelischwartz, Assaf SukenikAbstract:The selective effect of DCMU on photosynthetic activity and growth rate was examined in several marine unicellular algae:Nannochloropsis sp. (Eustigmatohyceae),Dunaliella salina (Chlorophyceae)Isochrysis galbana (Prymnesiophyceae) andChaetoceros sp. (Bacillariophyceae). DCMU at 10−7 M caused an immediate decrease in the photosynthetic rate ofDunaliella andIsochrysis (about 50% inhibition), whereas 10−6 M imposed 80% inhibition in the photosynthetic rate ofChaetoceros. InNannochloropsis the rate was affected only when DCMU concentration exceeded 10−6M. Cellular growth rate of all studied algae was affected by DCMU in a similar manner to photosynthesis. The differential effect of DCMU was further examined in mixed cultures in whichNannochloropsis was cultivated together with an additional species simulating a contamination situation of aNannochloropsis culture. When DCMU was added at concentrations higher than 10−7 M, the growth of the competing algae significantly decreased, whileNannochloropsis maintained a relatively high growth rate. Consequently, after a growth period of 4 to 7 days a clear domination ofNannochloropsis was observed. These results demonstrate that DCMU and probably other herbicides of similar characteristics can be used effectively as a selective tool to suppress contaminating unicellular algae in open ponds in order to maintain a monoculture ofNannochloropsis.
Rafael Picorel - One of the best experts on this subject based on the ideXlab platform.
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Photobleaching of photosynthetic pigments in spinach thylakoid membranes. Effect of temperature, oxygen and DCMU
Biophysical chemistry, 2004Co-Authors: Maya Velitchkova, Rafael PicorelAbstract:The time dependence of photobleaching of photosynthetic pigments under high light illumination of isolated spinach thylakoid membranes at 22 and 4 degrees C was investigated. At 22 degrees C, the bleaching at 678, 472 and 436 nm was prominent but lowering the temperature up to 4 degrees C during illumination prevented the pigments from bleaching almost completely. The accelerating effect on pigment photobleaching by the presence of 3-(3,4 dichlorophenyl)-1,1-dimethyl-urea)-(DCMU), a well-known inhibitor of the electron transport and known to prevent photosystem I (PSI) and photosystem II (PSII) against photoinhibitory damage, was also suppressed at low temperature. At 22 degrees C in the presence and absence of DCMU, the decrease of the absorption at 678 and 472 nm was accompanied by a shift to the shorter wavelengths. To check the involvement of reactive oxygen species in the process, pigment photobleaching was followed in anaerobiosis. The effects of the three different environmental factors--light, temperature and DCMU--on the dynamics of photobleaching are discussed in terms of different susceptibility of the main pigment-protein complexes to photoinhibition.
Maya Velitchkova - One of the best experts on this subject based on the ideXlab platform.
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Photobleaching of photosynthetic pigments in spinach thylakoid membranes. Effect of temperature, oxygen and DCMU
Biophysical chemistry, 2004Co-Authors: Maya Velitchkova, Rafael PicorelAbstract:The time dependence of photobleaching of photosynthetic pigments under high light illumination of isolated spinach thylakoid membranes at 22 and 4 degrees C was investigated. At 22 degrees C, the bleaching at 678, 472 and 436 nm was prominent but lowering the temperature up to 4 degrees C during illumination prevented the pigments from bleaching almost completely. The accelerating effect on pigment photobleaching by the presence of 3-(3,4 dichlorophenyl)-1,1-dimethyl-urea)-(DCMU), a well-known inhibitor of the electron transport and known to prevent photosystem I (PSI) and photosystem II (PSII) against photoinhibitory damage, was also suppressed at low temperature. At 22 degrees C in the presence and absence of DCMU, the decrease of the absorption at 678 and 472 nm was accompanied by a shift to the shorter wavelengths. To check the involvement of reactive oxygen species in the process, pigment photobleaching was followed in anaerobiosis. The effects of the three different environmental factors--light, temperature and DCMU--on the dynamics of photobleaching are discussed in terms of different susceptibility of the main pigment-protein complexes to photoinhibition.