Publications by authors named "M Duysen"

The levels of total chlorophyll (Chl), total carotenoids, light-harvesting Chl a/b apoprotein of photosystem II (LHCPII), and light-harvesting Chl a/b apoprotein (LHCP) mRNA were examined in the CD3 chlorina mutant wheat (Triticum aestivum, L.) after 18 hours greening at either a low (3 micromoles of photons per square meter per second) or moderate (200 micromoles of photons per square meter per second) irradiance. The Chl b and LHCPII deficient mutant wheat accumulated significantly greater levels of Chl and LHCPII when greened under low irradiance than when greened under a moderate irradiance level.

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Biogenesis of thylakoid membranes in the conditional chlorophyll b-deficient CD3 mutant of wheat is dramatically altered by relatively small differences in the light intensity under which seedlings are grown. When the CD3 mutant is grown at 400 microE/m2 S (high light, about one-fifth full sunlight) plants are deficient in chlorophyll b (chlorophyll a/b ratio greater than 6.0) and lack or contain greatly reduced amounts of the chlorophyll a/b-binding complexes CPII/CPII (mobile or peripheral LHCII), CP29, CP24 and LHCI, as shown by mildly denaturing 'green gel' electrophoresis, by fully denaturing SDS-PAGE, and by Western blot analysis.

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We previously reported that applications of chloramphenicol to the chlorina wheat mutant, CD3, decreased the leaf Chl a/b ratio and enhanced accumulations of LHC proteins and LHC complexes during greening (Duysen et al. 1985). We have now examined Chl degradation and the change in Chl a/b ratios in wheat leaves kept in the dark as a measure of LHC destruction.

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As compared with normal wheat leaves, the chlorina wheat mutant, designated CD3, has a high chlorophyll a/b ratio and a deficiency in the light harvesting chlorophyll protein (LHCP) complex. Applications of 200 micrograms per milliliter of d-threo-chloramphenicol to etiolated seedlings decreased the chlorophyll a/b ratio and increased the accumulation of the 27 kilodalton LHCP polypeptide and the LHCP complex in thylakoids of the mutant during greening. These data led to the suggestion that a protein encoded in chloroplast genes impaired either transcriptional, translational, or posttranslational events in CD3 wheat limiting the accumulation of the LHCP complex.

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Corn was grown under greenhouse and controlled light quality conditions incluing full spectrum, red (R), and far-red (FR) sources. Young leaf samples were analyzed for pigments, pigment-proteins, membrane polypeptides, and ultrastructure. Chloroplast development in full spectrum white light was similar to that found in R but different from that found in FR plus low R.

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