ABSTRACT
Thylakoid membranes were isolated and purified from diploid filamentous sporophytes of Porphyra yezoensis Ueda using sucrose density gradient ultracentrifugation (SDGUC). After thylakoid membranes were solubilized with SDS, the phtosystem II (PSII) particles with high 2, 6-dichloroindophenol (DCIP) photoreduction activity were isolated by SDGUC. The absorption and fluorescence spectra, DCIP photoreduction activity and oxygen evolution activity of the thylakoid membranes and PSII particles were determined. The polypeptide composition of purified PSII particles was distinguished by SDS-PAGE. Results showed that PSII particles of sporophytes differed from the gametophytes in spectral properties and polypeptide composition. Apart from 55 kDa D1-D2 heterodimer, CP47, CP43, 33 kDa protein, D1, D2, cyt b559 and 12 kDa protein were identified from PSII particles from sporophytes; a new 102 kDa protein was also detected. However, cyt c-550, 20 kDa, 14 kDa and 16 kDa proteins found in PSII particles from gametophytes were not detected in the sporophytes.
Subject(s)
2,6-Dichloroindophenol/pharmacology , Dimerization , Electrophoresis, Polyacrylamide Gel , Molecular Weight , Photosystem II Protein Complex/chemistry , Porphyra/chemistry , Sodium Dodecyl Sulfate/chemistry , Solubility , Spectrometry, Fluorescence , Thylakoids/chemistry , UltracentrifugationABSTRACT
Differential display (DD) experiments were performed on drought-tolerant rice (Oryza sativa L.) genotype N22 to identify both upregulated and downregulated partial cDNAs with respect to moisture stress. DNA polymorphism was detected between drought-stressed and control leaf tissues on the DD gels. A partial cDNA showing differential expression, with respect to moisture stress was isolated from the gel. Northern blotting analysis was performed using this cDNA as a probe and it was observed that mRNA corresponding to this transcript was accumulated to high level in rice leaves under water deficit stress. At the DNA sequence level, the partial cDNA showed homology with psb A gene encoding for Dl protein.
Subject(s)
Base Sequence , Biochemistry/methods , Blotting, Northern , Chloroplasts/metabolism , DNA, Complementary/metabolism , DNA, Plant , Expressed Sequence Tags , Gene Expression Profiling , Genes, Plant , Molecular Sequence Data , Oryza/enzymology , Photosystem II Protein Complex/chemistry , Polymorphism, GeneticABSTRACT
Exposure to 0.4 M NaCl resulted in higher PS I/PS II stoichiometry and increase in the rate of photosynthesis in planktonic cyanobacterium M. aeruginosa. Altered ratios of PS I/PS II as well as photosynthesis and respiration were stabilized within 72 hr of exposure to salt, leading to adaptation of the organism to the changed conditions.