Effects of nitrogen starvation on the function and organization of the photosynthetic membranes in Cryptomonas maculata (Cryptophyceae)

• Published in: Planta Vol. 169; no. 3; pp. 361 - 369
• Main Authors: Rhiel, E., Krupinska, K., Wehrmeyer, W.
• Format: Journal Article
• Language: English
• Published: Berlin Springer-Verlag 01-11-1986; Springer
• Subjects: Applied sciences; Biological and medical sciences; cell membranes; Cell physiology; Cells, cell elements: structure and function; Chemical suspensions; Chlorophylls; Cryptomonas maculata; Emission spectra; Exact sciences and technology; Fluorescence; Fundamental and applied biological sciences. Psychology; Gels; Marine; membrane proteins; Nitrogen; nitrogen sources; Other techniques and industries; photosynthesis; photosynthetic apparatus; photosystem I; Photosystem II; Plant physiology and development; Plants; proteins; Starvation; thylakoid membranes; Thylakoids; Photosystem; Light harvesting system; Algae; Deficiency; Pigment protein complex; Fluorescence; Pyrrophycophyta; Nitrogen; Photosynthesis; Thylakoid; Thallophyta
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/BF00392132

Nitrogen deficiency affects both photosystems and the antennae pigment systems in the photosynthetic apparatus of the marine alga, Cryptomonas maculata. Under increasing energy fluence rates, O2 evolution in nitrogen-deficient (-N) cell suspensions never reached a positive value; in control cultures (+N), O2 evolution increased and was saturated at about 6.4 W·m-2 with about 100 μmol O2·mg chlorophyll-1·h-1. During fluorescence-induction experiments at room temperature, Fo and Fmax were significantly increased in -N cells whereas the Fvar/Fmax ratio decreased from 0.6 to 0.1. These observations can be correlated with a significantly decreased population of 12.5-nm-size particles in the exoplasmic-fracture (EF) faces of freeze-cleaved thylakoid membranes in -N cells (Rhiel et al., 1985, Protoplasma 129, 62—73). The EF particles are suggested to represent photosystem II associated with chlorophyll a/c-protein complexes (LHCP). The banding pattern of isolated and Triton X-100-solubilized thylakoid membranes of both +N and -N cells in sucrose gradients showed that the LHCP is still present in -N cells. The same applies to sodium dodecyl sulfate-polyacrylamide gel electrophoresis of these membrane fractions. The reduced number of the 12.5-nm particles in the EF faces of -N cells may be a result of decoupling of the LHCP constituents of the photosystem-II complex rather than their degradation. This is supported by high values for the initial fluorescence Fo in fluorescence-induction experiments and, in part, is indicated by the shift of the maximal fluorescence emission from 693 nm in +N to 684 nm in -N cells. The lack of the CP1 band in the gels of sodium dodecyl sulfate-solubilized thylakoid membranes from -N cells after electrophoresis demonstrates that photosystem I is also severely affected.