Algal tests have developed into routine tools for testing toxicity of pollutants in aquatic environments. Meanwhile, in addition to algal growth rates, an increasing number of fluorescence based methods are used for rapid and sensitive toxicity measures. The present study stresses the suitability of delayed fluorescence (DF) as a promising parameter for biotests. DF is based on the recombinatio...

Cyanobacterium Plectonema boryanum IU 594 and cyanophage LPP-1 were used as indicator organisms in a bioassay of 16 pesticides. Experiments such as spot tests, disk assays, growth curves, and one-step growth experiments were used to examine the effects of pesticides on the host and virus. Also, experiments were done in which host or virus was incubated in pesticide solutions and then assayed fo...

Inhibitor Binding, Photosystem II, Binary Oscillation, Chlorophyll Fluorescence Binding o f radioactively labelled DCM U, ioxynil and terbutryn to spinach chloroplasts is determined following preillumination by single-turnover, saturating light flashes. W ith all o f the three herbicides binary oscillations o f binding are observed. Dark-adapted samples, or those pre­ illuminated by an even num...

Light-induced swelling of guard cell protoplasts (GCP) from Vicia faba was accompanied by increases in content of K(+) and malate. DCMU inhibited the increase of K(+) and malate, and consequently swelling.Effect of light on the activity of selected enzymes that take part in malate formation was studied. When isolated GCP were illuminated, NADP-malate dehydrogenase (NADP-MDH) was activated, and ...

Dissipating excess energy of light is critical for photosynthetic organisms to keep the photosynthetic apparatus functional and less harmful under stressful environmental conditions. In the green alga Chlamydomonas reinhardtii, efficient energy dissipation is achieved by a process called non-photochemical quenching (NPQ), in which a distinct member of light harvesting complex, LHCSR, is known t...

Transcription factors of the APETALA 2/Ethylene Response Factor (AP2/ERF)- family have been implicated in diverse processes during development, stress acclimation and retrograde signaling. Fifty-three leaf-expressed AP2/ERFs were screened for their transcriptional response to abscisic acid (ABA), 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), methylviologen (MV), sucrose and high or low light,...

PSII antenna size heterogeneity has been intensively studied in the past. Based on DCMU fluorescence rise kinetics, multiple types of photosystems with different properties were described. However, due to the complexity of fluorescence signal analysis, multiple questions remain unanswered. The number of different types of PSII is still debated as well as their degree of connectivity. In Chlamyd...

The rate of cyclic electron flow measured in dark-adapted leaves under aerobic conditions submitted to a saturating illumination has been performed by the analysis of the transmembrane potential changes induced by a light to dark transfer. Using a new highly sensitive spectrophotometric technique, a rate of the cyclic flow of approximately 130 s(-1) has been measured in the presence or absence ...

An antiserum to violaxanthin inhibits photosynthetic electron transport between water, iodide or tetramethylbenzidine and various electron acceptors in chloroplasts from green tobacco (N icotiana tabacum var. John W illiam ’s B roadleaf). However, electron transport from manganese or diphenylcarbazide to these acceptors is not impaired. The typical photosystem I reaction from D P IP / ascorbate...

Nitrogen-starved Plectonema boryanum 594 cultures flushed with N(2)/CO(2) or A/CO(2) (99.7%/0.3%, vol/vol) exhibited nitrogenase activity when assayed either by acetylene reduction or hydrogen evolution. Oxygen evolution activities and phycocyanin pigments decreased sharply before and during the development of nitrogenase activity, but recovered in the N(2)/CO(2) cultures after a period of acti...