ABSTRACT
Oscillatoria laetevirens produces an algicide, named oscillatorin (OS), which inhibits growth of higher plants. Effect of purified oscillatorin and some 'urea-triazine type' herbicides was studied on photosystem II activity and composition of pigment protein complex in spinach thylakoid membrane. For oscillatorin the I50 at 10 microg chlorophyll concentration, inhibitor constant (Ki), specific binding sites and Hill coefficient were calculated to be 1.45, 0.15, 2.3 and 0.2 microM respectively. Metribuzin and oscillatorin affected towards the donor side and brought about identical changes in polypeptide composition of PSII complex. Further, metribuzin and atrazine exerted antagonistic and synergistic responses on oscillatorin action. Some of these parameters were also studied on weed plants to assess upon the weedicidal potential of oscillatorin.
Subject(s)
Cyanobacteria/chemistry , Electrophoresis, Polyacrylamide Gel , Herbicides/pharmacology , Light-Harvesting Protein Complexes , Organic Chemicals , Photosynthetic Reaction Center Complex Proteins/antagonists & inhibitors , Photosystem II Protein ComplexABSTRACT
Mouse toxicity due to microcystin (hepatotoxin) was detected in water bloom of a local lake, comprising mainly Microcystis aeruginosa. Both toxicity and biomass content of the phytoplankton varied seasonally. Incubations with an algicidal metabolite from Oscillatoria late-virens and a herbicide 3-(3,4-dichlorophenyl)-1, 1-dimethyl urea (DCMU) caused depigmentation and detoxification in bloom samples. Algicide-incubation also encouraged growth of protozoa and bacteria, pathogenic form included.