title: [Effect of methylmercury chloride on the primary photosynthetic activity of higher plants].
abstract: The effect of methylmercury chloride (MeHg) on the fluorescence characteristics of pea seedling leaves and thylakoids isolated from these leaves was studied by the pulse-amplitude-modulation (PAM) fluorometric method. In 3-4 days after the addition of MeHg (20 microM) to the nutritious solution, the maximal (Fv/Fm) and real (under steady state actinic light illumination) (deltaF/F'm) quantum photochemical yield of PS II decreased. The nonphotochemical fluorescence quenching coefficient in control (qN) decreased after its maximum value has been reached. In MeHg-treated samples, this decrease was not observed, possibly due to the disturbance of delta pH energy transducing processes in ATP synthase. This was confirmed by the results of experiments on isolated thylakoids. After MeHg (5 microM) treatment of thylakoids, the photophosphorylation rate and light-triggered Mg2+-dependent H+-ATPase activity were suppressed by 20-40%, depending on the duration of MeHg exposure. However, in experiments with isolated thylakoids, no decrease either in the electron transport rate or in the Fv/Fm ratio was observed. In total, the results obtained allow one to assume that MeHg at concentrations and time duration used directly damages the coupling complex. The PS II inactivation in leaves and algae cells may be a result of the oxidative stress processes.
authors.forename: G P
authors.initials: GP
authors.lastname: Kukarskikh
authors.forename: E E
authors.initials: EE
authors.lastname: Graevskaia
authors.forename: O G
authors.initials: OG
authors.lastname: Lavrukhina
authors.forename: T E
authors.initials: TE
authors.lastname: Krendeleva
authors.forename: A B
authors.initials: AB
authors.lastname: Rubin
mesh_terms: D025222:Chloroplast Proton-Translocating ATPases / Q000378:metabolism; D008767:Methylmercury Compounds / Q000494:pharmacology*; D018532:Pisum sativum / Q000187:drug effects* / Q000201:enzymology; D010788:Photosynthesis / Q000187:drug effects*; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D018515:Plant Leaves / Q000187:drug effects; D020524:Thylakoids / Q000187:drug effects
chemical_list: D008767:Methylmercury Compounds; D045332:Photosystem II Protein Complex; D025222:Chloroplast Proton-Translocating ATPases; C004925:methylmercuric chloride