Fluorescence characteristics and photophysical parameters of light-harvesting chlorophyll <Emphasis Type="Italic">a/b</Emphasis> complex aggregates

Fluorescence characteristics and molecular photophysical parameters of light-harvesting chlorophyll a/b complexes isolated from pea were studied in relation to their aggregation state. The aggregate size was varied by changing the Triton X-100 concentration from 0 to 0.23 mM at a chlorophyll concentration of 2.45 μg/ml. Molecular photophysical parameters were determined with laser fluorimetry. Dispersion of large aggregates into smaller ones drastically decreased the intensity of low-temperature (77 K) fluorescence at 700 nm, reduced the singlet-singlet annihilation rate by more than two orders of magnitude, and prolonged the fluorescence lifetime from 0.16 to 3.2 ns.     

Tolerance of an aquatic macrophyte <Emphasis Type="Italic">Potamogeton crispus</Emphasis> L. to sodium dodecyl sulphate

The effects of the anionic surfactant sodium dodecyl suplphate on the aquatic macrophyte Potamogeton crispus L. are studied. Concentrations of 83–133 mg/l caused fragmentation of the stems of plants. The tolerance of the plants to the negative effects of the surfactant was higher in the spring (April) than in the autumn (September).     

The search for proteins with immunochemical affinity to plant stress proteins at cold-adapted endemic Baikal fishes

The search for proteins with immunochemical affinity to plant stress proteins in endemic Baikal fishes shows the presence of proteins, immunochemically related to plant heat-stabile proteins and plant uncoupling protein CSP 310. Western blotting showed that among the native cytoplasmic proteins of endemic Baikal fishes there are proteins immunochemically related to heat-stabile plant proteins with molecular weights about 480, 200-290, 150, 140 and about 90-100kD. SDS-electrophoresis showed the presence of polypeptides with molecular weights 23, 17 and 14kD in all species investigated and an additional 35kD polypeptide in Cottocomephorus grewingki. The search for polypeptides with immunochemical affinity to plant stress uncoupling protein CSP 310 in endemic Baikal fishes shows the presence of a 14kD polypeptide, immunochemically related to it.     

The biosorption of cadmium and cobalt and iron ions by yeast <Emphasis Type="Italic">Cryptococcus humicola</Emphasis> at nitrogen starvation

Yeasts Cryptococcus humicola accumulated cadmium, cobalt, and iron (~?50, 17, and 4% of the content in the medium, respectively) from the medium containing glucose, phosphate, and 2 mmol/L of metal salts. The effects of metal absorption on the levels of orthophosphate (Pi) and inorganic polyphosphate (polyP) varied for the metals under study. The levels of Pi and polyP increased in the case of cadmium and cobalt, respectively. In the case of iron, no changes in the levels of Pi and polyP were observed. Multiple DAPI-stained polyP inclusions were observed in the cytoplasm of cadmium-containing cells. The intensity of DAPI staining of the cell wall especially increased in case of cobalt and iron accumulation.     

An Amphiphilic Substance Inhibits the Mollusk Capacity to Filter out Phytoplankton Cells from Water

The effect of synthetic anionic surface active substance (SAS) sodium dodecylsulfate (SDS, 4 mg/l) on the kinetics of water filtration by mussel Mytilus edulis was studied. A suspension of algae Isochrysis galbana was added to the vessel with the mussels, and their filtration activity was measured by counting the concentration of the algae cells in the experimental vessels. Algae concentration was measured every 30 min for an hour and a half. The inhibiting effect on the mollusk filtration rate (FR) was qualitatively described. After the first 30 min filtration at 4 mg/l initial SDS concentration, the cell density was 322% of the control. The inhibiting effect was observed later as well. Due to FR inhibition in the vessels with the above specified initial SDS concentration, the algae cell density was 6.4 and 14.7 times that of the control after 1 and 1.5 h, respectively. Thus, SAS SDS can decrease the natural capacity of aquatic ecosystems for self-purification and disturb other aspects of ecosystem functioning through inhibiting the filtration activity of mussels. The obtained data are discussed in the context of environment and hydrosphere protection from pollution.     

On the possibilities of diagnosis of the state of the phytoplankton photosynthetic apparatus by the method of nonlinear laser fluorimetry

The possibilities of diagnosis of the state of the phytoplankton photosynthetic apparatus by the method of nonlinear laser fluorimetry (saturation fluorimetry), which can be realized in remote sensing mode, were investigated. A procedure for the determination of the nonsaturated fluorescence parameter phi0, which is proportional to the concentration of chlorophyll a molecules, and the parameter A, which is a product of three photophysical parameters of chlorophyll a molecule in native chloroplast, was elaborated. Laboratory experiments with the axenic culture of eurihaline Thalassiosira weissflogii showed that the parameter A depends on the state of the photosynthetic apparatus of the alga, which was varied by either DCMU treatment or exposure to actinic light.