Effect of Lincocin Treatment on the Greening Process in Bean (Phaseolus vulgaris) Leaves

The effect of lincocin (a plastid protein synthesis inhibitor) treatment on the greening process of bean (Phaseolus vulgaris L.) leaves have been studied. In comparison with control leaves treated ones had a decreased rate of chloroplast development. They had a marked chlorophyll deficiency and a decreased chlorophyll a/b ratio. Some long and short wavelength forms of chlorophyll a were lacking as evidenced from the absorption spectra at 25°C and the fluorescence spectra at 77°K. The –¹⁴CO₂ fixation was inhibited by 80–90% in treated leaves. The fluorescence induced by the measuring light was greater in the treated leaves than in the control ones, and the kinetics of the decline of the relative fluorescence intensity were also different. Electron microscopic studies showed macrogranum-like structures and incomplete membrane vesicles in the treated plastids. After longer treatment a destruction of membranes was observed. The results indicate some structural and functional membrane deficiencies and instability of the membranes.     

Lecithotrophic development and metamorphosis in the Indo-West Pacific brittle star Ophiomastix venosa (Echinodermata: Ophiuroidea)

Summary

The larval development of the ophiocomid ophiuroid Ophiomastix venosais described using SEM. The gastrula transforms into a uniformly ciliated early larva which progressively changes into a lecithotrophic late premetamorphic larva with a continuous bilateral ciliated band. This stage is short-lived and equivalent to a highly reduced ophiopluteus. Comparisons between O. venosa and other ophiuroid species whose development has been investigated suggest that, whatever the developmental mode (lecithotrophic or planktotrophic), a pluteus stage always occurs in ophiuroids with planktonic development. Two metamorphic stages were identified, the late metamorphic larva differing from the early one by the closure of the larval mouth. The appearance of the permanent mouth marks the end of the metamorphosis. The postlarva still possesses remnants of larval features. The transformation of the reduced ophiopluteus into a barrel-shaped metamorphic larva with transverse ciliated bands, a vitellaria larva, is followed. The possible occurrence of a unique type of metamorphic larva in non-brooding ophiuroids is discussed. Verification of this, however, needs further SEM investigations on metamorphic larva from species having “regular” planktotrophic development.     

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.