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.     

Effect of preliminary adaptive irradiation on the concentration of lipid peroxidation products in blood serum and degradation of DNA in thymus of irradiated mice

The animals were irradiated within adaptive dose of 0.1 Gy and 5 hours later with a challenge dose of 2 Gy. The adaptive dose reduced the effects induced by the challenge dose of 2 Gy: the increased content of the products of lipid peroxidation reactive to thiobarbituric acid in blood serum, and the increased number of breaks in thymus DNA of irradiated mice.     

Comparative efficiency of injurious action of radiation and stress on thymus and lipid peroxidation

Exposure to radiation, as well as holding under conditions of limited mobility during 24 h, induced decrease in thymus cell number, increase in number of DNA breaks. The content the products of lipid peroxidation reactive with thiobarbituric acid in blood serum of mice decreased as well. The stress effect is comparable with radiation doses in the range of 50-60 cGy.     

Oxidative effects of nanosecond pulsed electric field exposure in cells and cell-free media

Nanosecond pulsed electric field (nsPEF) is a novel modality for permeabilization of membranous structures and intracellular delivery of xenobiotics. We hypothesized that oxidative effects of nsPEF could be a separate primary mechanism responsible for bioeffects. ROS production in cultured cells and media exposed to 300-ns PEF (1-13kV/cm) was assessed by oxidation of 2',7'-dichlorodihydrofluoresein (H(2)DCF), dihidroethidium (DHE), or Amplex Red. When a suspension of H(2)DCF-loaded cells was subjected to nsPEF, the yield of fluorescent 2',7'-dichlorofluorescein (DCF) increased proportionally to the pulse number and cell density. DCF emission increased with time after exposure in nsPEF-sensitive Jurkat cells, but remained stable in nsPEF-resistant U937 cells. In cell-free media, nsPEF facilitated the conversion of H(2)DCF into DCF. This effect was not related to heating and was reduced by catalase, but not by mannitol or superoxide dismutase. Formation of H(2)O(2) in nsPEF-treated media was confirmed by increased oxidation of Amplex Red. ROS increase within individual cells exposed to nsPEF was visualized by oxidation of DHE. We conclude that nsPEF can generate both extracellular (electrochemical) and intracellular ROS, including H(2)O(2) and possibly other species. Therefore, bioeffects of nsPEF are not limited to electropermeabilization; concurrent ROS formation may lead to cell stimulation and/or oxidative cell damage.     

Astasian: A new stimulator of peritoneal macrophages

Immunological properties of astasin, a novel substance isolated from Astasia longa was studied. 3-4 days after intraperitoneal administration of astasin in a dose of 1000 micrograms per a mouse (50 mg/kg) in the form of suspension in physiological solution or gel in dimethylsulfoxide there was observed maximum increase in the number of the Fc-receptor cells of the macrophage plasmatic membranes and intensity of sheep red blood cell phagocytosis (3.6-4 and 3.2-4-fold, respectively). Dimethylsulfoxide solution of astasin increased migration of the cells into the abdominal cavity by 5.8 times. The respective figure for the astasin suspension was 28. times. Therefore, differences in the nature of the effect and quantitative indices after the exposure to astasin in the above two forms were observed. Sodium chloride isotonic solution of astasin had a retarded but more prolonged effect on the macrophages which was probably due to gradual digestion of the polysaccharide phagocyted granules by the macrophages.