The Role of Malate Dehydrogenase Isoforms in the Regulation of Anabolic and Catabolic Processes in the Colorless Sulfur Bacterium Beggiatoa leptomitiformis D-402

The functional role of tetrameric and dimeric isoforms of malate dehydrogenase in the carbon metabolism of the colorless sulfur bacterium Beggiatoa leptomitiformis, strain D-402, was studied. This strain can grow both lithotrophically and organotrophically. By use of inhibition analysis, the tetrameric isoenzyme was shown to operate in the glyoxylate cycle and the dimeric form was found to be involved in the TCA cycle. The dynamics of the dimeric isoenzyme conversion to the tetrameric isoform was found to be determined by the rate of thiosulfate oxidation. The regulation of the carbon metabolism in Beggiatoa leptomitiformis is supposed to be accomplished by means of structural and functional changes in the protein molecule of malate dehydrogenase.     

The Neuroprotective Effect of the Thr–Ser–Lys–Tyr Peptide in a Goldfish Mauthner Cell Model in vivo

The effects of the Thr–Ser–Lys–Tyr peptide, which was shown to display neuroprotective activity in cell cultures in vitro, were studied in the model of paired Mauthner cells of goldfish. It was found that intracerebral injections provided the peptide to be applied into the zone of the right Mauthner cell under the fourth ventricle of the hindbrain lead to a dose-dependent decrease in the number of spontaneous turns of the goldfish to the left. It was shown that this effect is not eliminated under long-lasting optokinetic stimulation when the fish instinctively follow stimuli with a low spatial frequency that are moving in the nasal-to-temporal direction. We used the method of three-dimensional reconstruction by serial histological sections to study the dendrite morphology of the Mauthner cells in control and experimental goldfish. It was found that optokinetic stimulation of control goldfish evokes the dystrophy of the ventral dendrite of the right Mauthner cell, which is the target of this type of stimulation. Conversely, the peptide stabilize the size of the ventral dendrite of the right Mauthner cell under stimulation. These data could be interpreted as evidence of the neuroprotective effect of the Thr–Ser–Lys–Tyr peptide in vivo.     

The Mechanisms and Time Factor of the Enzyme Structure of a Paleosoil

The data on the enzyme activity of paleosoils of archaeological sites are given. It is shown that the activity of phosphatases and urease in soils of ancient settlements is significantly higher than in modern soils: 1.5–2.0 times for urease and 7–15 times for phosphatase in some cultural layers of the Bronze Age. This is related to a large amount of organic material (garbage, rubbish, excrement, and urea), which entered the soil in ancient times and stimulated soil microorganisms to produce a greater amount of enzymes, whose high activity has been preserved for 4000 years. The location of the enzymes was determined by soil fumigation using chloroform and activation of extracellular enzymes by glycine. The release of intracellular enzymes as a result of fumigation caused a significant increase in phosphatase activity in modern soils and soils of ancient settlements in contrast to the virgin paleosoil of the Bronze Age. The treatment by glycine exerted a smaller effect on the activity of phosphatases, but caused a significant increase in urease activity. This may indicate the predominating extracellular localization of urease in paleosoils of ancient settlements, while phosphatase is characterized by both extra- and intracellular localization.

     

Changes in the Dendrite Morphology of Mauthner Neurons in Goldfish under the Conditions of Monocular Deprivation and Sensory Stimulation

Biophysics - Abstract—The effects of sensory stimulation on the model of paired Mauthner neurons of monocularly deprived goldfish have been studied by light- and electron microscopy....     

Effects of Various Phytoimmunocorrectors on Fruit and Soft Fruit Cultures

Catalase activity and induction of delayed chlorophyll fluorescence were shown to be the markers of the plant native state. The dependence of reaction of the plant to exogenous elicitors, stimulators or inhibitors of the defense system, on the age, cultivar and/or species was found. Prolonged effect of the treatment with phytoimmunocorrectors was observed. The necessity of careful choice of elicitors depending on the plant state was shown.