Changes in superoxide dismutase activity in the presence of electron donors and acceptors

The activity of superoxide dismutase (SOD) from bovine erythrocytes was measured by the inhibition of nitrotetrazolium blue reduction rate in superoxide anion radical generation systems--xanthine/xanthine oxidase of NADH/phenazine methasulfate. The enzyme activity increases in the presence of compounds acting as electron donors in radical-involving reactions and decreased in the presence of compounds possessing the properties of electron acceptors. Activation of SOD by electron donors and its inhibition by electron acceptors was dependent on the concentration of the above compounds. In the absence of SOD electron donors and acceptors did not change the rate of tetrazolium blue reduction by superoxide anion radicals. The role of the new type of SOD regulation for the enzyme functioning in the cell is discussed.     

Inhibition of mitochondrial ATP-synthetase by redox-agents]

Effects of phenol and phenothiazine on ATP synthesis and electron transport in submitochondrial particles were studied. Nitrophenols and phenothiazines inhibited ATP synthesis without notable effect on electron transport. On the contrary chlorphenols equally decreased the velocities of electron transport and ATP synthesis. The inhibitors studied showed the properties of electron acceptors in relation to the radicals, their acceptor properties corresponding to their ability to inhibit ATP synthesis.     

Effect of Metalaxyl on the incidence and severity of Pearl millet downy mildew disease in Northern Nigeria

Pearl millet downy mildew (DM) incidence, severity and yield losses of two pearl millet varieties (local and improved) due to the disease were determined in the field. Significant differences in the disease incidence and severity were recorded in the plots sown with metalaxyl-treated seeds and those sown with non-treated seeds, indicating the efficacy of the fungicide on the fungus. Yield losses due to non-treatment of seeds with metalaxyl was 40.88 and 45.39% in a local variety and 43.00 and 18.60% in an improved variety in the 2000 and 2001 cropping seasons respectively. Significant differences between plots sown with metalaxyl-treated and those sown with non-treated seeds were obtained for other yield components such as 1000-grains weight, panicle length and weight.     

Gene expression and the evolution of phenotypic diversity in social wasps

Background  

Organisms are capable of developing different phenotypes by altering the genes they express. This phenotypic plasticity provides a means for species to respond effectively to environmental conditions. One of the most dramatic examples of phenotypic plasticity occurs in the highly social hymenopteran insects (ants, social bees, and social wasps), where distinct castes and sexes all arise from the same genes. To elucidate how variation in patterns of gene expression affects phenotypic variation, we conducted a study to simultaneously address the influence of developmental stage, sex, and caste on patterns of gene expression in Vespula wasps. Furthermore, we compared the patterns found in this species to those found in other taxa in order to investigate how variation in gene expression leads to phenotypic evolution.     

Rotaliida (Foraminifera) from the Upper Cretaceous of Western Siberia

Paleontological Journal - The distribution of the foraminifera of the order Rotaliida in the Upper Cretaceous reference sections of Western Siberia is analyzed. The narrow stratigraphic range of...     

Mechanical characteristics of the canine thoracic duct: what are the driving forces of the lymph flow?

This study is designed to better understand the mode of lymph transport, particularly through the extrinsic pumping by external compression of the lymph vessel. The pressure-diameter relationship of lymphatic segments isolated from the canine thoracic duct was examined using a laser optical micrometer measurement system. Results revealed that the thoracic duct displayed a high extensibility or compliance in the physiological pressure range, yet became progressively less so with increasing internal pressure. The calculated incremental circumferential modulus of the thoracic duct under physiological pressure (range of 2 to 6 cm H2O) showed values ranging from 1.2 x 10(4) to 3.61 x 10(5) dyn/cm2. At a pressure of 35 cm H2O, the modulus reached a limiting value of approximately 6.0 x 10(6) dyn/cm2. In the physiological pressure range, the relative wall thickness (h/R0) of the canine thoracic duct was approximately 3.5%, which was much lower than that reported for canine arterial segments and similar in value to that of the canine jugular vein. In conclusion, the pressure-diameter curve of the canine thoracic duct was shown to resemble that of venous vessels. However, the circumferential elastic modulus of the thoracic duct wall was lower than the moduli of veins, proving that lymphatics are more compliant than veins. This suggests lymph flow in the thoracic duct may be better promoted by external compression of the lymphatic vessel.     

Redox properties of local anesthetics: A structural determinant of closed channel blockers in BTX-modified Na+ channels

Single channel analyses and macroscopic current measurements have shown that benzocaine is a predominantly closed channel blocker in BTX-modified Na+ channels; cocaine is an open channel blocker; and tetracaine, a dual channel blocker (Wang & Wang, 1994; Wang et al., 1994). The reason for such a selective state-dependent block by local anesthetics in BTX-modified Na+ channels is not clear. We assessed the redox properties of tetracaine, benzocaine, cocaine, and various derivatives by their ability to donate electrons to radical intermediates of eosin dye excited by visible light. Electron-donor properties of the drugs were previously proposed to be involved in Na+ channel blockade (Marinov, 1991). Our results provide evidence that redox properties of tetracaine, benzocaine, and their homologs correlate with their ability to enhance Na+ channel inactivation in BTX-modified Na+ channels. This correlation may be explained in terms of the previously proposed redox model of ion channels.     

Phosphoinositide 3-Kinase C2beta regulates cytoskeletal organization and cell migration via Rac-dependent mechanisms

Receptor-linked class I phosphoinositide 3-kinases (PI3Ks) induce assembly of signal transduction complexes through protein-protein and protein-lipid interactions that mediate cell proliferation, survival, and migration. Although class II PI3Ks have the potential to make the same phosphoinositides as class I PI3Ks, their precise cellular role is currently unclear. In this report, we demonstrate that class II phosphoinositide 3-kinase C2beta (PI3KC2beta) associates with the Eps8/Abi1/Sos1 complex and is recruited to the EGF receptor as part of a multiprotein signaling complex also involving Shc and Grb2. Increased expression of PI3KC2beta stimulated Rac activity in A-431 epidermoid carcinoma cells, resulting in enhanced membrane ruffling and migration speed of the cells. Conversely, expression of dominant negative PI3KC2beta reduced Rac activity, membrane ruffling, and cell migration. Moreover, PI3KC2beta-overexpressing cells were protected from anoikis and displayed enhanced proliferation, independently of Rac function. Taken together, these findings suggest that PI3KC2beta regulates the migration and survival of human tumor cells by distinct molecular mechanisms.     

Cloning and sequencing of cDNA encoding glutamine synthetase from the sea anemone Aiptasia pallida

Glutamine synthetase (GS) catalyzes the addition of ammonium to glutamic acid to form glutamine and plays a crucial role in the nitrogen assimilation of the sea anemone Aiptasia pallida and its endosymbiotic algae. We describe the cDNA cloning and sequence analysis of GS mRNA from A. pallida based on polymerase chain reaction (PCR) technology that employed a combination of degenerate and A. pallida-specific primers. The sequenced cDNA approximates 1620 nucleotides and is characterized by an open reading frame of 1107 nucleotides that encodes a protein of 369 amino acid residues. Comparisons of the deduced sea anemone GS protein to a wide range of species demonstrated greatest amino acid sequence identity to sea urchin GS (66%) and least identity to green algae GS (51%). The sequenced cDNA can be used in future research to study GS gene expression in A. pallida.     

Response to Martin and colleagues: mitochondria do not boost the bioenergetic capacity of eukaryotic cells

A recent paper by (Gerlitz et al., Biol Direct 13:21, 2018) questions the validity of the data underlying prior analyses on the bioenergetics capacities of cells, and continues to promote the idea that the mitochondrion endowed eukaryotic cells with energetic superiority over prokaryotes. The former point has been addressed previously, with no resultant changes in the conclusions, and the latter point remains inconsistent with multiple lines of empirical data.