Beneficial and deleterious effects of HCN-producing pseudomonads on rhizosphere interactions

Rhizobacteria live around roots but also inside the cortical root tissues by utilizing organic substances released from root cells into the intercellular spaces and the root environment. The effects of metabolites of these rhizosphere-inhabiting bacteria on root physiology and plant development have hardly been studied. However, recent studies indicate that, depending on environmental factors and plant species, certain strains of rhizosphere Pseudomonas spp. and some of their metabolites such as HCN may inhibit or enhance plant establishment or inhibit development of plant disease. Cultural practices such as cropping frequency, no tillage, and soilless cultivation, as well as edaphic factors seem to determine these rhizosphere interactions.     

Mechanical Model of Nuclei Ordering in Drosophila Embryos Reveals Dilution of Stochastic Forces

During the initial development of syncytial embryos, nuclei go through cycles of nuclear division and spatial rearrangement. The arising spatial pattern of nuclei is important for subsequent cellularization and morphing of the embryo. Although nuclei are contained within a common cytoplasm, cytoskeletal proteins are nonuniformly packaged into regions around every nucleus. In fact, cytoskeletal elements like microtubules and their associated motor proteins exert stochastic forces between nuclei, actively driving their rearrangement. Yet, it is unknown how the stochastic forces are balanced to maintain nuclear order in light of increased nuclear density upon every round of divisions. Here, we investigate the nuclear arrangements in Drosophila melanogaster over the course of several nuclear divisions starting from interphase 11. We develop a theoretical model in which we distinguish long-ranged passive forces due to the nuclei as inclusions in the elastic matrix, namely the cytoplasm, and active, stochastic forces arising from the cytoskeletal dynamics mediated by motor proteins. We perform computer simulations and quantify the observed degree of orientational and spatial order of nuclei. Solely doubling the nuclear density upon nuclear division, the model predicts a decrease in nuclear order. Comparing results to experimental recordings of tracked nuclei, we make contradictory observations, finding an increase in nuclear order upon nuclear divisions. Our analysis of model parameters resulting from this comparison suggests that overall motor protein density as well as relative active-force amplitude has to decrease by a factor of about two upon nuclear division to match experimental observations. We therefore expect a dilution of cytoskeletal motors during the rapid nuclear division to account for the increase in nuclear order during syncytial embryo development. Experimental measurements of kinesin-5 cluster lifetimes support this theoretical finding.     

The use of fallout 137Cs and 239,240Pu for dating of lake sediments

The distribution of ¹³⁷Cs and ^239,240Pu in sediment core samples of the Finnish lakes Laukunlampi, Lovojärvi and Pääjärvi were determined. The sediment samples were collected using dry ice and liquid nitrogen freezing methods. The sediments of these lakes are annually laminated. A clear maximum concentration of ¹³⁷Cs and ^239,240Pu was found in sediment layers formed during 1962–1964, the years of maximum fallout, and the middle of the 1950's can be estimated from the ¹³⁷Cs and ^239,240Pu profiles. The highest concentrations, 11 500 and 820 pCi kg^–1 dry wt for ¹³⁷Cs and ^239,240Pu, respectively, were found in the sediment of Laukunlampi. The vertical distribution was similar for ¹³⁷Cs and ^239,240Pu in the lakes investigated. A slight migration of ^239,240Pu and ¹³⁷Cs was found and the migration of ¹³⁷Cs seems to be higher than that of ^239,240Pu. The advantages of ¹³⁷Cs dating method are rapidity and simplicity. ^239,240Pu is preferable when the sample size is small. The agreement found between ¹³⁷Cs and ^239,240Pu dates and the annual laminae show that these fallout radio isotopes can be used for dating sediments formed during the past 25 years.     

Alcohol detoxification accelerated by oxygenated drinking water.

The liver eliminates ethanol through several oxygen dependent processes. Since the liver receives most of its blood flow through the portal vein, it should be possible to increase its oxygen tension by augmenting the oxygen saturation of the portal vein. We therefore studied elimination of ethanol administered intravenously to three monkeys who received strongly oxygenated drinks at 20 to 30 minute intervals during the whole experiment. From these drinks dissolved oxygen was presumably released in the stomach and upper intestine and arrived to the liver along the portal vein. As a consequence of this treatment the elimination rate of ethanol increased 60 % on the average. The increase was significant on the level of p < 0.02. The production of acetaldehyde also increased but less significantly. Measurements of oxygen tensions in the portal blood of two anaesthetized dogs indicated 7 and 8 % increases lasting for 10 and 15 minutes after infusion of oxygenated water into the stomach.     

Immunohistochemical demonstration of carbonic anhydrase

Summary Rabbits were immunized using human erythroxyte carbonic anhydrase B (HCA B) purified. by the modified methods of Armstrong et al. (1966) and Bernstein and Schraer (1972). The globulin fraction was isolated by ammonium sulphate precipitation. The anti-HCA B globulin was specific, when judged using the double diffusion technique of Ouchterlony and immunoelectrophoresis. No cross reaction with human erythrocyte carbonic anhydrase C was found, but cross reactions with erythrocyte carbonic anhydrase from rat, mouse and guinea pig were observed. Fluorescein isothiocyanate conjugated goat anti-rabbit globulin was used for the localization of HCA B in tissue sections and erythrocytes on slides.     

Structure of Cytokine Hydrophobic Cores

Diagrams were constructed that describe, using a common frame of reference, the interactions that occur within the hydrophobic cores of the left-handed four-helix bundles of interleukin-2, -4, -5, granulocyte/macrophage-, granulocyte-, macrophage-colony-stimulating factor, β- and γ-interferon, growth hormone, and leukemia inhibitory factor. Based on the assumption that the topologies of the ligand-receptor complexes are similar, analogous patterns were obtained from these diagrams and lead to the detailed comparison of the hydrophobic cores. These patterns were then used to obtain pairwise rigid-body superpositions among all of the four-helix bundles: values of the root-mean-square deviations (Cα-atoms) over the four α-helices of the bundles range from 1.14 Å to 3.22 Å. Two distinct groups are formed after clustering based on structural superposition of the ten cytokines.