Reconstruction of erythrocyte shape during modified morphological response

Changes in erythrocyte shape during morphological response modified by benzalkonium chloride (BzA) were studied in sucrose solutions. Fixation of the cells with glutaraldehyde- and formaldehyde-containing fixatives at some time points is usually inadequate to maintain the current cell shape. Considering the reconstruction of erythrocyte shape, which takes into account the mode of fixative action, we showed that the echinocyte-forming activity of BzA depends on the concentration of this surfactant. It can induce a direct spherostomatocyte-spheroechinocyte transition without altering the near-spherical shape of the cells. On the other hand, the reverse spheroechinocyte-spherostomatocyte transition was always accompanied by some flattening of the cells, although in some instances discoidal shape was not achieved. The data point to asymmetric shape transitions of erythrocytes in sucrose solution, which contradicts the continuum and bilayer-couple models of shape regulation. It seems that the nonuniform structure of native erythrocyte membrane plays a more important role in morphological transitions of these cells than suggested earlier.     

Photosynthetic electron flow to oxygen and diffusion of hydrogen peroxide through the chloroplast envelope via aquaporins

Light-induced generation of superoxide radicals and hydrogen peroxide in isolated thylakoids has been studied with a lipophilic spin probe, cyclic hydroxylamine 1-hydroxy-4-isobutyramido-2,2,6,6-tetramethylpiperidinium (TMT-H) to detect superoxide radicals, and the spin trap α-(4-pyridyl-1-oxide)-N-tert-butylnitron (4-POBN) to detect hydrogen peroxide-derived hydroxyl radicals. Accumulation of the radical products of the above reactions has been followed using electron paramagnetic resonance. It is found that the increased production of superoxide radicals and hydrogen peroxide in higher light is due to the enhanced production of these species within the thylakoid membrane, rather than outside the membrane. Fluorescent probe Amplex red, which forms fluorescent product, resorufin, in the reaction with hydrogen peroxide, has been used to detect hydrogen peroxide outside isolated chloroplasts using confocal microscopy. Resorufin fluorescence outside the chloroplasts is found to be suppressed by 60% in the presence of the inhibitor of aquaporins, acetazolamide (AZA), indicating that hydrogen peroxide can diffuse through the chloroplast envelope aquaporins. It is demonstrated that AZA also inhibits carbonic anhydrase activity of the isolated envelope. We put forward a hypothesis that carbonic anhydrase presumably can be attached to the envelope aquaporins. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.     

Crosses of two independently derived transgenic mice demonstrate functional complementation of the genes encoding heavy (HLA-B27) and light (beta 2-microglobulin) chains of HLA class I antigens

In man a number of diseases are associated with certain alleles of MHC antigens. The most pronounced example is ankylosing spondylitis, which is strongly associated with HLA-B27. As a first step towards a model system to study the basis of this association, transgenic mice were generated that showed cell surface expression of the HLA-B27 antigen biochemically indistinguishable from HLA-B27 antigen expressed on human cells. This result was obtained by crossing two independently derived strains of mice, one of which is transgenic for the HLA-B27 heavy chain gene, and the other carrying and expressing the human beta 2m gene. Examination of HLA-B27 and human beta 2m mRNA in various tissues shows the two genes to be expressed in a coordinate fashion. The mRNA levels follow those of endogenous H-2 Class I genes.     

Bluetongue Virus Detection Using Microspheres Conjugated with Monoclonal Antibodies against Group-Specific Protein Vp7 by Flow Virometry

Russian Journal of Bioorganic Chemistry - Bluetongue is a reemerging transmissive infectious disease that threatens all countries with intensive livestock production. In cattle, bluetongue may...     

Analogs of S-Adenosyl-L-Methionine in Studies of Methyltransferases

Molecular Biology - Methyltransferases (MTases) play an important role in the functioning of living systems, catalyzing the methylation reactions of DNA, RNA, proteins, and small molecules,...     

Simulation of lower ionosphere heating by modulated radio-frequency waves

The heating of the lower equatorial ionosphere by a radio-frequency (RF) electromagnetic wave is simulated. Estimates of the electron temperature and ionospheric conductivity have been obtained for the cases of quasi-longitudinal and quasi-transverse propagation of an RF heating wave with a low-frequency modulated amplitude.