Compensatory adjustment of hemopoietic stem cell pool of CBA mice after acute intake of 90Sr

It was investigated the functional status of stem cell pool (CFUs) of bone marrow, spleen and peripheral blood in mice (CBA) in early (1-30 days) and late (180-360 days) period after acute intake of 90Sr (29.6 kBq/g). Cumulative dose in red bone marrow due to incorporated 90Sr was 0.98-87.7 Gy. The kinetics, proliferative and differentiative potential of stem hemopoietic cells (CFUs) and productivity of hemopoietic tissues were significantly influenced by dose rate, absorbed dose and degree of suppresssion of bone marrow functions.The obtained results indicated that the sarcomogenous doses of 90Sr (29.6 kBq/g) resulted in realization of compensatory reactions in hemopoietic stem cell pool to support the life ability of irradiated animals: higher proliferative potential of CFUs and its repopulation, redistribution of cell subpopulations during differentiation and activation of spleens hemopoiesis.     

A regulatory role for p38 delta MAPK in keratinocyte differentiation. Evidence for p38 delta-ERK1/2 complex formation

p38 MAPK isoforms are important in the regulation of a variety of cellular processes. Among the four described p38 isoforms, p38 alpha, beta, and delta are expressed in keratinocytes (Dashti, S. R., Efimova, T., and Eckert, R. L. (2001) J. Biol. Chem. 276, 8059-8063). However, very little is known about how individual p38 isoforms regulate keratinocyte function. In the present study, we use okadaic acid (OA) as a tool to study the role of p38 MAPKs as regulators of keratinocyte differentiation. We demonstrate that OA activates p38 delta but not other p38 isoforms. p38 delta activation is increased as early as 0.5 h after OA addition, and activity is maximal at 8 and 24 h. ERK1 and ERK2 activity are reduced on an identical time course. We show that p38 delta forms a complex with ERK1/2, and overexpression of p38 delta inhibits ERK1/2 activity without reducing ERK1/2 level. Thus, p38 delta may directly suppress ERK1/2 activity. Additional studies show that p38 delta is expressed in the epidermis, suggesting a role for p38 delta in regulating differentiation. To evaluate its function, we show that increased p38 delta activity is associated with increased levels of AP1 and CAATT enhancer binding protein factors, increased binding of these factors to the involucrin (hINV) promoter, and increased expression. Moreover, these responses are maintained in the presence of SB203580, an agent that inhibits p38 alpha and beta, further suggesting a central role for the p38 delta isoform. Dominant-negative p38 also inhibits these responses. These unique observations suggest that p38 delta is the major p38 isoform driving suprabasal hINV gene expression and that p38 delta directly regulates ERK1/2 activity via formation of a p38 delta-ERK1/2 complex.     

Reversibility of structural rearrangements in the negative vesicular membrane upon electrostatic adsorption/desorption of the polycation

Interaction of small unilamellar vesicles (SUVs), composed of negative diphosphatidylglycerol (cardiolipin, CL(2-)) and neutral dipalmitoylphosphatidylcholine (DPPC), with poly(N-ethyl-4-vinylpyridinium bromide) (PEVP) was studied in water solution above and below the vesicular membrane melting point by means of differential scanning calorimetry, photon correlation spectroscopy, microelectrophoresis, conductometry, and fluorescence techniques. It has been found that CL(2-) species are homogeneously distributed within DPPC-CL(2-) SUV membrane leaflets and between them. Interaction of PEVP with DPPC-CL(2-) SUVs led to drastic structural rearrangements in the membrane if it was in the fluid state (liquid SUVs). Negative CL(2-) molecules migrated from the inner to the outer membrane leaflet and segregated in the vicinity of adsorbed PEVP chains. In addition, PEVP adsorption terminated completely the exchange of lipid molecules between the SUVs. At the same time, the integrity of liquid SUVs contacting PEVP remained unchanged. Since the interaction of PEVP with liquid SUVs was predominantly electrostatic in nature, the polycation could be completely removed from the vesicular membrane by addition of an excess of polyacrylic acid (PAA) polyanions forming a more stable electrostatic complex with PEVP. Removal of PEVP resulted in complete resumption of the original distribution of lipids in lateral and transmembrane directions as well as intervesicular lipid exchange. In contrast, PEVP interacting with DPPC-CL(2-) SUVs formed defects in the vesicular membrane if it was in the gel state (solid SUVs). Such interaction was contributed not only by electrostatic but most likely by hydrophobic interactions involving the defected membrane sites. PEVP kept contacting solid SUVs in the presence of an abundant amount of PAA. The established phenomena may be important for understanding the biological effects of polycations.     

Exogenous Melatonin Protects Canola Plants from Toxicity of Excessive Copper

Physiological mechanisms of canola (Brassica napus L., cv. Westar) plant protection afforded by melatonin (at 0.1–100 μM) from copper salts (at 10–100 μM) were studied. Plants were cultivated on Hoagland–Snyder medium. At the age of 5 weeks, they were subjected to melatonin, copper sulfate, or their combination for 7 days. It was found that excessive copper in a nutrient medium inhibited the dry biomass accumulation against the control by 25–85%. Copper sulfate diminished the content of chlorophylls and carotenoids and functional activity of the thylakoid membranes in the chloroplasts. It increased 2.0–2.5 times the lipid peroxidation (LPO) intensity and the proline level up to 20 times. Melatonin reduced the changes caused by copper, and the degree of the protection depended on melatonin and CuSO₄ concentrations. It was found that melatonin decreased the oxidative stress and proline accumulation, both induced by CuSO₄. At first, we established the positive correlation (with the coefficient 0.8240) between the level of oxidative stress and proline content in the presence of CuSO₄. Possible mechanisms of protection by melatonin and its biological role under conditions of technogenic stress are discussed.     

Erratum to: Distribution and Some Biological Features of Ixodid Ticks (Parasitiformes,Ixodidae) in Kuznetsk-Salair Mountain Area (Kemerovo Province,Russia)

Entomological Review - The figure on p. 1381 should be as follows:     

Growth and wax ester production of an <Emphasis Type="Italic">Acinetobacter baylyi</Emphasis> ADP1 mutant deficient in exopolysaccharide capsule synthesis

Acinetobacter baylyi ADP1 naturally produces wax esters that could be used as a raw material in industrial applications. We attempted to improve wax ester yield of A. baylyi ADP1 by removing rmlA, a gene involved in exopolysaccharide production. Growth rate, biomass formation and wax ester yield on 4-hydroxybenzoate were not affected, but the rmlA ^? strain grew slower on acetate, while reaching similar biomass and wax ester yield. The rmlA ^? cells had malformed shape and large size and grew poorly on glucose without expression of the gene for pyruvate kinase (pykF) from Escherichia coli. The pykF-expressing rmlA ^? strain had similar growth rate, lowered biomass formation and improved wax ester production on glucose as compared to the wild-type strain expressing pykF. Cultivation of the pykF-expressing rmlA ^? strain on an elevated glucose concentration in a medium supplemented with amino acids resulted in doubled molar wax ester yield and acetate production.     

Formation of specific T3-RNA-polymerase complexes with oligoribonucleotides and inhibition of DNA-dependent RNA synthesis

It was shown previously that E. coli RNA polymerase and T7 RNA polymerase being incubated with oligonucleotides of different length derived from RNA endonuclease hydrolysate bind selectively to certain oligonucleotides with the length larger than or equal to 5. The data presented demonstrate that T3 RNA polymerase also binds selectively from the isoplith mixtures certain oligonucleotides starting from pentanucleotides. Adding of excess of T3 RNA polymerase it was possible to exhaustively extract the recognizable oligonucleotides from the isoplith mixture. However, the exhausted by T3 RNA polymerase mixture of pentanucleotides still contained those which are bound selectively by T7 and E. coli RNA polymerases. The data suggest that various RNA-polymerases recognize different oligoribonucleotides. It was shown that T3 DNA inhibits the selective binding of penta-or heptaribonucleotides to T3 RNA polymerase competing obviously for the enzyme. The T3 RNA polymerase bound penta- or heptanucleotides inhibit DNA-dependent RNA synthesis carried out by the enzyme; the isoplith mixtures which do not contain T3 RNA polymerase bound oligonucleotides are deprived of the inhibitory properties. Only those isoplith mixtures contain T3 RNA polymerase bound oligonucleotides which were derived from symmetrically transcribed RNA which have obviously promoter simulating sequences. The data provide evidence that T2 RNA polymerase binds selectively the oligonucleotides mimicking the promotor recognition sites.     

Superoxide dismutase activity and methemoglobin content of human and animal erythrocytes

In healthy newborn babies, superoxide dismutase activity and MetHb content of the erythrocytes are higher than those in adult subjects. It was also demonstrated that low activity of superoxide dismutase in guinea pigs, albino mice and teleost fish Coregonus autumnalis (in autumn period) is paralleled by a higher level of MetHb. On the contrary, high enzymic activity in albino rats and C. autumnalis (spring period) accounts of a lower level of MetHb. Seasonal changes in the activity of superoxide dismutase were found in guinea pigs and fish.