Recombinant proteasomal alpha-type subunits exhibit endoribonuclease activity

26S proteasome is a multi-subunit protein complex that consists of the regulatory 19S and the catalytic 20S subcomplexes. The major cellular function of the proteasome is protein degradation. It has been found recently that the 20S particle, besides its proteolytic activity, also possesses endoribonuclease activity. The latter is mediated by two alpha-type subunits (alpha1 and alpha5). In this report we have analyzed the remaining alpha-type subunits for their ability to hydrolyze RNA. We found that all of the recombinant subunits tested exhibited endoribonuclease activity which depended on the origin of RNA and the presence of bivalent ions in the reaction. These results indicate that the endoribonuclease activity of proteasomes may play an important role in cellular metabolism of RNA.     

Comparative study of the "membrane reserve" of blood cells of reptiles and mammals

Based on the method of hypoosmotic loads, the value of membrane reserve and its use by blood cells of reptiles and mammals have been studied. It has been shown that lymphocytes of the both animal species have the highest reserve of plasmalemma, while frog heterophils - the lowest one. A significantly lower part of the membrane reserve participates in formation of phagosomes by mammalian neutrophils as compared with amphibian erythrocytes.     

Severe defect in thymic development in an insertional mutant mouse model

Transgenic mice were generated expressing NK1.1, an NK cell-associated receptor, under control of the human CD2 promoter. Unexpectedly, one of the founder lines, Tg66, showed a marked defect in thymic development characterized by disorganized architecture and small size. Mapping of the transgene insertion by fluorescence in situ hybridization revealed integration in chromosome 2, band G. Already from postnatal day 3, the thymic architecture was disturbed with a preferential loss of cortical thymic epithelial cells, a feature that became more pronounced over time. Compared with wild-type mice, total thymic cell numbers decreased dramatically between 10 and 20 days of age. Thymocytes isolated from adult Tg66 mice were predominantly immature double-negative cells, indicating a block in thymic development at an early stage of differentiation. Consequently, Tg66 mice had reduced numbers of peripheral CD4(+) and CD8(+) T cells. Bone marrow from Tg66 mice readily reconstituted thymi of irradiated wild-type as well as RAG-deficient mice. This indicates that the primary defect in Tg66 mice resided in nonhemopoietic stromal cells of the thymus. The phenotype is observed in mice heterozygous for the insertion and does not resemble any known mutations affecting thymic development. Preliminary studies in mice homozygous for transgene insertion reveal a more accelerated and pronounced phenotype suggesting a semidominant effect. The Tg66 mice may serve as a useful model to identify genes regulating thymic epithelial cell differentiation, thymic development, and function.     

Characterization of plant phenolic compounds by cyclic voltammetry

Phenolic acids and flavonoids were characterized by cyclic voltammetry and total antioxidant activity in the reaction with the ABTS cation radical. Anode peak voltages (E_ap) and their pH dependences were determined for the studied phenolic acids and flavonoids. The E_ap and Trolox equivalent antioxidant capacity (TEAC) values were found to correlate for polyphenols, which react with the ABTS cation radical in two steps. Correlation between the half-wave potential (E_1/2) and TEAC was determined for electrochemically irreversible compounds. Mechanisms of the reaction of phenolics on the electrode involving one-and two-electron oxidation are proposed.     

Carnosine: endogenous physiological corrector of antioxidative system activity

The results of research of camosine as an antioxidative system corrector in conditions of oxidative stress caused by the action of damaging factors (y-rays, overcooling, hypobaric hypoxia, brain ischemia, neurotoxin impact) are summarized in the present review. The effects of carnosine are characterized not only at the level of the whole organism but also in "in vitro" models with use of a whole series of enzymatic systems. The results of the experiments conducted displayed the ability of carnosine to protect animals from oxidative stress based on the combination of direct antioxidative effects and a modulation of enzymes' activities which participate in controlling of reactive oxygen species level in tissues.     

Quantitative surface-enhanced resonance Raman scattering of phthalocyanine-labelled oligonucleotides

The evaluation of phthalocyanine labels for the surface-enhanced resonance Raman scattering (SERRS) detection of oligonucleotides is reported. Three phthalocyanine-labelled oligonucleotides were assessed, each containing a different metal centre. Detection limits for each labelled oligonucleotide were determined using two excitation frequencies where possible. Limits of detection as low as 2.8 × 10⁻¹¹mol.dm⁻³ were obtained which are comparable to standard fluorescently labelled probes used in previous SERRS studies. The identification of two phthalocyanine-labelled oligonucleotides without separation was also demonstrated indicating their suitability for multiplexing. This study extends the range of labels suitable for quantitative surface-enhanced resonance Raman scattering with silver nanoparticles and offers more flexibility and choice when considering SERRS for quantitative DNA detection.     

Basic aspects of ovarian development in Drosophila melanogaster

Modern views of the development and structural organization of the female reproductive system in Drosophila melanogaster are reviewed. Special emphasis is placed on the generation and development of follicles in the germarium and the interactions of germline and somatic cells in the egg chamber. Detailed consideration is given to the main events that ensure and regulate the transport of mRNA, proteins, and organelles from nurse cells to the oocyte in the germarium and at later stages of egg chamber development.     

Characterization of plant phenolic compounds by cyclic voltammetry

Phenolic acids and flavonoids were characterized by cyclic voltammetry and total antioxidant activity in the reaction with the ABTS cation radical. Anode peak voltages (Eap) and their pH dependences were determined for the studied phenolic acids and flavonoids. The Eap and Trolox equivalent antioxidant capacity (TEAC) values were found to correlate for polyphenols, which react with the ABTS cation radical in two steps. Correlation between the half-wave potential (Ep/2) and TEAC was determined for electrochemically irreversible compounds. Mechanisms of the reaction of phenolics on the electrode involving one- and two-electron oxidation are proposed.     

Fluorescence spectroscopic and (19)f NMR studies of human thymidylate synthase with its cognate RNA

In order to investigate the interaction between hTS protein and its cognate mRNA, a 29nt fragment of TS mRNA was synthesized. This region has been suggested as a putative stem-loop involved in translational autoregulation. The melting temperature of the 29ntRNA was 65 degrees C, suggesting that this region does indeed form a stem-loop. Fluorescence spectroscopy was used to monitor the RNA: hTS protein interaction [dissociation constant (K(d)) 3.9 +/- 0.8 nM; stoichiometry of binding 1dimeric hTS: 1RNA]. When hTS was titrated against FdUMP, this gave the expected stoichiometry of 1dimeric hTS: 1.7 FdUMP but in the presence of the 29ntRNA, the stoichiometry of binding changed to 1dimeric hTS: 1RNA: 1FdUMP. Experiments using methotrexate (MTX) gave a stoichiometry of 1dimeric hTS: 1MTX and in the presence of 29ntRNA, the stoichiometry was unchanged. (19)F-NMR spectra of human TS: FdUMP complexes were found to be strikingly similar to analogous NMR spectra of complexes formed by L.casei TS and mouse TS. In the presence of FdUMP, spectra exhibited two additional resonances (-1.50 ppm and -34.4 ppm). The resonance at -1.50 ppm represents non-covalently bound FdUMP, the peak at -34.4 ppm represents covalently bound FdUMP. The addition of methotrexate to the binary TS-FdUMP complex caused a displacement of the internal equilibrium, with only the covalently-bound form seen, and with a slightly disturbed (19)F chemical shift (-36.5 ppm). Similar results were found when MTX was replaced by folinic or folic acid. The addition of 29ntRNA caused no changes to the (19)F spectra of either the binary or ternary complexes.     

Proteomic Markers and Early Prediction of Alzheimer’s Disease

Biochemistry (Moscow) - Alzheimer’s disease (AD) is the most common socially significant neurodegenerative pathology, which currently affects more than 30 million elderly people worldwide....