Biological effectiveness of helium ions and relativistic-energy protons

It was shown that RBE coefficients of protons (9 GeV) and accelerated helium ions (4 GeV/nucleon) are within the range from 1.0 to 11.6 and 1.0 to 7.2, respectively, depending on the object under study, the criterium of estimation, the registration time, and the dose value.     

Determination of myelin marker enzymes in the blood serum in peripheral nervous system diseases

The activity of 2',3'-cyclonucleotide-3-phosphohydrolase (CNP) and leucine aminopeptidase (LAP) was studied for the first time in the blood of patients with diseases of the peripheral nervous system. A spectrophotometric method for CNP activity detection was described. The activity absent from the blood of normal subjects was detectable with statistical significance in the patients with the diseases in question. Analogous results were obtained in the animals with an experimental injury to the myelin coat of the peripheral nerves. Study into the activity of LAP in the pathological conditions under consideration revealed no significant deviations. It is emphasized that CNP may transfer to the blood serum from myelin decay foci and that the method described may be used for diagnostic purposes.     

Cloning, sequencing, and expression of the gene encoding extracellular alpha-amylase from Pyrococcus furiosus and biochemical characterization of the recombinant enzyme.

The gene encoding the hyperthermophilic extracellular alpha-amylase from Pyrococcus furiosus was cloned by activity screening in Escherichia coli. The gene encoded a single 460-residue polypeptide chain. The polypeptide contained a 26-residue signal peptide, indicating that this Pyrococcus alpha-amylase was an extracellular enzyme. Unlike the P. furiosus intracellular alpha-amylase, this extracellular enzyme showed 45 to 56% similarity and 20 to 35% identity to other amylolytic enzymes of the alpha-amylase family and contained the four consensus regions characteristic of that enzyme family. The recombinant protein was a homodimer with a molecular weight of 100,000, as estimated by gel filtration. Both the dimer and monomer retained starch-degrading activity after extensive denaturation and migration on sodium dodecyl sulfate-polyacrylamide gels. The P. furiosus alpha-amylase was a liquefying enzyme with a specific activity of 3,900 U mg-1 at 98 degrees C. It was optimally active at 100 degrees C and pH 5.5 to 6.0 and did not require Ca2+ for activity or thermostability. With a half-life of 13 h at 98 degrees C, the P. furiosus enzyme was significantly more thermostable than the commercially available Bacillus licheniformis alpha-amylase (Taka-therm).     

Physical–Chemical Properties,Physiological Activity,and Usage of Alginates,the Polysaccharides of Brown Algae

This review summarizes data on alginates, polysaccharides isolated from brown algae. Their raw sources, chemical structure, and physical–chemical properties are discussed briefly. This paper is mainly focused on the physiological activity and usage of alginates in food and pharmaceutical industries. The data on alginate toxicity and necessary safety measures are also presented. The capability of alginates to bind and eliminate heavy metals and radionuclides from animal and human organisms is discussed. This paper also deals with the effects of alginates on the metabolism of lipids, carbohydrates, etc., and their usage in medicine, dietetics, and biotechnology.     

Isolation and characterization of a xanthophyll-rich fraction from the thylakoid membrane of Dunaliella salina(green algae).

Long-term acclimation to irradiance stress (HL) of the green alga Dunaliella salina Teod. (UTEX 1644) entails substantial accumulation of zeaxanthin along with a lowering in the relative amount of other pigments, including chlorophylls and several carotenoids. This phenomenon was investigated with wild type and the zea1 mutant of D. salina, grown under conditions of low irradiance (LL), or upon acclimation to irradiance stress (HL). In the wild type, the zeaxanthin to chlorophyll (Zea/Chl)(mol : mol) ratio was as low as 0.009 : 1 under LL and as high as 0.8 : 1 under HL conditions. In the zea1 mutant, which constitutively accumulates zeaxanthin and lacks antheraxanthin, violaxanthin and neoxanthin, the Zea/Chl ratio was 0.15 : 1 in LL and 0.57 : 1 in HL. The divergent Zea/Chl ratios were reflected in the coloration of the cells, which were green under LL and yellow under HL. In LL-grown cells, all carotenoids occurred in structural association with the Chl-protein complexes. This was clearly not the case in the HL-acclimated cells. A beta-carotene-rich fraction occurred as loosely bound to the thylakoid membrane and was readily isolated by flotation following mechanical disruption of D. salina. A zeaxanthin-rich fraction was specifically isolated, upon mild surfactant treatment and differential centrifugation, from the thylakoid membrane of either HL wild type or HL-zea1 mutant. Such differential extraction of beta-carotene and Zea, and their separation from the Chl-proteins, could not be obtained from the LL-grown wild type, although small amounts of Zea could still be differentially extracted from the LL-grown zea1 strain. It is concluded that, in LL-grown D. salina, xanthophylls (including most of Zea in the zea1 strain) are structurally associated with and stabilized by the Chl-proteins in the thylakoid membrane. Under HL-growth conditions, however, zeaxanthin appears to be embedded in the lipid bilayer, or in a domain of the chloroplast thylakoids that can easily be separated from the Chl-proteins upon mild surfactant treatment. In conclusion, this work provides biochemical evidence for the domain localization of accumulated zeaxanthin under irradiance-stress conditions in green algae, and establishes protocols for the differential extraction of this high-value pigment from the green alga D. salina.     

The hydroperoxide lyase branch of the oxylipin pathway protects against photoinhibition of photosynthesis

Main conclusion

This study describes a new role for hydroperoxide lyase branch of oxylipin biosynthesis pathway in protecting photosynthetic apparatus under high light conditions.

Lipid-derived signaling molecules, oxylipins, produced by a multi-branch pathway are central in regulation of a wide range of functions. The two most known branches, allene oxide synthase (AOS) and 13-hydroperoxide lyase (HPL) pathways, are best recognized as producers of defense compounds against biotic challenges. In the present work, we examine the role of these two oxylipin branches in plant tolerance to the abiotic stress, namely excessive light. Towards this goal, we have analyzed variable chlorophyll fluorescence parameters of intact leaves of Arabidopsis thaliana genotypes with altered oxylipin profile, followed by examining the impact of exogenous application of selected oxylipins on functional activity of photosynthetic apparatus in intact leaves and isolated thylakoid membranes. Our findings unequivocally bridge the function of oxylipins to photosynthetic processes. Specifically, HPL overexpressing lines display enhanced adaptability in response to high light treatment as evidenced by lower rate constant of photosystem 2 (PS2) photoinhibition and higher rate constant of PS2 recovery after photoinhibition. In addition, exogenous application of linolenic acid, 13-hydroperoxy linolenic acid, 12-oxophytodienoic acid, and methyl jasmonate individually, suppresses photochemical activity of PS2 in intact plants and isolated thylakoid membranes, while application of HPL-branch metabolites—does not. Collectively these data implicate function of HPL branch of oxylipin biosynthesis pathway in guarding PS2 under high light conditions, potentially exerted through tight regulation of free linolenic acid and 13-hydroperoxy linolenic acid levels, as well as competition with production of metabolites by AOS-branch of the oxylipin pathway.

     

Antimicrobial immunity in patients with acute epiglottitis

Fifty-three patients with catarrhal epiglottitis and 31 patients with epiglottic abscess aged 16-60 years were examined. It was determined that development of epiglottitis is tightly related to abnormalities in reactivity of phagocytic and humoral arms of immunity. Decreased affinity of produced antibodies, opsonizing properties of serum as well as phagocytic and biocide activity of neutrophils were revealed in patients. In patients with catarrhal and necrotic epiglottitis similar abnormalities of immunoreactivity were observed although in patientswith necrotic epiglottitis they were more pronounced.