In memory of Igor’ Petrovich Ashmarin

Chronicle

In memory of Igor’ Petrovich Ashmarin     

Antioxidant Systems in Tissues of Senescence Accelerated Mice

Significant decrease in the level of lipid antioxidants (measured from the kinetics of the induced chemiluminescence in brain homogenate) and of the hydrophilic antioxidant carnosine as well was observed in the brain of 14-16-month-old mice of SAMP1 line, which is characterized by accelerated accumulation of senile features, in comparison with the control line SAMR1. In the brain of SAMP1 animals the activity of cytosolic Cu/Zn-containing superoxide dismutase (SOD) was reduced, while the activity of membrane-bound Mn-SOD was at an extremely low level. The activity of glutathione-dependent enzymes (glutathione peroxidase, glutathione reductase, and glutathione transferase) did not differ in the brain of SAMP1 and SAMR1 animals, and catalase activity was similarly low in both cases. At the same time, excess concentration of excitotoxic compounds, significantly exceeding that for the control line, was determined in the brain and blood of SAMP1 animals. The activity of glutathione enzymes in liver and heart as well as the activity of cytosolic Cu/Zn-SOD in liver did not differ in the two studied lines, while the activity of erythrocyte glutathione peroxidase was slightly increased, and the activity of liver catalase and erythrocyte Cu/Zn-SOD was significantly decreased for SAMP1 compared with SAMR1. The results demonstrate that the accelerated ageing of SAMP1 animals is connected to a significant extent with the decreased efficiency of the systems utilizing reactive oxygen species (ROS) in tissues.     

Laminin-binding protein as a cellular receptor for the equine Venezuelan encephalomyelitis virus: Report 2. Inhibition of replication of equine Venezuelan encephalomyelitis virus by blocking laminin-binding protein on the surface of Vero cells

A possible inhibition of the Venezuelan equine encephalomyelitis (VEE) virus replication in Vero cells through the laminin-binding protein (LBP) blocking in the surface of such cells was investigated in order to verify the LBP value. It was demonstrated, on the basis of the flow scanning cytometry and FITC-labeled antibodies to LBP, that there are at least 263 thousand LBP molecules in the Vero cells' surface. Blocking of the molecules by rabbit polyclonal antibodies to 43 kD of the recombinant LBP (rLBP) was shown to inhibit the VEE virus replication in Vero cells by more than 300,000 times, which made them virtually resistant to the possibility of VEE virus infection. This also confirmed that LBP is a target-molecule for VEE virus in Vero cells with the interplay between VEE virus and LBP in the cells' surface being the initial stage of virions' penetration into the cell and of their replication inside the cell.     

Mutation of the putative hydrogen-bond donor to P700 of photosystem I

The primary electron donor of photosystem I (PS1), called P(700), is a heterodimer of chlorophyll (Chl) a and a'. The crystal structure of photosystem I reveals that the chlorophyll a' (P(A)) could be hydrogen-bonded to the protein via a threonine residue, while the chlorophyll a (P(B)) does not have such a hydrogen bond. To investigate the influence of this hydrogen bond on P(700), PsaA-Thr739 was converted to alanine to remove the H-bond to the 13(1)-keto group of the chlorophyll a' in Chlamydomonas reinhardtii. The PsaA-T739A mutant was capable of assembling active PS1. Furthermore the mutant PS1 contained approximately one chlorophyll a' molecule per reaction center, indicating that P(700) was still a Chl a/a' heterodimer in the mutant. However, the mutation induced several band shifts in the visible P(700)(+) - P(700) absorbance difference spectrum. Redox titration of P(700) revealed a 60 mV decrease in the P(700)/P(700)(+) midpoint potential of the mutant, consistent with loss of a H-bond. Fourier transform infrared (FTIR) spectroscopy indicates that the ground state of P(700) is somewhat modified by mutation of ThrA739 to alanine. Comparison of FTIR difference band shifts upon P(700)(+) formation in WT and mutant PS1 suggests that the mutation modifies the charge distribution over the pigments in the P(700)(+) state, with approximately 14-18% of the positive charge on P(B) in WT being relocated onto P(A) in the mutant. (1)H-electron-nuclear double resonance (ENDOR) analysis of the P(700)(+) cation radical was also consistent with a slight redistribution of spin from the P(B) chlorophyll to P(A), as well as some redistribution of spin within the P(B) chlorophyll. High-field electron paramagnetic resonance (EPR) spectroscopy at 330-GHz was used to resolve the g-tensor of P(700)(+), but no significant differences from wild-type were observed, except for a slight decrease of anisotropy. The mutation did, however, provoke changes in the zero-field splitting parameters of the triplet state of P(700) ((3)P(700)), as determined by EPR. Interestingly, the mutation-induced change in asymmetry of P(700) did not cause an observable change in the directionality of electron transfer within PS1.     

Laminin-binding protein (LBP) as a cellular receptor for the virus of Venezuelan equine encephalomyelitis (VEE): Part 1. A study of the interaction between VEE virus virions and the human recombinant LBP

The interaction of the VEE virus virions with human LBP was investigated. The affinely purified 43 kDa recombinant LBP (rLBP) of man was found to interact effectively with the VEE virus virions purified in immune enzyme assay. The affinity constant of 43 kDa rLBP with virions was equal to 4.3-4.8 x 10(7) M-1. The rabbit antiviral polyclonal antibodies blocked the interaction of rLBP with the VEE virus virions. According to Western blot, rLBP is capable of interacting with the E1 glycoprotein of the VEE virus, which suggests the presence of a specific epitope of binding with LBP in the surface of the E1-E2 heterodimer of the VEE virus. The results confirm that human LBP could be a receptor for the VEE virus.     

The synthesis of short- and medium-chain-length poly(hydroxyalkanoate) mixtures from glucose- or alkanoic acid-grown <Emphasis Type="Italic">Pseudomonas oleovorans</Emphasis>

Pseudomonas oleovorans NRRL B-778 accumulated mixtures of poly-3-hydroxybutyrate (PHB) and medium-chain-length poly(hydroxyalkanoates) (mcl-PHAs) when grown on glucose, octanoic acid or oleic acid, whereas growth on nonanoic acid or undecanoic acid resulted in copolymers of poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHB-co-HV). Acetone fractionation verified the presence of PHB/mcl-PHA mixtures. The acetone-insoluble (AIS) fractions of the polymers derived from glucose (PHA-glucose), octanoic acid (PHA-octanoic) and oleic acid (PHA-oleic) were exclusively PHB while the acetone-soluble (AS) fractions contained mcl-PHA composed of differing ratios of 3-hydroxy-acid monomer units, which ranged in chain length from 6 to 14 carbon atoms. In contrast, both the AIS and AS fractions from the polymers derived from nonanoic acid (PHA-nonanoic) and undecanoic acid (PHA-undecanoic) were composed of comparable ratios of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV). The unfractionated PHA-glucose, PHA-octanoic and PHA-oleic polymers had melting temperatures (T _m) between 177 and 179°C, enthalpies of fusion (ΔH _f) of 20 cal/g and glass transition temperatures (T _g) of 3–4°C. This was due to the large PHB content in the polymer mixtures. On the other hand, the PHA-nonanoic and PHA-undecanoic polymers had thermal properties that supported their copolymer nature. In both cases, the T _m values were 161°C, ΔH _f values were 7cal/g and T _g values were −3°C. Journal of Industrial Microbiology & Biotechnology (2002) 28, 147–153 DOI: 10.1038/sj/jim/7000231 Received 30 July 2001/ Accepted in revised form 04 November 2001     

Carotenoids as scavengers of free radicals in a Fenton reaction: antioxidants or pro-oxidants?

The spin trapping EPR technique was used to study the influence of carotenoids (beta-carotene, 8'-apo-beta-caroten-8'-al, canthaxanthin, and ethyl 8'-apo-beta-caroten-8'-oate) on the yield of free radicals in the Fenton reaction (Fe(2+) + H(2)O(2) --> Fe(3+) + .OH + -OH) in the organic solvents, DMSO, and methanol. DMPO and PBN were used as spin trapping agents. It was demonstrated that carotenoids could increase or decrease the total yield of free radicals depending on the oxidation potential of the carotenoids and the nature of the radicals. A reaction mechanism is suggested which includes the reduction of Fe(3+) to Fe(2+) by carotenoids. The effectiveness of this carotenoid-driven Fenton reaction increases with a decrease of the scavenging rates for free radicals and with decreasing oxidation potentials of carotenoids.     

Role of the microbial community in formation of speleothem (moonmilk) in the Snezhnaya carst cave (abkhazia)

The results of investigation of speleothem (moonmilk) from the Snezhnaya cave (West Caucasus, Abkhazia) are reported. The structure of microbial complexes from moonmilk was investigated by quantitative PCR; strains of culturable microorganisms were isolated and their preferred temperature and carbon sources were determined. Among eubacteria, ~34% belonged to the iron bacteria (Rhodoferax). Most bacterial strains were shown to be facultative psychrophiles with the maximum growth rate at 4°C. The microstructure and elemental composition of moonmilk were investigated using a scanning electron microscope (EVO-40HV, Carl Zeiss) and silicon drift X-ray detector X-MAX 80mm². The visually plastic and homogeneous mass of moonmilk was shown to be highly heterogeneous, containing various microstructures. The elemental composition of some nanostructures depended on the structure of bacterial biofilms. Some loci of the biofilm were found to contain up to 46% (wt/wt) of iron oxides. High calcium content, up to 61.5% (wt/wt), was found only in cubic crystalline structures which were not involved in microbiological processes.     

Evolution of anaerobic ciliates from the gastrointestinal tract: phylogenetic analysis of the ribosomal repeat from Nyctotherus ovalis and its relatives

The 18S and 5.8S rDNA genes and the internal transcribed spacers ITS-1 and ITS-2 of ciliates living in the hindgut of frogs, millipedes, and cockroaches were analyzed in order to study the evolution of intestinal protists. All ciliates studied here belong to the genus Nycrotherus. Phylogenetic analysis revealed that these ciliates from a monophyletic group that includes the distantly related anaerobic free-living heterotrichous ciliates Metopus palaeformis and Metopus contortus. The intestinal ciliates from the different vertebrate and invertebrate hosts are clearly divergent at the level of their rDNA repeats. This argues for the antiquity of the associations and a predominantly vertical transmission. This mode of transmission seems to be controlled primarily by the behavior of the host. The different degrees of divergence between ciliates living in different strains of one and the same cockroach species most likely reflect the different geographical origins of the hosts. In addition, host switches must have occurred during the evolution of cockroaches, since identical ciliates were found only in distantly related hosts. These phenomena prevent the reconstruction of potential cospeciation events.