Identification of Streptomyces coelicolor M145 genomic region involved in biosynthesis of teichulosonic acid–cell wall glycopolymer

The cell wall of the model actinomycete Streptomyces coelicolor M145 has recently been shown to contain the novel glycopolymer teichulosonic acid. The major building block of this polymer is 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid (Kdn), suggesting initial clues about the genetic control of biosynthesis of this cell wall component. Here, through genome mining and gene knockouts, we demonstrate that the sco4879–sco4882 genomic region of S. coelicolor M145 is necessary for biosynthesis of teichulosonic acid. Specifically, mutants carrying individual knockouts of sco4879, sco4880 and sco4881 genes do not produce Kdn-containing glycopolymer and instead accumulate the minor cell wall component poly(diglycosyl 1-phosphate). Our studies provide evidence that this region is at least partly responsible for biosynthesis of Kdn, whereas flanking genes might control the other steps of teichulosonic acid formation.     

Large-conductance cationic channels in the nuclear envelope of Purkinje neurons from the rat cerebellum

Using a patch-clamp technique, we studied the biophysical properties of large-conductance channels in the nuclear envelope of rat cerebellar Purkinje neurons. Our experiments showed that channels with identical conductance, selectivity, and kinetics are expressed in the external and internal nuclear membranes of these cells. These channels connect the perinuclear space with the cyto-and nucleoplasm; they are not channels of the complex of the nuclear pores for passive diffusion of ions and small molecules, as was believed earlier [17]. We hypothesize that large-conductance cationic channels in the membranes of the nuclear envelope are identical to ion channels of the endoplasmic reticulum and are necessary for functioning of the intermembrane space of the envelope as a calcium store. Neirofiziologiya/Neurophysiology, Vol. 39, No. 2, pp. 113–118, March–April, 2007.     

Twenty years after the Chernobyl accident: solid cancer incidence in various groups of the Ukrainian population

Several major international studies such as those performed on the A-bomb survivors, have shown a clear linkage between the exposure to ionizing radiation and the occurrence of various cancer types including leukemia. While these studies are mostly characterized by high dose rates, studies on populations exposed after the Chernobyl accident are in most cases characterized by low dose rates which are typical for occupational radiation protection. Here, data on more than 60,000 Ukrainian workers who participated in recovery operation works in Chernobyl in 1986–1987, more than 50,000 evacuees from the city of Prypyat and the 30 km zone, and about 360,000 residents of most contaminated territories are presented, which cover a period of observation from 1980 to 2004. For all cancers combined, statistically significant higher incidence rates than the national rates were found only for the recovery workers (standardized incidence ratio (SIR) 117.2%, 95% confidence interval: 114.1–120.3), while those for the other investigated groups were lower. In all groups under study a significant increase of thyroid cancer incidence rates has been registered. This increase appears to be associated, at least partly, with the fallout of radioiodine, and it was found not only in children, but also in adolescents and adults. For example, the most significant excess was found for male recovery workers corresponding to a factor of 8.0. It is important to keep in mind, however, that the contribution of confounding factors such as an intensified thyroid screening after the Chernobyl accident could not be quantified, in the present study. For female recovery workers there was also an excess of breast cancer over the national rates (SIR 190.6%; 95% confidence interval: 163.6–217.7%). An analysis of the two other groups (evacuees and residents of contaminated territories) gave controversial results: relative to the local standard there was a statistically significant excess, while comparison with the national level did not substantiate this conclusion.     

Comparative analysis of genetic structure in natural populations of two <Emphasis Type="Italic">Arabidopsis</Emphasis> species with different degree of panmixia

Comparative analysis of genetic structure of northern natural populations of two Arabidopsis species with different degrees of panmixia was performed. The variability of 121 RAPD loci in seven populations of model plant A. thaliana possessing high degree of self fertility was studied together with 93 RAPD loci in population of cross-pollinating species A. lyrata ssp. petraea. The population of A. l. petraea demonstrated higher level of genetic variability (P _99% = 62.50%; H _exp = 0.169) than the populations of A. thaliana, which is obviously connected with biological features of reproduction of the species. A significant level of genetic variability (P _99% = 42.27%; H _exp = 0.126) was revealed in populations of A. thaliana, which is not typical for self-pollinating plant species. The high population polymorphism of A. thaliana in the northern part of its range may be connected with adverse environmental conditions. The genetic distances between populations of the species studied (average D _N = 0.494) confirm close relatedness between A. thaliana and A. l. petraea.     

Nanostructuring of Continuous Gold Film by Laser Radiation Under Surface Plasmon Polariton Resonance Conditions

The physical mechanisms of metallic nanoparticles formation by laser technology were studied. The system air/Au film/glass was irradiated by laser at the conditions of surface plasmon resonance. A surface electromagnetic wave was excited in Kretchmann configuration by the fundamental and second harmonics of the Q-switched YAG/Nd⁺³ laser with pulse power density close to the threshold of melting. Nanostructuring of Au film was observed only for the second harmonic (λ = 0.532 μm) irradiation at the surface plasmon polariton resonance (SPR) conditions. Estimations were done using the interference model of the differently directed plasmon polariton waves excited by a surface electromagnetic wave on the metal surface. It was shown that a regular pattern of locally heated spots can be formed in a metallic film by pulsed laser irradiation. The spatial distribution of this pattern is close to the period of interference. The observed effect of laser nanofragmentation is explained by the self-organization of plasmon polariton subsystem in the process of Au nanoparticles formation at high laser intensity levels. These methods open new possibilities for nanostructured surfaces formation utilizing simple self-organization processes.     

Genetic variation of Azov and Black sea herring Alosa pontica (Eihwald, 1838), (Clupeiformes, Alosinae) in Danube river: analysis of biochemical gene markers

Genetic variation and structure of Danube stock of Aloca pontica pontica were investigated during the spawning moving by means of biochemical genetic marking. The level of heterozygosity was Hobs = 0,009. It is essentially lower than the average level for populations of other Teleostei and Clupeidae representatives. Polymorphism was defined only for Es-D of 20 analyzed loci expressed in muscle tissues. The allele frequencies for this locus were reliably different in the early spawning and later spawning parts of the stock, as well as proportion of heterozygotes and genotype diversity which was higher at the beginning of spawning moving. These results are discussed from two points of view: genetic differences between subpopulations in the course of spawning moving and presence of two close species of herring which come for the spawning together and hybridize to each other.     

Hybridization of crucian carp, Carassius carassius (Linnaeus, 1758), in Ukrainian reservoirs and genetic structure of hybrids

Hybridization of crucian carps Carassius carassius in polyspecific crucian populations of reservoirs of Ukraine and genetic structure of the hybrids were investigated using biochemical gene marking and cytometric procedure. The fact of wide hybridization between C. auratus and C. carassius was proved to be true by large number of hybrids which can form populations consisting only from hybrid individuals. Hybrids C. auratus x C. carassius were diploid, tryploid and in exceptional cases tetraploid; females and males which most likely breed by hybridogenesis. Besides, some clonal hybrids C. carassius x C. gibelio-1 appearing as tetraploid females, and one triploid female C. carassius x Tinca tinca were revealed. It is supported that hybridization of alien C. auratus with endemic C. carassius became one of mechanisms of replacement and depressions of populations of the last.     

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.