Evolution of the epidemiology of cholera

The problems of the evolution of cholera at the stages of its pandemic spread are described. A short characterization of endemic zones in the countries of Asia, Africa and Latin America, stipulating the preservation of infection and the appearance of periodic epidemics in the world, is presented. Special attention is paid to the genesis of epidemic outbreaks in endemic and introduced foci of cholera, differing in the specific features of their formation and the accumulation of the epidemic variant of the infective agent in aqueous habitat. The role of the ecosystem of surface water reservoirs in the prolonged survival of cholera vibrios is evaluated. The necessity of the detailed study of the mechanisms and forms of existence of serogroup 0139 vibrio in open water reservoirs is substantiated. In the system of epidemiological surveillance on cholera the microbiological monitoring of environmental objects assumes the leading importance.     

Identification of leaf rust resistance genes in wheat (Triticum aestivum L.) cultivars using molecular markers

A collection of 68 cultivars of common wheat has been screened for leaf rust resistance genes with the use of molecular markers. Markers of genes Lr1, Lr9, Lr10, Lr19, Lr20, Lr21, Lr24, and Lr26 have been used. It has been suggested that allele Xgwm295 be used as a marker for identifying the Lr34 gene. The genes originating from Triticum aestivum L., as well as the Lr26 gene contained in rye translocation 1RS, are the most frequent. Genes originating from wild wheats were rarer in the cultivars studied.     

Participation of non-specific rat liver microsome oxidases in destruction of Nl-furanidylpyrimidines]

N1-(3'-Butyrolactono)-5-fluorouracil, N1-(2'-furanidyl) 5-trifluoromethyluracil, N1-(2'-furanidyl)-5-fluoracil are split in the rat organism with the formation of free 5-fluorouracil. The destruction of the C--N bonds in the molecule of the N1-(2'-furanidyl)-5-fluoracil takes place in the liver microsomes. This process is strengthened by NADPH and weakened by SKF-525A. All the three furanidylpyrimidines studied induced differential spectra of type I in the suspension of the liver microsomes. This fact testifies to the interaction of these substances with the cytochrome P-450.     

PCR-detection of markers for epidemiologically-significant strains of Vibrio cholerae 0139, isolated in Siberia]

Fourteen V. cholerae 0139 strains were isolated in 1996-1999 in Siberia from the Ob river (Novosibirsk) and bogs and lakes (Irkutsk). The strains were tested in PCR for the key virulence determinants (ctx AB, tcp, acf). The genomes lacked these elements, and therefore the strains were acknowledged avirulent. The results correlate completely with the data of phenotypical analysis, characterizing the pathogenic characteristics of isolated strains.     

Model of Vibrio cholerae biofilm as a mechanism of its survival in surface water reservoirs

Vibrio cholerae eltor strains with different epidemic importance isolated from river water in the city of Vladivostok during a cholera outbreak (1999) and in the city of Irkutsk during a safe cholera period (2005) are used in the experiment. A biofilm structure consisting of a peripheral part, bundles, polysaccharide matrix, canals, and polymorphic vibrios is presented by light and luminescent microscopy. The metachromatic pink coloring of the matrix (crystal violet and toluidine blue) or fluorescent reddish orange color (acridine orange) are evidence of acid mucopolysaccharide (glucosaminoglycans) content. The biofilm of a toxigenic strain as opposed to a nontoxigenic one is formed much later, while the elements comprising its structure are more apparent. The viability of vibrio cells during the experiment (90 days) preserving the initial pathogenic potential testifies to the highly adaptable properties of the Vibrio cholerae eltor, which promotes its survival and existence in surface water reservoirs under favorable ecological conditions (optimal temperature, existence of chitin-containing substratum, etc.).     

Study of genetic variability of representatives of <Emphasis Type="Italic">Ribes</Emphasis> L. grown in Belarus

The study of genetic variability of Ribes L. representatives grown in Belarus using seven loci of microsatellite sequences showed that modern Belarusian varieties of black currant are characterized by high genetic variability and have a close genetic relationship with foreign selection varieties. The number of alleles in the studied loci varied from 5 to 11. The average number of unique genotypes among 65 samples was 43.1. The discrimination power of the markers varied from 0.67 to 0.95 and the mean value was 0.84. All markers have rather high diagnostic value and make it possible to identify black currant and gooseberry varieties at the molecular level and, therefore, can be recommended for DNA-identification of these cultures.     

Studying Genetic Diversity in Inbred Sunflower Lines by RAPD and Isozyme Analyses

Genetic diversity of 30 inbred sunflower lines was examined by RAPD and isozyme analyses. The inbred lines were shown to be highly polymorphic by RAPD markers. The line distribution on genetic similarity dendrograms based on the RAPD and isozyme data was analyzed. High effectiveness of RAPD analysis for differentiating genotypes of inbred sunflower lines was demonstrated.     

Identification and genetic diversity of plum cultivars grown in Belarus

A study of the collection of sour cherry, sweet cherry, common plum, diploid and tetraploid types of plums, and apricots grown in Belarus carried out using 20 SSR markers showed that they are characterized by high genetic diversity. Among 106 genotypes, 524 polymorphic alleles were identified. The average number of alleles was 15.4 in common plum samples, 11.3 in diploid and tetraploid plum, 9.3 in sour cherry, 6.0 in apricot, and 4.9 in sweet cherry. The greatest genetic diversity is characteristic of common plum cultivars (PD = 0.811). The genetic diversity decreases as follows: diploid plum (PD = 0.741), sour cherry (PD = 0.721), apricot (PD = 0.673), and sweet cherry (PD = 0.655). Cluster analysis shows that the degree of intraspecific divergence in sour cherry and sweet cherry cultivars is less than that of common plum, diploid plum, and apricot plum. Although apricots and plums belong to the subgenus Prunophora, according to the results of SSR analysis, apricot cultivars form a cluster that is more distant from both Cerasus and Prunophora. A set of seven SSR markers (EMPA001, EMPA005, EMPA018, EMPA026 and BPPCT025, BPPCT026, BPPCT039) was selected for DNA identification of cultivars of sour cherry, sweet cherry, common plum, diploid plum, and apricot, as well as species and interspecies hybrids.     

Eltor cholera in Latin America

Cholera epidemics in South and Central America in the period 1991-1999 are characterized. The mechanisms of existence of Vibrio eltor in environmental objects have been substantiated. The causes and conditions of endemic foci formation which determine the infection spread not only within the countries of the subcontinent, but also far beyond its borders are shown. The effectiveness of cholera control interventions is evaluated.