Dormant forms of Yersinia pseudotuberculosis during interaction with green algae and their exometabolites (population dynamics and ultrastructure)

The dynamics of the transition of Y.pseudotuberculosis to the latent (noncultivable) state in sterile soil extraction and in soil extraction, containing Scenedesmus algae or their exometabolites, was evaluated by the bacteriological method and with the use of polymerase chain reaction. The formation of Y.pseudotuberculosis latent forms achieved its highest rate under the action of algal exometabolites (on day 11), while in the presence of algal cells such formation was delayed to 3-5 months. The partial reversion of Y.pseudotuberculosis nonculativable forms to vegetative, bacteriologically detectable forms occurred under the action of fetal serum, as well as live or killed infusoria. Transmission electron microscopy demonstrated that noncultivable Y.pseudotuberculosis had a round form, diminished cell size, denser cytoplasm and enlarged cytoplasmic space. The reversible transition of bacteria to the latent state is regarded as their adaptation to unfavorable factors during their existence in soils and water reservoirs.     

Genotypic basis of low viability in vestigial mutants of Drosophila melanogaster

The role of a marker mutation and other genes in a decrease in viability was studied in the Drosophila melanogaster vg line. In flies of the C-S line, chromosome 2 was substituted by the homologous chromosome of the vg flies. In addition, the flies of the mutant phenotype with mutant genes partially or completely substituted by the wild-type C-S genes were obtained in saturating crosses C-S x vg. In the reciprocal variant of chromosome 2 substitution, the flies of the C-S phenotype with chromosomes 1, 3, and 4 from the vg line were obtained. Chromosome 2 of the vg line, introduced into C-S fly karyotype, proved to substantially reduce the heat resistance and life span of flies. In the case of reciprocal replacement (C-S line chromosome 2 substituted for the homologous chromosome of vg flies), a significant increase in viability was observed, which, however, never reached the level characteristic of the C-S line. As the vg genotype became saturated with C-S genes, the heat resistance and life span of flies increased substantially. However, even the complete saturation of mutant chromosomes with wild-type genes never resulted in the equal viability of vg and C-S flies. These data suggest that the low viability of the vg mutant is largely accounted for by the gene composition of the second chromosome and, primarily, by the presence of the vg gene. Nevertheless, there is evidence that, along with the pleiotropic effect of the marker mutation, other genes not linked to chromosome 2 are responsible for the studied physiological properties of the vg flies.     

Liquid chromatography of aromatic amines with photochemical derivatization and tris(bipyridine)ruthenium(III) chemiluminescence detection

We have shown by flow injection that tris(bipyridyl)ruthenium(III) [Ru(bpy)3(3+)] chemiluminescence (CL) detection of some aromatic amines can be enhanced by on-line photochemical derivatization. Two of the aromatic amino acids, tryptophan, and tyrosine as well as the peptide phenylalanine-alanine and other primary aromatic amines such as L-dopa, phentermine, and tryptamine upon irradiation with UV light are found to give an increased CL signal on the order of 4-9 times that for nonirradiated compounds. For benzylamine, phenethylamine, and phenylalanine, the improved CL detectability upon photolysis is about 15-16 times better. Chemiluminescence detection limits of the photolyzed compounds are generally 2-20 pmol, significantly better than those by UV-Vis detection at 254 nm. GC-MS work has been done to identify the products of some of the photolysis reactions and explain the enhanced CL detectability. The fact that other aromatic amines without a one or two carbon spacer from the aromatic ring to the amine group such as aniline, m- and p-phenylenediamine, and N,N'-dimethylaniline did not show any CL signal improvement upon irradiation with UV light suggests that there is some selectivity in the reaction. CL detection of aromatic amino acids after on-line photochemical derivatization and HPLC has been shown.     

The influence of nationality on the accuracy of face and voice recognition

Sixty English and U.S. citizens were tested to determine the effect of nationality on accuracy in recognizing previously witnessed faces and voices. Subjects viewed a frontal facial photograph and were then asked to select that face from a set of 10 oblique facial photographs. Subjects listened to a recorded voice and were then asked to select the same voice from a set of 10 voice recordings. This process was repeated 7 more times, such that subjects identified a male and female face and voice from England, France, Belize, and the United States. Subjects demonstrated better accuracy recognizing the faces and voices of their own nationality. Subgoups analysis further supported the other-nationality effect as well as the previously documented other-race effect.     

Byssotoxin A, a secondary metabolite of Byssochlamys fulva

Byssochlamys fulva, isolated from corn, was grown on nutrient-amended shredded wheat medium for 14 days at 25 C. Crude solvent extract from these cultures was toxic to brine shrimp, chicken embryos, and rats. The extract was slightly inhibitory to the germination of of pea seeds, but was nontoxic to ten species of bacteria and one of yeast. One metabolite was isolated, given the trivial name byssotoxin A, and partially characterized chemically and physically.     

Discrete scatter model for microwave radar and radiometer responseto corn: comparison of theory and data

As part of the Multisensor Aircraft Campaign, MACHYDRO, two microwave sensors, NASA's Airborne Synthetic Aperture Radar (AIRSAR) and Pushbroom Microwave Radiometer (PBMR) collected data over the same corn fields during the summer of 1990. During these flights, measurements were made on the ground of soil moisture and plant parameters. In this paper the measured canopy and soil parameters are used in a discrete scatter model to predict the response of both sensors (radar and radiometer). A distorted Born approximation is used to compute the scattering coefficient for the corn canopy. The backscatter coefficient gives the radar response and the radiometer response is obtained by integrating the bistatic coefficient over all scattering angles above ground. The objective of this analysis is to test the model and, in particular, to determine how well a single set of plant parameters and single model can yield agreement with both the radar and radiometer measurements. The model values are in reasonably good agreement with the measurements at horizontal polarization and reflect observed changes in soil moisture     

Residential colonization of orbital complex "Mir" environment by penicillium chrysogenum and problem of ecological safety in long-term space flight

Results of many years of the survey of highly specific evolution of quantitative and species composition of microflora of the MIR environment are reviewed. Analysis of the data enabled listing of microorganisms-declinous fungi with the ability of residential colonization of structural materials of the interior and equipment of habitable modules of the space station. Results of the studies of variability and level of similarity/affinity on the basis of DNA, polymorphism of strains isolated in space flight, convincingly confirmed this characteristic in the Penicillium chrysogenum cultures. In view of the common origin determined from the signs of genetic alliance, the P. chrysogenum strains isolated on MIR in 1995 can be considered descendants of the cultures found at the beginning of the MIR operation. This ecological expansion of P. chrysogenum in the space station environment gains in prominence due to the fact that representative of this particular species known for its active biodestructive nature were, as a rule, detected in the areas where structural materials of the SALYUT and MIR space stations incurred biological degradation.