Can genomics clarify the origins of Boreioglycaspis melaleucae in California,USA?

The Australian psyllid Boreioglycaspis melaleucae is a biological control agent of Melaleuca quinquenervia in Florida (USA) but was observed attacking M. quinquenervia trees in southern California (USA). Genotyping revealed the California population matched three of eight Australian haplotypes and all three Florida haplotypes. It remains unclear if the California psyllid population arrived directly from Australia or via Florida.     

Membrane potential before and after deep freezing of Escherichia coli in the presence of dimethyl sulfoxide and diethyl sulfoxide

It was shown by the method of penetrating tetraphenylphosphonium cations that low-temperature freezing (-196 degrees C) of Escherichia coli leads to a sharp decrease (from 198 to 85 mV) in membrane potential. Incubation of bacteria in a medium containing dimethyl sulfoxide and diethyl sulfoxide as cryoprotectors results in a reduction of the potential by 16 and 27 mV, respectively. It was also shown that diethyl sulfoxide is more effective in maintaining the membrane potential after freezing--thawing than dimethyl sulfoxide.     

Variation of mini- and microsatellite DNA markers in populations of parthenogenetic rock lizard Darevskia rostombekovi

Variation and clonal diversity in populations of the parthenogenetic rock lizard Darevskia rostombekovi was examined by means of multilocus DNA fingerprinting using mini- and microsatellite DNA markers M13, (GATA)4, and (TCC)50). The animals examined were shown to exhibit a clonally inherited, species-specific pattern of DNA markers (fingerprint profile) that is different from the species-specific patterns of parthenogenetic species D. dahli, D. armeniaca, and D. unisexualis. The mean intraspecific similarity index S was 0.950 (0.003) for a sample of 19 animals from three isolated populations of North Armenia. This significantly differed from the estimate of this parameter for a sample of 21 animals including two individuals from mountainous, relict population from the vicinity of the Sevan Lake, which was equal to 0.875 (0.001). A comparison of DNA fingerprints showed differences between 21 individuals attaining 79 DNA fragments of 1801 mini- and microsatellite markers included in the analysis. The results obtained show that intraspecific variation in D. rostombekovi is higher than that in the previously studied parthenogenetic species D. dahli (S = 0.962) and D. unisexualis (S = 0.950) (P < 0.001). Taking into account that D. rostombekovi is considered monoclonal on the basis of allozyme data, the problem of clonal variability is discussed with regard to the evidence on nuclear DNA markers. It is suggested that the hybrid karyotype of D. rostombekovi, which is more unstable than that of D. dahli and D. unisexualis, generates a series of chromosomal rearrangements (mutations). This may lead to the appearance of a geographically isolated chromosomal race (clone) in the population inhabiting the southeastern coast of the Sevan Lake.     

The action of infrasound oscillations on the properties of water and of a DNA solution

The effect of mechanical vibrations (MV) electrical conductivity of water and optical density of aqueous DNA solution. Distilled water was treated with MV of several frequencies from 3 to 5000 Hz with an intensity of 90 dB for 30 minutes. Different sensitivities of water specific electrical conductivity (SEC) were determined (the value of distilled water SEC was 209 +/- 2 microS/m). The greatest decrease of SEC (by 15.7%) under the influence of MV was observed at the frequency of 4 Hz. There was no effect at frequencies higher than 100 Hz. The treatment of DNA water solutions with MV of frequencies 4 and 10 Hz decreased its optical density by 4.2 +/- 1.1 and 4.8 +/- 1.2% correspondingly in comparison with control. In cases of treatment with frequencies of 20 and 50 Hz no effect was observed. The mechanism of MV effect on water can be connected with the changes of system structural characteristics. It is confirmed by experiments with DNA solution, where the decrease of optical density (at 260 nm) under MV treatment is conditioned with the increase of the probability of hydrogen binding formation between the bases.     

The influence of gangliosides on the hydrophilic pore edge line tension and monolayer fusion of lipid membranes

It is shown that inclusion of gangliosides into planar phospholipid bilayers leads to an essential suppression of their monolayer fusion. In contrast to phospholipid lysoforms, the gangliosides do not cause an associative decrease of the specific energy of the hydrophilic pore edge determined in the experiments on the electrical breakdown of membranes. This phenomenon depends on the effective size of the polar headgroup of the gangliosides. It is supposed that the effect of gangliosides on the parameters mentioned is based on the fact that they have large hydrated polar headgroups which create steric hindrances, which prevent (i) the membranes to come into contact during monolayer fusion; (ii) the gangliosides to take part in hydrophilic pore formation.     

Response, to polymyxin, of plague microbe strains isolated from various natural foci and of their mutants with a decreased requirement in nutritional factors

Investigation of the response to polymyxin of 65 strains of Pasteurella isolated from various foci and 46 their back mutants showed that all of them were usually highly resistant to polymyxin (MIC 200--500 micrograms/ml). The Pasteurella strains isolated in the Gissaro-Darvaz natural focus, Turkey and Congo were highly sensitive to polymyxin (MIC 10--25 micrograms/ml). Single cultures highly sensitive to the antibiotic were detected among the polymyxin-resistant strains. Polymyxin-sensitive mutants of these cultures with lowered requirements in the growth factors were obtained.