A blue-purple pigment-producing bacterium isolated from the Vezelka river in the city of Belgorod

The purpose of the present work was to study the properties of a newly isolated bacterium capable of synthesizing blue-purple pigment. An aboriginal bacterium was isolated from the coastal zone of the Vezelka River in the city of Belgorod. Based on chemical and spectrophotometric studies of the crude ethanol extract, the pigment was identified as violacein, and the isolate was assigned to the group of violacein-forming bacteria, which includes bacteria of the genera Chromobacterium, Iodobacter, Janthinobacterium, Duganella, Collimonas, and Massili

Assessment of the antifungal activity of the violacein-forming strain Janthinobacterium sp. B-3515 against the mould fungus Alternaria brassicicola F-1864

A study of antifungal properties of violacein-forming strain Janthinobacterium sp. B-3515 as well as its secondary metabolite, violacein, against Alternaria brassicicola F-1864 is presented. Regardless of the presence of bacteria, mycelium growth in the first two days proceeded at the same rate. The effect of the bacterial strain was manifested after the third day of incubation. In general, during co-culture, the bacterial strain statistically significantly reduced the average growth of the mycelium of the mould fungus by 10

A New Mixed-Backbone Oligonucleotide against Glucosylceramide Synthase Sensitizes Multidrug-Resistant Tumors to Apoptosis

Enhanced ceramide glycosylation catalyzed by glucosylceramide synthase (GCS) limits therapeutic efficiencies of antineoplastic agents including doxorubicin in drug-resistant cancer cells. Aimed to determine the role of GCS in tumor response to chemotherapy, a new mixed-backbone oligonucleotide (MBO-asGCS) with higher stability and efficiency has been generated to silence human GCS gene. MBO-asGCS was taken up efficiently in both drug-sensitive and drug-resistant cells, but it selectively suppressed GCS overexpression, and sensitized drug-resistant cells. MBO-asGCS increased doxorubicin sensitivity by 83-fold in human NCI/ADR-RES, and 43-fold in murine EMT6/AR1 breast cancer cells, respectively. In tumor-bearing mice, MBO-asGCS treatment dramatically inhibited the growth of multidrug-resistant NCI/ADR-RE tumors, decreasing tumor volume to 37%, as compared with scrambled control. Furthermore, MBO-asGCS sensitized multidrug-resistant tumors to chemotherapy, increasing doxorubicin efficiency greater than 2-fold. The sensitization effects of MBO-asGCS relied on the decreases of gene expression and enzyme activity of GCS, and on the increases of C18-ceramide and of caspase-executed apoptosis. MBO-asGCS was accumulation in tumor xenografts was greater in other tissues, excepting liver and kidneys; but MBO-asGCS did not exert significant toxic effects on liver and kidneys. This study, for the first time in vivo, has demonstrated that GCS is a promising therapeutic target for cancer drug resistance, and MBO-asGCS has the potential to be developed as an antineoplastic agent

Development of a cooling system for 6U module based on Elbrus microprocessor

The article discusses the design features of cooling systems for compact Eurocard format modules based on the Elbrus microprocessor. The issue of ensuring the necessary thermal regime of the processor module in the space shortage conditions in order to accommodate the cooling system has been solved. The estimated calculation showed the underperformance of the passive cooling of the Elbrus-4S microprocessor with a heat output of 60 W. In this regard, a 3D model of an active cooling system with 5.5×10.3×4.6 cm dimensions was developed. Thermal calculations were performed using the SolidWorks Flow Simulation program in order to optimize the radiator geometry and fan speed. It was assumed that an optimized cooling system will ensure that the chip temperature of the Elbrus-4S processor is no more than +87 °C (at an ambient temperature of +55 °C). Based on the results of the study, three prototypes were produced for testing. Further tests conducted on prototypes showed the efficiency of the cooling system and the high accuracy of the simulation results. During tests in a climatic chamber at a temperature of +55 °C, the temperature on the microprocessor chip did not exceed +84 °C (a difference of 3 °C compared to the estimated one)

Ionospheric Alfv6n resonator revisited' Feedback instability I V. Khruschev i •/[. Parrot 2 S. Senchenkov, 1

International audienceThe theory of ionospheric Alfv6n resonator (IAR) and IAR feedback instability is reconsidered. Using a. simplified model of the topside ionosphere, we have reanalyzed the physical properties of the IAR interaction with magnetospheric convective flow. It is found tha, t in the absence of the convective flow the IAR eigenmodes exhibit a strong da, mping due to the leakage of the wa,ve energy through the resonator upper wall and Joule dissipation in the conductive ionosphere. It is found that maximum of the dissipation rate appears when the ionospheric conductivity approaches the "IAR wave conductivity" and becomes infinite. However, the presence of Hall dispersion, associated with the coupling of Alfv•n wave modes with the compressional perturbations, reduces the infinite damping of the IAR eigenmodes in this region and makes it dependent on the wavelength. The increase in the convection electric field lea, ds to a. substantial modification of the IAR eigenmode frequencies a. nd to reduction of the eigenmode damping rates. For a given perpendicular wa,velength the position of inaximum damping rate shifts to the region with lower ionospheric conductivity. When the convection electric field approaches a certain critical va,lue, the resona,tor becomes unstable. This results in the IAR feedback instability. A new type of the IAR feedba, ck instability with the lowest threshold value of convection velocity is found. The physica,1 mecha, nism of this instability is similar to the Cerenkov radiation in collisionless plasma,s. The favorable conditions for the insta, bility onset are realized when the ionospheric conductivity is low, i.e., for the nighttime conditions. We found that the lowest value of the marginal electric field which is ca, pa, ble to trigger the feedback instability turns out to be nearly twice smaller tha, n tha,t predicted by the previous analysis. This effect may result in the decrease of the critical value of the electric field of the magnetospheric convection tha,t is necessary for the forma, tion of the turbulent Alfv•n boundary layer and appearance of the a, nomalous conductivity in the IAR region