Accumulation of oxacarbocyanine dyes with different alkyl chain length in bone marrow cells and hepatocytes

A study was made of the inclusion of fluorescent probe H-510 based on 3,3′-dialkyloxacarbocyanine bromide (where alkyl is ethyl, nonyl, or octadecyl) into cells of different types. Alkyl chain length (C2, C9, or C18) was found to largely determine the accumulation dynamics and mechanism. Similar spectral characteristics for all probe types in bone marrow cells were found by microfluorimetry, suggesting insertion of dye molecules irrespective of their lipophilicity into micelle-like structures formed probably by cell phospholipids. Spectroscopy data indicate interaction of 3,3′-diethyloxacarbocyanine bromide (H-510/C2) and 3,3-dinonyloxacarbocyanine bromide (H-510/C9) dyes in hepatocytes with a less polar microenvironment (nonpolar and low-polar lipids that constitute a significant part of the total content of cell lipids). The fluoresccence maximum of long-chain dye H-510/C18 in hepatocytes is shifted to the short-wavelength region and strictly coincides with the fluorescence maximum of the probe in an albumin solution. It is not excluded that inclusion of the probe into cells occurs via endocytosis upon its binding to surface proteins.     

The effect of lipase from Penicillium sp. on the membrane fraction of the levorin-producing Streptomyces levoris

The effect of a lipase preparation from Penicillium sp. on the membranes of the levorin producer Streptomyces levoris was being studied. The enzyme preparation was found preferably to hydrolyse neutral lipids in the Str. levoris membranes, which makes it possible to use the lipase from Penicillium sp. for studying neutral lipids in microbial membranes.     

Effect of inorganic phosphate on levorin biosynthesis and on the mycelial makeup of Streptomyces levoris]

The effect of inorganic phosphate on biosynthesis of the polyenic antibiotic levorin by Streptomyces levoris and composition of the culture mycelium was studied. It was found that the synthetic medium with 0.4 mM of phosphate was optimal for growth of Str. levoris. When the concentration of phosphate was higher, the biomass increased, while the synthesis of levorin appeared to be inhibited and morphological changes in the culture were observed. Phosphate had a significant effect on the mycelium composition. When its concentration was increased 10 times as compared to the optimal one, the amounts of protein, RNA, total phosphorus and polyphosphates increased 1.3--1.4, 1.6--1.7, 2--3 and 10 times respectively, while the synthesis of levorin decreased 5 times. Changes in the lipid component of the mycelium were also observed. In the absence of inorganic phosphate in the medium the acetone precipitating fraction of the lipids contained 20--40 per cent of the phosphoruless compounds. During cultivation their portion increased up to 70--77 per cent. However, in the presence of its excess the polar lipids were represented only by phospholipids during the whole life cycle. The fatty acid spectrum of the lipids did not depend on the phosphate concentration and was represented mainly by saturated fatty acids with a branched chain of a series of iso- and anteiso-structures containing 14--18 carbon atoms.     

Reactive derivative of adenosine-5′-triphosphate formed by irradiation of ATP γ-p-azidoanilide

UV and ¹H NMR spectra changes demonstrate that p-azidoanilides of ATP, ITP, pyrophosphate after irradiation at 313 nm, transform to similar reactive intermediates. The latter react readily with morpholine, iso-propylamine, tert-butylamine, imidazole, mercaptoethanol the reactivity being qualitatively correlated with nucleophilicity. By analogy with the transformation of p-azidoanilide, it is concluded that the reactive intermediate is the respective derivative of quinone diimine. Photoaffinity labelling of proteins with p-azidoanilide derivatives may proceed as the reaction of the nucleophilic centers of proteins with this quinone diimine derivative, rather than as a direct attack by a nitrene biradical.     

Exploring the environmental diversity of kinetoplastid flagellates in the high-throughput DNA sequencing era

The class Kinetoplastea encompasses both free-living and parasitic species from a wide range of hosts. Several representatives of this group are responsible for severe human diseases and for economic losses in agriculture and livestock. While this group encompasses over 30 genera, most of the available information has been derived from the vertebrate pathogenic genera Leishmaniaand Trypanosoma. Recent studies of the previously neglected groups of Kinetoplastea indicated that the actual diversity is much higher than previously thought. This article discusses the known segment of kinetoplastid diversity and how gene-directed Sanger sequencing and next-generation sequencing methods can help to deepen our knowledge of these interesting protists.     

A high-power vircator operating as an X-ray bremsstrahlung generator

Avircator capable of generating high-power X-ray pulses due to the multiple transitions of electrons through a thin anode foil transparent to X radiation has been created and put into operation for the first time. The vircator is created on the basis of a direct-action electron accelerator supplied from an inductive energy storage operating with a plasma opening switch. Self-consistent two-dimensional simulations of the electron beam dynamics in the vircator chamber are performed, and the spectra of the generated microwave radiation are determined. Self-consistent one-dimensional simulations of the beam dynamics with allowance for electron scattering in the foil were also carried out, and the X-ray bremsstrahlung spectra were measured. Results are presented from the first experiments on the generation of X-ray bremsstrahlung in vircators with thin (10 μm) and thick (100 μm) tantalum anode foils. For a thin foil, the X-ray (E _γ>30 keV) dose is eight times as high as that for a thick foil and the average photon energy is 30 keV (against 80 keV for a thick foil). __________ Translated from Fizika Plazmy, Vol. 30, No. 9, 2004, pp. 828–834. Original Russian Text Copyright ￠ 2004 by Selemir, Dubinov, Ryaslov, Kargin, Efimova, Loyko.