Cation binding to 15-TBA quadruplex DNA is a multiple-pathway cation-dependent process

A combination of explicit solvent molecular dynamics simulation (30 simulations reaching 4 μs in total), hybrid quantum mechanics/molecular mechanics approach and isothermal titration calorimetry was used to investigate the atomistic picture of ion binding to 15-mer thrombin-binding quadruplex DNA (G-DNA) aptamer. Binding of ions to G-DNA is complex multiple pathway process, which is strongly affected by the type of the cation. The individual ion-binding events are substantially modulated by the connecting loops of the aptamer, which play several roles. They stabilize the molecule during time periods when the bound ions are not present, they modulate the route of the ion into the stem and they also stabilize the internal ions by closing the gates through which the ions enter the quadruplex. Using our extensive simulations, we for the first time observed full spontaneous exchange of internal cation between quadruplex molecule and bulk solvent at atomistic resolution. The simulation suggests that expulsion of the internally bound ion is correlated with initial binding of the incoming ion. The incoming ion then readily replaces the bound ion while minimizing any destabilization of the solute molecule during the exchange.     

The host‐specific parasite Nippotaenia mogurndae confirms introduction vectors of the fish Perccottus glenii in the Volga river basin

Two alternative hypotheses about aquarium vs fish‐farm vectors of non‐native distribution of the fish rotan, Perccottus glenii (Odontobutidae), within the Volga River Basin were assessed using a parasitological approach. Three separate locations were studied where rotan populations were assumed to have different introduction histories: (i) vicinities of Tarakanovo pond, Moscow province (aquarium release in 1950), (ii) Ilev fish farm, Nizhniy Novgorod province (unintentional transportation together with stocking of commercial fish in 1970), (iii) the lower Volga River, Saratov province (unknown origin; first record in 1983). The odontobutid‐specific tapeworm Nippotaenia mogurndae was the most informative species because it has a complex life cycle and therefore does not persist in aquarium conditions. Absence of this tapeworm in the rotan populations in the first locality and presence in the second location are in agreement with the available information about appropriate vectors of introduction. Populations of rotan in the lower Volga (third locality) where N. mogurndae occurs could originate from individuals unintentionally transported to fish farms together with commercial fish species or have mixed origins. Thus, the presented parasitological data are in agreement with information concerning introduction vectors of P. glenii and confirm that the specific parasite N. mogurndae is a valuable biological tag for analysing vectors and pathways of geographical dispersal of rotan, P. glenii.     

A planktivorous specialist turns rapacious: piscivory in invading vendace Coregonus albula

Following invasion and establishment in a subarctic watercourse, small-sized vendace Coregonus albula were surprisingly found to include fish prey in their diet. The zooplankton resource was severely depleted and only made a minor dietary contribution.     

Genome sequence of the haloalkaliphilic methanotrophic bacterium Methylomicrobium alcaliphilum 20Z

Methylomicrobium strains are widespread in saline environments. Here, we report the complete genome sequence of Methylomicrobium alcaliphilum 20Z, a haloalkaliphilic methanotrophic bacterium, which will provide the basis for detailed characterization of the core pathways of both single-carbon metabolism and responses to osmotic and high-pH stresses. Final assembly of the genome sequence revealed that this bacterium contains a 128-kb plasmid, making M. alcaliphilum 20Z the first methanotrophic bacterium of known genome sequence for which a plasmid has been reported.     

Foreign DNA in developing embryos of the loach Misgurnus Fossilis L

The fate of pAT153 DNA microinjected into the embryos of loach was examined. At the earliest stages of development (2 h) the high molecular weight transgenome consisting of pAT153 sequences is formed. The transgenome replicates intensively during the course of early development (until the blastula--early gastrula stages), but later the replication slows down which results in the elimination of the transgenome from the majority of embryos at more advanced stages. The analyses of the transgenome structure with the help of restriction endonucleases have shown that, after microinjection of linear DNA, the high molecular weight transgenome is formed by stochastic ligation of the sticky ends of injected molecules. Our data suggest that the transgenome formation from circular or supercoil DNA occurs after its linearization by host endonuclease.     

Preparation and certain properties of the liposomal substance 2,4-di(1-methyl-3-hydroxybutyl)deuteroporphyrin-IX

A liposome preparation of a porphyrin photosensitizer for photodynamic therapy of tumors (PDT) was obtained. The in vitro efficiency of the photosensitizer was enhanced 2.5-fold through the liposome formulation. The composition and some properties of the new preparation were studied. An algorithm for a complex approach to the prediction of photosensitizer efficiencies by model experiments in vitro was developed. This approach is based on the use of two models: the determination of coefficient of distribution between n-octanol and a phosphate buffer, pH 7.4, and the determination of the cytotoxic effect on the culture of CaOv ovarian adenocarcinoma cells.     

Use of macrolides in pregnancy and lactation according to evidence-based medicine: pro et contra

The use of macrolides in the treatment of chlamydial infection during pregnancy and breast feeding is reviewed from the viewpoint of evidence-based medicine. The clinical experience and research data suggest azithromycin to be safe and effective in the obstetric practice.