Genetic structure of crucian carp (Cypriniformes, Cyprinidae, Carassius L. 1758) populations of middle-Dnieper basin

Comparative analysis of Middle Dnieper crucian carp's population structure was made by means of biochemical gene marking, cytometry and biological analysis. As a result the structure was found, which may by expounded like association of the genetically related species and forms. This association consists of diploid C. auratus (which predominates in population), C. carassius (which was found in the some of north-eastern reservoirs only) and triploid C. gibelio. In Ukraine the homogeneous populations of C. gibelio can be found on the north-east of Eastern Ukraine only. Though some of individuals maybe present with diploid C. auratus. Besides were found hybrid form: diploid C. auratus-C. carassius and presumably tetraploid C. auratus-C. gibelio and C. gibelio-C. carassius. However in the tetraploid's spectra were absent a number of specific alleles, that marking C. species-one of the parental species of triploid C. gibelio. Therefore presumptive tetraploids have not difference from C. auratus and diploid C. auratus-C. carassius on the gene markers level. Nevertheless they are neatly diagnose by the erythrocytes which have good difference and are bigger then diploid species erythrocytes in 40% (C. auratus-C. gibelio) and 100% (C. gibelio-C. carassius).     

Preparation of soybean seed samples for FT-IR microspectroscopy

Typical preparation of seed samples for infrared (IR) microspectroscopy involves imbibition of the seed for varying time periods followed by cryosectioning. Imbibition, however, may initiate germination even at 4° C with associated changes in the chemistry of the sample. We have found that it is possible to section seeds that are sufficiently hard, such as soybeans, on a standard laboratory microtome without imbibition. The use of dry sectioning of unimbibed seeds is reported here, as well as a comparison of different mounting media and modes of analysis. Glycerol, Tissue-Tek, and ethanol were used as mounting media, and the quality of the resulting spectra was assessed. Ethanol was the preferred mountant, because it dried quickly with no residue and thus did not interfere with the spectrum of interest. Analysis in transmission mode using barium fluoride windows to hold the samples was compared with transmission-reflection analysis with sections mounted on special infrared-reflecting slides. The two modes of analysis performed well in different regions of the spectrum. The mode of analysis (transmission vs. transmission-reflection) should be based on the components of greatest interest in the sample.     

Anti-tumor therapy with macroencapsulated endostatin producer cells

Background  

Theracyte is a polytetrafluoroethylene membrane macroencapsulation system designed to induce neovascularization at the tissue interface, protecting the cells from host's immune rejection, thereby circumventing the problem of limited half-life and variation in circulating levels. Endostatin is a potent inhibitor of angiogenesis and tumor growth. Continuous delivery of endostatin improves the efficacy and potency of the antitumoral therapy. The purpose of this study was to determine whether recombinant fibroblasts expressing endostatin encapsulated in Theracyte immunoisolation devices can be used for delivery of this therapeutic protein for treatment of mice bearing B16F10 melanoma and Ehrlich tumors.     

Univalent ions in phospholipid model membranes: Thermodynamic and hydration aspects

By means of differential scanning calorimetry, effects of systematic series of Group I and VII ions on the phase state of model multibilayer dimyristoylphosphatidylcholine (di(14:0)PC) membranes have been studied at a lipid/ion molar ratio of 3/1. The sign-changing correlations between the ionic radii of cations and temperature shifts of di(14:0)PC phase transition were obtained. For cosmotropic Li⁺ and Na⁺, the observed shifts were positive (LiCl: ΔT _m = 0.6°C; ΔT _p = 1.9°C), whereas chaotropic K⁺ and Rb⁺ presence resulted in negative shifts (RbCl: ΔT _m = ?0.3°C; ΔT _p = ?2.5°C). The anions (Cl^?, Br^?, I^?) showed a similar effect increasing with the ion chaotropicity. An essentially weaker effect of Cs⁺ as compared to other alkali metal ions (CsCl: ΔT _m ≈ 0°C; ΔT _p = ?0.1°C) can be one of the reasons of its accumulation in living organisms. Generalization of all available data allowed us to specify some important factors of lipid-ion interactions that should be taken into account in further investigations in this field.     

The characteristics of interactions of pharmaceuticals and their active ingredients with lipid membranes

A comparative study of the effects of the active pharmaceutical ingredients of amixin, aspirin, metronidazole, phenibut, and fenspiride, as well as corresponding pharmaceuticals on lipid membranes was carried out. Lipid membranes of L-α-dipalmitoylphosphatidylcholine and native carp spermatozoa were used as models. A decrease in the melting temperature of L-α-dipalmitoylphosphatidylcholine membranes in the presence of all active ingredients and pharmaceuticals was found using differential scanning calorimetry. The only exception was the group of phenibut, where a splitting of the melting peak was observed. It was found that in the pharmaceuticals studied the active pharmaceutical ingredients exhibit a determinative membranotropic effect, whereas excipients play a modulating role. Changes in the parameters of water ν_ОН bands in the L-α-dipalmitoylphosphatidylcholine membranes containing active pharmaceutical ingredients were quantitatively characterized by Fourier transform infrared spectroscopy. According to these parameters, the effect of the phenibut group differed in these parameters from that of the other ingredients. The changes of ν_ОН bands caused by excipients were elucidated. An increase in the permeability of carp sperm cell membranes to water was observed in vitro for pharmaceuticals that induced a decrease in the phase transition temperature of a model membrane (amixin) and lipid lateral phase separation (phenibut).     

Effects of membranotropic agents on mono- and multilayer structures of dipalmitoylphosphatidylcholine

We have studied the action of some membranotropic agents (MTAs) on the parameters of mono- and multilayers of dipalmitoylphosphatidylcholine (DPPC). The MTAs used included an antimicrobial drug, decamethoxinum, the model amphiphilic agent stearoyl-L-alpha-alanine, and cholesterol as a reference substance. Using differential scanning calorimetry and the Langmuir monolayer technique, we measured the temperature and enthalpy of the main phase transition of DPPC, the mean molecular area, the collapse pressure and the free energy of the mixed monolayers of DPPC and MTA. A good correlation has been obtained between the structure of the MTA used and changes in the parameters of both mono- and multilayers. Thus, for cholesterol, its well-known condensing effect in the L alpha phase correlates with its behavior in the mixed monolayers. The disturbing action of decamethoxinum (depression of the phase transition in DPPC multilayers and relatively high free energy of mixing in monolayers) is presumably connected with interaction of its charged ammonium moieties with polar phospholipid heads. At the same time, stearoyl-L-alpha- alpha-alanine condensed the lipid layers and increased the melting point of DPPC, owing to its interaction with both polar and non-polar lipid moieties. One can conclude that the three MTAs used can really be considered as representative examples of three different types of behavior in mono- and multilayers.     

Single-nucleotide polymorphism,linkage disequilibrium and geographic structure in the malaria parasite <Emphasis Type="Italic">Plasmodium vivax</Emphasis>: prospects for genome-wide association studies

Background

The ideal malaria parasite populations for initial mapping of genomic regions contributing to phenotypes such as drug resistance and virulence, through genome-wide association studies, are those with high genetic diversity, allowing for numerous informative markers, and rare meiotic recombination, allowing for strong linkage disequilibrium (LD) between markers and phenotype-determining loci. However, levels of genetic diversity and LD in field populations of the major human malaria parasite P. vivax remain little characterized.

Results

We examined single-nucleotide polymorphisms (SNPs) and LD patterns across a 100-kb chromosome segment of P. vivax in 238 field isolates from areas of low to moderate malaria endemicity in South America and Asia, where LD tends to be more extensive than in holoendemic populations, and in two monkey-adapted strains (Salvador-I, from El Salvador, and Belem, from Brazil). We found varying levels of SNP diversity and LD across populations, with the highest diversity and strongest LD in the area of lowest malaria transmission. We found several clusters of contiguous markers with rare meiotic recombination and characterized a relatively conserved haplotype structure among populations, suggesting the existence of recombination hotspots in the genome region analyzed. Both silent and nonsynonymous SNPs revealed substantial between-population differentiation, which accounted for ~40% of the overall genetic diversity observed. Although parasites clustered according to their continental origin, we found evidence for substructure within the Brazilian population of P. vivax. We also explored between-population differentiation patterns revealed by loci putatively affected by natural selection and found marked geographic variation in frequencies of nucleotide substitutions at the pvmdr-1 locus, putatively associated with drug resistance.

Conclusion

These findings support the feasibility of genome-wide association studies in carefully selected populations of P. vivax, using relatively low densities of markers, but underscore the risk of false positives caused by population structure at both local and regional levels.See commentary: http://www.biomedcentral.com/1741-7007/8/90

     

The combined effects of nitrates on multibilayer lipid membranes: Thermodynamic effects

Model multibilayer membranes based on L-α-dimyristoylphosphatidylcholine containing nitrates of silver, sodium, potassium, and copper as AgNO₃–NaNO₃, AgNO₃–KNO₃, and AgNO₃–Cu(NO₃)₂ pairs were investigated. In each system studied the molar fraction of nitrates relative to the lipid was kept unchanged at 0.35, whereas the molar fraction of silver nitrate (x _Ag) was varied from 0.0 tо 1.0 within the pair. Thermodynamic parameters of the main phase transition and pre-transition of the model membranes were determined using differential scanning calorimetry. Positive deviations from additivity as a function of x _Ag for a number of these parameters were detected, including changes in the main phase transition and the pre-transition temperatures of up to 0.5 and 2.7°C, respectively; the deviation for hysteresis and half-width of the main phase transition reached up to 30%. The physicochemical mechanisms of competitive interactions between cations in membranes composed of L-α-dimyristoylphosphatidylcholine are discussed.