Placental lactogen as a regulator of luteal cells function during pregnancy in sheep

The luteotropic activity of ovine placental lactogen (oPL) on different days of gestation in ewes was assessed using in vitro methods. Corpora lutea (CL) harvested on Days 45, 70, 95, 120 and 135 of gestation and during parturition were enzymatically dispersed and plated on multiwell plates. After 48 h of incubation, all cultures were terminated and media were frozen for further steroid analysis. Cells were cultured in control medium, with addition of oPL alone, or in combination with PGE2 or PGF2alpha. Supplementation of culture media with oPL increased basal progesterone secretion by cells isolated on Days 45 and 70 of gestation. There was no effect on progesterone secretion by cells isolated on other days of gestation; PGE2 added to the culture media increased progesterone production only by cells isolated on Day 70 of pregnancy. Simultaneous oPL treatment with PGE2 had a statistically significant and stimulatory effect on progesterone production by luteal cells collected on Days 70 and 95 of pregnancy. In contrast, PGF2alpha alone in culture media decreased progesterone secretion by cells isolated on Days 45, 70 and 95 of gestation, while oPL plus PGF2alpha on Days 70 and 95 of gestation protected against luteolytic action of PGF2alpha. The results showed 1) a direct effect of the oPL on luteal cells isolated on Days 45 and 70 of gestation; 2) synergism between PL and PGE2 in progesterone production; by cells isolated on Day 70; 3) and a luteoprotective effect of oPL against the luteolytic action of prostaglandin F (PGF2alpha) observed on Days 70 and 95 of gestation.     

Ampicillin resistance in Listeria monocytogenes acquired as a result of transposon mutagenesis

We have used plasmid pLTV3, which carries transposon Tn917, to obtain a series of mutants of Listeria monocytogenes EGD showing varied degrees of resistance to ampicillin and other beta-lactam antibiotics, including imipenem. In this paper we focus on the characteristics of two strains in which decreased susceptibility to ampicillin is accompanied by changes in the structure of the cell wall murein and cell-wall related changes of phenotype.     

Current knowledge on aquaporin water channels: clinical implications

The discovery of the aquaporin family of water channels has explained to a high degree the mechanism of water transport across cell membranes. The molecular structure of the first purified aquaporin shows its tetrameric organization with each subunit containing an individual aqueous pore selectively permeable for water but not for protons. At least 11 human aquaporins have been identified. Definition of sites of their expression enabled explanation of their physiological role as well as pathological importance in congenital cataract or nephrogenic diabetes insipidus.     

Das Horizontal-Porometer

Ohne ZusammenfassungMit 2 Textabbildungen.     

DFT calculations of the anomeric and exo-anomeric effect of the hydroperoxy and peroxy groups

DFT calculations were carried out on axially and equatorially oriented 2-hydroperoxy and 2-peroxy tetrahydropyran, cyclohexyl hydroperoxide, hydroperoxides of 2,3-unsaturated hexapyranoses, and hydroperoxides of OMe and OBn substituted derivatives of 2-deoxy-glucopyranose and 2-deoxy-galactopyranose to investigate the anomeric and exo-anomeric effects of these groups. The structure and energy of the conformers were calculated at the B3LYP/6-311++G** level. Calculations showed that the peroxy anion group exhibits a strong anomeric effect, comparable in magnitude to the methoxy group, and that the anomeric effect of the hydroperoxy group is similar to the hydroxyl group. These results revealed that hydroperoxy and peroxy anion groups display an exo-anomeric effect, but the orientation around the C1-O1 bond is also affected by hydrogen bonding and electrostatic interactions.     

Chloroplast movement in Mougeotia induced by blue light pulses

The profile-to-face chloroplast movement in the green alga Mougeotia has been induced by strong blue and near-ultraviolet light pulses (6 J m^-2). Simultaneously, strong red or far-red light (10 W m^-2) was applied perpendicularly to the inducing beam. The response was measured photometrically. Against the far-red background the reciprocity law was found to hold for pulse durations varying two orders of magnitude. The action spectrum exhibited a maximum near 450 nm and a distinct increase in near-ultraviolet. The time-course and the spectral dependence of pulse responses of chloroplasts in Mougeotia were similar to those recorded for other plants which are sensitive only to blue. This points to an alternative sensor system active in the short-wavelength region in addition to the phytochrome system.Abbreviations FR far-red light - Pr red absorbing form of phytochrome - Pfr far-red absorbing form of phytochrome - R red light This paper is dedicated to the memory of Professor Jan Zurzycki     

Age-related changes in chromatin of liver cell nuclei of different ploidity

Summary A comparsion of the Feulgen hydrolysis curves and the chromatin compactness of the liver cell nuclei of young and old rats was made. It was found that the rate of DNA depurination and chromatin compactness are higher in the liver cell nuclei of old rats, both in di-and tetraploidal cells. The effect of fixation upon the course of the hydrolysis curves is discussed.This investigation was supported by grant 474/VI Committee of Cell Pathology, Polish Academy of Sciences     

Trends in solventless sample preparation techniques for environmental analysis

The paper presents recent trends in solventless sample preparation techniques for environmental analysis. First, a general classification of solventless methods is given. Next, three of them, treated as preferable techniques, i.e. SPME, SDME and HS, are presented in detail, with respect to their usability and effectiveness for environmental samples. Examples of all discussed techniques are given in the tables.