Comparison of ESBL – And AmpC Producing Enterobacteriaceae and Methicillin-Resistant Staphylococcus aureus (MRSA) Isolated from Migratory and Resident Population of Rooks (Corvus frugilegus) in Austria

In order to test whether rooks (Corvus frugilegus) represent good indicators for the potential circulation of antibiotics in their native habitat, two populations with different migratory behavior were tested for the presence of beta-lactamase producing Enterobacteriaceae and methicillin-resistant Staphylococcus aureus (MRSA). In all, 54 and 102 samples of fresh feces of a migratory and a resident population were investigated. A total of 24 and 3 cefotaxime-resistant enterobacterial isolates were obtained from the migratory and resident population, respectively. In these isolates CTX-M-1 (n = 15), CTX-M-3 (n = 3), and CTX-M-15 (n = 3) genes were detected. TEM-1 and OXA-1 were associated with CTX-M in 3 and 2 isolates, respectively. In two E. coli isolates CMY-2 could be detected, where from one isolate displayed an overexpression of chromosomal AmpC as well. Among E. coli isolates the most common phylogenetic group was A (n = 11) and ST1683 (n = 5). In one E. coli of B2-ST131 the rfbO25b locus was detected. Three Enterobacter isolates were stably derepressed AmpC-producers. In five samples of the migratory population, PVL positive MRSA could be isolated. Two isolates were typed SCCmec IVa, spa type t127, and ST1. Three isolates carried a SCCmec type IVc, with spa type t852 and ST22. The highly significant difference of the occurrence of antibiotic resistance between the migratory population from eastern Europe compared to resident population in our study indicates that rooks may be good indicator species for the evaluation of environmental contamination with antibiotic resistant bacteria, especially due to their ecology, foraging behavior and differing migratory behavior.     

The spatial arrangement of germ line cells in ovarian follicles of the mutantdicephalic inDrosophila melanogaster

Summary The pattern of intercellular connections between germ line cells has been studied in follicles of the mutantdicephalic (dic), which possess nurse cell clusters at both poles. Staining of follicles with a fluorescent rhodamine conjugate of phalloidin reveals ring canals and cell membranes and thus allows us to reconstruct the spatial organization of the follicle. Each germ line cell can be identified by the pattern of cell-cell connections which reflect the mitotic history of individual cells in the 16-cell cluster. The results indicate that in both wild-type anddicephalic cystocyte clusters one of the two cells with four ring canals normally becomes the pro-oocyte. However, in some follicles (dicephalic and wild-type) oocytes were found with fewer or more than four ring canals. Indic follicles, one or several nurse cells may become disconnected from the other cells during oocyte growth at stage 9–10. Such disconnected cells cannot later on empty their cytoplasm into the oocyte. This, in turn, might be of consequence for the determination of axial polarity of the embryo.     

Inhibition of apoptosis by calcium ionophores in IL-3-dependent bone marrow cells is dependent upon production of IL-4+.

Calcium ionophores inhibit apoptosis in the IL-3-dependent cell line BAF3 and maintain the cells in a viable noncycling state. In this report, an identical effect of ionophore was also demonstrated on the multipotent IL-3-dependent progenitor cell line FDCP-MIX and on the primary IL-3-dependent cell population that could be cultured from murine bone marrow. Inhibition of apoptosis required extracellular calcium and could be blocked by cyclosporin A. Nuclei from IL-3-dependent cells were found to lack a calcium-activatable nuclease that degrades chromatin in the linker region between nucleosomes, unlike the nuclei of lymphoid cells. The mechanism of action of calcium ionophore could be divided into two distinct steps. First, ionophore induced the production of a survival factor that stimulated DNA synthesis and was identified as IL-4. Second, ionophore inhibited the cell cycle of the various IL-3-dependent cells. IL-4 production could be inhibited by cyclosporin A and required extracellular calcium, whereas cell cycle arrest did not. This implied that factor production was the step that was necessary for inhibition of apoptosis and maintenance of cell viability. This was confirmed by the use of an anti-IL-4R antibody, which blocked the inhibition of apoptosis induced by calcium ionophores.     

Effect of Feed Restriction on Performance and Postprandial Nutrient Metabolism in Pigs Co-Infected with Mycoplasma hyopneumoniae and Swine Influenza Virus

As nutritional status and inflammation are strongly connected, feeding and nutritional strategies could be effective to improve the ability of pigs to cope with disease. The aims of this study were to investigate the impact of a feed restriction on the ability of pigs to resist and be tolerant to a coinfection with Mycoplasma hyopneumoniae (Mhp) and the European H1N1 swine influenza virus, and the consequences for nutrient metabolism, with a focus on amino acids. Two groups of specific pathogen-free pigs were inoculated with Mhp and H1N1 21 days apart. One group was fed ad libitum, the other group was subjected to a two-week 40% feed restriction starting one week before H1N1 infection. The two respective mock control groups were included. Three days post-H1N1 infection, 200 g of feed was given to pigs previously fasted overnight and serial blood samples were taken over 4 hours to measure plasma nutrient concentrations. Throughout the study, clinical signs were observed and pathogens were detected in nasal swabs and lung tissues. Feed-restricted pigs presented shorter hyperthermia and a positive mean weight gain over the 3 days post-H1N1 infection whereas animals fed ad libitum lost weight. Both infection and feed restriction reduced postprandial glucose concentrations, indicating changes in glucose metabolism. Post-prandial plasma concentrations of the essential amino acids histidine, arginine and threonine were lower in co-infected pigs suggesting a greater use of those amino acids for metabolic purposes associated with the immune response. Altogether, these results indicate that modifying feeding practices could help to prepare animals to overcome an influenza infection. Connections with metabolism changes are discussed.     

Photolabeling of brain membrane proteins by lysergic acid diethylamide

³H-Lysergic acid diethylamide (³H-LSD) is irreversibly incorporated into bovine caudate membranes during ultraviolet light illumination. The incorporated radioligand apparently forms a covalent bond with a sub-population of the membrane proteins. Although the photolabeling pattern differs significantly from the Coomassie blue staining pattern on SDS gels, the photolabeling is apparently not specific for LSD binding sites associated with neurotransmitter receptors. ³H-LSD photolabeling can occur during prolonged exposure of membrane samples to room lighting and thus may introduce artifacts into receptor binding assays.     

Intensive RNAi with lentiviral vectors in mammalian cells

RNAi is a powerful technology for analyzing gene function in human cells. However, its utility can be compromised by inadequate knockdown of the target mRNA or by interpretation of effects without rigorous controls. We review lentiviral vector-based methods that enable transient or stable knockdowns to trace mRNA levels in human CD4+ T cell lines and other targets. Critical controls are reviewed, including rescue of the pre-knockdown phenotype by re-expression of the targeted gene. The time from thinking about a potential knockdown target to analysis of phenotypes can be as short as a few weeks.     

Solubility characteristics of Micrococcus lysodeikticus membrane components in detergents and chaotropic salts analyzed by immunoelectrophoresis

In order to evaluate the effectiveness and selectivity of various reagents in the solubilization of bacterial membranes, membranes of Micrococcus lysodeikticus were treated with detergents and chaotropic agents. The composition of the extracts so obtained was analyzed by rocket and two-dimensional immunoelectrophoretic techniques. Recovery of succinate-, malate-, and reduced nicotinamide adenine dinucleotide- (NADH) dehydrogenases, ATPase, succinylated lipomannan and cytochromes in the extracts was measured. Treatment with a variety of non-denaturing detergents produced extracts that were generally qualitatively uniform although quantitative differences were observed. The degree of extraction of various components was correlated with the hydrophile-lipophile balance. Several chaotropic agents were also evaluated as reagents for membrane solubilization. These agents were less effective in extraction of bulk protein, but produced extracts enriched in some membrane components.