Hypoxia-stimulated membrane trafficking requires T-plastin.

AIM: Traffic between the plasma membrane and the endomembrane compartments is an essential feature of eukaryotic cells. The secretory pathway sends cargoes from biosynthetic compartments to the plasma membrane. This is counterbalanced by a retrograde endocytic route and is essential for cell homoeostasis. Cells need to adapt rapidly to environmental challenges such as the reduction of pO2 which, however, has not been analysed in relation to membrane trafficking in detail. Therefore, we determined changes in the plasma membrane trafficking in normoxia, hypoxia, and after reoxygenation. METHODS: Membrane trafficking was analysed by using the bulk membrane endocytosis marker FM 1-43, the newly developed membrane probe mCLING, wheat germ agglutinin as well as fluorescently labelled cholera toxin subunit B. Additionally, the uptake of specific membrane proteins was determined. In parallel, a non-biased SILAC screen was performed to analyse the abundance of membrane proteins in normoxia and hypoxia. RESULTS: Membrane trafficking was increased in hypoxia and quickly reversed upon reoxygenation. This effect was independent of the hypoxia-inducible factor (HIF) system. Using SILAC technology, we identified that the actin-bundling protein T-plastin is recruited to the plasma membrane in hypoxia. By the use of T-plastin knockdown cells, we could show that T-plastin mediates the hypoxia-induced membrane trafficking, which was associated with an increased actin density in the cells as determined by electron microscopy. CONCLUSION: Membrane trafficking is highly dynamic upon hypoxia. This phenotype is quickly reversible upon reoxygenation, which suggests that this mechanism participates in the cellular adaptation to hypoxia.

[Furazolidone resistance of E. coli from chicken intestines after prophylactic treatment with bioptivet GB in animal feed]. / Furazolidonresistenz von E. coli aus dem Geflügeldarm nach prophylaktischer Gabe des Fütterungsarzneimittels bioptivet GB.

This study describes the influence of bioptivet GB on minimum inhibitory concentrations (MIC) for furazolidone of the intestinal E. coli flora of young broiler chickens after prophylactic treatment. From day 6 until day 15 one group of 50 birds received a diet containing 326 ppm furazolidone, another group of 75 birds served as non medicated control. Investigated E. coli had been isolated from cloacal swabs and from caecal contents. MIC of 1581 E. coli strains were determined by agar dilution test. MIC of furazolidone for the investigated strains ranged from 2 micrograms/ml to 64 micrograms/ml. For classification as "resistant" or "susceptible" limits of 16 micrograms/ml and 8 micrograms/ml respectively were used. Strains obtained from undosed birds mainly had MIC values of 4 micrograms/ml or 8 micrograms/ml, i.e. two or three times higher than MIC of E. coli ATCC 25 922, MIC values of 16 micrograms/ml or more were recorded only among isolates obtained from chickens which had received the drug. Administration of bioptivet GB resulted in a statistically significant increase in the average MIC. Statistically higher average MIC were recorded among isolates from cloacal swabs only during application of the drug. For strains from caecal contents, the effect became obvious only at the end of the experiment.