No abstract

To rapidly assess early inflammatory cell responses provoked by biomaterials in the full complexity of the living organism, we developed a zebrafish embryo model which allows real time analysis of these responses to biomaterial microspheres. Fluorescently labeled microspheres with different properties were injected into embryos of selected transgenic zebrafish lines expressing distinct fluorescent proteins in their neutrophils and macrophages. Recruitment of leukocytes and their interactions with microspheres were monitored using fluorescence microscopy. We developed a novel method using ImageJ and the plugin ObjectJ project file "Zebrafish-Immunotest" for rapid and semi-automated fluorescence quantification of the cellular responses. In the embryo model we observed an ordered inflammatory cell response to polystyrene and poly (e-caprolactone) microspheres, similar to that described for mammalian animal models. The responses were characterized by an early infiltration of neutrophils followed by macrophages, and subsequent differentially timed migration of these cells away from the microspheres. The size of microspheres (10 and 15 mm) did not influence the cellular responses. Poly (e-caprolactone) microspheres provoked a stronger infiltration of neutrophils and macrophages than polystyrene microspheres did. Our study shows the potential usefulness of zebrafish embryos for in vivo evaluation of biomaterial-associated inflammatory cell responses.

A novel bacterial strain Klebsiella sp. Y1 was isolated from the soil of a constructed wetland, and it was identified based on the 16S rDNA sequence analysis. The co-metabolic degradation of nicosulfuron with glucose by Klebsiella sp. Y1 was investigated. The response surface methodology analysis indicated that the optimal pH and temperature were 7.0 and 35 °C, respectively, for the degradation of nicosulfuron. Under the optimal conditions, the degradation of nicosulfuron fitted Haldane kinetics model well. The removal of nicosulfuron was triggered by the acidification of glucose, which accelerated the hydrolysis of nicosulfuron. Then, the C-N bond of the sulfonylurea bridge was attacked and cleaved. Finally, the detected intermediate 2-amino-4,6-dimethoxypyrimidine was further biodegraded.