Neural stem and progenitor cell (NSPC) fate is strongly influenced by mechanotransduction as modulation of substrate stiffness affects lineage choice. Other types of mechanical stimuli, such as stretch (tensile strain), occur during CNS development and trauma, but their consequences for NSPC differentiation have not been reported. We delivered a 10% static equibiaxial stretch to NSPCs and examined effects on differentiation. We found static stretch specifically impacts NSPC differentiation into oligodendrocytes, but not neurons or astrocytes, and this effect is dependent on particular extracellular matrix (ECM)-integrin linkages. Generation of oligodendrocytes from NSPCs was reduced on laminin, an outcome likely mediated by the α6 laminin-binding integrin, whereas similar effects were not observed for NSPCs on fibronectin. Our data demonstrate a direct role for tensile strain in dictating the lineage choice of NSPCs and indicate the dependence of this phenomenon on specific substrate materials, which should be taken into account for the design of biomaterials for NSPC transplantation.

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Corrosion inhibition of SAE 1018 steel by pure-culture biofilms of Pseudomonas fragi and Escherichia coli DH5 alpha has been evaluated in complex Luria-Bertani medium, seawater-mimicking medium, and modified Baar's medium at 30 degrees C. In batch cultures, both bacteria inhibited corrosion three to six fold compared to sterile controls, and the corrosion was comparable to that observed in anaerobic sterile media. To corroborate this result, a continuous reactor and electrochemical impedance spectroscopy were used to show that both P. fragi K and E. coli DH5 alpha decreased the corrosion rate by 4- to 40-fold as compared to sterile controls; this matched the decrease in corrosion found with sterile medium in the absence of oxygen and with E. coli DH5 alpha grown anaerobically. In addition, the requirement for live respiring cells was demonstrated by the increase in the corrosion rate that was observed upon killing the P. fragi K biofilm in continuous cultures, and it was shown that fermentation products do not cause an increase in corrosion. Hence, pure-culture biofilms inhibit corrosion of SAE 1018 steel by depleting oxygen at the metal surface.

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The sections in this article are Biofilm Formation Corrosion Promoting Mechanisms Sulfur, Sulfate and Thiosulfate Reduction Practical Aspects Sulfur/Sulfide Oxidation Metal‐oxidizing Bacteria Metal‐reducing Bacteria Acid‐producing Organisms Slime‐producing Bacteria Corrosion Inhibiting Mechanisms