Micropatterning of ECM proteins on glass substrates to regulate cell attachment and proliferation

Micropatterning is becoming a powerful tool for studying cells in vitro. This method not only uses very small amount of material but also mimic the microenvironment structure present in living tissues better than flash cul-turing techniques. In previous studies using micropatterning of extracellular matrix proteins on glass surfaces, the rate of protein detachment from the surface was so high that the proteins and the cultivated cells detached after 3 three days of cell seeding. Here we optimized the glass surface modification method to fulfill the requirement of most in vitro studies. in our study we showed that the optimum time for glass surface modification reaction is 1.5 hr, and the cells could be tracked in vitro for over 15 days after cell seeding which is enough for the most in vitro studies. As a model, we cultivated HEK 293T and HepG2 cells on the collagen micro-patterns and showed that they have normal growth and morphology on these micropatterns. The HEK cells also transfected with pmaxCFP plasmid vector to show that the cells on collagen micropatterns could also used in trans-fection studies. Taking these together, this novel method is promising for efficient cell culture studies on micropatterened surfaces in the future

Isolation and identification of anionic surfactant degrading bacteria from activated sludge

Linear alkylbenzene sulfonate [LABS] is an anionic surfactant widely used all over the world. They will eventually end-up and accumulate in household or industrial sewage. Due to their high foaming capabilities which can cause numerous problems in sewage treatment facilities as well as direct toxic effects on many different organisms in ecosystem; they are generally considered as serious pollutants. Many reports have indicated that common bacteria can readily degrade LABS. In this survey, two different bacteria were isolated from Tehran municipal active sludge that showed the ability to degrade LABS rapidly and actively upon using it as their sole source of carbon. Biochemical tests as well as 16S rRNA gene sequencing performed. Results have indicated the two isolates to be Acinetobacter johnsoni and Pseudomonas beteli. After experiments to optimize the pH and temperature for growth of the two bacterial isolates, the extent of LABS, utilization was evaluated by HPLC method. The Pseudomonas beteli and Acinetobacter johnsoni isolates were able to degrade 96.4% and 97.2% of the original LABS levels after 10 days of growth, respectively. Mixed culture of the two isolates did not significantly increase LABS utilization [97.6%]. Our study showed the ability of two isolated steains to rapidly biodegrade LABS under aerobic conditions

Physiological and morphological changes of recombinant E. coli during over-expression of human interferon-gamma in HCDC

The objective of this research was to investigate the influence of the over-expression of recombinant interferon-gamma during high cell density cultivation on cellular characteristics of recombinant E. coli. Batch and fedbatch culture techniques were employed to grow Escherichia coli BL21 for production of human gamma-interferon in pET expression system. Final cell densities in batch and fed-batch cultivations were approximately 7 and 127 g cell dry weight [CDW] l[-1], respectively. In both systems, specific growth rate decreased and reached zero, 4 hours after the induction. It was found that high cell density and overexpression of interferon-gamma had no substantial effects on cell lysis and plasmid stability. Plasmid content of the cells was nearly similar and remained constant during the post-induction period in both batch and fed-batch cultures [60 mg plasmid per g[-1] CDW]. In both systems, time profiles of acetate and lactate production were similar, lactate concentration was lower than that of acetate and the concentrations of both were lower than the inhibitory level. Maximum extracellular cAMP concentration occurred at the start of induction in fedbatch culture and was higher than the amount produced during the batch process. The size of E. coli cells reduced significantly as cell density increased and the morphology of the cells in high cell density changed from the usual rod shape to spherical, while the expression of interferon-gamma remained almost constant