Genetically-engineered mouse models for pancreatic cancer:Advances and current limitations

Recently,there has been significant progress in the development of genetically-engineered mouse(GEM)models.By introducing genetic alterations and/or signaling alterations of human pancreatic cancer into the mouse pancreas,animal models can recapitulate human disease.Pancreas epithelium-specific endogenous Kras activation develops murine pancreatic intraepithelial neoplasia(mPanIN).Additional inactivation of p16,p53,or transforming growth factor-βsignaling,in the context of Kras activation,dramatically accelerates mPanIN progression to invasive pancreatic ductal adenocarcinoma(PDAC)with abundant stromal expansion and marked fibrosis(desmoplasia).The autochthonous cancer models retain tumor progression processes from pre-cancer to cancer as well as the intact tumor microenvironment,which is superior to xenograft models,although there are some limitations and differences from human PDAC.By fully studying GEM models,we can understand the mechanisms of PDAC formation and progression more precisely,which will lead us to a breakthrough in novel diagnostic and therapeutic methods as well as identification of the origin of PDAC.

Cell-based biosensors:Towards the development of cellular monitoring

Cell-based biosensors (CBBs), a research hot-spot of biosensors, which treat living cells as sensing elements, can detect the functional information of biologically active analytes. They characterize with high sensitivity, excellent selectivity and rapid response, and have been applied in many fields, such as biomedicine, environmental monitoring and pharmaceutical screening. Recently cell-cultured technology, silicon microfabrication technology and genetic technology have promoted exploration of CBBs dramatically. To elucidate the novel research findings and applications of cell- based biosensors, this paper summarizes various research approaches, presents some challenges and proposes the research trends.

Enhanced atrazine removal using membrane bioreactor bioaugmented with genetically engineered microorganism

Bioaugmentation with genetically engineered microorganisms(GEMs)in a membrane bioreactor(MBR)for enhanced removal of recalcitrant pollutants was explored.An atrazine-degrading genetically engineered microorganism(GEM)with green fluorescent protein was inoculated into an MBR and the effects of such a bioaugmentation strategy on atrazine removal were investigated.The results show that atrazine removal was improved greatly in the bioaugmented MBR compared with a control system.After a start-up period of 6 days,average 94.7%of atrazine was removed in bioaugmentedMBRwhen atrazine concentration of influent was 14.5 mg/L.The volumetric removal rates increased linearly followed by atrazine loading increase and the maximum was 65.5 mg/(L?d).No negative effects were found on COD removal although carbon oxidation activity of bioaugmented sludge was lower than that of common sludge.After inoculation,adsorption to sludge flocs was favorable for GEM survival.The GEM population size initially decreased shortly and then was kept constant at about 104–105 CFU/mL.Predation of micro-organisms played an important role in the decay of the GEM population.GEM leakage from MBR was less than 102 CFU/mL initially and was then undetectable.In contrast,in a conventionally activated sludge bioreactor(CAS),sludge bulking occurred possibly due to atrazine exposure,resulting in bioaugmentation failure and serious GEM leakage.So MBR was superior to CAS in atrazine bioaugmentation treatment using GEM.

A New Genetically Engineered Vaccine for Animal Growth Promotion

The chemically synthesized somatostatin (ss) gene was fused in phase with the 3′-end ofhepatitis B virus surface antigen (HBsAg) gene.The fusion gene HBs/ss was then recomhined into thegenome of vaccinia virus.This recombinant virus (w-HBs/ss) can express hybrid HBsAg/ss particles whichpresent ss determinants on their surfaces,thereby bearing a good immunogenicity.This new strategical vac-cine of ss can elicit the production of antibody capable of neutralizing ss in the plasma,and consequently en-hance the growth of animals.