Novel therapeutic targets for post-traumatic stress disorder:endocannabinoid system / 中国病理生理杂志

Post-traumatic stress disorder (PTSD) is a kind of mental disorder that usually occurs after life-threatening and strong mental traumas .Clinical studies showed that the PTSD patients are 3 times more likely to have can-nabis as compared with the healthy people .The use of cannabinoids has a close relationship with the occurrence and clini-cal manifestations of PTSD .Experimental studies revealed that endocannabinoid ( eCB) signal alterations in animal models of PTSD influenced fear memory of the animals , suggesting a close correlation between the eCB system and the pathogenesis of PTSD.Given that the eCB system was reported to regulate affective states and participate in memory consolidation , re-trieval and extinction , targeting the eCB system may improve the emotional and cognitive features of PTSD , thereby holding out great promise for the development of novel approaches for clinical treatment of PTSD .

Gene cloning, expression and characterization of a novel phytase from Hafnia alvei / 生物工程学报

A gene appA encoding a novel phytase was firstly cloned from Hafnia alvei by PCR and sequenced. The gene was consisted of 1335 bp, encoding 444 amino acids. The calculated molecular weight of the mature APPA was about 45.2 kD. The gene appA was expressed in E. coli BL21 (DE3). Recombinant APPA was purified and its enzymatic properties were determined. The optimum pH for the enzyme was 4.5 and the optimum temperature was 60 degrees C. The pH stability of r-APPA is good, the relative phytase activity was above 80% after treated in buffers of pH 2.0-10.0. The specific activity of r-APPA is 356.7 U/mg, and the Km value was 0.49 mmol/L and Vmax of 238 U/mg. The enzyme showed resistance to pepsin and trypsin treatment.

Improving phytase expression by increasing the gene copy number of appA-m in Pichia pastoris / 生物工程学报

In order to improve the fermentation potency of phytase in recombinant host and decrease the production cost, the pichia expression vector pGAPZalpha-A was modified by introduction of an AOX1 promoter from vector pPIC9 and the resulted vector pAOXZalpha is an methanol induced vector. After that, a phytase gene appA-m was cloned into pAOXZalpha to construct the recombinant vector pAOXZalpha-appA-m. The recombinant Pichia pastoris 74#, which already contains one copy of appA-m and its fermentation potency exceeded 7.5 x 10(6) IU/mL, was used as the host strain for the transformation of pAOXZalpha-appA-m. The Pichia pastoris transformants were gained by electroporation. PCR results indicated that the appA-m expression box has integrated into the genome of Pichia pastoris and the original construction of phytase gene has not changed. SDS-PAGE analysis revealed that phytase was overexpressed and secreted into the medium supernatant. Recombinants with high expression level were screened and used for fermentation. In 5L fermentor, the expression level of phytase protein achieved 4 mg/mL and the phytase activity (fermentation potency) exceeded 1.2 x 10(7) IU/mL, which was about 1.6-fold compared with that of the host strain 74#. Moreover, the improved recombinant Pichia pastoris is excellent at expression stability and heredity stability.