Optimization of UDP-glucose supply module and production of ginsenoside F1 in Saccharomyces cerevisiae / 中国中药杂志

Ginsenoside F1 is a rare ginsenoside in medicinal plants such as Panax ginseng,P. notogingseng and P. quinquefolius. It has strong pharmacological activities of anti-tumor,anti-oxidation and anti-aging. In order to directly produce ginsenoside F1 by using inexpensive raw materials such as glucose,we integrated the codon-optimized P.ginseng dammarenediol-Ⅱ synthase(Syn Pg DDS),P.ginseng protopanaxadiol synthase(Syn Pg PPDS),P. ginseng protopanaxatriol synthase(Syn Pg PPTS) genes and Arabidopsis thaliana cytochrome P450 reductase(At CPR1) gene into triterpene chassis strain BY-T3. The transformant BY-PPT can produce protopanaxatriol. Then we integrated the Sacchromyces cerevisiae phosphoglucomutase 1(PGM1),phosphoglucomutase 2(PGM2) and UDP-glucose pyrophosphorylase 1(UGP1) genes into chassis strain BY-PPT. The UDP-glucose supply module increased UDP-glucose production by 8. 65 times and eventually reached to 44. 30 mg·L-1 while confirmed in the transformant BY-PPT-GM. Next,we integrated the UDPglucosyltransferase Pg3-29 gene which can catalyze protopanaxatriol to produce ginsenoside F1 into chassis strain BY-PPT-GM. The transformant BY-F1 produced a small amount of ginsenoside F1 which was measured as 0. 5 mg·L-1. After the fermentation process was optimized,the titer of ginsenoside F1 could be increased by 900 times to 450. 5 mg·L-1. The high-efficiency UDP-glucose supply module in this study can provide reference for the construction of cell factories for production of saponin,and provide an important basis for further obtaining high-yield ginsenoside yeast cells.

Construction of efficient yeast cell factories for production of ginsenosides precursor dammarenediol-II / 药学学报

Dammarenediol-Ⅱ is an important precursor in the biosynthesis pathway of ginsenosides which are the main active components of Panax quinquefolius and Panax ginseng. For constructing a dammarenediol- Ⅱ-producing cell factory, the triterpenoid precursors of yeast are improved significantly by the modular pathway engineering strategy on the basis of an MVA optimized strain. The strain overexpressing Salvia miltiorrhiza SmFPS and Arabidopsis thaliana AtSQS2 could yield 67.4 mg·g−1 squalene, accounting for about 6.74% of cell dry weight. In our further work, an Arabidopsis thaliana 2,3-oxidosqualene synthase AtSQE2 was found to be able to increase the downstream lanosterol yield by 22-fold, reaching 47.9 mg·g−1. Then, regulating dammarenediol-Ⅱ synthase gene expression, using anti-sense RNA technology for regulation of ERG7 in the ergosterol pathway, and optimizing fermentation process were successively performed. Finally, the synthesis flux of triterpenes was increased to 10 g·L−1 for the first time, and we constructed an efficient cell factory that can produce 15 g·L−1 dammarenediol-Ⅱ, which lays a solid foundation of industrial synthesis of dammarane-type ginsenosides.

A study of the impact of occupational stress on sleep disorders among male freight train dispatchers / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To explore tentatively the impact of occupational stress on sleep disorders.</p><p><b>METHODS</b>ninety three male freight train dispatchers participated in this study (response rate 80.87%). Sleep disorders, occupational stressors, personalities, and occupational strain response were measured with questionnaires.</p><p><b>RESULTS</b>Workers with high psychological demands, job stressors,depressive symptoms,physical symptoms, daily life stress, work locus of control had higher sleep disorders scores than their counterparts (P < 0.01 or P < 0.05), workers with high job control had lower sleep disorders scores than their counterparts (P < 0.05). Sleep disorders were positively related to psychological demands, job stressors, depressive symptoms, physical symptoms, daily life stress, state-anxiety, strait-anxiety, and susceptibility to stress (P < 0.01 or P < 0.05), but negatively to job control and mental health (P < 0.05). Low job control, depressive symptoms, daily life stress and meaningless job were risk factors of sleep disorders.</p><p><b>CONCLUSION</b>The sleep disorders are associated with some aspects of occupational stress among male freight train dispatchers.</p>