A Theory for Valiant's Matchcircuits (Extended Abstract)

The computational function of a matchgate is represented by its character matrix. In this article, we show that all nonsingular character matrices are closed under matrix inverse operation, so that for every $k$, the nonsingular character matrices of $k$-bit matchgates form a group, extending the recent work of Cai and Choudhary (2006) of the same result for the case of $k=2$, and that the single and the two-bit matchgates are universal for matchcircuits, answering a question of Valiant (2002)

A strategy of gene overexpression based on tandem repetitive promoters in Escherichia coli

<p>Abstract</p> <p>Background</p> <p>For metabolic engineering, many rate-limiting steps may exist in the pathways of accumulating the target metabolites. Increasing copy number of the desired genes in these pathways is a general method to solve the problem, for example, the employment of the multi-copy plasmid-based expression system. However, this method may bring genetic instability, structural instability and metabolic burden to the host, while integrating of the desired gene into the chromosome may cause inadequate transcription or expression. In this study, we developed a strategy for obtaining gene overexpression by engineering promoter clusters consisted of multiple core-<it>tac-</it>promoters (MCP<it>tac</it>s) in tandem.</p> <p>Results</p> <p>Through a uniquely designed <it>in vitro </it>assembling process, a series of promoter clusters were constructed. The transcription strength of these promoter clusters showed a stepwise enhancement with the increase of tandem repeats number until it reached the critical value of five. Application of the MCP<it>tac</it>s promoter clusters in polyhydroxybutyrate (PHB) production proved that it was efficient. Integration of the <it>phaCAB </it>genes with the 5CP<it>tac</it>s promoter cluster resulted in an engineered <it>E.coli </it>that can accumulate 23.7% PHB of the cell dry weight in batch cultivation.</p> <p>Conclusions</p> <p>The transcription strength of the MCP<it>tac</it>s promoter cluster can be greatly improved by increasing the tandem repeats number of the core-<it>tac</it>-promoter. By integrating the desired gene together with the MCP<it>tac</it>s promoter cluster into the chromosome of <it>E. coli</it>, we can achieve high and stale overexpression with only a small size. This strategy has an application potential in many fields and can be extended to other bacteria.</p

Coping and compromise:a qualitative study of how primary health care providers respond to health reform in China

Abstract Background Health reform in China since 2009 has emphasized basic public health services to enhance the function of Community Health Services as a primary health care facility. A variety of studies have documented these efforts, and the challenges these have faced, yet up to now the experience of primary health care (PHC) providers in terms of how they have coped with these changes remains underdeveloped. Despite the abundant literature on psychological coping processes and mechanisms, the application of coping research within the context of human resources for health remains yet to be explored. This research aims to understand how PHC providers coped with the new primary health care model and the job characteristics brought about by these changes. Methods Semi-structured interviews with primary health care workers were conducted in Jinan city of Shandong province in China. A maximum variation sampling method selected 30 PHC providers from different specialties. Thematic analysis was used drawing on a synthesis of theories related to the Job Demands-Resources model, work adjustment, and the model of exit, voice, loyalty and neglect to understand PHC providers’ coping strategies. Results Our interviews identified that the new model of primary health care significantly affected the nature of primary health work and triggered a range of PHC providers’ coping processes. The results found that health workers perceived their job as less intensive than hospital medical work but often more trivial, characterized by heavy workload, blurred job description, unsatisfactory income, and a lack of professional development. However, close relationship with community and low work pressure were satisfactory. PHC providers’ processing of job demands and resources displayed two ways of interaction: aggravation and alleviation. Processing of job demands and resources led to three coping strategies: exit, passive loyalty, and compromise with new roles and functions. Conclusions Primary health care providers employed coping strategies of exit, passive loyalty, and compromise to deal with changes in primary health work. In light of these findings, our paper concludes that it is necessary for the policymakers to provide further job resources for CHS, and involve health workers in policy-making. The introduction of particular professional training opportunities to support job role orientation for PHC providers is advocated

De novo production of resveratrol from glucose or ethanol by engineered <i>Saccharomyces cerevisiae</i>

Resveratrol is a natural antioxidant compound, used as food supplement and cosmetic ingredient. Microbial production of resveratrol has until now been achieved by supplementation of expensive substrates, p-coumaric acid or aromatic amino acids. Here we engineered the yeast Saccharomyces cerevisiae to produce resveratrol directly from glucose or ethanol via tyrosine intermediate. First we introduced the biosynthetic pathway, consisting of tyrosine ammonia-lyase from Herpetosiphon aurantiacus, 4-coumaryl-CoA ligase from Arabidopsis thaliana and resveratrol synthase from Vitis vinifera, and obtained 2.73±0.05mgL-1 resveratrol from glucose. Then we over-expressed feedback-insensitive alleles of ARO4 encoding 3-deoxy-D-arabino-heptulosonate-7-phosphate and ARO7 encoding chorismate mutase, resulting in production of 4.85±0.31mgL-1 resveratrol from glucose as the sole carbon source. Next we improved the supply of the precursor malonyl-CoA by over-expressing a post-translational de-regulated version of the acetyl-CoA carboxylase encoding gene ACC1; this strategy further increased resveratrol production to 6.39±0.03mgL-1. Subsequently, we improved the strain by performing multiple-integration of pathway genes resulting in resveratrol production of 235.57±7.00mgL-1. Finally, fed-batch fermentation of the final strain with glucose or ethanol as carbon source resulted in a resveratrol titer of 415.65 and 531.41mgL-1, respectively

Di-(2-ethylhexyl) phthalate induces precocious puberty in adolescent female rats

Objective(s): Nowadays, Di-(2-ethylhexyl) phthalate (DEHP) is widely used in different kinds of commercial products as a plasticizer. Previous studies have revealed that exposures to DEHP could be associated with precocious puberty in teenagers, but the exact mechanism is yet to be known. Materials and Methods: In this study, 48 prepubertal Wistar female rats were randomly apportioned into 4 groups and orally treated with 0, 250, 500, and 1000 mg/kg/d DEHP from postnatal day 21 up to 4 weeks. Subsequently, we examined the indicators related to the initiation of sexual development. Results: DEHP was able to shorten the vaginal opening time and prolong the estrous cycles of female rats. IGF-1 expression was significantly upregulated by 1000 mg/kg/d DEHP in the hypothalamus, and the hypothalamic, as well as serum levels of GH, were also upregulated by DEHP. It also caused decrements in serum levels of FSH, LH, and T and the increment in level of progesterone. Meanwhile, DEHP was able to exert its effect on the mRNA and protein expression levels of Kiss-1, GPR54, and GnRH in the hypothalamus in pubertal female rats. Conclusion: These findings are revealing that DEHP exposure more likely causes imbalances of hypothalamus functioning in pubertal female rats and thus induces precautious puberty in these animals