The transcription activator AtxA from Bacillus anthracis was employed for developing a tight-control, high-level, modulable and stationary-phase-specific transcription activity in Escherichia coli.

The strong transcriptional activity of the virulent gene pagA in Bacillus anthracis has been proven to be anthrax toxin activator (AtxA)-regulated. However, the obscure pagA transcription mechanism hinders practical applications of this strong promoter. In this study, a 509-bp DNA fragment [termed 509sequence, (-508)-(+1) relative to the P2 transcription start site] was cloned upstream of rbs-GFPuv as pTOL02B to elucidate the AtxA-regulated transcription. The 509sequence was dissected into the -10 sequence, -35 sequence, ATrich tract, SLI/SLII and upstream site. In conjunction with the heterologous co-expression of AtxA (under the control of the T7 promoter), the -10 sequence (TATACT) was sufficient for the AtxA-regulated transcription. Integration of pTOL02F + pTOLAtxA as pTOL03F showed that the AtxA-regulated transcription exhibited a strong specific fluorescence intensity/common analytical chemistry term (OD600) of 40 597 ± 446 and an induction/repression ratio of 122. An improved induction/repression ratio of 276 was achieved by cultivating Escherichia coli/pTOL03F in M9 minimal medium. The newly developed promoter system termed PAtxA consists of AtxA, the -10 sequence and Escherichia RNA polymerase. These three elements synergistically and cooperatively formed a previously undiscovered transcription system, which exhibited a tight-control, high-level, modulable and stationary-phase-specific transcription. The PAtxA was used for phaCAB expression for the stationary-phase polyhydroxybutyrate production, and the results showed that a PHB yield, content and titer of 0.20 ± 0.27 g/g-glucose, 68 ± 11% and 1.5 ± 0.4 g/l can be obtained. The positive inducible PAtxA, in contrast to negative inducible, should be a useful tool to diversify the gene information flow in synthetic biology. Graphical Abstract.

Effect of minimally invasive repair of pectus excavatum on postoperative chest flatness, cardiopulmonary function, and bone metabolism indexes in children at different ages.

OBJECTIVE: To observe the effects of minimally invasive surgical repair of pectus excavatum (NUSS) on the degree of chest flatness, cardiopulmonary function, and bone metabolism indexes in children of various age groups. METHODS: In this retrospective study, 62 children with pectus excavatum admitted to our hospital were divided into two groups: group A (3-12 years old) and group B (>12 years old), with 31 cases in each group. All of them were treated with NUSS. The treatment effectiveness, perioperative indexes (operation time, blood loss, ground time, and hospitalization time), degree of chest flatness, cardiopulmonary function, bone metabolism indicators, and complications were compared between the two groups. RESULTS: There was no significant difference between patients in the two groups in terms of operation time, blood loss, ground time, and hospitalization time (all P>0.05). The overall response rate to treatment in group A (93.55%) was higher than that of group B (70.97%; P<0.05). Three months after the operation, the chest flatness as well as serum alkaline phosphatase and its bone isoform levels in both groups were decreased, while left ventricular ejection fraction, cardiac index, stroke volume, FEV1, and peak expiratory flow levels were increased compared to before the operation, and the improvement in the above indicators of group A was better than Group B (all P<0.05). There was no significant difference in the incidence of complications between the two groups (16.13% vs. 9.68%; P>0.05). CONCLUSION: NUSS surgery can achieve satisfactory results in treating children with pectus excavatum at different ages. However, in a certain age range, a younger age indicates a better effect. NUSS procedure effectively improves postoperative flat chest, cardiopulmonary function, and bone metabolism indexes.