ABSTRACT
The antibiotic 2,4-diacetylphoroglucinol (2,4-DAPG), produced by the Gram-negative rod-shaped bacterium Pseudomonas fluorescens 2P24, is active against various soil-borne bacterial and fungal pathogens that cause plant diseases. Biosynthesis of 2,4-DAPG is controlled by regulating expression of the phlACBD operon at the post-transcriptional level. The phlG gene is located between the phlF and phlH genes, upstream of the phlACBD biosynthetic operon. Herein, we cloned the phlG gene, generated a phlG deletion mutant, and investigated its regulatory role in 2,4-DAPG biosynthesis. The results showed that deletion of phlG had no effect on the biosynthesis of 2,4-DAPG, but it affected conversion of 2,4-DAPG to its precursor monoacetylphloroglucinol (MAPG). The global regulatory factor encoded by gacS positively regulated expression of phlG, while rsmE negatively regulated its expression. Deleting phlG did not alter the ability of the bacterium to colonise plants or promote plant growth. These results suggest that phlG collaborates with other factors to regulate production of the antibiotic 2,4-DAPG in P. fluorescens 2P24.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacterial Proteins/metabolism , Phloroglucinol/analogs & derivatives , Plant Diseases/immunology , Pseudomonas fluorescens/growth & development , Triticum/growth & development , Bacterial Proteins/genetics , Phloroglucinol/metabolism , Plant Diseases/microbiology , Pseudomonas fluorescens/metabolism , Triticum/drug effects , Triticum/microbiologyABSTRACT
Ischemic edema can alter the structure and permeability of the blood-brain barrier. Recent studies have reported that progesterone reduces cerebral edema after cerebral ischemia. However, the underlying mechanism of this effect has not yet been elucidated. In the present study, progesterone effectively reduced Evans blue extravasation in the ischemic penumbra, but not in the ischemic core, 48 hours after cerebral ischemia in rats. Progesterone also inhibited the down-regulation of gene and protein levels of occludin and zonula occludens-1 in the penumbra. These results indicate that progesterone may effectively inhibit the down-regulation of tight junctions, thereby maintaining the integrity of the blood-brain barrier and reducing cerebral edema.
ABSTRACT
The contents of aspirin and free salicylic acid in lysinipirine injection were determined by high performance liquid chromatography (HPLC). A Hypersil BDS C18 column was used with the mobile phase of methanol-water-acetic acid (35:65:3, volume ratio) and the detection wavelength of 280 nm. The average recoveries of aspirin and salicylic acid added were 99.27% (RSD = 0.8%) and 99.61%(RSD = 1.3%), respectively. The calibration curves had good linearity in the range of 0.028 g/L -0.141 mg/L and 0.77 mg/L -3.85 mg/L, and the correlation coefficients were 0.9999 and 0.9998 for aspirin and salicylic acid respectively.
