ABSTRACT
Ginsenoside Rh_2 is a rare active ingredient in precious Chinese medicinal materials such as Ginseng Radix et Rhizoma, Notoginseng Radix et Rhizoma, and Panacis Quinquefolii Radix. It has important pharmacological activities such as anti-cancer and improving human immunity. However, due to the extremely low content of ginsenoside Rh_2 in the source plants, the traditional way of obtaining it has limitations. This study intended to apply synthetic biological technology to develop a cell factory of Saccharomyces cerevisiae to produce Rh_2 by low-cost fermentation. First, we used the high protopanaxadiol(PPD)-yielding strain LPTA as the chassis strain, and inserted the Panax notoginseng enzyme gene Pn1-31, together with yeast UDP-glucose supply module genes[phosphoglucose mutase 1(PGM1), α-phosphoglucose mutase(PGM2), and uridine diphosphate glucose pyrophosphorylase(UGP1)], into the EGH1 locus of yeast chromosome. The engineered strain LPTA-RH2 produced 17.10 mg·g~(-1) ginsenoside Rh_2. This strain had low yield of Rh_2 while accumulated much precursor PPD, which severely restricted the application of this strain. In order to further improve the production of ginsenoside Rh_2, we strengthened the UDP glucose supply module and ginsenoside Rh_2 synthesis module by engineered strain LPTA-RH2-T. The shaking flask yield of ginsenoside Rh_2 was increased to 36.26 mg·g~(-1), which accounted for 3.63% of the dry weight of yeast cells. Compared with those of the original strain LPTA-RH2, the final production and the conversion efficiency of Rh_2 increased by 112.11% and 65.14%, respectively. This study provides an important basis for further obtaining the industrial-grade cell factory for the production of ginsenoside Rh_2.
Subject(s)
Humans , Fermentation , Ginsenosides , Panax/genetics , Panax notoginseng , Saccharomyces cerevisiae/genetics , Uridine Diphosphate GlucoseABSTRACT
<p><b>OBJECTIVE</b>To evaluate pathologically the effect of the single or combined application of UDP-glucose, GDNF and memantine on the improvement of white matter injury in neonatal rats with periventricular leukomalacia (PVL) under light and electron microscopy.</p><p><b>METHODS</b>A five-day-old neonatal rat model for PVL was established by ligation of the lateral common carotid artery following 120-minute hypoxia. Rats were randomly divided into six groups (30 rats in each group): sham-operated, PVL, UDP-glucose (UDP-glucose 2000 mg/kg intraperitoneally after PVL), GDNF (GDNF 100 μg/kg intracerebrally after PVL), tmemantine (memantine 20 mg/kg intraperitoneally after PVL), and a combination administration of three drugs (UDP-glucose, GDNF and memantine). The rats were sacrificed 7 or 21 days after PVL for assessment of pathological changes in the white matter under both light and electron microscopy. The number and thickness of the myelin sheath in the white matter were measured under electron microscopy, and both of pathological grading and scoring were undertaken under light microscopy.</p><p><b>RESULTS</b>There was rare and sparse myelinogenesis with a loose arrangement of nerve fibers in the white matter under electron microscopy in the PVL group at 7 and 21 days after PVL. The number and thickness of the myelin sheath in the PVL group were significantly less than in the sham-operated, UDP-glucose, GDNF, memantine and combination administration groups (P<0.01). The results of pathological grading of white matter under light microscopy showed that all rats in the PVL group manifested either mild injury (38%-50%) or severe injury (50%-62%) at 7 and 21 days after PVL. The majority of rats (50%-88%) in the four drug administration groups had normal white matter at 7 and 21 days after PVL. The pathological scores at 7 and 21 days after PVL in the PVL group were the highest, and they were significantly higher than in the other five groups (P<0.05).</p><p><b>CONCLUSIONS</b>The single or combined application of UDP-glucose, GDNF and memantine may significantly improve pathological changes in the white matter of rats with PVL. The favorable effect is inferred to be closely correlated with the improvement of brain microenvironment and the enhancement of nerve regeneration promoted by the three drugs.</p>
Subject(s)
Animals , Female , Humans , Infant, Newborn , Male , Rats , Brain Ischemia , Drug Therapy , Pathology , Cerebral Ventricles , Pathology , Glial Cell Line-Derived Neurotrophic Factor , Therapeutic Uses , Leukomalacia, Periventricular , Drug Therapy , Memantine , Therapeutic Uses , Microscopy, Electron , Rats, Sprague-Dawley , Uridine Diphosphate Glucose , Therapeutic UsesABSTRACT
In plants, UDP-L-rhamnose is one of the major components of cell wall skeleton. Rhamnose synthase plays a key role in rhamnose synthesis which converts UDP-D-glucose into UDP-L-rhamnose in plants. In this study, we isolated the 1058 bp promoter region of the rhamnose synthase gene AtRHM1 from Arabidopsis genome by PCR, and created a series of deletions of AtRHM1 promoter ranging from -931 bp to +127 bp. The full length of the promoter and its deletion derivatives fused with GUS reporter gene were introduced into wild-type Arabidopsis by Agrobacterium-mediated transformation respectively. The GUS staining and GUS enzymatic activity assay showed that the expression of AtRHM1 is induced at transcriptional level by glucose and the regulatory elements involved in the glucose response are located in the region of -931 bp - -752 bp which contains three G-box motifs.