Twenty-seven antarctic bacteria producing extracellular polysaccharide （EPS） were selected from 57 strains by staining technology. The effects of major environmental factors on the growth and EPS production of Pseud...Twenty-seven antarctic bacteria producing extracellular polysaccharide （EPS） were selected from 57 strains by staining technology. The effects of major environmental factors on the growth and EPS production of Pseudoalteromonas sp. S - 15 - 13 were investigated, and the EPS was separated and purified for characterization analysis. The results showed that the optimal conditions for the EPS production were culture period, 56 h; growth temperature, 8 ℃ ; carbon source, 1.0% glucose; NaCI concentration, 3.0% ; pH 6.0 - 7.0. The EPS was purified by cold ethanol precipitation, proteins removal, ion exchange chromatography and gel chromatography technology. The molecular mass of EPS - H was 62 kDa as determined by the high performance gel permeation chromatography. Its sugar composition was a homopolymer of marmose analyzed by gas chromatograph spectroscopy. After repeated freezing and thawing of the bacteria hiomass in the presence of EPS, the bacterial growth was much higher than that observed after freezing in the absence of EPS and the difference augmented with the increase of freeze-thaw cycles. It is hypothesized that the adaptation of Pseudoalteromonas sp. S- 15 - 13 to the antarctic marine conditions, characterized by low temperature, high NaCl concentration and repeated freeze-thaw cycles, might be related to the EPS production ability.展开更多
New highly stereoregular 2, 3 -di- O-(p-azidobenzyl )-(1 →5 ) - α-D -ribofuranan was synthesized byselective ring-opening polymerization of 1, 4-anhydro-2, 3 - di-O -(p-azidobenzyl )-α-D -ribopyranose(ADABR) using ...New highly stereoregular 2, 3 -di- O-(p-azidobenzyl )-(1 →5 ) - α-D -ribofuranan was synthesized byselective ring-opening polymerization of 1, 4-anhydro-2, 3 - di-O -(p-azidobenzyl )-α-D -ribopyranose(ADABR) using phosphorus pentafluoride or tin tetrachloride as catalyst at low temperature indichloromethane. The monomer was obtained by the reaction of p - bromomethyl -phenyleneazide with 1, 4 -anhydro-α-D-ribose in DMF. The structure of poly(ADANR) was identified by specific rotation and ^(13)C-NMR spectroscopy. Acid chloride-AgCl_4 complex catalyst such as CH_2=C(CH_3)C^+OClO_4^- used in thepolymerization resulted in polymers with mixed structures, i.e. (1→5)-α-D-ribofuranosidic and (1→4)-β-D-ribopyranosidic units. However, with C_6H_5C^+OClO_4^- as catalyst, pure (1→5)-α-D-ribofuranan was obtained.The effects of catalyst, polymerization temperature and time on polymer stereoregularity were examined, andthe mechanism of the ring-opening polymerization was discussed.展开更多
Background and Aims:This study was designed to uncov-er the mechanism for extracellular polysaccharide(EPS1-1)-mediated effects on hepatocellular carcinoma(HCC)devel-opment.Methods:HCC cells were treated with EPS1-1,m...Background and Aims:This study was designed to uncov-er the mechanism for extracellular polysaccharide(EPS1-1)-mediated effects on hepatocellular carcinoma(HCC)devel-opment.Methods:HCC cells were treated with EPS1-1,miR-494-3p mimic,sh-TRIM36,and pcDNA3.1-TRIM36.The levels of miR-494-3p and TRIM36 were measured in nor-mal hepatocytes,THLE-2,and HepG2 and HuH7HCC cell lines,along with the protein expression of cyclin D/E and p21.The proliferation,cell cycle,and apoptosis of HCC cells were assayed.The interactions between miR-494-3p and TRIM36,and between TRIM36 and cyclin E were assessed.Finally,the expression and localization of TRIM36 and cyclin E were monitored,and tumor apoptosis was detected,in tumor xenograft model.Results:EPS1-1 suppressed HCC cell proliferation and cyclin D/E expression and promoted apoptosis and p21 expression.miR-494-3p was upregulated and TRIM36 was downregulated in HCC cells.Transfection with miR-494-3p mimic or sh-TRIM36 facilitated HCC cell proliferation and the expression of cyclin D/E protein but they inhibited apoptosis and p21 expression in the pres-ence of EPS1-1.Overexpression of TRIM36 further con-solidated EPS1-1-mediated inhibition of HCC proliferation,cyclin D/E,and the promotion of apoptosis and p21 expres-sion.Those effects were reversed by miR-494-3p overex-pression.TRIM36 was a target gene of miR-494-3p,and TRIM36 induced cyclin E ubiquitination.EPS1-1 suppressed cyclin E expression,promoted TRIM36 expression and tu-mor apoptosis,all of which were abrogated by increasing the expression of miR-494-3p in vivo.Conclusions:EPS1-1 protected against HCC by limiting its proliferation and sur-vival through the miR-494-3p/TRIM36 axis and by inducing cyclin E ubiquitination.展开更多
文摘Twenty-seven antarctic bacteria producing extracellular polysaccharide （EPS） were selected from 57 strains by staining technology. The effects of major environmental factors on the growth and EPS production of Pseudoalteromonas sp. S - 15 - 13 were investigated, and the EPS was separated and purified for characterization analysis. The results showed that the optimal conditions for the EPS production were culture period, 56 h; growth temperature, 8 ℃ ; carbon source, 1.0% glucose; NaCI concentration, 3.0% ; pH 6.0 - 7.0. The EPS was purified by cold ethanol precipitation, proteins removal, ion exchange chromatography and gel chromatography technology. The molecular mass of EPS - H was 62 kDa as determined by the high performance gel permeation chromatography. Its sugar composition was a homopolymer of marmose analyzed by gas chromatograph spectroscopy. After repeated freezing and thawing of the bacteria hiomass in the presence of EPS, the bacterial growth was much higher than that observed after freezing in the absence of EPS and the difference augmented with the increase of freeze-thaw cycles. It is hypothesized that the adaptation of Pseudoalteromonas sp. S- 15 - 13 to the antarctic marine conditions, characterized by low temperature, high NaCl concentration and repeated freeze-thaw cycles, might be related to the EPS production ability.
文摘New highly stereoregular 2, 3 -di- O-(p-azidobenzyl )-(1 →5 ) - α-D -ribofuranan was synthesized byselective ring-opening polymerization of 1, 4-anhydro-2, 3 - di-O -(p-azidobenzyl )-α-D -ribopyranose(ADABR) using phosphorus pentafluoride or tin tetrachloride as catalyst at low temperature indichloromethane. The monomer was obtained by the reaction of p - bromomethyl -phenyleneazide with 1, 4 -anhydro-α-D-ribose in DMF. The structure of poly(ADANR) was identified by specific rotation and ^(13)C-NMR spectroscopy. Acid chloride-AgCl_4 complex catalyst such as CH_2=C(CH_3)C^+OClO_4^- used in thepolymerization resulted in polymers with mixed structures, i.e. (1→5)-α-D-ribofuranosidic and (1→4)-β-D-ribopyranosidic units. However, with C_6H_5C^+OClO_4^- as catalyst, pure (1→5)-α-D-ribofuranan was obtained.The effects of catalyst, polymerization temperature and time on polymer stereoregularity were examined, andthe mechanism of the ring-opening polymerization was discussed.
文摘Background and Aims:This study was designed to uncov-er the mechanism for extracellular polysaccharide(EPS1-1)-mediated effects on hepatocellular carcinoma(HCC)devel-opment.Methods:HCC cells were treated with EPS1-1,miR-494-3p mimic,sh-TRIM36,and pcDNA3.1-TRIM36.The levels of miR-494-3p and TRIM36 were measured in nor-mal hepatocytes,THLE-2,and HepG2 and HuH7HCC cell lines,along with the protein expression of cyclin D/E and p21.The proliferation,cell cycle,and apoptosis of HCC cells were assayed.The interactions between miR-494-3p and TRIM36,and between TRIM36 and cyclin E were assessed.Finally,the expression and localization of TRIM36 and cyclin E were monitored,and tumor apoptosis was detected,in tumor xenograft model.Results:EPS1-1 suppressed HCC cell proliferation and cyclin D/E expression and promoted apoptosis and p21 expression.miR-494-3p was upregulated and TRIM36 was downregulated in HCC cells.Transfection with miR-494-3p mimic or sh-TRIM36 facilitated HCC cell proliferation and the expression of cyclin D/E protein but they inhibited apoptosis and p21 expression in the pres-ence of EPS1-1.Overexpression of TRIM36 further con-solidated EPS1-1-mediated inhibition of HCC proliferation,cyclin D/E,and the promotion of apoptosis and p21 expres-sion.Those effects were reversed by miR-494-3p overex-pression.TRIM36 was a target gene of miR-494-3p,and TRIM36 induced cyclin E ubiquitination.EPS1-1 suppressed cyclin E expression,promoted TRIM36 expression and tu-mor apoptosis,all of which were abrogated by increasing the expression of miR-494-3p in vivo.Conclusions:EPS1-1 protected against HCC by limiting its proliferation and sur-vival through the miR-494-3p/TRIM36 axis and by inducing cyclin E ubiquitination.
