农业干旱监测问题对农业生产具有重要影响,因此精确监测农业干旱具有现实意义。该研究基于MOD16A2全球蒸散产品,计算作物缺水指数(Crop Water Stress Index,CWSI),结合地表温度、植被指数、降水量以及土壤湿度等多源遥感数据为自变量,以...农业干旱监测问题对农业生产具有重要影响,因此精确监测农业干旱具有现实意义。该研究基于MOD16A2全球蒸散产品,计算作物缺水指数(Crop Water Stress Index,CWSI),结合地表温度、植被指数、降水量以及土壤湿度等多源遥感数据为自变量,以3个月时间尺度的标准化降水蒸散指数(Standardized Precipitation Evapotranspiration Index,SPEI-3)为因变量,基于偏差校正随机森林算法构建山东省2000—2019年作物生长季(4—10月)的偏差校正随机森林干旱状况指数(Bias-corrected Random Forest Drought Condition Index,BRF-DCI)。并分析CWSI对于构建山东省农业干旱监测模型的影响。结果表明:加入CWSI后,所提出的BRF-DCI指数与SPEI-3观测指数的决定系数为0.72~0.85,优于未加入CWSI之前;加入CWSI后提高了干旱等级监测的准确率;BRF-DCI指数能较好地拟合各月份的SPEI-3指数,决定系数均在0.94以上;BRF-DCI指数能够准确反映山东省典型干旱年的干旱情况,有效监测山东省农业干旱情况。该研究对山东省农业旱情监测及旱灾防御具有较大的应用潜力。展开更多
Lysozyme is an enzyme that is essential for protection against bacterial infections.In this study,a T4 lysozyme gene was cloned into the yeast expression vector pPIC9K under the control of the Pichia pastoris glyceral...Lysozyme is an enzyme that is essential for protection against bacterial infections.In this study,a T4 lysozyme gene was cloned into the yeast expression vector pPIC9K under the control of the Pichia pastoris glyceraldehyde-3-phosphate dehydrogenase promoter (pGAP).A Hansenula polymorpha-derived ribosomal DNA (rDNA)-targeting element was inserted into the expression vector and was critical for stable DNA integration into the H.polymorpha chromosome.Recombinant T4 lysozyme was successfully expressed in the yeast H.polymorpha A16;0.49 g L-1 secreted recombinant T4 lysozyme was obtained 72 h after incubation in culture broth that had an initial pH of 6.0.Recombinant T4 lysozyme showed lytic activity against the cell walls of the gram positive bacteria,Micrococcus lysodeikticus,and the gram negative bacteria Xanthomonas campestris pv.malvacearum and Xanthomonas oryzae pv.oryzae.The zone of inhibition assay was used to evaluate antimicrobial activity.Mass spectrometry showed the N-terminal sequence of recombinant T4 lysozyme was identical to that of the native enzyme.SDS-PAGE indicated that the molecular mass of recombinant T4 lysozyme was 18.7 kD which corresponds to a monomer of the native enzyme.SDS-PAGE without 0.2 mol L-1 dithiothreitol treatment detected two bands (15 and 31 kD) suggesting that some recombinant T4 lysozyme formed interand intra-molecular disulfide bonds which resulted in loss of enzyme activity.展开更多
基金supported by the National High Technology Research & Development Program of China (Grant No. 2007AA02Z111)National Technology for the 10th Five-year Plan of China (Grant No. 2006BAD31B01-04)+1 种基金National Biotechnology Development Plan (Grant Nos. 2008ZX08005-004 and 2009ZX08005-004B)the Researcher Foundation of the Chinese Academy of Agricultural Sciences
文摘Lysozyme is an enzyme that is essential for protection against bacterial infections.In this study,a T4 lysozyme gene was cloned into the yeast expression vector pPIC9K under the control of the Pichia pastoris glyceraldehyde-3-phosphate dehydrogenase promoter (pGAP).A Hansenula polymorpha-derived ribosomal DNA (rDNA)-targeting element was inserted into the expression vector and was critical for stable DNA integration into the H.polymorpha chromosome.Recombinant T4 lysozyme was successfully expressed in the yeast H.polymorpha A16;0.49 g L-1 secreted recombinant T4 lysozyme was obtained 72 h after incubation in culture broth that had an initial pH of 6.0.Recombinant T4 lysozyme showed lytic activity against the cell walls of the gram positive bacteria,Micrococcus lysodeikticus,and the gram negative bacteria Xanthomonas campestris pv.malvacearum and Xanthomonas oryzae pv.oryzae.The zone of inhibition assay was used to evaluate antimicrobial activity.Mass spectrometry showed the N-terminal sequence of recombinant T4 lysozyme was identical to that of the native enzyme.SDS-PAGE indicated that the molecular mass of recombinant T4 lysozyme was 18.7 kD which corresponds to a monomer of the native enzyme.SDS-PAGE without 0.2 mol L-1 dithiothreitol treatment detected two bands (15 and 31 kD) suggesting that some recombinant T4 lysozyme formed interand intra-molecular disulfide bonds which resulted in loss of enzyme activity.
