Inorganic N turnover and availability in annual- and perennial-dominated soils in a northern Utah shrub-steppe ecosystem

The exotic annual grass Bromus tectorum has replaced thousands of hectares of native perennial vegetation in semi-arid ecosystems of the western United States. Inorganic N availability and production were compared in soil from monodominant patches of Bromus tectorum, the perennial bunchgrass Elymus elymoides, and the shrub Artemisia tridentata, in Curlew Valley, a salt-desert shrub site in Northern Utah. Bromus-dominated soil had greater %N in the top 10 cm than Artemisia or Elymus-dominated soils. As determined by spring isotope-dilution assays, gross mineralization and nitrification rates were higher in Bromus-dominated than Artemisia-dominated soils, but gross rates of NH₄ ⁺ and NO₃ ^– consumption were also higher. Litterbags had greater mass loss and N mineralization when buried in Bromus stands than in Artemisia stands, indicating the soil environment under the annual grass promotes decomposition. As determined by nitrification potential assays, nitrifier populations were higher under Bromus than under Artemisia and Elymus. Soil inorganic N concentrations were similar among vegetation types in the spring, but NO₃ ^– accumulated under Bromus once it had senesced. An in situ net mineralization assay conducted in autumn indicated that germinating Bromus seedlings are a strong sink for soil NO₃ ^–, and that net nitrification is inherently low in soils under Artemisia and Elymus. Results of the study suggest that differences in plant uptake and the soil environment promote greater inorganic N availability under Bromus than under perennial species at the site.     

Improved growth of Artemisia annua L hairy roots and artemisinin production under red light conditions

Hairy root cultures of Artemisia annua L were cultivated for 30 days under either white, red, blue, yellow or green light. Red light at 660 nm gave the highest biomass of hairy roots (5.73 g dry wt cells l^–1 medium) and artemisinin content (31 mg arteminsinin g^–1 dry cells) which were, respectively, 17% and 67% higher than those obtained under white light.     

Artemisinin Production by Adventitious Shoots of Artemisia annua in a Novel Mist Bioreactor

A novel ultrasonic inner-loop bioreactor was used for artemisinin production by adventitious shoots in a multiplate culture of Artemisia annua L. The bioreactor was designed to allow the nutrient mist to uprise along a concentric draught-cylinder until it overflows from the top opening and the side-holes of the central tube downward and out of the annulus, so that the nutrient mist can be fulfilled in the bioreactor within 2 ~ 3 minutes. Under the misting cycles of every 3-minute misting in every 90 minute interval, artemisinin production reached totally 46.9 mg DW/L of culture medium at an airflow rate of 0.5 L/min for 25 d of culture in batches. The product amounted 2.9 and 3.2 folds of those obtained from culturing in solid medium and in shaking flasks respectively.     

绿色荧光蛋白基因在青蒿转基因芽中的表达

将改良的绿色荧光蛋白（ＧＦＰ）基因,插入到植物表达载体中,构建双ＣａＭＶ３５Ｓ启动子驱动下的植物表达载体ｐＢＩＧＦＰ,在Ｋａｍ浓度为２０ｍｇ／Ｌ的筛选培养基上,用含有ｐＢＩＦＰ质粒的根癌农杆菌ＬＢＡ４４０４感染青蒿叶片,获得５个抗Ｋａｎ阳性丛生芽系。Ｓｏｕｔｈｅｒｎ ｂｌｏｔｔｉｎｇ分析表明,外源ＧＦＰ基因已整合到青蒿转基因芽Ｇ－１系的基因组中。在ＯＬＹＭＰＵＳ－ＢＨ２型荧光显微镜下,观察到转基因     

不同降水量处理时5种蒿属植物瘦果粘液溶出

用粘沙法对科尔沁沙地西部5种蒿属植物冷蒿(Artemisiafrigida)、差巴嘎蒿(A.halodendron)、大籽蒿(A.sieversiana)、黄蒿(A.scoparia)、乌丹蒿(A.wudanica)进行了瘦果粘液溶出及粘沙量的比较。主要模拟埋深5mm、降水量为1、2、4、8mm时瘦果的粘液溶出。5种供试植物均有粘液瘦果。在降水量1mm时,供试植物的粘液瘦果就能溶出粘液。当降水量达到2～4mm时,典型的沙生植物乌丹蒿和差巴嘎蒿的粘液瘦果粘沙量平均值分别达到7.31～13.56mg、0.63～2.55mg。除冷蒿外,其它4种植物均有随降水增多、粘液溶出量加大的趋势。粘液瘦果比例从大到小的排序是冷蒿>乌丹蒿>差巴嘎蒿>大籽蒿>黄蒿。在各种处理时,粘沙瘦果百粒瘦果粘沙量由大到小的顺序是乌丹蒿>差巴嘎蒿>大籽蒿>冷蒿>黄蒿。溶出粘液粘沙后,冷蒿瘦果所形成沙团重量达到瘦果重量的5～7倍,差巴嘎蒿2～9倍,大籽蒿3～5倍,黄蒿5～8倍,乌丹蒿5～29倍。流沙先锋植物乌丹蒿和差巴嘎蒿百粒瘦果粘沙量较其它植物大、在较低降水量时这两种植物粘液瘦果粘沙量较大表明瘦果溶出粘液粘沙是植物针对沙地流动性的进化适应之一。     

陕北撂荒地上优势蒿类叶片解剖结构及其生态适应性

对陕北丘陵区撂荒地上处于自然恢复演替不同时期的3种优势种蒿类铁杆蒿（Artemisia gmelinii Web．）、茭蒿（Artemisia giraldii Pamp．）、猪毛蒿（Artemisia scoparia）的叶片解剖结构进行了观察研究的结果表明,随着演替序列的发展,3种蒿类的栅栏组织随演替时间的推移呈现出全栅型-环栅型-过渡型的趋势,叶片解剖结构说明越靠近演替前期的蒿类对干旱的适应性越强。此外,3种蒿类的栅栏组织排列都很紧密,表皮细胞排列不规则,且具有表皮毛和腺毛等旱生适应结构;在猪毛蒿和茭蒿中还发现了特化的气腔结构。这些特征均能说明这些蒿类植物具有很好的抗旱适应性,作为环境改造的先锋物种,它们在当地的自然植被恢复演替中起着积极的正向推动作用。     

沙地油蒿群落生产力动态的能量生态学研究

从鄂尔多斯高原固定沙地油蒿群落光合作用所积累的能量的动态变化研究入手,从能量生态学的角度探讨了油蒿群落生产力动态的形成机制。研究表明：群落地上生物量与能量现存量变化趋势相一致,均在９月初达全年最大值。油蒿光合强度在７、８月份较大。群落地上能量现存量增长率、群落生长速率及能量转化率均在这两个月中较高,即它们的变化趋势一致。植物光合作用积累能量的动态变化与群落生产力变化机制是密不可分的。     

微生物发酵青蒿叶和叶渣的研究

为扩大青蒿原料的应用途径,延伸青蒿产业链,对青蒿叶和叶渣进行发酵研究.拟开发可用于动物保健的青蒿来源的产品.采用微生物发酵青蒿及青蒿叶渣,检测枯草芽孢杆菌、酿酒酵母菌、植物乳杆菌等菌株发酵青蒿叶和叶渣后其粗蛋白、粗脂肪、粗纤维素以及青蒿素、青蒿乙素、双氢青蒿酸、青蒿酸含量变化.青蒿叶发酵产物及功效成分含量与对照组比较,...     

Production of the Artemisinin Precursor Amorpha-4,11-diene by Engineered Saccharomyces cerevisiae

The gene encoding for amorpha-4,11-diene synthase from Artemisia annua was transformed into yeast Saccharomyces cerevisiae in two fundamentally different ways. First, the gene was subcloned into the galactose-inducible, high-copy number yeast expression vector pYeDP60 and used to transform the Saccharomyces cerevisiae strain CEN·PK113-5D. Secondly, amorpha-4,11-diene synthase gene, regulated by the same promoter, was introduced into the yeast genome by homologous recombination. In protein extracts from galactose-induced yeast cells, a higher activity was observed for yeast expressing the enzyme from the plasmid. The genome-transformed yeast grows at the same rate as wild-type yeast while plasmid-carrying yeast grows somewhat slower than the wild-type yeast. The plasmid and genome-transformed yeasts produced 600 and 100 μg/l of the artemisinin precursor amorpha-4,11-diene, respectively, during 16-days’ batch cultivation. Revisions requested 14 November 2005; Revisions received 17 January 2006     

Isolation, characterization and structural studies of amorpha - 4, 11-diene synthase (ADS(3963)) from Artemisia annua L

With the escalating prevalence of malaria in recent years, artemisinin demand has placed considerable stress on its production worldwide. At present, the relative low­yield of artemisinin (0.01­1.1 %) in the source plant (Artemisia annua L. plant) has imposed a serious limitation in commercializing the drug. Amorpha­4, 11­diene synthase (ADS) has been reported a key enzyme in enhancing the artemisinin level in Artemisia annua L. An understanding of the structural and functional correlations of Amorpha­4, 11­diene synthase (ADS) may therefore, help in the molecular up­regulation of the enzyme. In this context, an in silico approach was used to study the ADS₃₉₆₃ (3963 bp) gene cloned by us, from high artemisinin (0.7­0.9% dry wt basis) yielding strain of A. annua L. The full­length putative gene of ADS₃₉₆₃ was found to encode a protein consisting of 533 amino acid residues with conserved aspartate rich domain. The isoelectric point (pI) and molecular weight of the protein were 5.25 and 62.2 kDa, respectively. The phylogenetic analysis of ADS genes from various species revealed evolutionary conservation. Homology modeling method was used for prediction of the 3D structure of ADS3963 protein and Autodock 4.0 version was used to study the ligand binding. The predicted 3D model and docking studies may further be used in characterizing the protein in wet laboratory.