Aggregation-based crystal growth and microstructure development in natural iron oxyhydroxide biomineralization products   总被引：1，自引：0，他引：1  

Banfield JF  Welch SA  Zhang H  Ebert TT  Penn RL 《Science (New York, N.Y.)》2000,289(5480):751-754

Crystals are generally considered to grow by attachment of ions to inorganic surfaces or organic templates. High-resolution transmission electron microscopy of biomineralization products of iron-oxidizing bacteria revealed an alternative coarsening mechanism in which adjacent 2- to 3-nanometer particles aggregate and rotate so their structures adopt parallel orientations in three dimensions. Crystal growth is accomplished by eliminating water molecules at interfaces and forming iron-oxygen bonds. Self-assembly occurs at multiple sites, leading to a coarser, polycrystalline material. Point defects (from surface-adsorbed impurities), dislocations, and slabs of structurally distinct material are created as a consequence of this growth mechanism and can dramatically impact subsequent reactivity.  相似文献   

Diverse plasma populations and structures in Jupiter's magnetotail     

McComas DJ  Allegrini F  Bagenal F  Crary F  Ebert RW  Elliott H  Stern A  Valek P 《Science (New York, N.Y.)》2007,318(5848):217-220

Jupiter's magnetotail is the largest cohesive structure in the solar system and marks the loss of vast numbers of heavy ions from the Jupiter system. The New Horizons spacecraft traversed the magnetotail to distances exceeding 2500 jovian radii (R(J)) and revealed a remarkable diversity of plasma populations and structures throughout its length. Ions evolve from a hot plasma disk distribution at approximately 100 R(J) to slower, persistent flows down the tail that become increasingly variable in flux and mean energy. The plasma is highly structured-exhibiting sharp breaks, smooth variations, and apparent plasmoids-and contains ions from both Io and Jupiter's ionosphere with intense bursts of H(+) and H(+)(3). Quasi-periodic changes were seen in flux at approximately 450 and approximately 1500 R(J) with a 10-hour period. Other variations in flow speed at approximately 600 to 1000 R(J) with a 3- to 4-day period may be attributable to plasmoids moving down the tail.  相似文献   

Life history traits and food supplementation affect productivity in a translocated population of the endangered Hihi (Stitchbird, Notiomystis cincta)     

Isabel Castro  Dianne H Brunton  Brice Ebert 《Biological conservation》2003,114(2):271-280

We studied the effect of food supplementation, female age and clutch order on productivity in a translocated species. Food supplementation increased clutch size from 3.9 to 4.4 (average) eggs per nesting attempt, and more than doubled fledging and recruitment success. Supplemented females started a second clutch 9 days sooner after fledging first clutch chicks than unfed females. During second clutches, supplemented females incubated the eggs for a shorter period of time (15.2 days vs. 16.8). Older females laid larger clutches (4.6 vs. 3.7 eggs) than yearlings and incubated second clutch eggs for a shorter period (15.4 vs. 16.6 days). Females laid more eggs in first clutches (4.2 vs. 3.8 eggs), and those eggs took approximately 30% longer to lay than eggs in second clutches. The successful maintenance of hihi populations on the available islands may be dependent on the permanent provision of supplemental food at nest sites.  相似文献   

Phosphorsäurewirkung in Komplexdüngern     

K. Ebert 《Archives of Agronomy and Soil Science》2013,59(5):383-398

In Inkubationsversuchen wurde das Mineralisierungsverhalten von Ernte‐und Wurzelrückständen (EWR) der auch als Industriepflanzen verwendeten Pflanzenarten Winterraps, Sonnenblume, Öllein, Miscanthus und Sachalinknöterich im Vergleich zu Winterweizen in Abhängigkeit vom Vegetationsstadium und der Bodentemperatur untersucht. Zwischen den Pflanzenarten, ihren Teilen und den Vegetationsstadien bestanden teilweise signifikante Unterschiede in der Mineralisierung. Von dem Pflanzenmaterial in der generativen Phase verblieben nach einer Inkubation von 70 Tagen unter optimalen Bedingungen (25°C, 60% WK_max) 55–70% der eingebrachten C‐Menge im Boden. Intermittierende Temperaturen (Wechsel 10 °C/25 °C) bewirkten eine geringere Mineralisierung, nur 28–34% des Pflanzenmaterials wurden umgesetzt.  相似文献   

Foliar Iron Fertilization: A Critical Review     

Victoria Fernández  Georg Ebert 《Journal of plant nutrition》2013,36(12):2113-2124

Application of foliar iron (Fe) sprays is a common means of correcting Fe deficiency of agricultural crops. However, variable plant responses to iron sprays, ranging from no effect to defoliation, have often been described in the Fe-fertilization literature. Knowledge is still limited concerning the mechanisms of penetration of a leaf-applied, Fe-containing solution and the role of Fe in the leaf. The complex and multi-disciplinary character of the factors determining the effects of Fe sprays hinder the development of suitable foliar fertilization strategies, applicable under variable local conditions and for different plant types. This review describes some key factors involved on the process of penetration of a leaf-applied, Fe-containing solution before briefly analyzing the available foliar Fe-fertilization literature. Iron chemistry, leaf penetration, and plant-nutrition principles will be merged with the aim of clarifying the constraints, opportunities, and future perspectives of foliar Fe sprays to cure plant Fe deficiency.  相似文献   

Relationship between survival and yield related traits in Solanum pimpinellifolium under salt stress   总被引：1，自引：0，他引：1  

Eguru Sreenivasa Rao  Palchamy Kadirvel  Rachael C. Symonds  Andreas W. Ebert 《Euphytica》2013,190(2):215-228

A subset of the Solanum pimpinellifolium collection maintained by AVRDC—The World Vegetable Center, Taiwan was evaluated to assess effects of salt stress on physiological traits and yield-related traits with the aim of identifying potential S. pimpinellifolium accessions useful for salt tolerance breeding in tomato. We undertook a comparative analysis of yield and plant survival traits under normal and salt stress conditions to obtain a first indication of the crucial traits associated with salt tolerance in S. pimpinellifolium. Although most traits of S. pimpinellifolium accessions showed a similar percent decrease in mean under salt stress compared with the cultivated checks, the former exhibited a wide range for all traits, suggesting great genetic diversity that can be exploited for the identification of salt tolerant genotypes. Genetic variability for yield and survival traits under salt stress was quantitative with low to moderate heritability. Results of correlation and path coefficient analysis revealed no correlation between any of the physiological traits with yield-related traits indicating that the ability to survive and yield under salt stress are two independent sets of traits in S. pimpinellifolium. Results of the path analysis along with heritability and genetic advance showed that shoot dry weight and K/Na ratio are the two most critical component traits for survival, while fruit number is critical for yield per plant. The large S. pimpinellifolium panel evaluated in this study revealed five genotypes possessing better survival traits, seven genotypes with good yield traits, and two genotypes combining both superior survival and yield traits under salt stress.  相似文献   

Ultrasound Guided Transplantation of Enriched and Cryopreserved Spermatogonial Cell Suspension in Goats     

G Kaul  J Kaur  TA Rafeeqi 《Reproduction in domestic animals》2010,45(6):e249-e254

Spermatogonial stem cells transplantation provides a unique approach for studying spermatogenesis. Initially developed in mice, this technique has now been extended in farm animals and provides an alternative means to preserve valuable male germ line and to produce transgenic animals. The aim of this study was to enrich type A spermatogonial cells amongst the isolated cells from goat testis, to cryopreserve these enriched populations of cells and their subsequent transplantation in unrelated recipient goats under ultrasound guidance. The cells were isolated enzymatically and enriched by differential plating and separation on discontinuous percoll gradient. Ultrasound guided injection of trypan blue dye into rete testis resulted in 20–30% filling of the seminiferous tubules. Prior to transplantation, the cells were labelled with a fluorescent dye to trace donor cells in recipient seminiferous tubules after transplantation. The fluorescent‐labelled cells were observed up to 12 weeks after transplantation.  相似文献   

皮、裸燕麦种质资源的性状表现和遗传差异分析   总被引：1，自引：0，他引：1  

塔娜  逯晓萍  张雅慧  张晓宇  薛春雷  赵卫国 《内蒙古农业科技》2010,(2):33-35,41

研究利用4份皮燕麦和5份裸燕麦为材料,对9份燕麦材料的产量性状和抗性进行了分析,结果表明:皮燕麦的产量低于裸燕麦的产量,而抗性表现是皮燕麦的抗性比裸燕麦的抗性强,特别是抗倒伏能力尤为突出。同时,采用RAPD分子标记技术,从DNA水平对9份燕麦种质的遗传差异性进行了研究。结果显示:从50条RAPD引物中筛选出6条多态性较强的引物,共扩增出DNA片段68条,其中具多态性带33条,多态率为48.5%,每引物平均多态位点5.5个。裸燕麦与皮燕麦的遗传距离较大,为0.087～0.496,而皮燕麦与皮燕麦以及裸燕麦与裸燕麦之间的遗传距离较小,分别为0.023～0.117和0.040～0.298。采用非加权类平均法(UPGAM)进行了聚类分析,当遗传距离为0.26时,将供试材料划分为3个类群,并与实际结果一致。  相似文献   

Statistical evaluation of transcriptomic data generated using the Affymetrix one-cycle, two-cycle and IVT-Express RNA labelling protocols with the Arabidopsis ATH1 microarray     

Tara J Holman  Michael H Wilson  Kim Kenobi  Ian L Dryden  Charlie T Hodgman  Andrew TA Wood  Michael J Holdsworth 《Plant methods》2010,6(1):9

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云南省猪布鲁氏杆菌病血清学调查     

杨渊  他月芬  杨红华  牛木存  杨贵树 《现代农业科技》2011,(4):319+324

采用虎红平板凝集试验与试管凝集试验相结合的方法,对云南省部分养殖场和屠宰厂采集的猪血清样本进行布病血清学检测,检测血清样本302份。经虎红平板凝集试验筛选,共检出阳性血清样本30例,检出率为9.934%。阳性者通过试管凝集试验证实,最终检出阳性血清样本14例,检出率为4.636%。其中屠宰厂检出率为6.091%,养殖场检出率为1.905%,屠宰场的检出率高于养殖场。  相似文献