Biolistic introduction of a synthetic Bt gene into elite maize     

M. Hill  K. Launis  C. Bowman  K. McPherson  J. Dawson  J. Watkins  M. Koziel  M. S. Wright 《Euphytica》1955,85(1-3):119-123

Summary A synthetic Bt gene encoding a truncated version of the CryIA(b) protein derived from Bacillus thuringiensis was successfully introduced into elite maize using microprojectile bombardment of immature embryos. The method used to initiate and identify transformation events is described. We describe the detailed parameters used for the Biolistics device as well as the plasmids used for the transformations. The plasmids contained the synthetic Bt gene driven by either the 35S CaMV promoter or a combination of two tissue-specific promoters, leaf and pollen, derived from maize. Specific conditions for the culture of Type I callus from immature embryos, the phosphinothricin (PPT) selection protocol, and the regeneration of plants are discussed. T0 and T1 plants were initially identified using the pH-dependent chlorophenol red test and/or the histochemical -glucuronidase (GUS) assay. PCR and Southern data confirm the presence of the 35S CaMV promoter and the synthetic Bt gene.  相似文献   

Breeding components for mixture performance     

J. Hill 《Euphytica》1996,92(1-2):135-138

Summary The problems posed by breeding components for use in binary mixtures are discussed. Breeding and selection strategies designed to overcome some of these problems are outlined.  相似文献   

Temporal and spatial dynamics of soil solution C and N concentrations during Lolium perenne L. sward establishment and the effects of elevated CO₂ and N additions     

P.W. Hill  D.L. Jones  J.F. Farrar 《Soil biology & biochemistry》2006,38(6):1290-1297

There is now clear evidence for a prolonged increase in atmospheric CO₂ concentrations and enrichment of the biosphere with N. Understanding the fate of C in the plant-soil system under different CO₂ and N regimes is therefore of considerable importance in predicting the environmental effects of climate change and in predicting the sustainability of ecosystems. Swards of Lolium perenne were grown from seed in a Eutric Cambisol at either ambient (ca. 350 μmol mol⁻¹) or elevated (700 μmol mol⁻¹) atmospheric pCO₂ and subjected to two inorganic N fertilizer regimes (no added N and 70 kg N ha⁻¹ month⁻¹). After germination, soil solution concentrations of dissolved organic C (DOC), dissolved inorganic N (DIN), dissolved organic N (DON), phenolics and H⁺ were measured at five depths down the soil profile over 3 months. The exploration of soil layers down the soil profile by roots caused transient increases in soil solution DOC, DON and phenolic concentrations, which then subsequently returned to lower quasi-stable concentrations. In general, the addition of N tended to increase DOC and DON concentrations while exposure to elevated pCO₂ had the opposite effect. These treatment effects, however, gradually diminished over the duration of the experiment from the top of the soil profile downwards. The ambient pCO₂ plus added N regime was the only treatment to maintain a notable difference in soil solution solute concentration, relative to other treatments. This effect on soil solution chemistry appeared to be largely indirect resulting from increased plant growth and a decrease in soil moisture content. Our results show that although plant growth responses to elevated pCO₂ are critically dependent upon N availability, the organic chemistry of the soil solution is relatively insensitive to changes in plant growth once the plants have become established.  相似文献   

TWO LIMESTONE FORMATIONS OF THE CRETACEOUS OF TEXAS WHICH TRANSGRESS TIME DIAGONALLY     

Hill RT 《Science (New York, N.Y.)》1921,53(1365):190-191

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Rapid-cycling populations of brassica     

Williams PH  Hill CB 《Science (New York, N.Y.)》1986,232(4756):1385-1389

Rapid-cycling populations of six economically important species in the genus Brassica have unusual potential for resolving many problems in plant biology and for use in education. Rapid-cycling brassicas can produce up to ten generations of seed per year and serve as models for research in genetics, host-parasite relations, molecular biology, cell biology, plant biochemistry, population biology, and plant breeding. Brassicas are a highly diverse group of crop plants that have great economic value as vegetables and as sources of condiment mustard, edible and industrial oil, animal fodder, and green manure. These plants can also be used in the classroom as convenient, rapidly responding, living plant materials for "hands on" learning at all levels of our educational system.  相似文献   

水稻整米率稳定性的估计     

戴君惕  耿旭  Jim Hill 《湖南农业大学学报(自然科学版)》1989,(1)

本文提出了测定水稻品种对环境稳定性的一个新参数,采用这一参数对美国加利福尼亚州多年多点的水稻品种整米率进行稳定性分析的结果表明,稳定性与熟期类型在统计上有一定的相关性,即整米率稳定性依晚熟品种、早熟品种、特早熟品种而顺序降低,回归分析说明整米率的稳定性有随整米率的提高而增加的趋向,本文还讨论了稳定性系数的优点和局限性。  相似文献   

Seal lungs collapse during free diving: evidence from arterial nitrogen tensions   总被引：4，自引：0，他引：4  

K J Falke  R D Hill  J Qvist  R C Schneider  M Guppy  G C Liggins  P W Hochachka  R E Elliott  W M Zapol 《Science (New York, N.Y.)》1985,229(4713):556-558

Arterial blood nitrogen tensions of free-diving Weddell seals (Leptonychotes weddelli) were measured by attaching a microprocessor-controlled blood pump and drawing samples at depth to determine how these marine mammals dive to great depths and ascend rapidly without developing decompression sickness. Forty-seven samples of arterial blood were obtained from four Weddell seals during free dives lasting up to 23 minutes to depths of 230 meters beneath the sea ice of McMurdo Sound, Antarctica. Peak arterial blood nitrogen tensions of between 2000 and 2500 millimeters of mercury were recorded at depths of 40 to 80 meters during descent, indicating that the seal's lung collapses by 25 to 50 meters. Then arterial blood nitrogen tensions slowly decreased to about 1500 millimeters of mercury at the surface. In a single dive, alveolar collapse and redistribution of blood nitrogen allow the seal to avoid nitrogen narcosis and decompression sickness.  相似文献   

SHOULD WE HAVE FACULTIES OF PUBLIC HEALTH?     

Hill HW 《Science (New York, N.Y.)》1924,59(1520):153-156

Public health is the science and art of conscious physical adjustment between man and his surroundings in the universe. The modern conception of man as a product of and a part of nature brings the subject of man's individual physical adjustments with his immediate surroundings into its proper place as the fundamental study-the basis of every form of education. Hence, public health is not only eligible for a position as an independent faculty in any university but is as definitely entitled to such a place as any of those now recognized. It is futile to consider the ordinary 45 hour course in public health, furnished as an incident in the ordinary 4000 to 5000 hour medical course, as more than a smattering, offered to medical students alone, of the 900 to 4500 hour courses in public health offered to professional public health students.  相似文献   

Language pollution     

Hill PA 《Science (New York, N.Y.)》1970,169(3945):534

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Crystal structure of defensin HNP-3, an amphiphilic dimer: mechanisms of membrane permeabilization   总被引：34，自引：0，他引：34  

C P Hill  J Yee  M E Selsted  D Eisenberg 《Science (New York, N.Y.)》1991,251(5000):1481-1485

Defensins (molecular weight 3500 to 4000) act in the mammalian immune response by permeabilizing the plasma membranes of a broad spectrum of target organisms, including bacteria, fungi, and enveloped viruses. The high-resolution crystal structure of defensin HNP-3 (1.9 angstrom resolution, R factor 0.19) reveals a dimeric beta sheet that has an architecture very different from other lytic peptides. The dimeric assembly suggests mechanisms by which defensins might bind to and permeabilize the lipid bilayer.  相似文献