Improved doubled haploid production protocol for Brassica napus using microspore colchicine treatment in vitro and ploidy determination by flow cytometry   总被引：1，自引：0，他引：1  

S. Weber    F. Ünker    W. Friedt 《Plant Breeding》2005,124(5):511-513

A rapid and efficient microspore culture protocol was applied to produce homozygous progeny of crosses between low erucic canola and high erucic resynthesized rapeseed (Brassica napus L.). Microspores of Canadian cultivars ‘Excel’ and ‘Profit’ as well as three F₁ hybrids with the resynthetic line ‘RS239’ were treated with colchicine immediately after isolation. Flow cytometry was applied for early identification of doubled haploid (DH) regenerants. The diploidization rate was subsequently verified by scoring flower morphology. In vitro colchicine treatment had a positive effect on induced diploidization, and was associated with the frequency of preliminary spontaneous diploidization which was, however, determined by the genotype. In addition, the effects of colchicine treatment on embryoid formation and regeneration have been evaluated. The method presented is feasible for commercial large‐scale production of DHs in rapeseed as the genotype‐specific diploidization can be efficiently balanced by in vitro colchicine treatment. In addition, the use of flow cytometry immediately after in vitro culture allows efficient selection for DHs, thus saving labour and cost and in the laboratory and subsequent greenhouse phase.  相似文献   

The accelerated reduction and elimination of toxics in Canada: The case of mercury-containing medical instruments in Quebec hospital centres     

P. Guerrier  J. -P Weber  R. Coté  M. Paul  M. Rhainds 《Water, air, and soil pollution》1995,80(1-4):1199-1202

In Canada, medical instruments containing mercury (Hg) are still widely used in hospitals. These are mostly thermometers and sphygmomanometers. Mercury present in these instruments does not in itself constitute a risk of contamination since this metal is contained within a closed system. However, breakage, inadequate maintenance and disposal of such instruments can expose workers and the public to this toxic substance. In Quebec, 80% of the 28 hospitals surveyed still use Hg sphygmomanometers and 45% Hg thermometers. Besides, 35% do not have any recovery procedures in case of spillage and most mercury spills are apparently not reported. Two main courses of action are recommended: the gradual replacement of these medical instruments by aneroid sphygmomanometers and electronic thermometers, and the establishment and communication, in the form of a handbook, of guidelines to handle and dispose of mercury safely.  相似文献   

Socioenvironmental influences on children's fruit, juice and vegetable consumption as reported by parents: reliability and validity of measures     

Weber Cullen K  Baranowski T  Rittenberry L  Cosart C  Owens E  Hebert D  de Moor C 《Public health nutrition》2000,3(3):345-356

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Agricultural and ecological aspects of a sandy soil as affected by the application of municipal solid waste composts   总被引：1，自引：0，他引：1  

J. Weber  A. Karczewska  J. Drozd  M. Licznar  S. Licznar  E. Jamroz  A. Kocowicz 《Soil biology & biochemistry》2007,39(6):1294-1302

We present the results of a plot experiment in which the changes in physical, chemical and physico-chemical properties of a sandy soil were examined after amending the soil with two different composts produced from municipal solid wastes. Triticale (X Triticosecale), cultivated in a 3-y monoculture, was used as a test plant. Both composts differed in their concentrations of heavy metals. Composts were applied non-recurrently in the spring before sowing, at the rates of 18, 36, and 72 t dry matter ha⁻¹. The plots without fertilization, and those fertilized annually with mineral nitrogen (N), phosphorous (P), and potassium (K) were used as controls. Soil samples were collected 1 month after compost application, as well as each year after harvesting. Application of both composts improved soil physical properties, associated with increasing content of organic carbon (OC). Statistically significant increases of total porosity, field water capacity and amounts of plant-available water were found only in the short time after compost application. Despite the fact that soil OC content decreased with time, a C:N ratio clearly increased in the third year after compost application, which was explained by a depletion of N reserve. Both composts caused a large increase of plant-available P, K, and magnesium (Mg), which was observed during the entire period of the experiment. Beneficial changes were also observed in soil humic substances composition. These were confirmed by increased humic acids content and humic/fulvic acid ratios. Soil cation exchange capacity and base saturation increased in all plots amended with composts. This effect was still observed 1 year after compost application, while in the third year it remained significant only at the highest compost rates. Compost originating from industrial areas, even if applied in low amounts, caused a significant increase in total concentration of soil heavy metals. This fact did not result, however, in any substantial changes in soil quality with regard to heavy metals content.  相似文献   

Aging of combustion particles in the atmosphere — Results from a field study in Zürich     

H. Burtscher  A. Leonardi  D. Steiner  U. Baltensperger  A. Weber 《Water, air, and soil pollution》1993,68(1-2):137-147

At different locations in Zürich (urban and suburban area) ambient aerosol has been measured by a variety of methods. Total mass concentration, black carbon mass concentration, size distribution, Fuchs surface and photoelectric charging of particles (as a measure for the PAH concentration) have been determined. As a reference for “fresh” aerosol, measurements have also been carried out in a car parking garage. By comparing the data obtained at different locations and different times of the day aging processes can be investigated. All measured signals show significant peaks during the rush-hours, indicating that the majority of the particles arise from automotive traffic. Aging is expressed by decreasing number concentrations, increasing diameter (coagulation) and decreasing black carbon and PAH content of the particles. The decrease in PAH and black carbon fraction may be due to mixing of the aerosol with non-combustion particles or by condensation of material from the gas phase on the particle; the decrease in PAH concentration may also be due to degradation of the PAHs.  相似文献   

Rapid identification of nonessential genes of herpes simplex virus type 1 by Tn5 mutagenesis   总被引：27，自引：0，他引：27  

P C Weber  M Levine  J C Glorioso 《Science (New York, N.Y.)》1987,236(4801):576-579

The large genome of herpes simplex virus type of (HSV-1) encodes at least 80 polypeptides, the majority of which have no recognized function. A subgroup of these gene products appears to be nonessential for virus replication in cell culture, but contributes to the complex life cycle of the virus in the host. To identify such functions, a simple insertional mutagenesis method has been used for selective inactivation of individual HSV-1 genes. The bacterial transposon Tn5 was allowed to insert randomly into cloned restriction fragments representing the entire short unique (US) region of the HSV-1 genome. Of the 12 open reading frames that were mutagenized with Tn5, mutant derivatives of US2, US4, and US5 were recombined into the virus. These three genes proved to be nonessential for HSV-1 replication in Vero (African Green monkey kidney) cells and the US4 gene appeared to be involved in viral pathogenesis in the central nervous system of mice. This rapid mutagenesis procedure should prove useful in exploring the entire HSV-1 genome as well as the genomes of other complex animal viruses.  相似文献   

Slow deformation and lower seismic hazard at the new madrid seismic zone   总被引：1，自引：0，他引：1  

Newman A  Stein S  Weber J  Engeln J  Mao A  Dixon T 《Science (New York, N.Y.)》1999,284(5414):619-621

Global Positioning System (GPS) measurements across the New Madrid seismic zone (NMSZ) in the central United States show little, if any, motion. These data are consistent with platewide continuous GPS data away from the NMSZ, which show no motion within uncertainties. Both these data and the frequency-magnitude relation for seismicity imply that had the largest shocks in the series of earthquakes that occurred in 1811 and 1812 been magnitude 8, their recurrence interval should well exceed 2500 years, longer than has been assumed. Alternatively, the largest 1811 and 1812 earthquakes and those in the paleoseismic record may have been much smaller than typically assumed. Hence, the hazard posed by great earthquakes in the NMSZ appears to be overestimated.  相似文献   

Conserved folding in retroviral proteases: crystal structure of a synthetic HIV-1 protease   总被引：57，自引：0，他引：57  

A Wlodawer  M Miller  M Jaskólski  B K Sathyanarayana  E Baldwin  I T Weber  L M Selk  L Clawson  J Schneider  S B Kent 《Science (New York, N.Y.)》1989,245(4918):616-621

The rational design of drugs that can inhibit the action of viral proteases depends on obtaining accurate structures of these enzymes. The crystal structure of chemically synthesized HIV-1 protease has been determined at 2.8 angstrom resolution (R factor of 0.184) with the use of a model based on the Rous sarcoma virus protease structure. In this enzymatically active protein, the cysteines were replaced by alpha-amino-n-butyric acid, a nongenetically coded amino acid. This structure, in which all 99 amino acids were located, differs in several important details from that reported previously by others. The interface between the identical subunits forming the active protease dimer is composed of four well-ordered beta strands from both the amino and carboxyl termini and residues 86 to 94 have a helical conformation. The observed arrangement of the dimer interface suggests possible designs for dimerization inhibitors.  相似文献   

Evidence for Alfvén waves in solar x-ray jets     

Cirtain JW  Golub L  Lundquist L  van Ballegooijen A  Savcheva A  Shimojo M  Deluca E  Tsuneta S  Sakao T  Reeves K  Weber M  Kano R  Narukage N  Shibasaki K 《Science (New York, N.Y.)》2007,318(5856):1580-1582

Coronal magnetic fields are dynamic, and field lines may misalign, reassemble, and release energy by means of magnetic reconnection. Giant releases may generate solar flares and coronal mass ejections and, on a smaller scale, produce x-ray jets. Hinode observations of polar coronal holes reveal that x-ray jets have two distinct velocities: one near the Alfvén speed ( approximately 800 kilometers per second) and another near the sound speed (200 kilometers per second). Many more jets were seen than have been reported previously; we detected an average of 10 events per hour up to these speeds, whereas previous observations documented only a handful per day with lower average speeds of 200 kilometers per second. The x-ray jets are about 2 x 10(3) to 2 x 10(4) kilometers wide and 1 x 10(5) kilometers long and last from 100 to 2500 seconds. The large number of events, coupled with the high velocities of the apparent outflows, indicates that the jets may contribute to the high-speed solar wind.  相似文献   

Spread of HTLV-I between lymphocytes by virus-induced polarization of the cytoskeleton     

Igakura T  Stinchcombe JC  Goon PK  Taylor GP  Weber JN  Griffiths GM  Tanaka Y  Osame M  Bangham CR 《Science (New York, N.Y.)》2003,299(5613):1713-1716

Cell contact is required for efficient transmission of human T cell leukemia virus- type 1 (HTLV-I) between cells and between individuals, because naturally infected lymphocytes produce virtually no cell-free infectious HTLV-I particles. However, the mechanism of cell-to-cell spread of HTLV-I is not understood. We show here that cell contact rapidly induces polarization of the cytoskeleton of the infected cell to the cell-cell junction. HTLV-I core (Gag protein) complexes and the HTLV-I genome accumulate at the cell-cell junction and are then transferred to the uninfected cell. Other lymphotropic viruses, such as HIV-1, may similarly subvert normal T cell physiology to allow efficient propagation between cells.  相似文献