5 resultados para 249

em Brock University, Canada


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Coarse grained sample with clasts ranging from small to medium. Clast shape ranges from angular to sub-angular. Lineations and rotation structures seen. Clay material and fine grained domains (darker colour) also seen.

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Members of the Allanburg Women's Institute sitting around a table.

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Fire blight is an economically important disease of apples and pears that is caused by the bacterium Erwinia amylovora. Control of the disease depends on limiting primaly blosson1 infection in the spring, and rapidly removing infected tissue. The possibility of using phages to control E.amylovora populations has been suggested, but previous studies have. failed to show high treatment efficacies. This work describes the development of a phage-based biopesticide that controls E. amylovora populations under field conditions, and significantly reduces the incidence of fire blight. This work reports the first use ofPantoea agglomerans, a non-pathogenic relative ofE. amylovora, as a carrier for E. amylovora.phages. Its role is to support a replicating population of these phages on blossom surfaces during the period when the flowers are most susceptible to infection. Seven phages and one carrier isolate were selected for field trials from existing collections of 56 E. amylovora phages and 249 epiphytic orchard bacteria. Selection of the . /' phages and carrier was based on characteristics relevant to the production and field perfonnance of a biopesticide: host range, genetic diversity, growth under the conditions of large-scale production, and the ability to prevent E. amylovora from infecting pear blossoms. In planta assays showed that both the phages and the carrier make significant contributions to reducirig the development of fire blight symptoms in pear blossoms. Field-scale phage production and purification methods were developed based on the growth characteristics of the phages and bacteria in liquid culture, and on the survival of phages in various liquid media. Six of twelve phage-carrier biopesticide treatments caused statistically signiflcant reductions in disease incidence during orchard trials. Multiplex real-time PCR was used to simultaneously monitor the phage, carrier, and pathogen populations over the course of selected treatments. In all cases. the observed population dynamics of the biocontrol agents and the pathogen were consistent with the success or failure of each treatment to control disease incidence. In treatments exhibiting a significantly reduced incidel1ce of fire blight, the average blossom population ofE.amylovora had been reduced to pre-experiment epiphytic levels. In successful treatments the phages grew on the P. agglomerans carrier for 2 to 3 d after treatment application. The phages then grew preferentially on the pathogen, once it was introduced into this blossom ecosystem. The efficacy of the successful phage-based treatnlents was statistically similar to that of streptomycin, which is the most effective bactericide currently available for fire blight prevention. The in planta behaviour ofE. amylovora was compared to that ofErwinia pyrifoliae, a closely related species that causes fire blight-like synlptoms on pears in southeast Asia. Duplex real-time PCR was used to monitor the population dynamics of both species on single blossonls. E. amylovora exhibited a greater competitive fitness on Bartlett pear blossoms than E. pyrifoliae. The genome ofErwinia phage Ea21-4 was sequenced and annotated. Most of the 8-4.7 kB genome is substantially different from previously described sequences, though some regions are notably similar to Salmonella phage Felix 01 . Putative functions were assigned to approximately 30% of the predicted open reading frames based on amino acid sequence comparisons and N-terminal sequencing of structural proteins.

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Owing to the fact that low-Mg calcite fossil shells are so important in paleoceanographic research, 249 brachiopod, cement and matrix specimens from two neighboring localities (Jemez Springs and Battleship Rock), of the Upper Pennsylvanian Madera Formation were analyzed. Of which, about 86% of the Madera brachiopods are preserved in their pristine mineralogy, microstructure and geochemistry. Cement and matrix samples, in contrast, have been subjected to complete but variable post-deposition~1 alteration. It is confirmed that the stable isotope data of brachiopods are much better than that of matrix material in defining depositional parameters. Because there is no uniform or constant relationship between the two data bases (e.g., from 0.1 to 3.0%0 for 0180 and from 0.2 to 6.7%0 for 013C in this study), it is not possible to make corrections for the matrix data. Regarding the two stratigraphic sections, elemental and petrographic analyses suggest that Jemez Springs is closer to Penasco Uplift than Battleship Rock. Seawater at Jemez Springs is more aerobic, and the water chemistry is more influenced by continental sources than that at Battleship Rock. In addition, there is a relatively stronger dolomitization in the mid-section of the Battleship Rock. Results further suggest that no significant biogenic fractionation or vital effects occurred during their shell secretion, suggesting that the Madera brachiopods incorporated oxygen and carbon isotopes in equilibrium with the ambient seawater. This conclusion is not only drawn from the temporal and spatial analyses, but also supported by brachiopod inter-generic comparison (Composita and Neospirifer) and statistical analysis ( t-test).

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Issues for the June 1813 Weekly Register newspaper (Baltimore, Maryland) are divided as follows: June 5th, pages 217-232 June 12th, pages 233-249 June 19th, pages 250-264 June 26th, pages 265-280 PLEASE CLICK ON THE WEEKLY PERIODICALS ON THE RIGHT OF THE SCREEN (PDF FILES)TO DOWNLOAD FILES. Look for other issues of the Weekly Register within this website. The Weekly Register, also known as Niles Weekly Register, was a weekly periodical edited by Hezekiah Niles (1777-1839) and published in Baltimore Maryland. Volumes of interest were published between 1811 (Vol. 1, No. 1, September 7, 1811) to 1814 (Vol. 5, No. 26, February 26, 1814). These volumes focus primarily on 19th century politics and government in the United States of America. Niles edited and published the Weekly Register until 1836, making it one of the most widely-circulated magazines in the United States. The popularity also made Niles into one of the most influential journalists of his day. Devoted primarily to politics, Niles' Weekly Register is considered an important source for the history of the period. The Register also recorded current economics, technology, science, medicine, geography, archaeology, the weather, and stories of human interest. Call Number: SPCL PER JK 1 N52