212 resultados para reproducible research


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This paper is a foreword to a series of papers commissioned on 'the impact of science on the beef industry', where the Beef CRC-related collaborative scientific work of Professor Bernard Michael Bindon will be reviewed. These papers will be presented in March 2006, as part of a 'festschrift' to recognise his wider contributions to the Australian livestock industries for over 40 years. Bindon's career involved basic and applied research in many areas of reproductive physiology, genetics, immunology, nutrition, meat science and more recently genomics, in both sheep and cattle. Together with his collaborators, he made large contributions to animal science by improving the knowledge of mechanisms regulating reproductive functions and in elucidating the physiology and genetics of high fecundity livestock. His collaborative studies with many colleagues of the reproductive biology and genetics of the Booroola Merino were amongst the most extensive ever conducted on domestic livestock. He was instrumental in the development of immunological techniques to control ovulation rate and in examining the application of these and other techniques to increase beef cattle reproductive output. This paper tracks his investigations and achievements both within Australia and internationally. In the later stages of his career he was the major influence in attracting a large investment in Cooperative Research Centres for the Australian cattle industry, in which he directed a multi-disciplinary approach to investigate, develop and disseminate science and technology to improve commercial cattle productivity.

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An improved method for counting virus and virus like particles by electron microscopy (EM) was developed. The procedure involves the determination of the absolute concentration of pure or semi-pure particles once deposited evenly on EM grids using either centrifugation or antibody capture techniques. The counting of particles was done with a Microfiche unit which enlarged approximately 50 x the image of particles on a developed negative film which had been taken at a relatively low magnification (2500 x) by EM. Initially, latex particles of a known concentration were counted using this approach, to prove the accuracy of the technique. The latex particles were deposited evenly on an EM grid using centrifugation (Modified Beckmen EM-90 Airfuge technique). Subsequently, recombinant Bluetongue virus (BTV) core-like particles (CLPs) captured by a Monoclonal antibody using a hovel sample loading method were counted by the Microfiche unit method and by a direct EM method. Comparison of the simplified counting method developed with a conventional method, showed good agreement. The method is simple, accurate, rapid, and reproducible when used with either pure particles or with particles from crude cell culture extracts.

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Phytophthora-resistant lucerne cultivars do not always perform well under conditions of high disease pressure in the field. To determine whether resistance expression remains stable under different infection intensities, tetraploid and diploid lucerne genotypes, genotypically defined for their reactions to Phytophthora medicaginis, were clonally propagated, and the influence of different reproducible inoculum levels (0 . 5 and 5 . 0 g dry weight mycelium/kg dry weight potting mix), the period of exposure to these levels (10-60 days), and temperature (16/22 degrees C and 24/30 degrees C) on disease expression was determined in controlled environments. Generally, expression of resistance by resistant genotypes, remained stable under these conditions. Biotic (e.g. Aphanomyces eutiches) or abiotic factors other than P. medicaginis may be responsible for the poorer than expected performance under field conditions in some instances, or the percentage of resistant plants in some cultivars currently classified as resistant is insufficient to provide buffering against productivity reductions under severe epidemics. Further research is needed to clarify the situation.

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This paper present: a synthesis of current research on the crocodilian cardiovascular system with a view to encourage discussion and debate about the intricacies of this unique system and to provide ideas and suggestions for future studies. Innovative experimental approaches combined with new technologies have helped to resolve the complex flow and pressure patterns observed during non-shunting conditions that predominate in resting instrumented animals and during pulmonary to systemic shunting, which has been observed to occur spontaneously and during diving. The mechanisms and structures that may induce and regulate shunting are presented and the functional significance of a pulmonary to systemic shunt is discussed. (C) 1997 Elsevier Science Inc.