Genetic susceptibility to systemic lupus erythematosus protects against cerebral malaria in mice.

Plasmodium falciparum has exerted tremendous selective pressure on genes that improve survival in severe malarial infections. Systemic lupus erythematosus (SLE) is an autoimmune disease that is six to eight times more prevalent in women of African descent than in women of European descent. Here we provide evidence that a genetic susceptibility to SLE protects against cerebral malaria. Mice that are prone to SLE because of a deficiency in FcγRIIB or overexpression of Toll-like receptor 7 are protected from death caused by cerebral malaria. Protection appears to be by immune mechanisms that allow SLE-prone mice better to control their overall inflammatory responses to parasite infections. These findings suggest that the high prevalence of SLE in women of African descent living outside of Africa may result from the inheritance of genes that are beneficial in the immune control of cerebral malaria but that, in the absence of malaria, contribute to autoimmune disease

Crop Updates 2000 - Oilseeds

This session covers seventeen papers from different authors: Introduction, Paul Carmody, Centre for Cropping Systems CANOLA AGRONOMY 2. Genotype, location and year influence the quality of canola grown across southern Australia, PingSi1, Rodney Mailer2, Nick Galwey1 and David Turner1, 1Plant Sciences, Faculty of Agriculture, The University of Western Australia, 2Agricultural Research Institute, New South Wales Agriculture 3. Development of Pioneer® Canola varieties for Australian market,Kevin Morthorpe, StephenAddenbrooke, Pioneer Hi-Bred Australia Pty Ltd 4. Canola, Erucic Acid, Markets and Agronomic Implications, Peter Nelson, The Grain Pool of Western Australia 5. The control of Capeweed in Clearfield Production System for Canola, Mike Jackson and ScottPaton, Cyanamid Agriculture Pty Ltd 6. Responsiveness of Canola to Soil Potassium Levels: How Low Do We Have To Go? Ross Brennan, Noeleen Edwards, Mike Bolland and Bill Bowden,Agriculture Western Australia 7. Adaption of Indian Mustard (Brassica juncea) in the Mediterranean Environment of South Western Australia, C.P. Gunasekera1, L.D. Martin1, G.H. Walton2 and K.H.M. Siddique2 1Muresk Institute of Agriculture, Curtin University of Technology, Northam, 2Agriculture Western Australia 8. Physiological Aspects of Drought Tolerance in Brassica napus and B.juncea, Sharon R. Niknam and David W. Turner, Plant Sciences, Faculty of Agriculture, The University of Western Australia 9. Cross resistance of chlorsulfuron-resistant wild radish to imidazolinones, Abul Hashem, Harmohinder Dhammu and David Bowran, Agriculture Western Australia 10. Canola Variety and PBR Update 2000, From The Canola Association of Western Australia 11. Development of a canola ideotype for the low rainfall areas of the western Australian wheat belt, Syed H. Zaheer, Nick W. Galwey and David W. Turner, Faculty of Agriculture, The University of Western Australia DISEASE MANAGEMENT 12. Evaluation of fungicides for the management of blackleg in canola, Ravjit Khangura and Martin J. Barbetti, Agriculture Western Australia 13. Impact-IFÒ: Intergral in the control of Blackleg, Peter Carlton, Trials Coordinator, Elders Limited 14. Forecasting aphid and virus risk in canola, Debbie Thackray, Jenny Hawkes and Roger Jones, Agriculture Western Australia and Centre for Legumes in Mediterranean Agriculture 15. Beet western yellow virus in canola: 1999 survey results, wild radish weed reservoir and suppression by insecticide, Roger Jones and Brenda Coutts, Agriculture Western Australia 16. Are canola crops resilient to damage by aphids and diamond back moths? Françoise Berlandier, Agriculture Western Australia ECONOMIC OUTLOOK 17. Outlook for prices and implications for rotations, Ross Kingwell1,2, Michael O’Connell1 and Simone Blennerhasset11Agriculture Western Australia 2University of Western Australi

Impact of Oxygen Transport Properties on Polypropylene Thermal Oxidation, Part 1: Effect of Oxygen Solubility

A general kinetic model is proposed to describe the polypropylene thermal oxidation of thin polypropylene films in a wide range of temperatures (from 60 to 200°C) and oxygen partial pressures (from 0.02 to 5 MPa) using a single set of parameters. This model was calibrated with several series of experimental data including analyses of primary (hydroperoxides) and secondary oxidation products (carbonyl species), and subsequent changes in macromolecular properties (average molecular masses). It predicts the experimental data previously published in the literature in terms of induction times and maximal oxidation rates. The variability of the oxygen solubility coefficient allows to explain the scattering of induction times and oxidation rates among the whole iPP family, but also the dependence of this latter quantity with oxygen partial pressure. This variability is presumably due to iPP polymorphism in the temperature range where oxygen permeability is commonly measured. It is concluded that the kinetic model can be used to study the direct effect of iPP morphology on its thermal oxidation kinetics (chemistry of oxidation)

The Formation of Collective Silk Balls in the Spider Mite Tetranychus urticae Koch

Tetranychus urticae is a phytophagous mite that forms colonies of several thousand individuals. These mites construct a common web to protect the colony. When plants become overcrowded and food resources become scarce, individuals gather at the plant apex to form a ball composed of mites and their silk threads. This ball is a structure facilitating group dispersal by wind or animal transport. Until now, no quantitative study had been done on this collective form of migration. This is the first attempt to understand the mechanisms that underlie the emergence and growth of the ball. We studied this collective behaviour under laboratory conditions on standardized infested plants. Our results show that the collective displacement and the formation of balls result from a recruitment process: by depositing silk threads on their way up to the plant apex, mites favour and amplify the recruitment toward the balls. A critical threshold (quorum response) in the cumulative flow of mites must be reached to observe the emergence of a ball. At the beginning of the balls formation, mites form an aggregate. After 24 hours, the aggregated mites are trapped inside the silk balls by the complex network of silk threads and finally die, except for recently arrived individuals. The balls are mainly composed of immature stages. Our study reconstructs the key events that lead to the formation of silk balls. They suggest that the interplay between mites' density, plant morphology and plant density lead to different modes of dispersions (individual or collective) and under what conditions populations might adopt a collective strategy rather than one that is individually oriented. Moreover, our results lead to discuss two aspects of the cooperation and altruism: the importance of Allee effects during colonization of new plants and the importance of the size of a founding group