Viruses' Life History: Towards a Mechanistic Basis of a Trade-Off between Survival and Reproduction among Phages [Article]
PLoS Biology
13 June 2006
Marianne De Paepe, François Taddei
Life history theory accounts for variations in many traits involved in the reproduction and survival of living organisms, by determining the constraints leading to trade-offs among these different traits. The main life history traits of phages—viruses that infect bacteria—are the multiplication rate in the host, the survivorship of virions in the external environment, and their mode of transmission. By comparing life history traits of 16 phages infecting the bacteria Escherichia coli, we show that their mortality rate is constant with time and negatively correlated to their multiplication rate in the bacterial host. Even though these viruses do not age, this result is in line with the trade-off between survival and reproduction previously observed in numerous aging organisms. Furthermore, a multiple regression shows that the combined effects of two physical parameters, namely, the capsid thickness and the density of the packaged genome, account for 82% of the variation in the mortality rate. The correlations between life history traits and physical characteristics of virions may provide a mechanistic explanation of this trade-off. The fact that this trade-off is present in this very simple biological situation suggests that it might be a fundamental property of evolving entities produced under constraints. Moreover, such a positive correlation between mortality and multiplication reveals an underexplored trade-off in host–parasite interactions.
Agencies to Monitor Wyoming Birds for Flu
Associated Press (Posted by billingsgazette.com)
13 June 2006
Ben Neary
Several government agencies plan to monitor wild and domestic bird populations in Wyoming for avian influenza, officials said Tuesday. Speaking at a news conference in Casper, officials emphasized that the H5N1 bird flu strain hasn't been found in North America and isn't considered a threat in Wyoming.
The virus has spread widely around the Eastern Hemisphere, however, sickening and often killing dozens of people who had contact with infected poultry. The concern is that bird flu could mutate into a form that could pass easily between people.
Wyoming Game and Fish Department spokesman Eric Keszler said the department plans to begin testing samples from geese starting this month. He said the procedure doesn't harm the birds.
Government Must Grasp Wildlife Controls
Western Mail (Posted by icWales.co.uk)
13 June 2006
Farmers are urging the Government to speed up a targeted cull of diseased badgers in the struggle against bovine TB. The call comes amid warnings that the epidemic of bTB could jeopardise new export markets.
Wales chief veterinary officer Christianne Glossop revealed that Brussels had tried to raise the issue during negotiations to lift the 10- year ban on British beef exports.
"I'm pretty sure that over the next year or so there will be huge pressure from Europe for us to have a TB eradication programme," she told the Farmers' Union of Wales annual meeting in Aberystwyth.
Efforts to tackle the problem by culling suspected cases in farm animals have failed to halt the spread of a disease that was almost completely eradicated by the early 1970s, but now cripples 706 Welsh farms, with 14,798 cattle under movement restrictions.
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