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Small Things Considered
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- February 14, 2011
- 12:00 PM
- 1,196 views
The Great Epidemic
by Merry Youle in Small Things Considered
When you read the title—The Great Epidemic—what came to mind? The Black Death (Yersinia pestis) that in two years killed 20 million people in Europe—approximately 30-60% of the population? The 1918 flu pandemic with its tally of 50 million dead in three years? AIDS, with a death toll projected to reach 200 million by 2025? Or perhaps that 20th century epidemic that struck down over three and a half billion in North America in the space of a few decades—the American chestnut blight? These chestnut trees, Castanea dentata to be precise, were stately giants often 100 feet or more in height with crowns that spanned 100 feet. Their straight trunks provided billions of dollars worth of beautiful, rot-resistant wood, and the bountiful nuts provided far more than the traditional stuffing for Thanksgiving turkeys. Combined they had made up a quarter of the forest canopy from Maine to Mississippi.... Read more »
Dawe AL, & Nuss DL. (2001) Hypoviruses and chestnut blight: exploiting viruses to understand and modulate fungal pathogenesis. Annual review of genetics, 1-29. PMID: 11700275
- January 31, 2011
- 12:00 PM
- 514 views
Hedging Your Bets
by Merry Youle in Small Things Considered
Bacteria that are born genetically equal aren't necessarily the same. The same genome, residing in cells side-by-side in the same medium in the same flask, does not guarantee the same phenotype. One example that comes to mind is the persisters in E. coli populations—the small number of cells that spontaneously stop growing. If the population is hit by a β-lactam antibiotic, those cells escape death. Similarly, under lab conditions that trigger genetic competence in B. subtilis, only a small fraction of the cells make the switch to competence.
B. subtilis cells growing in a rich growth medium offer yet another example. Here genetically identical cells comprise two distinct types. Most are flagellated and actively swimming about as individuals, while a minority have no flagella and form long chains. The game is different in cells in the stationary phase where virtually all of the cells are found in long chains, bound together by an abundant matrix. Losick, Kolter, and colleagues have been working with this system for some years (for earlier papers, click here and here) seeking to determine how such bimodal cell populations are established and maintained in growing cultures.... Read more »
Chai Y, Norman T, Kolter R, & Losick R. (2010) An epigenetic switch governing daughter cell separation in Bacillus subtilis. Genes , 24(8), 754-65. PMID: 20351052
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