Co-investigator Tami Lieberman says the images spark the curiosity of lay and professional viewers alike.<\/span><\/p>\n\u201cThis is a stunning demonstration of how quickly microbes evolve,\u201d said Lieberman, who was a graduate student at the Kishony lab at the time and is now a postdoctoral research fellow at MIT. “When shown the video, evolutionary biologists immediately recognize concepts they\u2019ve thought about in the abstract, while non-specialists immediately begin to ask really good questions.\u201d<\/span> \n<\/span> \n<\/b>Bacteria On the Move <\/b><\/p>\n Beyond providing a telegenic way to show evolution, the device yielded some key insights about the behavior of bacteria exposed to increasing doses of a drug. Some of them are:<\/span><\/p>\n\nBacteria spread until they reached a concentration (antibiotic dose) in which they could no longer grow.<\/span><\/li>\nAt each concentration level, a small group of bacteria adapted and survived. Such resistance occurred through the successive accumulation of genetic changes. As drug-resistant mutants arose, their descendants migrated to areas of higher antibiotic concentration. Multiple lineages of mutants competed for the same space. The winning strains progressed to the area with higher drug dose, until they reached a drug concentration at which they cannot survive. <\/span> \n<\/span><\/li>\nProgressing sequentially through increasingly higher doses of antibiotic, low-resistance mutants gave rise to moderately resistant mutants, which eventually spawned highly resistant strains able to fend off the highest doses of antibiotic.<\/span> \n<\/span><\/li>\nUltimately, in a dramatic demonstration of acquired drug resistance, bacteria spread to the highest drug concentration. In the span of 10 days, bacteria produced mutant strains capable of surviving a dose of the antibiotic trimethoprim 1,000 times higher than the one that killed their progenitors. When researchers used another antibiotic\u2014ciprofloxacin\u2014bacteria developed 100,000-fold resistance to the initial dose.<\/span><\/li>\nInitial mutations led to slower growth\u2014a finding that suggests bacteria adapting to the antibiotic aren\u2019t able to grow at optimal speed while developing mutations. Once fully resistant, such bacteria regained normal growth rates. <\/span> \n<\/span><\/li>\nThe fittest, most resistant mutants were not always the fastest. The fittest mutants stayed behind weaker strains that braved the frontlines of higher antibiotic doses.<\/span><\/li>\n<\/ul>\nThe classic assumption has been that mutants that survive the highest concentration are the most resistant, but the team\u2019s observations suggest otherwise.<\/span><\/p>\n\u201cWhat we saw suggests that evolution is not always led by the most resistant mutants,\u201d Baym said. \u201cSometimes it favors the first to get there. The strongest mutants are, in fact, often moving behind more vulnerable strains. Who gets there first may be predicated on proximity rather than mutation strength.\u201d<\/span> \n<\/span><\/p>\nCo-investigators included Eric Kelsic, Remy Chait, Rotem Gross and Idan Yelin.<\/span> \n<\/span><\/p>\nThe work was supported by the National Institutes of Health under grant R01-GM081617 and by the European Research Council FP7 ERC Grant 281891.<\/span> \n<\/span><\/p>\nHarvard Medical School (<\/span><\/i>http:\/\/hms.harvard.edu<\/span><\/i><\/a>) has more than 9,500 full-time faculty working in 10 academic departments located at the School\u2019s Boston campus or in hospital-based clinical departments at 15 Harvard-affiliated teaching hospitals and research institutes: Beth Israel Deaconess Medical Center, Boston Children\u2019s Hospital, Brigham and Women\u2019s Hospital, Cambridge Health Alliance, Dana-Farber Cancer Institute, Harvard Pilgrim Health Care Institute, Hebrew SeniorLife, Joslin Diabetes Center, Judge Baker Children\u2019s Center, Massachusetts Eye and Ear\/Schepens Eye Research Institute, Massachusetts General Hospital, McLean Hospital, Mount Auburn Hospital, Spaulding Rehabilitation Network and VA Boston Healthcare System.<\/span><\/i><\/p>\n\n","protected":false},"excerpt":{"rendered":"
A Cinematic Approach to Drug Resistance Scientists film bacteria\u2019s maneuvers as they become impervious to drugs At a glance: Scientists at Harvard Medical School and Technion-Israel Institute of Technology have built a giant Petri dish to help visualize how bacteria move as they become immune to drugs. The device represents a new, more realistic, platform… Continue Reading A Cinematic Approach to Drug Resistance<\/span><\/a><\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[24],"tags":[],"class_list":["post-84163","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"acf":[],"yoast_head":"\nA Cinematic Approach to Drug Resistance - \u05d4\u05d8\u05db\u05e0\u05d9\u05d5\u05df-\u05de\u05db\u05d5\u05df \u05d8\u05db\u05e0\u05d5\u05dc\u05d5\u05d2\u05d9 \u05dc\u05d9\u05e9\u05e8\u05d0\u05dc<\/title>\n \n \n \n \n \n \n \n \n \n \n \n \n\t \n\t \n\t \n