On pages 120-121, Dr. Sharon Moalem talks about the idea of "domesticating" bacteria by changing the course of their evolution toward strains of bacteria that are less harmful. This entails changing the manner in which the bacteria spreads so that it is a manner that is less harmful to humans but more advantageous to the bacteria. This relates to Big Idea 1 (The process of evolution drives the diversity and unity of life). Through the process of evolution, different strains of bacteria are created, which is an example of diversity. Through this diversity, scientists are hoping that populations of bacteria will become modified over generations to be less dangerous to humans.
Using your knowledge from the evolution unit as well as its specific terminology, describe how human-directed evolution of bacteria occurs. Explain why, as Dr. Moalem mentions, some pathogens, such as anthrax, can't be domesticated. Besides the bacteria mentioned in the book, find another type of bacteria that could be steered toward a milder variation and explain how this would happen, given that bacteria's method of spreading and other factors. Then think of one possible use that domesticating bacteria could have for humans outside of being milder.
Austin Hua (auhua4@students.d125.org)
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ReplyDeleteControlling bacteria by changing the course of their evolution toward strains of bacteria that are less harmful to humans but more advantageous to the bacteria can be related to big idea 1 (The process of evolution drives the diversity and unity of life) because the bacteria is evolving in its own. This human-directed evolutions of the bacteria is evidently mentioned from Unit 1 (Evolution) and Unit 3 (Cells, Membranes, and Transport): the relationship between mitochondria and chloroplasts were describes how a large host cell and ingested bacteria could easily become dependent on one another for survival-- to survive and to reproduce more. Endosymbiotic theory is a form of horizontal gene transfer as a critical step in the evolution of eukaryotic cells. Between different species of bacteria, this transfer of genetic material came to the attention of scientists because of its huge potential to play a major role in the spread of antibiotic cells.
ReplyDeleteAnthrax, the deadly bacteria, can exist outside a host for long period of time, which gets hard to affect virulence by reducing the pathogen’s transmission channels because of its ability to survive outside a host that enables to make it less concerned with transmission from an evolutionary perspective. A pathogen that can lie in wait for years until a potential host happens upon it isn’t very reliant on transmission pressure (122). There is another example: cholera. A microbe must balance the amount of harm it does to its unwilling host against its ability to transmit itself. Therefore, virulence remains high, and infected people suffer and die. When water is purified and kept clean, the microbe cannot spread quickly; Thus the bacteria that can spread are the milder form that do not kill their host.
Instead of using these weapons -- antibiotics and vaccines and hygiene improvements -- as a way of knocking down the organism, we can use those interventions to control the evolution of the organisms instead of getting the organisms evolving around our interventions. Making them evolve to be mild enough, “conventional” harmful organisms are already being used; later, we introduce those used organisms as a vaccine. We can get the organisms to evolve to be less harmful than they have been in the past and rather use interventions like vaccines or like hygienic improvements to domesticate these organisms.
http://www.pbs.org/wgbh/evolution/library/10/4/l_104_01.html
http://www.stat.rice.edu/~mathbio/Ochman2000.pdf
(Hyung Eun (Ginny) Lee, helee4@students.d125.org)