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Author Topic: Now that food is plentiful, do we need symbiotic bacteria?  (Read 2465 times)

Offline ironmunya

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munya toby  asked the Naked Scientists:
   
Hey Chris

Just wondering, I understand we evolved with these microbes, and that its a recent thing that food became plentiful.

Why haven't our immune systems realized that we don't have to tolerate intracellular pathogens, and why don't macrophages change their modus operandi, given the abundance of energy.

cheers

Ironmunya

What do you think?
« Last Edit: 18/06/2010 22:30:03 by _system »


 

Offline LeeE

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Now that food is plentiful, do we need symbiotic bacteria?
« Reply #1 on: 19/06/2010 16:14:43 »
When did food become plentiful?  A lot of starving people around the world would disagree with that assertion.
 

Offline ironmunya

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Now that food is plentiful, do we need symbiotic bacteria?
« Reply #2 on: 25/06/2010 21:35:47 »
Ok, true, many will disagree with my assertion. I may have to tidy things up a bit.

Listed are some definitions, Intracellular pathogen: a microbe capable of causing host damage whereby the lifestyle in the host is associated with intracellular residence,survival, or replication
Pathogen: a microbe capable of causing host damage
Obligate intracellular pathogen: a microbe capable of causing host damage that is completely dependent on a host cell for survival and replication(Casadevall 2008)
In a Nature Genetics article, the author states, “Co-evolution can occur between any interacting populations: prey and predator, plant and herbivore, competitors or mutualists, but it is expected to be particularly important in host–pathogen systems because of the intimate nature of the association and the strong selective pressures that each can exert on the other”.(Woolhouse, Webster et al. 2002)

Regarding to the future of co-evolution, the author highlights some of the difficulties in demonstrating co-evolution, as stated, “Part of the problem is that there are many reasons why demonstrating co-evolution involving vertebrate hosts may be particularly difficult: lack of understanding of either the genetics or molecular basis of the host–pathogen interaction; involvement of polygenic traits; fitness constraints on these traits, including constraints imposed by simultaneous interactions with
multiple hosts or multiple pathogens; phenotypic plasticity; and the long time scales involved.

The method with which each pathogen is able to establish its self  is unique and complex, but each organism has become successful at exploiting a niche. I cannot imagine that some of these pathogens will continue to be able to exploit these niches forever as we continue to evolve alongside them. Changes have to happen at a genetic level, and a molecular approach to understanding the complex interactions between host and organism is required.

Casadevall, A. (2008). "Evolution of Intracellular Pathogens." Annual Review of Microbiology 62(1): 19-33.
   
Woolhouse, M. E. J., J. P. Webster, et al. (2002). "Biological and biomedical implications of the co-evolution of pathogens and their hosts." Nat Genet 32(4): 569-577.
 

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Now that food is plentiful, do we need symbiotic bacteria?
« Reply #2 on: 25/06/2010 21:35:47 »

 

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