OK. But the point is that these microorganisms were always present and have never changed. IOW, they always had to be present in every living organism with a digestive tract. And when you use terms such as mutualistic and symbiotic well that carries a lot of weight. The remain just as they always were and always will be - constant, never changing, never evolving. http://en.wikipedia.org/wiki/Gut_flora http://en.wikipedia.org/wiki/Microorganisms Without them there is no life - period. Moderator Note: This thread is split from Is a virus alive?
1. You're wrong. Microorganisms change constantly, all the time. Evolution (from selective pressures or otherwise) has been repeatedly observed in microorganisms because they have such short generation times. 2. What the FUCK are you going on about? Are you trying to make the argument that because two organisms depend on each for their existence now, there was no way for them to exist in the past without the other, in any other state than their current one? Because that one is pretty easily explained away. Nothing in my post is about gut flora or evolution. I simply gave an example where it was discovered the previously thought magical life force that was turning chunks of food into nourishment was actually a common laboratory chemical.
From my link: "Gut flora have a continuous and dynamic effect on the host's gut and systemic immune systems. The bacteria are key in promoting the early development of the gut's mucosal immune system both in terms of its physical components and function and continue to play a role later in life in its operation. The bacteria stimulate the lymphoid tissue associated with the gut mucosa to produce antibodies to pathogens. The immune system recognizes and fights harmful bacteria, but leaves the helpful species alone, a tolerance developed in infancy.[2][11][4][5] As soon as an infant is born, bacteria begin colonizing its digestive tract. The first bacteria to settle in are able to affect the immune response, making it more favorable to their own survival and less so to competing species; thus the first bacteria to colonize the gut are important in determining the person's lifelong gut flora makeup." No matter how long, be it millions of years\billions of years these organisms were just as they are from the very beginning. "Recent findings have shown that gut bacteria play a role in the expression of Toll-like receptors (TLRs) in the intestines, molecules that help the host repair damage due to injury. TLRs cause parts of the immune system to repair injury caused for example by radiation" There is no doubt of their function and this cannot be disputed, just as i said without there would not be one life, no humans, no fish - NOTHING. No you are wrong. Without these beneficial organisms that had to be present from the very beginning nothing with a stomach can survive adn if you think that the fundamental organisms that need to be present have changed then you dont even know the basics of life and its requirements. http://pruned.blogspot.com/2006/12/gut-flora.html
This part is your own addition, yes? Where does the source indicate that gut flora have somehow bypassed evolution? I'm going to predict that you misread this: "The first bacteria to settle in are able to affect the immune response, making it more favorable to their own survival and less so to competing species; thus the first bacteria to colonize the gut are important in determining the person's lifelong gut flora makeup." This pretty much spells out the struggle taking place within the digestive tract through which evolution takes place. It is the exact opposite of saying that gut flora are beyond evolution. You should start your own thread on this topic.
John, I'm not quite getting how you're making the jump from this: to this: Nowhere in your cited example was there any suggestion that these bacteria couldn't change. In modernity, for modern organisms. Now, in ages past, when the gut was first evolving, what then? Your argument only holds true if you presume that modern organisms were identical 600 million years ago. They were most definitely not. Way back, there were some bacteria, and some worms. The bacteria did their thing where they ate food where they could find it. Of course, being so tiny, they had trouble dispersing to other places where they could find more food. The worms had recently developed a specialized organ that allowed them to digest food- the gut. It excreted acid into a compartment where it put its food. Specialized cells would then absorb the nutrients. Previously, it has just excreted acidic mucous directly into the environment, but this worked much better. Now, a worm gains a mutation that allows some bacteria to live in its stomach, and some bacteria gains the ability to live in the worm. The bacteria produce novel enzymes that greatly increase what foods the worm can eat; the bacteria gain a place to live and all the food they need. There are, of course, problems, at first. Gut flora ends up eating the host. The host kills the gut flora. But if having bacteria in the gut outweigh the costs (there are always costs), then they stayed. And since those worms with the bacteria, and the bacteria with the worms did so well, they passed their genes down to the next generation. When those worms later became bigger, more complex organisms, the benefit of having gut flora was retained. All the way to people.
Yes it is my own addidtion but how could we know they were there if we didnt know what to look for? How did they evolve- how could they? Same digestive system with now upgrades, they disappear you have nothing but rocks and dry dirt. And what would they evolve into? http://www.actionbioscience.org/newfrontiers/jeffares_poole.html I say they are exactly like today, every different species providing a unique function. They dont think, there is no need to change, no battles. Roman, I never said they could not change but the benficial ones have not. And you are wrong to believe that they evolved because they are the reason we are here. Do you think they decided that 'hey this is a nice place to be, so we are going to evolve just to make Roman happy'. I dont think you are grasping their monumental importance.
http://en.wikipedia.org/wiki/Gut_flora http://en.wikipedia.org/wiki/Microorganisms Without them there is no life - period. What about on taking antibiotics for prolonged time? Do antibiotics not change microorganisms in GUT?
I attended this talk last week on intestinal microflora. Apaprently we all have a microflora fingerprint. That is, if fecal samples are collected on a regular basis and subjected to a DGGE (density gradient gel electrophosis, the bacterial rRNA migrate across the gel), the migration patterns are unique for the bacterial types, the density (or thickness of bands which shows the amount), and every person has a unique combination and amount of bacterial flora that is usually produced. Why this happens is still a mystery, since I cannot think why we should have such a consistent pattern of bacterial population. Interesting though. This is what the gel looks like; each column is a unique sample and the bands along the column represent different bacterial rRNA Please Register or Log in to view the hidden image! edit: Uh I forgot to say the subjects are on a strictly controlled diet. Its standard practice in such experiments.
Hmm, interesting. Do the same patterns reappear after the gut flora's been wiped with antibiotics? Would it have something to with a histo-compatibility complex? Did they do any of those allergy tests with different gut bacteria to see if people were more allergic to strains that they were never positive for? [edit] It appears that that is not addressed in the paper. Oh well.
The paper was just methods. The talk I attended is still unpublished data. (author Ariefdjohan, M) And yes, there was a washout period with antibiotics. She (the researcher) used some cool 3D graphics to show the patterns of repetition. On the same kind of diet, individuals faithfully replicated their microflora foorprint. This was a part of some other bigger study, so no allergen testing etc was done.
The bacterial rRNA are just the end product of feces processing used for DGGE. Probably because they have an rRNA library and can use it to identify the products. I haven't used the method myself but I assume they use PCR to get enough product to run a gel.
It's also standard practice to have control subjects who aren't on a special diet. How many control subjects are there?
As I said, it was just one part of a larger study, which was a randomised double blind crossover clinical trial. In long term administration, yes it does decrease them, but I'm not certain about the effects in the short term. ------------------------------------ Another interesting aspect of intestinal microflora, is the new wave of functional foods under the generic term "probiotics". Living cultures of "beneficial" bacteria that enhance digestion and boost immunity, added to foods to alter the microflora population in a favorable manner. Please Register or Log in to view the hidden image! I'm wondering what this means in the light of the yet unexplored observation of individual micorflora fingerprints.
Humans are loaded with bacteria, even after death. No bacteria, no life - PERIOD. Especially no new life, IOW's its over. Same bacteria as the first sign of life on the planet, this is how i know for a fact that the same exact type of bacteria present from day one is still here. We owe it all to bacteria Roman....EVERYTHING, every living creature, every breath you take, every glass of water you drink. Eat an apple BAM - bacteria, eat a bananna - BAM - bacteria. And when it leaves you - BAM - bacteria. I figure this out myself so if i am wrong, so be it. Now you, Roman, show me where i am wrong.
Thanks. What does mucosal immunity mentioned in conclusion of link prvided by you? Whether antibiotic effect alter mucus in intestines?
Just to clarify, rRNA sequences are diagnostic to specific species. DGGE is a quicker but less specific method to assess the population. rRNA is reversed-transcribed, usually subjected to nested PCR. In the end you got PCR products of a conserved region of the rRNA-gene which differs in few bases from species to species. This affect the melting behaviour of the resulting PCR products, which can be monitored in a denaturing gel. Unless you already know what populations exist a DGGE can not be used to unambigously identify the underlying species, though. In any case it is a well-known fact that diets change the gut flora (the working principle of pre-biotic foods). So much for the technical aspect. Now regarding the often repeated "no bacteria no life phrase used in this thread". In a way this is correct. The ecosystem would collapse without bacteria (in fact the atmosphere was shaped by bacteria). Also, eukaryotes would not exist (mitochondria). However, sterile organism can live on without gut or other bacteria, provided that they are protected from infections. Also the assumption that the present bacteria are the same as billions years ago is absolutely stupid. The first bacteria were likely to be anaerobic extremophiles which are now living for the most part restricted to certain niches. Now the majority of pioneer bacteria are aerobes, for examples, which of course did not exist since the first photosynthetic bacteria evolved. In fact you can see the little bugger changing over time even if you freeze them for a prolonged time. just my 2 cents.
