Wednesday, 21 May 2014

You Got Your Gut Bacteria From Mother's Mouth

Baby's first gut bacteria may come from mum's mouth - health - 21 May 2014 - New Scientist

A lovely example of how through evolution of 'selfish' genes over a prolonged period, humans, and very probably other placental mammals, have formed a mutually cooperative alliance with bacteria. Science has long recognised the role our microbiome of bacteria and fungi play in maintaining our health, and especially the role certain bacteria have in our gut where they are essential for absorbing some nutrients and vitamins.

Of course, there is no reason to think this system of mutual cooperation is unique to humans or even mammals since we share an essentially similar digestive system with all the deuterostome which are believed to have evolved some 558 million years ago, so it's a system which has been being refined and perfected for a very long time.

So how do we get our gut bacteria in early childhood? We have certainly acquired them within a few days of birth and it had been assumed babies are born with a sterile gut and acquire their bacteria from the mother's vagina during birth and from their general environment soon afterwards. Now, however a team led by Kjersti Aagaard of Texas Children's Hospital in Houston, Texas, USA has found that gut bacteria are present in meconium, the tary black fecal matter babies pass in the first day or two after birth which means they must have been present before birth.

Abstract
Humans and their microbiomes have coevolved as a physiologic community composed of distinct body site niches with metabolic and antigenic diversity. The placental microbiome has not been robustly interrogated, despite recent demonstrations of intracellular bacteria with diverse metabolic and immune regulatory functions. A population-based cohort of placental specimens collected under sterile conditions from 320 subjects with extensive clinical data was established for comparative 16S ribosomal DNA–based and whole-genome shotgun (WGS) metagenomic studies. Identified taxa and their gene carriage patterns were compared to other human body site niches, including the oral, skin, airway (nasal), vaginal, and gut microbiomes from nonpregnant controls. We characterized a unique placental microbiome niche, composed of nonpathogenic commensal microbiota from the Firmicutes, Tenericutes, Proteobacteria, Bacteroidetes, and Fusobacteria phyla. In aggregate, the placental microbiome profiles were most akin (Bray-Curtis dissimilarity <0.3) to the human oral microbiome. 16S-based operational taxonomic unit analyses revealed associations of the placental microbiome with a remote history of antenatal infection (permutational multivariate analysis of variance, P = 0.006), such as urinary tract infection in the first trimester, as well as with preterm birth <37 weeks (P = 0.001).

Copyright © 2014, American Association for the Advancement of Science.

K. Aagaard, J. Ma, K. M. Antony, R. Ganu, J. Petrosino, J. Versalovic, The Placenta Harbors a Unique Microbiome.
Sci. Transl. Med. 6, 237ra65 (2014).

To try to understand where they came from the team then examined the placenta from 320 women after birth, taking tissue samples from deep in the placenta to minimise the risk of contamination. Not only did they find bacteria present but they included the gut bacteria essential for metabolising nutrients and vitamins. However when they checked the genetic profile of these bacteria the result was even more surprising. They most closely resembled the bacteria normally found in the mouth, not the vagina. The conclusion was obvious, if more than a little surprising - bacteria must have travelled from the mothers' mouths to the fetal intestines, yet the only route must be via the mother's blood to the placenta and then either into the amniotic fluid to be swallowed by the fetus, or via the fetal circulation into the developing gut.

The placenta has its own ecology and these were not the bacteria we were expecting. Most people would have expected it to be a vaginal flora.

James Kinross, colon surgeon,
Imperial College, London, UK
The team also found that some species of bacteria were more common in the placentae of women who had delivered before 37 weeks, i.e., prematurely, suggesting a link between bacteria and premature birth which ties in with other findings showing a link between gum disease in women premature births.

So, knowing how fond creationists are of my blog, here's a little something for them to ponder on, and explain if they can. Why would an intelligent, benevolent creator invent this idiotic mechanism to help animals with guts absorb essential nutrients and vitamins from their food in the first place when it could have designed an efficient gut and why did it come up with a mechanism for getting these bacteria into the guts of developing fetuses which entails the risk of premature births and babies being born with serious illnesses?

There is, of course, no problem in understanding this as an evolved system in which the benefits outweigh the risks and which 'favours' only those genes which result in more descendants. Our guts evolved in the presence of bacteria, some of which had a utility value in helping us absorb certain nutrients which in turn removed any pressure to evolve more complex solutions and so we became committed to that evolutionary pathway. Cooperative alliances between replicators, even replicators from different species, are absolutely what the selfish gene view of Darwinian evolution predicts.

I appreciate it can't be easy trying to force-fit these little pieces of scientific evidence into a primitive superstition, but never-the-less, I'd appreciate if it a creationist or two could try.

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2 comments :

  1. Yes, Rosa, there are - and will always be - lots of details that creationists or ID-iots can't explain. But they believe they know all the correct answers since religious faith is about believing, not about knowing.

    BTW: Here is another good article about this topic: http://holysmoke.org/cretins/cre.htm .

    And now an interesting article about, at least partly, much of the same topic you brought up, Rosa, with yesterday's brand new blog article: Check out: http://www.nytimes.com/2013/05/19/magazine/say-hello-to-the-100-trillion-bacteria-that-make-up-your-microbiome.html?emc=tnt&tntemail1=y&_r=1& .

    That essay is about our microbiota and microbiomes, i.e. the several hundred microbial species with whom we share our bodies).

    Here are some thrilling quotes from that essay, to enjoy and be ravished by.

    1) It turns out that we are only 10 percent human: for every human cell that is intrinsic to our body, there are about 10 resident microbes — including commensals (generally harmless freeloaders) and mutualists (favor traders) and, in only a tiny number of cases, pathogens. (MY REMARK: It won't be easy for God and His angels to resurrect our bodies and at the same time give those bodies back their "normal" microbiota and microbiomes. But as we all know: For Almighty God nothing is impossible. But it will surely take some time to get all these bacteria, which number around 100 trillion, in place again so that we can feel that this is really our old body, now resurrected.)

    2) To the extent that we are bearers of genetic information, more than 99 percent of it is microbial. And it appears increasingly likely that this “second genome,” as it is sometimes called, exerts an influence on our health as great and possibly even greater than the genes we inherit from our parents. But while your inherited genes are more or less fixed, it may be possible to reshape, even cultivate, your second genome. (MY REMARK: You see, our omniscient God has already made it possible to reshape and re-create our microbiota and microbiomes. It will go like clockwork on Resurrection Day.)

    To be continued.

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  2. Here are four more quotes from the same essay (and with my remarks).

    3) [W]hen the contents of a lean donor’s microbiota were transferred to the guts of male patients with metabolic syndrome, the researchers found striking improvements in the recipients’ sensitivity to insulin, an important marker for metabolic health. Somehow, the gut microbes were influencing the patients’ metabolisms. (MY REMARK: Maybe the trick for God and His angels is to work with fecal transplants. A dirty and filthy task, I'm the first one to admit that, but we all also know that God loves His creation - so what?)

    4) Our resident microbes also appear to play a critical role in training and modulating our immune system, helping it to accurately distinguish between friend and foe and not go nuts on, well, nuts and all sorts of other potential allergens. Some researchers believe that the alarming increase in autoimmune diseases in the West may owe to a disruption in the ancient relationship between our bodies and their “old friends” — the microbial symbionts with whom we coevolved. (MY REMARK: In short: This work of recreating the microbiome and microbiota is nothing for careless fellows. I therefore expect that God and His angels are, and act, more like very responsible brain surgeons.)

    5) [It's a] remarkable process by which a baby’s gut community, which in utero is sterile and more or less a blank slate, is colonized. This process begins shortly after birth, when a distinctive infant community of microbes assembles in the gut. Then, with the introduction of solid food and then weaning, the types of microbes gradually shift until, by age 3, the baby’s gut comes to resemble an adult community much like that of its parents.(MY REMARK: A very smart solution, indeed, but on Resurrection Day this process must of course be much quicker, so I think that God must try something else then. Oh, how i look forward to Resurrection Day to see God in action.)

    6) Babies born by Caesarean, however, a comparatively sterile procedure, do not acquire their mother’s vaginal and intestinal microbes at birth. Their initial gut communities more closely resemble that of their mother’s (and father’s) skin, which is less than ideal and may account for higher rates of allergy, asthma and autoimmune problems in C-section babies: not having been seeded with the optimal assortment of microbes at birth, their immune systems may fail to develop properly. (MY REMARK: Does this mean that God is against Caesarean births? What's your idea about that, Rosa?)

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