My last post was concerned with the way mice regulate the set of bacteria which reside in their intestines. Which specific bacteria are present in one's gut is known to be predictive of obesity, but new research suggests that it isn't the bacteria themselves that are important so much as the genes that they carry1.
Scientists at Washington University in St. Louis studied the bacteria present in the intestines of pairs of twins (a useful methodology for exploring many kinds of similarities amongst individuals with similar genes) and their mothers, expecting to find that those who were obese would have similar species of gut flora (similarly expecting comparable special cross-sections in those who were not obese). Interestingly, they found that the set of bacteria differed widely, but that the core "bacteriome" (the set of all the genes in all the bacteria in a person's gut) was highly conserved across the obese (and separately across the non-obese). They further found that related individuals were more likely to harbor the same set of species.
This is not incredibly surprising. After all, the functional utility - in terms of digestive assistance, molecular synthesis, and nitrogen uptake - of these bacteria is defined by their genes. That is to say, bacteria can only be useful to us and our internal environment in that they are in possession of metabolic pathways that we lack. Furthermore, given the massive number of bacterial species, it is unsurprising that one person gets a specific part of the benefits from species A, while another person obtains that benefit from species B. It is a happy surprise to me that this research is progressing at an increasing pace. I hope it continues as such.
References:
1. Turnbaugh PJ, Hamady M, Yatsunenko T, Cantarel BL, Duncan A, Ley RE, Sogin ML, Jones WJ, Roe BA, Affourtit JP, Egholm M, Henrissat B, Heath AC, Knight R, Gordon JI. A core gut microbiome in obese and lean twins. Nature [Epub ahead of print], 2008.
1 comment:
Huh, this suggests to me that the bacteria may be evolving certain genes in response to their environment. In other words, the obesity may be causing the bacteria, rather than the reverse. Has this been investigated?
Interestingly, I have been looking into bacterial mutation/evolution in fluctuating environments such as the gut, in connection to my evolutionary dynamics work.
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