Sunday, June 3, 2012

Microbes within us

Microbes have a very long history associated with human beings. In a human there are about 10^13 cells and about 25,000 genes, but within our GI Tract there are about 10^14 cells of bacteria, about 1000 species with about 2,500,000 genes. Research into what Pasteur and Koch called the "germ theory of disease," which is that diseases are caused by agents that could fester and grow and to help with any disease you must find the culprit behind it. This was the beginning of seriously looking into what caused the sicknesses many become inflicted with. Not until Flemming accidentally discovered Penicillin and found that it possessed antibacterial properties were many infections able to be treated rather than resulting in death. 
            There is a problem inflicting on the world of today though, what penicillin used to destroy is now resistant to it and many of the microbes that used to exist have gone extinct. Dr. Karen Guillemin asked, "Are human activities causing microbe extinction?" in her talk on May 29, 2012. Each human being is different in many ways, including the microbes that live on and within us, but could exposure to certain microbes, diet and genetic make-up factor into our microbe composition and how does this composition change through time? This question is still up in the air, but this is not the only question, there are many about the microbes and how they effect our lives through the health and sicknesses we endure.
            It has been found that the mode of a person’s birth, C-section versus vaginal birth, has substantial effects on the microbiota of the baby. A C-section has been shown to expose the baby to microbiota on the skin before any others, while a vaginal birth has been shown to expose the baby to microbiota in the vagina before any others. Researchers have not shown how this affects a baby later in life, but it could have an effect. Nursing of a baby provides nutrients, such as sugars, to the microbes living within the baby’s gut. Could breastfeeding effect what microbes are found in the baby’s gut later in life? Would it be different for a baby not breastfed? It has been shown in mice that diets do influence the guts microbial community, based on what food is given and the complexity of the food. Today our food is much more processed than ever before, could this be killing necessary microbes to keep us healthy and not allergic to foods? 

Bacterial 16S rRNA gene surveys reveal that the first microbiotas of human newborns are primarily structured by delivery mode. (A) Communities clustered using principal coordinates analysis of the unweighted UniFrac distance matrix. PC1 and PC2 are plotted on x- and y-axes. Each point corresponds to
a community colored according to the mother’s body habitat or the newborn’s delivery mode. All newborn body habitats are shown. The percentage of variation explained by the plotted principal coordinates is indicated on the axes. The white arrow indicates a pair of superimposed points. Vaginal samples were not obtained from two of the mothers who delivered by C-section.
Dominguez-BelIo, M. , Costello, E. , Contreras, M. , Magris, M. , Hidalgo, G. , et al. (2010). Delivery mode shapes the acquisition and structure of the initial microbiota across multiple body habitats in newborns. Proceedings of the National Academy of Sciences of the United States of America, 107(26), 11971-11975.
            Dr. Guillemin discussed David Strachan’s hygiene hypothesis, saying that if we live in a cleaner world/ environment we are no longer being exposed to allergens or microbes good and bad that could actually help us. Dr. Guillemin has done research on Zebrafish, a model organism, to learn about microbiota in the gut. This research has found that the gut environment influences the gut microbe community, which influences gut health. Her research engineered a zebrafish that is germ-free. This germ free zebrafish has been looked at to discover the impacts of gut bacteria and lack there of. Our microbiota is very important to our health and much research has been done that says microbes may affect us being prone to diseases. At the end of her talk she talked about things we can be doing today to cultivate the microbes in our gut, such as using antibiotics sparingly, and to avoid foods that our grandparents microbes would not recognize, i.e. stay away from super processed foods.  

The gut associated microbiota of a zebrafish larva. Bacteria are in red, nuclei are in blue, and fish tissue is in green.

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