Iron / Living Things

    Survival of the Sickest was an interesting read. It was made clear from the introduction where the author's message was heading: it spoke of how Dr. Sharon Moalem witnessed the long sickness and struggle of his grandfather, who eventually succumbed to Alzheimer's disease. As a fifteen year old, he intuited a connection between his grandfather's blood disease, hemochromatosis, and the onset of dementia. This early hunch was substantiated by research he did as a PhD candidate, by which he discovered that there was a link between hemochromatosis and certain types of Alzheimer's disease. 

     In the following chapter, he states that "Parasites hunt us for our iron; cancer thrives on our cells. Finding, controlling, and using iron is the game of life. For bacteria, fungi, and protozoa, human blood and tissue are an iron gold mine" (6). Upon reading this statement, the book The Selfish Gene by Richard Dawkins came to mind. This publication similarly makes a rather weighty statement concerning one player, so to speak, belonging to a unfathomably large living system. In the moment of reading the statement that finding, controlling, and using iron was "the game of life", I was unsure whether it was hyperbole or simply an amazing fact, or if I was reading the entire thing wrong. 

     I tried to find some literature online about whether bacteria in general-- whether their entire life cycle-- was based on the obtainment of iron. The 2008 Science Daily article How Some Bacteria May Steal Iron From Human Hosts summarizes an effort made by a research team at Syracuse University to investigate how certain types of gram positive bacteria obtain iron from their environments. The lead researcher, Robert Doyle, comments that "iron is the single most important micronutrient bacteria need to survive" (SD). According to the article, iron is not easily accessible to bacteria living in soil or in humans. Much iron available in the soil is bound as "iron-citrate". With the knowledge that citrate was a substance that cells use as an energy source, the research team tried to uncover whether bacteria in human hosts also metabolized it. They discovered that some bacteria are equipped with a gene enabling the harvest of iron from human hosts in a "unique and energy efficient manner" (SD). Their experiments also demonstrated that citrate was ignored when it was not bonded to iron or bonded to other metals. 

     The article reinforced Moalem's argument concerning iron. I better understood his point that our dependency on iron gives a "proverbial leg up to just about every biological threat to our lives" (19).