Next up: a hypothesis for evolution of signaling by fatty acids

On tuesday November 15th, I will present a hypothesis for the evolution of inflammation from dietary fat, an idea I developed with coauthors Chris Kuzawa and Melissa Franklin.

The basic idea is thus: Humans have coevolved with commensal organisms and pathogens probably since our distant ancestors became multicellular. Today, our bodies are a habitat for a multitude of microbes and viruses, the majority of which inhabit the gut, making up a community known as the microbiome. It turns out that these microbes number as many as 100 trillion, and the sum of their genes outnumber human genes by a ratio of more than ten to one. Thus, for as long as humans and our predecessors have been eating, we have shared the food we eat with the bacteria in our guts.  Nutrients have Jekyll and Hyde characteristics on the microbiome, and are sometimes helpful and sometimes harmful. Those nutrients that enhance the barrier function of the gut and prevent pathogen colonization and growth have evolved a signaling function that is thrifty, reducing the costs of an immune defense. Nutrients that impair the barrier function of the gut and increase the risk of pathogen colonization and invasion have the opposite effects. In class, we will present evidence that pro-inflammatory and anti-inflammatory signaling by nutrients help compensate for the positive and negative influence that nutrients have on the microbiome.

I will present this hypothesis in the format that I expect you to use for your final presentations, with no more than 15 slides, and taking no more than 20 minutes. However, I will allow more time for discussion afterwards, than you will have for your presentations (professor’s prerogative)!

Eat well, my friends,

JA

P.S. Please read Cani and Delzenne. For your writing assignment, please answer the following question:

Writing assignment: Evidence suggests that a high fat diet changes the composition of the gut microbes. Please explain the effect of eating vegetables and whole grains (high fiber diet) on gut bacteria and the gut’s ability to keep bacteria and their breakdown products where they belong (in the gut).  Explain also why eating a double meat double cheese Lotaburger with fries might be bad for your gut.

1 point extra credit (no more than 1/2 page): In class today, we discussed how maternal delivery of resources to the fetus  (resulting in a big baby or a small baby) can result in developmental programming that can lead to diabetes and obesity down the line. We also mentioned that maternal nutrient transfer to offspring does not end with birth; it continues with breastfeeding. Knowing this, speculate on the effect of breastfeeding on a baby’s likelihood of developing later obesity and diabetes. Defend your answer.

Please remember, the purpose of these writing assignments is to make sure that you read the reading, synthesize the information, and explain the ideas using your own words. I encourage you to read the assignments carefully with plenty of time before class, and thoughtfully craft a brief, logical argument on this topic. A usual these are due in class, on 11/15/11, in hardcopy. Homework turned in after class will receive one point off for lateness, if turned in after 11/15/11 will receive one extra point off per day it is late.

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