Fighting "The Glaze"
Flannery, Maura C., The American Biology Teacher
I love protein structure, but my students don't find it quite as fascinating as I do--to say the least. However, one thing many of us do agree on is that we like coffee. I know this because I often meet students in the coffee line at one of the cafes that have sprung up around campus. They are ordering elaborate, caffeine-laced concoctions while I'm getting a medium decaf. The beauty of biology is that I'm able to use this coffee mania to elicit a little interest in protein structure, while throwing in some immunology and zoology to boot. The link here is a new caffeine test being developed to monitor whether or not decaf drinks really are decaffeinated. The test is based on llama antibodies against caffeine. Yes, llama antibodies--isn't biology wonderful! Some llama antibodies are composed of heat-resistant chains of amino acids. Antibodies to caffeine from other animals are presently used in tests, but these proteins denature at the high temperatures of hot coffee (Webb, 2006). Antibodies from llamas and their fellow camelids, camels, retain their activity at temperatures up to 90[degrees]C, which makes for pretty hot coffee. Researchers are now working on a dipstick assay for random testing of decaf right in a cafe.
In the Gut
This item on llamas is the sort of rather useless but interesting information that can make my day. I may use it in my class because of its relationship to protein folding and how heat causes protein denaturation. It is also a good example of employing biological material in chemical tests, something that is becoming more and more common. The reason why I'm not positive that I'll mention this in class is that there are so many wonderful ideas like this afloat in the literature that it's easy to inundate, and even drown, students in information. But such items are great to keep in mind for those days when "the glaze" is particularly rife. This phenomenon is on my mind because I've had several conversations with faculty recently about what to do to counter those glaze-eyed stares that are the bane of every teacher. There are many remedies, most of them involving active learning--getting students to sit up, think, do, and learn. However, it's often good to start the ball rolling with a tasty bit of information. In this column, I'll share a few I've come across, that I, at least, find interesting, and some have even been student-tested. For example, they sat up and took notice on one particularly bleak and cold winter morning when I mentioned that more than 2000 bacterial species live on and in the average human--definitely a factoid with "yuck" value, and one that's a great lead-in to a discussion of the digestive system, since so many of these bugs live happily there.
Discussing gut bacteria can also lead to immunology since Margaret McFall-Ngai (2007) contends that the rich bacterial diversity in the vertebrate gut, much greater than in invertebrates, could explain the development of immunological memory. Invertebrates, which harbor a relatively sparse number of gut bacterial species, only possess innate immunity that is not adaptive like that in vertebrates. McFall-Ngai argues that adaptive immunity, involving antibodies and immunological memory, is an adaptation to the development of complex bacterial communities of coevolved species that are beneficial to their host. These microbes produce needed substances like vitamins and also aid in digestion. In humans, such communities are composed no only of bacteria but of archaea and protists as well; all work together to break down complex carbohydrates (Hooper, 2006). In order to accommodate such diverse organisms in the body, the immune system had to become flexible, that is, adaptive.
Another attention grabber is new research indicating a link between gut flora and obesity (Bajzer & Seeley, 2006). Firmicutes and Bacteroidetes are the two predominant microbiota in both mice and humans, and in both species the Firmicutes are more abundant in the guts of obese individuals. …