Researchers led by Graham Walker, a Howard Hughes Medical Institute (HHMI) professor and American Cancer Society research professor at the Massachusetts Institute of Technology, have discovered the first known mutant bacteria with a specific defect in a gene involved in the least-understood part of B12 synthesis. They report their findings in the early online edition of the Proceedings of the National Academy of Sciences, published February 20, 2006. HHMI professors are leading research scientists who received $1 million grants from the Institute to find ways to bring the excitement of the research lab into undergraduate science classrooms.

In the ancient world, B12 was probably catalyzing reactions before cells even existed. Now, all animals need B12 to help make the building blocks of DNA, and children need enough of the vitamin to help their brain develop normally. Most people consume enough B12 through animal products or fortified foods in their diet. On the other hand, animals that do not eat other animal products acquire the nutrient from bacteria in their guts or from bacteria-infected dirt on their plant food. An estimated one-quarter of people older than 60 in this country have trouble absorbing B12. B12 deficiency can lead to nerve damage, anemia, and forgetfulness.

Walker's team's genetic discovery was made possible by a gimmick Walker designed to capture the attention of undergraduate biology students in the early 1980s. When he added a laundry whitener to a lab dish, the symbiotic bacteria he studied glowed in ultraviolet light, just as the additive makes clothes look brighter in the sun.

The teaching trick soon became a popular to
'"/>

Contact: Jennifer Donovan
donovanj@hhmi.org
301-215-8859
Howard Hughes Medical Institute
21-Feb-2006