in the Dec. 23 issue of Nature, the researchers show that a jumping
gene called Hermes, still active in the common house fly, creates
changes in DNA very much like those created by the process behind
"Hermes behaves more like the process used by the immune system to
recognize a million different proteins, called antigens, than any
previously studied jumping gene," says Nancy Craig, Ph.D., professor of
molecular biology and genetics in Johns Hopkins' Institute for Basic
Biomedical Sciences and a Howard Hughes Medical Institute investigator.
"It provides the first real evidence that the genetic processes behind
antigen diversity might have evolved from the activity of a jumping
gene, likely a close relative of Hermes."
Recognition of so many antigens allows the immune system to fight
infection and distinguish friend from foe. The "big picture" behind
this ability is that cells build proteins called antibodies that bind
to particular antigens, but the early steps of that process have been
difficult to study. Hermes should help reveal some secrets of this
process, the researchers say.
"The immune system takes an approach to protein building similar to
that of diners creating a meal at a cafeteria, but how the immun