The head of the National Institutes of Health (NIH) is leaving the agency, he announced today, marking at least the second departure of a scientist from the Bush Administration in the last 24 hours.

Elias Zerhouni says he'll depart the NIH at the end of next month to write. His announcement on the NIH Web site, follows yesterday's resignation of Conrad Lautenbacher, chief of the National Oceanographic and Atmospheric Administration. Both were long-time Bush appointees, Zerhouni having served for six years and Lautenbach for seven.

"It's with mixed emotions that I move on," Zerhouni, 57, said in a press conference today, according to The Scientist, adding that he doesn't "have a job lined up."

Though he opposed limits on federally funded stem-cell research, it wasn’t until last year that Zerhouni split with President Bush and told Congress that the Bush administration ban on research that used embryonic lines created after Aug. 9, 2001 should be lifted.

"It is clear today that American science will be better served and the nation would be better served if we let our scientists have access to more cell lines," Zerhouni said then.  "It is very clear from my point of view that the current cell lines will not be sufficient to do the research we want to do…. It's not possible for me to see how we can continue the momentum of science and in stem cell research with the lines we currently have."

Zerhouni cracked down on ethics violations at NIH, including its researchers' membership on the boards of blockbuster pharmaceutical companies. He also backed a plan to use robots to test some toxic compounds instead of animals.

(Image of Elias Zerhouni by NIH)