The Howard Hughes Medical Institute announced today that one of the research foundation’s longtime investigators, Robert Tjian, would be its new president.

Mr. Tjian, a biochemist at the University of California at Berkeley, has worked as an HHMI investigator since 1987. He will succeed Thomas R. Cech, the president since 2000, who this year announced he was stepping down to work as a full-time researcher and professor at the University of Colorado at Boulder.

Mr. Tjian received his Ph.D. from Harvard University after studying biochemistry as an undergraduate at Berkeley and now serves as director of the Berkeley Stem Cell Center. He will take office on April 1, 2009.

The institute was founded by the aviator and filmmaker Howard Hughes in 1953 and employs about 350 researchers, including 12 Nobel Prize recipients. It has spent more than $8.3-billion on research over the last 20 years, according to a news release. —David DeBolt