Two professors at UC Davis have been elected to prestigious professional academies. Stephen Kowalczykowski, who studies the molecular machines that copy and repair DNA, has been elected to the National Academy of Sciences. Charles "Chuck" Langley, an expert on evolution and population genetics, has been elected to the American Academy of Arts and Sciences.

Kowalczykowski is a distinguished professor in the sections of Microbiology and of Molecular and Cellular Biology in the College of Biological Sciences. Langley is a distinguished professor in the Section of Evolution and Ecology and the Center for Population Biology, also in the College of Biological Sciences.

"We feel quite honored that the two UC Davis faculty recognized this year by these prestigious academies are distinguished professors of the College of Biological Sciences," said dean Ken Burtis.

"Professor Kowalczykowski is an internationally renowned scholar whose group has used novel single-molecule techniques to answer fundamental questions that simply could not be addressed using previously available methods," Burtis said. "And Professor Langley has been a pioneer in integrating the fields of molecular biology and population genetics, and more recently in applying the powerful tools of genomics to understand genetic variation in populations."

Kowalczykowski learned of his election to the national academy when he was awakened shortly after 6 a.m. May 1 by congratulatory phone calls from colleagues on the East Coast.

"I'm certainly honored to be chosen by such an impressive group of scientists," he said.

Errors in copying or translating DNA can lead to cancer and birth defects. Working with Ron Baskin, professor of molecular cell biology, Kowalczykowski's lab developed techniques to study this process at the level of single molecules, providing new insights into fundamental biology.

Kowalczykowski calls this work "visual biochemistry," because he can literally watch the machinery that makes life possible at work. For example, his lab has extensively studied a bacterial enzyme called RecBCD, which unwinds the DNA double helix. The single-molecule approach has allowed them to understand how two parts of RecBCD act as motors that run along the DNA strands, and to see how a specific sequence of DNA can switch off those motors, causing the enzyme to slow down or stop.

The Kowalczykowski lab is working toward reassembling the entire process, which includes DNA molecules and dozens of proteins, in the test tube.

Some of the key proteins involved in DNA repair in humans have recently been linked to breast cancer. Kowalczykowski, whose work has been continuously supported by the National Institutes of Health since 1981, said that this showed how decades of basic science contribute to understanding human health.

Kowalczykowski received his bachelor's degree from Rensselaer Polytechnic Institute in New York in 1972 and a doctorate in chemistry and biochemistry from Georgetown University in Washington, D.C., in 1976. He was a faculty member at Northwestern University, Chicago, from 1981 to 1991, when he joined UC Davis. He is a fellow of the American Association for the Advancement of Science and of the American Academy of Microbiology. He was elected as a member of the American Academy of Arts and Sciences in 2005.

Langley said he was "honored and happy" to be elected to the American Academy of Arts and Sciences, noting that many people had contributed to his work over the years. "I think it reflects an appreciation of the science," he said.

Working mostly with the Drosophila fly, Langley seeks to understand the forces that shape genetic variation in natural populations, or how and why individuals are different.

In the past few years, geneticists have gone from having a tiny window on the genome to having the biological equivalent of a telescope that can see the whole heavens, he said. Researchers can compare whole genomes to see where variation occurs. Some parts of the genome are clearly under strong pressure from natural selection, while others appear to have no apparent function and accumulate random changes. With new tools, scientists are learning how to interpret these changes.

"It's becoming more and more exciting as more comes into view," he said.

Langley received his bachelor's degree in zoology from the University of Texas, Austin, in 1968 and his doctorate from the same university in 1971. He was a research scientist at the National Institute of Environmental Health Sciences, part of the National Institutes of Health, from 1973 until he joined UC Davis in 1989. In 1999, he received the Genetics Society of America Medal.

Founded in 1780, the American Academy of Arts and Sciences includes about 4,000 active members and 600 foreign associates drawn from a wide range of fields. Among the eclectic list of 227 new fellows and associates elected this year are former Vice President Al Gore; retired U.S. Supreme Court Justice Sandra Day O'Connor; filmmakers Robert Redford and Spike Lee; John Lasseter of Pixar Studios; and Eric Schmidt, president and chief executive officer of Google. Twelve members of the UC Davis faculty, including Langley, are current members of the academy.

The National Academy of Sciences was established in 1863 with a congressional charter to advise the nation on scientific matters. This year, the academy elected 72 new members, bringing the active membership to 2,025. Including Kowalczykowski, 34 UC Davis faculty are now members of the academy or its sibling organizations, the Institute of Medicine and the National Academy of Engineering.