A Gathering of NAS Members

It was a gathering of scientific giants.

Five UC Davis distinguished professors, all members of the National Academy of Sciences (NAS),  recently gathered at the home of UC Davis distinguished professor Walter Leal, newly elected member of NAS, to congratulate him, to orient him to NAS, to recommend committee memberships and to detail how the NAS election works.

Leal, with the Department of Molecular and Cellular Biology (MCB), is a former professor and chair of the Department of Entomology (now the Department of Entomology and Nematology). Among those attending was his 25-year friend and colleague, UC Davis distinguished professor Bruce Hammock, who holds a joint appointment with the Department of Entomology and Nematology and the UC Davis Comprehensive Cancer Center.  Hammock is a 25-year member of NAS.

It was Hammock who persuaded Leal to apply for UC Davis position and "lured" him way from his tenure in Japan.  Leal, a native of Brazil and the ifrst non-Japanese person to earn tenure at Japan's Ministry of Agriculture, Forestry, and Fisheries,  holds a Ph.D. in applied biochemistry from the University of Tsukuba, Japan, with subsequent postdoctoral training in entomology and chemical ecology at the National Institute of Sericultural and Entomological Science (NISES) and Cornell University, respectively. 

Election to NAS, a private, non-profit organization of the country's leading researchers, is considered one of the highest honors that a scientist can receive. They are elected for their distinguished and continuing achievements in original research. Current NAS membership totals approximately 2,400 members and 500 international members, of which approximately 190 have received Nobel prizes, according to the NAS website.  NAS "recognizes and promotes outstanding science" through election to membership; publication in its journal, Proceedings of the National Academy of Sciences (PNAS); and its awards, programs, and special activities.

The UC Davis group included:

• Distinguished professor Bruce Hammock, elected to NAS in 1999.
• Distinguished  professor emeritus J. Clark Lagarias of MCB, elected to NAS in 2001
• Distinguished professor emeritus Tilahun Yilma of the School of Veterinary Medicine and School of Medicine, elected  to NAS in 2004
• Distinguished professor Stephen Kowalczykowski of MCB and the Department of Microbiology and Molecular Genetics,  elected to NAS in 2007
• Distinguished professor Walter Leal of MCB, elected in 2024.  
   

Bruce Hammock,  Animal, Nutritional, and Applied Microbial Sciences   

When Hammock was elected in 1999, NAS posted his research interests as:
"My laboratory conducts three areas of research that are generally related to agriculture and that have both basic and applied aspects. The first of these is fundamental insect developmental biology, including the study of some of the enzymes involved in metamorphosis. An applied aspect of this work is the development of recombinant baculoviruses for insect control. The second area involves a study of enzymes of the alpha/beta hydrolase fold family of enzymes in vertebrates. This work includes the structural biochemistry of the enzymes, the alteration of their activities by exposure to foreign compounds, and their role in the metabolism of lipids in chemical mediation. The final area concentrates on the development of immunoassays and other biosensor systems for the detection of foreign chemicals in the environment, food, and human body fluids. These assays often represent a significant cost savings, especially when large numbers of samples are analyzed or when the analysis is done in developing countries. They also represent a way to monitor human exposure to pesticides and other foreign compounds." 

J. Clark Lagaria, Biochemist and Plant Biologist  
His research interests, as posted on the NAS website: 
"My laboratory's current research focuses on defining the rules for spectral tuning and signal transfer within the phytochrome photoreceptor superfamily leveraging the molecular diversity that has arisen in nature. We seek to understand the design principles that underlie the successful fusion of bilin-binding, light-input modules with diverse, often nucleotide-binding signal output modules, which include protein kinases, nucleotidyl cyclases, transcription factors, amongst others. By functioning as bistable photoswitches, members of the extended phytochrome superfamily sense the color, intensity, direction and predictable/random fluctuations of light in the natural environment to effect behavioral responses ranging from motility, feeding, reproduction, circadian clock entrainment to the initiation/arrest of key developmental transitions of eubacteria, plants, eukaryotic algae, and fungi. Our studies exploit the profound evolution of spectra tuning, range of light intensity range responsiveness and temperature dependence of extant phytochrome light sensing that have been shaped by the environments to which these organisms are best adapted."

Tlahun Yilma, Microbiologist, Virologist, Immunologist 
Research interests, as posted on the NAS website: 
"Dr. Yilma’s research focuses on the development of recombinant vaccines and rapid diagnostic kits for viral diseases of humans and animals. Among his notable accomplishments has been the development of a genetically engineered vaccine for a fatal cattle disease, rinderpest, which is caused by a virus. He also developed an inexpensive kit for quick diagnosis of rinderpest. The disease, brought to Ethiopia by three infected cows during the Italian invasion of 1888, had reached epidemic proportions throughout Africa before Dr. Yilma’s vaccine was introduced. He spent several years in the 1970s tracking the spread of the disease in Ethiopia and vaccinating cattle. In 1997 the vaccine was approved for use throughout Africa. The diagnostic kit and vaccine are now expected to eradicate rinderpest around the world. Dr. Yilma has developed vaccines and diagnostic tools for other diseases as well and is currently experimenting with recombinant DNA to create an effective vaccine for AIDS."

Stephen Kowalczykowski, Biochemist and Geneticist
Research interests, as posted on the NAS website: 
"I am interested in the chemistry and physics of life processes. I have focused on the biochemical mechanisms by which DNA is copied and maintained. DNA is broken almost every time a cell divides. Preservation of genetic information requires the repair of such DNA breaks, a chromosomal "restoration" that occurs by genetic recombination. My laboratory studies the biochemistry of recombinational DNA repair in prokaryotes, eukaryotes, and archaea. DNA recombination requires many protein machines acting in concert. We study proteins responsible for recognition of DNA sequence homology and exchange of DNA strands (RecA, Rad51, RadA); for annealing complementary strands of DNA (Rec0, Rad52, Rad59); for processing DNA breaks (RecBCD, RecQ-helicases); and for accelerating assembly and disassembly of the recombination machinery (RecFOR, Rad52, Rad54, RecQ-helicases, Srs2). Recently, we developed biophysical methods to visualize single molecules of these proteins in action - "visual biochemistry". This is achieved using a laser to trap an individual DNA molecule. Then, using fluorescence and microscopic imaging, we can visualize DNA motor proteins translocating along DNA strands - their "tracks". We also can build assemblies of individual proteins, one molecule at a time, on single DNA molecules to see their unique, rather than collective, dynamic behavior in real-time."

Walter Leal, Chemical Ecologist and Entomologist
NAS hasn't posted Leal's research interests yet, but Hammock provided this: "Walter is an internationally recognized entomologist and a world leader in his field for his groundbreaking and transformative research in insect olfaction and chemical ecology. He is truly a renaissance man. I've long admired (1) his rigorous fundamental research programs supported by National Science Foundation, National Institutes of Health, and the U.S. Department of Food and Agriculture, and other agencies, (2) how he tackles and solves multiple challenging problems in insect olfaction and chemical ecology, (3) his grasp of how to organize and moderate highly successful worldwide research webinars (4) his generosity in helping other succeed and (4) his finely honed sense of humor. Dr. Leal  solves entomological problems spanning agriculture, human health, and welfare. He translates pheromone technology to agriculturists and serves as a principal investigator for the  Pacific Southwest Regional Center of Excellence for Vector-Borne Diseases (affiliated with the Centers for Disease Control and Prevention).  He holds more than 20 patents.  I especially applaud him for elucidating the mode of action of the insect repellent DEET, developed in 1946 and known as ‘the gold standard of repellents.' Its mode of action remained an enigma for six decades until Walter's discovery. In researching the neurons in mosquito antennae sensitive to DEET, he isolated the first DEET-sensitive odorant receptor, paving the way for the development of better repellents.” (See news story on his election to NAS). 

Hammock successfully nominated Leal for the UC Davis Academic Senate's 2024 Faculty Distinuished Research Award.

Hammock Career Updates
Professor Hammock, who joined the UC Davis faculty in 1980, is an internationally recognized for discovering a new group of human chemical mediators. He co-discovered a human enzyme termed Soluble Epoxide Hydrolase (sEH), a key regulatory enzyme involved in the metabolism of fatty acids. It regulates a new class of natural chemical mediators, which in turn regulates inflammation, blood pressure and pain.  Hammock and his lab have been involved in enzyme research for more than 50 years. Hammock founded the Davis-based pharmaceutical company, EicOsis LLC, formed in 2011 to develop an orally active non-addictive drug for inflammatory and neuropathic pain. The former chief executive officer, he now serves on the board of directors.

Hammock directed the UC Davis Superfund Research Program (funded by the National Institutes of Health's National Institute of Environmental Health Sciences) for nearly four decades, supporting scores of pre- and postdoctoral scholars in interdisciplinary research in five different colleges and graduate groups on campus. He is a fellow of the National Academy of Inventors, Entomological Society of America, and the California Academy of Sciences.  He is the recipient of scores of awards, including the first McGiff Memorial Awardee in Lipid Biochemistry; and the Bernard B. Brodie Award in Drug Metabolism, sponsored by the America Society for Pharmacology and Experimental Therapeutics. At UC Davis he received the Distinguished Teaching Award and the Faculty Research Lectureship. In 2020, he received a Lifetime Achievement Award from UC Davis Chancellor Gary May.