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In Memoriam: Robert Blair Painter, PhD

robert painter

We are sad to announce the passing of one of UCSF’s memorable and esteemed researchers, Dr. Robert B. Painter, who worked at UCSF from 1965 until retirement. Bob was a professor in the Department of Microbiology and a researcher in the Laboratory of Radiobiology and Environmental Health. At the “Rad Lab,” Bob created a special place where he influenced an entire generation of young scientists through mentorship. Today, few know that this small building located between the nursing and dental buildings was the site of important advances in radiation biology and DNA repair that were foundational to understanding and treating human cancers.

His colleagues at the “Rad Lab” have written the following eulogy:

Although he would be the last to tell you, Bob was famous for many key discoveries which laid the groundwork for the fields of DNA repair and the cellular response to DNA damage.

  • In the 1950s, he was part of the team at Brookhaven National Laboratory that first synthesized tritiated thymidine, a radioactive DNA precursor, and used it to study DNA replication (Hughes, Bond, Brecher, Cronkite, Painter, Quastler and Sherman, PNAS. 44:476 1958). This achievement was instrumental in defining and quantifying the cell cycle, and in demonstrating that chromosomes segregated as if they were single double helical DNA molecules.

  • At the NASA Ames Research Center, his research on the incorporation of tritiated thymidine into DNA in cells not in the DNA synthesis phase of the cell cycle, called unscheduled DNA synthesis, provided the first evidence that human cells were capable of DNA repair (Rasmussen and Painter, Nature 203:1360, 1964). Bob also used ionizing radiation to demonstrate that the replication of DNA was organized in domains with multiple replicating units (Painter and Rasmussen, Nature 201:162, 1964).

  • After moving to UCSF, he demonstrated that cells from people with the genetic disease Ataxia-Telangiectasia failed to delay DNA synthesis in response to ionizing radiation, termed radioresistant DNA synthesis. This was the first demonstration that the gene for Ataxia-telangiectasia, now known to be ATM, was a key player in cell cycle regulation in response to DNA damage (Painter and Young, PNAS 77:7315, 1980).

    • Other major discoveries in the Rad Lab that can be attributed to his mentorship include:

      • The human disease Xeroderma Pigmentosum was due to a defect in DNA repair, which was the first demonstration that DNA repair was involved in human disease

      • Ionizing radiation could induce persistent genomic instability

      • The health effects of incorporated radioisotopes

      • The alternative pathway for telomere maintenance in human cells, now called the ALT pathway

Acknowledging Bob’s tremendous role in radiation biology, the Radiation Research Society awarded him their highest honor in 1985, the Fialla Memorial Lecture.

Bob was outstanding role model and scientist and those who knew him will never forget the impact that Bob had on their careers. He was especially loved by the young scientists at the Rad Lab; he was a character who could always be counted on for an honest opinion, which could be very direct and displeasing. However, all who trained under him knew that under his gruff exterior was a caring and thoughtful person. Some saw his tough outlook on life as a result of his World War II experience while others attributed his gentler side to his wonderful wife Norma. Regardless, Bob created an environment for flourishing scientific discovery where young scientists thrived and people met and became friends and collaborators. His lab’s Friday afternoon beer and wine parties were a primary gathering place and many late night poker games were held at Bob and Norma’s house.

The nurturing side of Bob would surprise many scientists in the field of radiation biology as Bob was formidable in his direct questioning of speakers. However, his questions always went to the heart of the issue, addressing key points that had been overlooked or ignored. Bob was so well-known for encouraging open and free discussion that the Radiation Research Society initiated the “Painter Debate’ which addressed controversial topics at its annual meeting.

Bob will be lovingly remembered as a wonderful person who was also a great scientist.