Biophysical Society Bulletin | June 2023

Biophysicist in Profile

Sharyn A. Endow Areas of Research Molecular motor proteins and mechanobiology

Institution Duke University

At-a-Glance

Sharyn A. Endow , Full Professor of Cell Biology at Duke University, grew up in rural Oregon. “The nearest town was three miles from my home and had a population at the time of only around 300 people. My parents owned an orchard and raised apples, pears, and cherries. My parents’ land was near Mt. Hood and on a hill that overlooked the Hood River Valley—the views were spectacular,” she shares. “As a child, my siblings and I went on long walks along the irrigation waterways on my par ents’ property and played in the wooded areas, picking wild berries and hazelnuts. It was an idyllic childhood and far removed from the real world—in retrospect, it is amazing that I ended up doing scientific research in biophysics.”

Sharyn A. Endow

In high school, Sharyn A. Endow had a wonderful teacher who inspired her love of science. “Mr. Bill Griffith taught almost all my high school science courses. He taught Chemistry, Phys ics, and Science Seminar, in which a small group of students, including myself, learned semi-quantitative microanalysis as seniors in high school. We also did independent projects in Science Seminar. My projects included growing crystals from the chemicals in the supply room and culturing chick embry os in the laboratory,” she explains. “I submitted a project for the Westinghouse Science Talent Search and I was thrilled to be among the national semi-finalists and one of the Oregon state awardees my senior year.” Endow graduated as valedictorian from Wy’East High School in Hood River Valley, and then attended Stanford Universi ty for her undergraduate studies, majoring in biology. “The courses at Stanford were exceptionally well taught. I espe cially remember the course in evolutionary biology which was taught by Peter Raven and Paul Ehrlich , and a few other pro fessors, and the co-evolution of plants and pollinators, as well as the impact of population growth on the world,” she says. “As a senior, I took the biochemistry course that was given by the Biochemistry Department for the medical students. The faculty included Paul Berg , Arthur Kornberg , Dave Hogness , and other notable faculty from the Biochemistry Department in the Stanford University Medical School. The lectures were stories of discovery and insight into the impact of biochemis try in understanding the basis of human diseases. I still have my lecture notes from the course.” After completing her bachelor’s degree, she attended Yale University for graduate studies, earning a Master of Philoso phy and then a PhD in Molecular and Cell Biology. She recalls, “I was a thesis student of Joe Gall , who is a cell biologist and worked on problems that many of us as students thought were taken directly from E. B. Wilson ’s The Cell . Joe applied mo lecular biology methods to classical problems in cell biology and discovered ribosomal gene amplification in oocytes of

amphibia and other organisms, as well as the molecular basis of other classical cell biological observations.” Upon leaving Yale, Endow undertook a position as a postdoc toral fellow at Cold Spring Harbor Laboratory (CSHL) in the lab of Rich Roberts , where she learned molecular biology for just over a year. Her second postdoc was at the now-defunct MRC Mammalian Genome Unit in Edinburgh, Scotland under Peter M. B. Walker , where she worked in the laboratory of Ed Southern for two and a half years. “These were both forma tive experiences and extremely exciting for different reasons. CSHL was exciting because of both the cutting-edge science and the famous (and infamous) scientists who came to the Laboratory to attend the summer and fall CSHL meetings. A few of the scientists from the former Carnegie Institution of Genetics were still there, including Barbara McClintock and Alfred Hershey , both of whom I was awed to see, not to men tion to meet,” she says. “The MRC Genome Unit was exciting, again because of the science, and also because living in the UK and doing science there was so different from the USA. While I was in Edinburgh, I started working on the ribosomal genes (rDNA) of Drosophila and changes in rDNA copy num ber in polytene cells and during magnification, a genetically induced increase in rDNA gene number.” Endow’s next move was to begin a faculty position at Duke University, where she continued work on the mechanism of rDNA copy number regulation and then entered the field of motor proteins through molecular work in cloning a gene in Drosophila that affects rDNA number when mutated. “This gene turned out to encode kinesin-14 Ncd, which is an un usual kinesin microtubule motor protein in that it moves on microtubules in the opposite direction as kinesin-1, the first discovered member of the kinesin family. Cloning the gene took around five years, because this was before the genome sequencing projects. We first made a transposable ele ment-induced ncd mutant and then cloned the gene locus by chromosome walking from a previously cloned DNA fragment.

June 2023

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