Biophysical Society Bulletin | September 2018

Biophysicist in Profile

KhaledMachaca Areas of Research Role and regulation of cellular signaling in physiology and pathology

Institution Weill Cornell Medicine Qatar

At-a-Glance

Khaled Machaca took a somewhat unconventional path to his current career as a biophysicist, starting out studying agricultural engineering and poultry science before falling in love with research: “The rest is history, as they say.” After completing his PhD and beginning as a professor in the American south, he moved to Qatar and has been instrumental in establishing a biomedical research enterprise in the country.

Khaled Machaca

Khaled Machaca , professor of physiology and biophysics at Weill Cornell Medicine and associate dean of research at Weill Cornell Medicine Qatar, grew up in Beirut, Lebanon, with a successful homemaker mother and a father who was the director of commercial traffic at the Port of Beirut. Growing up, he did not have a particular passion for science or any real idea of what career he planned to pursue, but he always enjoyed the sciences in school more than writing, and he liked tinkering and fixing things in his spare time. He earned his bachelor’s degree in agriculture engineering from the American University of Beirut. “I had no intentions then to be involved in research as I was not familiar with what that would entail. Nonetheless, I was interested in pursu- ing graduate school out of a pure sense of seeking a better understanding of the science underlying approaches in the agriculture industry,” Machaca shares. “I chose to pursue an MS degree in Poultry Science [at the University of Georgia in Athens] with the thinking that this was a robust industry in Lebanon to pursue a career in.” Looking to make some money with a graduate assistantship, he was offered a research assistant position where he worked on biochemical mechanisms governing cell death. “The rest is history, as they say. I quickly developed a passion for research as a career path. So, after the completion of my MS studies I pursued a PhD in cell and developmental biology at Emory University,” he says. “At Emory I chose to work on the genet- ic mechanisms controlling C. elegans spermatogenesis and spermiogenesis. However, I realized quickly that although ge- netic approaches are extremely powerful, especially in model organisms like C. elegans , they were too slow for my taste as I needed more immediate feedback.” He combined the genetic approach with electrophysiological recordings on C. elegans sperm using the patch clamp technique, in the first patching experiments on sperm. “That was my first exposure to bio- physics. The ability to tweak and control experiments in real time was very appealing and made me switch my focus to the regulation of ionic currents in cellular physiology,” he shares.

Following completion of his PhD, Machaca pursued his post- doctoral work in the lab of Criss Hartzell at Emory, focusing on the role and regulation of Ca 2+ -activated Cl channels in the frog oocyte using Xenopus laevis as a model system. He then established his own lab as an assistant professor at the University of Arkansas for Medical Sciences. “I’ve had a long-standing interest in animal reproduction and gamete biology as early as my undergraduate days. Having done my PhD studies on the amoeboid worm sperm, I later focused on oocyte maturation, and in particular the regulation of Ca 2+ signaling pathways during this cellular differentiation pathway,” he explains. “When I started my own lab I was fas- cinated by the fact that Ca 2+ has been conserved throughout phylogeny as the signal that initiates egg activation and as such triggers organismal development through the egg-to- embryo transition. Hence, a Ca 2+ rise at fertilization provides the spark of life to initiate development. Nonetheless, the fully grown oocyte in the ovary is unable to respond properly to sperm or trigger egg activation. It requires a differentiation period know as oocyte maturation during which many signal- ing and morphological processes remodel in preparation for fertilization and embryonic development.” Machaca is now professor of physiology and biophysics at Weill Cornell Medicine and associate dean of research at Weill Cornell Medicine Qatar. When he moved to Qatar nearly a decade ago, there was very little scientific research estab- lished in the country. “We truly started that effort from the ground up. Contrary to the current situation, the research enterprise nationally in Qatar was practically non-existent at the time,” he shares. “The leadership in Qatar had an excep- tional vision driven by the Qatar Foundation to establish a research enterprise nationally, with the goal of transitioning away from an economy built solely on fossil fuels towards a knowledge-based economy.”

September 2018

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