Time Flies, But How Do Flies Tell Time? Ask Yao Cai

If you attended the 2018 campuswide UC Davis Picnic Day and headed over to see the insects at Briggs Hall, home of the Department of Entomology and Nematology, you may have seen an enthusiastic drummer performing in The Entomology Band.

That was molecular geneticist Yao Cai, entertaining with several other members of the UC Davis Entomology Graduate Student Association (EGSA). He was dressed--quite appropriately, too--as a fruit fly, Drosophila melanogaster, which he described as “our favorite model organism in Insecta!” (See Bug Squad blog.)

Entomology Today, a publication of the Entomological Society of America, picked up the story, headlining it as "Bugs and Beats."

Now fast forward...past the two-year pandemic...and way over to 2022. Time flies, right?

Cai now holds a doctorate in entomology (as of September) and will present his exit seminar, "How Do Flies Tell the Time of Day?" at the next UC Davis Department of Entomology and Nematology seminar, set Wednesday, Oct. 26.

He will deliver his seminar both in-person and virtually at 4:10 p.m. in 122 Briggs Hall. The Zoom link:
https://ucdavis.zoom.us/j/95882849672.

Cai will be introduced by his major professor, molecular geneticist and physiologist Joanna Chiu, professor and vice chair of the department. 

"Circadian clocks time daily rhythms inorganismal physiology and behavior to optimize health and fitness," Cai says in his abstract. In Drosophila, phosphorylation regulates time-of-day function of core clock proteins, including the transcriptional activator CLOCK (CLK). However, it remains unclear whether CLK phosphorylation facilitates the closure of the negative feedback loop. In this study, we demonstrated casein kinase 1 alpha (CK1α) as a CLK kinase and mapped CK1α-dependent CLK phosphorylation sites using mass spectrometry. Our genetic and biochemical analyses revealed that upon CK1α phosphorylation at CLK(S13), CLK occupancy at circadian promoters decreases, thereby sequestering CLK transcriptional activity. Moreover, our results suggest that the transcriptional repressor PERIOD (PER) facilitates CK1α-CLK interaction."

"This study highlights the importance of post-translational regulation of circadian rhythms," Cao noted. "Finally, together with previous studies in fungi and mammals, our results suggest a conserved feature in eukaryotic clocks by which transcriptional repressors recruit CK1s to modulate the activity of transcription activators."

A native of southeast Asia, Cai holds two degrees from China Agricultural University, Beijing: a bachelor of science degree (2014) in plant protection and a master's degree in entomology (2016).

What sparked his interest in entomology? "The insect world presented to me the diversity of species when I was a kid," he related. "Since then, I have wondered about the origin and evolution of species. I was lucky to cultivate my interest as an undergrad and then a master student in Chinese Agricultural University. As a PhD student in the Department of Entomology andNematology at UC Davis, this interest expanded to the cellular and molecular mechanisms of evolution and adaptation. Upon my graduation in summer 2022, I continued my postdoctoral research in the Chiu lab. I hope this will prepare me to become a professor in biological sciences."

Cai completed an International Chronobiology Summer School (virtual) in 2020 and a UC Davis Comprehensive Course in Flow Cytometry in 2019. His publications include: 

• Cai YD*, Joshi R*, Xia Y, Chiu JC, Emery P (2022) PERIOD phosphoclusters control temperature compensation of the Drosophila circadian clock, Frontiers in Physiology. 13: 888262.
  
  
• Cai YD, Sotelo SH, Jackson K, Chiu JC (2022) Assaying circadian locomotor activity rhythm in Drosophila, in “Circadian Rhythms” in NeuroMethods series. ed. M. Hatori, T. Hirota, and S. Panda. Springer Nature, Switzerland.
  
  
• Cai Y.D., Y. Xue, C. Truong, J. Del-Carmen Li, C. Ochoa, J.T. Vanselow, K.A. Murphy, Y.H. Li, X. Liu, B.L. Kunimoto, H. Zheng, C. Zhao, Y. Zhang, A. Schlosser, J.C. Chiu (2021). CK2 inhibits TIMELESS nuclear export and modulates CLOCK transcriptional activity to regulate circadian rhythms. Current Biology 31(3): 502-514.
  
  
• Cai, Y.D., J.C. Chiu (2021). Timeless in animal circadian clocks and beyond. FEBS Journal (Online ahead of print). doi: 10.1111/febs.16253.
  
  
• Abrieux, A., Y. Xue, Y. Cai, K.M. Lewald, H.N. Nguyen, Y. Zhang, J.C. Chiu. (2020). EYES ABSENT and TIMELESS integrate photoperiodic and temperature cues to regulate seasonal physiology in Drosophila. Proceedings of the National Academy of Sciences. U.S.A. 117(26): 15293-15304. 

Active in academics, Cai served as a guest lecturer for Entomology 102 on the "Insect Nervous System" and for Entomology 10 on "Insect Circadian Rhythm." He also served as a teaching assistant for a number of UC Davis classes, including Applications, Values, and Ethics in Animal Research; Insect Physiology; Introduction to Biology: Ecology and Evolution; Introduction to Biology: Cell Functions; and Calculus for Biology and Medicine. In addition, he has assisted at Bohart Museum of Entomology open houses and at science program provided by Peregrine School, Davis.

Honored with a number of awards, Cai received a 2021 Chinese Government Award for Outstanding Self-Finance Students Abroad; a 2021 UC Davis Entomology W. Harry Lange, Jr. Memorial Travel Fund; 2021 UC Davis Marv Kinsey Scholarship; a 2020 Boroughs Welcome Fund Society for Research on Biological Rhythms (SRBR) Excellence Award; a 2020 UC Davis Sean and Anne Duffey and Hugh and Geraldine Dingle Research Fellowship; a 2019 UC Davis McBeth Memorial Scholarship; and a 2018 and 2017 UC Davis Henry A. Jastro Graduate Research Awards, among others.

Emily Meineke, assistant professor of urban landscape entomology, UC Davis Department of Entomology and Nematology, coordinates the department's seminars for the 2022-23 academic year. All 11 seminars will take place both person and virtually at 4:10 p.m. on Wednesdays in Room 122 of Briggs Hall except for the Nov. 9th and Dec. 7th seminars, which will be virtual only, she said.  (See list of seminars)

For further information on the seminars or to resolve any technical difficulties with Zoom, contact Meineke at ekmeineke@ucdavis.edu.