- Author: Kathy Keatley Garvey
And how do animals use changes in day length and temperature to adapt their physiology and behavior to seasonal environmental changes?
Those are the questions that UC Davis postdoctoral researcher Sergio Hidalgo Sotelo asked himself, and now newly published research that he spearheaded in the laboratory of molecular geneticist-physiologist Joanna Chiu—building on previous Chiu lab research--sheds more light on the topic.
The research article, “Seasonal Cues Act Through the Circadian Clock and Pigment Dispersing Factor to Control EYES ABSENT and Downstream Physiological Changes,” appears in the current edition of the journal Current Biology.
Sotelo, a Pew Latin American Fellow in the Biomedical Sciences fellow in the lab of Professor Chiu, vice chair of the UC Davis Department of Entomology and Nematology, collaborated with Chiu and two lab members: Christine Tabuloc, a doctoral candidate, and Maribel Anguiano, now a doctoral student in the UC Davis Neuroscience graduate program and a former member of National Institutes of Health Postbaccalaureate Research Education Program (PREP).
“This work,” Chiu said, “certainly helps us progress towards a more complete picture of how animal seasonality is regulated at the molecular and cellular level. Excitingly, it also raises many more interesting questions, which Sergio and our team cannot wait to answer.”
Organisms adapt to seasonal changes in photoperiod and temperature to survive; however, the mechanisms by which these signals are integrated in the brain to alter seasonal biology are poorly understood. We previously reported that EYES ABSENT (EYA) shows higher levels in cold temperature or short photoperiod and promotes winter physiology in Drosophila. Nevertheless, how EYA senses seasonal cues is unclear. Pigment-dispersing factor (PDF) is a neuropeptide important for regulating circadian output rhythms. Interestingly, PDF has also been shown to regulate seasonality, suggesting that it may mediate the function of the circadian clock in modulating seasonal physiology. In this study, we investigated the role of EYA in mediating the function of PDF on seasonal biology. We observed that PDF abundance is lower on cold and short days as compared with warm and long days, contrary to what was previously observed for EYA. We observed that manipulating PDF signaling in eya+ fly brain neurons, where EYA and PDF receptor are co-expressed, modulates seasonal adaptations in daily activity rhythm and ovary development via EYA-dependent and EYA-independent mechanisms. At the molecular level, altering PDF signaling impacted EYA protein abundance. Specifically, we showed that protein kinase A (PKA), an effector of PDF signaling, phosphorylates EYA promoting its degradation, thus explaining the opposite responses of PDF and EYA abundance to changes in seasonal cues. In summary, our results support a model in which PDF signaling negatively modulates EYA levels to regulate seasonal physiology, linking the circadian clock to the modulation of seasonal adaptations.”
Sotelo, who specializes in chronobiology (the study of biological rhythms), molecular genetics and biochemistry, won the 2021 Young Neuroscientist Symposium Award at the meeting of the Chilean Society for Neuroscience, Chile, and received a merit award for his presentation at the 2022 Society for Research on Biological Rhythms (SRBR) Biennial Conference in Amelia Island, Florida.
A native of Puente Alto, Santiago, Chile, Sotelo joined the Chiu lab as a postdoctoral fellow in the summer of 2020. He is one of 10 post-docs from across Latin America—including Argentina, Brazil, Chile, Mexico, Peru, and Uruguay—to receive two years of funding to conduct research. The fellows work under the mentorship of prominent biomedical scientists, including alumni of the Pew Scholars Program in the Biomedical Sciences.
Sotelo holds three degrees from Pontificia Universidad Católica de Chile: a bachelor's degree in biochemistry, with distinction (2015), a master's degree in neurochemistry (2017) and a doctorate in cellular and molecular biology, with distinction (2020). Also in 2020, he received a doctorate in sensory physiology and animal. Behavior from the University of Bristol, Bristol, UK.
EYES ABSENT and TIMELESS Integrate Photoperiodic and Temperature Cues to Regulate Seasonal Physiology in Drosophila, published June 15, 2020, Proceedings of the National Academy of Sciences (PNAS), lead author Antoine Abrieux and co-authors Joanna Chiu, Yao Cai, and Yongbo Xue.