Molecular geneticist-physiologist Joanna Chiu, Professor and Chair of the UC Davis Department of Entomology and Nematology, is the 2023 faculty recipient of the Chancellor's Award for Excellence in Mentoring Undergraduate Research.  

The three-pronged Chancellor's Award, launched in 1994, annually honors three outstanding mentors: a graduate student; a postdoctoral fellow or project scientist; and a faculty member.

Professor Chiu, who joined the faculty in 2010, focuses her research on the molecular and cellular biology of circadian rhythms and seasonal rhythms.

Chiu lab member and doctoral candidate Christine Tabuloc, who will be receiving her PhD this month, nominated her for the award. A team of five other Chiu lab alumni submitted a group letter of recommendation.

"I joined Dr. Chiu's laboratory at the beginning of my second year here at UC Davis and remained a member of the lab for 3 years as an undergraduate, 2 years as a technician, and 6 years as a graduate student," Tabuloc wrote. "Throughout all my time in the Chiu lab, Joanna has never failed to amaze me with her kindness, patience, and her consistency and perseverance in helping all students, both in her lab and in other labs, succeed. I cannot think of anyone more deserving of this award than Dr. Chiu."

"Dr. Chiu welcomed me into her lab back in 2012," Tabuloc related. "I had just finished my first year of college, and I had virtually no research experience. Despite this, Joanna took a chance on me and invited me to join her lab. Throughout the years, Joanna has taught me many skills—both at the bench and skills that translate outside the lab and even beyond academia. Joanna has taught me everything I know from performing an experiment with all the proper controls to mentoring students and giving effective and clear presentations. What makes her so outstanding is her commitment to helping us improve as scientists and researchers and preparing us for our future career endeavors."

"She has taught me many technical skills at the bench, but more than that, she has taught me how to be an effective teacher and mentor to the undergraduate students I work with. She has encouraged me to learn new molecular techniques that are in high demand so that I will be prepared and competitive for jobs after I graduate. ;a I am immensely grateful that Joanna took a chance on me—someone who didn't even know what a pipet was—and work tirelessly to help me be the best scientist I can be...It is her consistent encouragement and constructive criticism that has allowed me to grow into the scientist I am today. After 11 years under her wing, I am leaving UC Davis with a B.S and soon, a PhD, and I owe all my success to Dr. Chiu and her incredible mentoring. It is because of her that I am an author on 14 publications—2 of which I authored as an undergraduate—and that I can be competitive in the job market."

Tabuloc praised Professor Chiu for teaching her effective communication, organization, time and personnel management, and resilience.

"One thing that I find unique about Joanna is her ability to see our potential before we even see it in ourselves," Tabuloc wrote. "Joanna often says that once we step into the doors of the lab, we are no longer students rather, we are scientists. She encourages us to think like scientists and gives everyone equal opportunity to pursue their scientific questions of interest and carry out independent projects."

"Not only have I experienced Dr. Chiu's mentorship first-hand, but I have also had the privilege of watching her mentor all the undergraduate students that have joined her lab throughout the years. In fact, since my time here, I have watched at least 35 undergraduates be mentored by Joanna, and many of these students were authors on publications in peer-reviewed journals such as Scientific Reports, Journal of Pest Science, BMC, Ecology, Current Biology, Nature Communications, Journal of Economic Entomology, and PLOS Genetics. More so, a true testament to her success as an undergraduate mentor are her students' successes: furthering their education at academic institutions such as Cornell, Stanford, Columbia, UCB,  and UCLA or landing industry jobs at companies such as 10X Genomics. Many of these students still keep in contact with Dr. Chiu, and she continues to provide advice and guidance such as reviewing resumes and helping them prepare for interviews. Joanna is not just our mentor when we are at UCD, she is our mentor for life."

Group Letter. The former lab members who teamed to write the group letter, all praised her impactful influence--her mentoring, her encouragement, her constructive feedback, and her strong support:

• Lisa Soyeon Baik, now a postdoctoral fellow at the Carlson lab, Department of Molecular, Cellular, and Developmental Biology, Yale University
• Daniel Ewels-Labolle, PhD student at Cornell 
• Jessica West, PhD student at Cornell
• Katherine "Katie" Freitas, PhD student at Stanford University
• Kiya Jackson, who received her bachelor's degree in biological sciences,  then joined the UC Davis Postbaccalaureate Research Education Program, and will be heading to UCLA for her PhD

"She helped me to gain confidence and to envision myself as a scientist. She not only gave me a start in my scientific career, but her mentorship has far exceeded my time in her laboratory. She has continually supported me through graduate school and now as a postdoctoral researcher."--Lisa Soyeon Baik

"I can say without a shadow of a doubt that I would not have been able to get to where I am now without Joanna's mentorship, advice and overwhelming support."--Daniel Ewels-Labolle

"As a PhD student at Cornell, I am immensely grateful for the training I received as an undergrad from Dr. Chiu. Not only did she train me thoroughly in basic biochemistry and molecular biology techniques, but she also pushed me to be independent and think critically about my science, skills essential for graduate school."--Jessica West

"Beyond teaching me practical research skills, Dr. Chiu helped to spark the most important thing a person needs to be a successful scientist: pure joy in the pursuit of knowledge."--Katie Freitas

"I believe Dr. Chiu is a valuable mentor for undergraduate researchers because she offers her time and expertise to train well-rounded scientists, regardless of the stage at which they start their career and regardless of what career they hope to pursue."--Kiya Jackson

Chiu joined the Department of Entomology and Nematology in 2010 as an Assistant Professor, and advanced to Associate Professor and Vice Chair in 2016, and to Professor and Vice Chair in 2021. She was named one of 10 UC Davis Chancellor's Fellows in 2019, a five-year honor awarded to associate professors who excel in research and teaching. The UC Davis Academic Senate honored her with a Distinguished Teaching Award, Graduate/Professional category, in 2022.

Chiu co-founded and co-directs (with professors Jay Rosenheim and Louie Yang) the campuswide Research Scholars Program in Insect Biology, launched in 2011 to provide undergraduates with a closely mentored research experience in biology. The program's goal is to provide academically strong and highly motivated undergraduates with a multi-year research experience that cultivates skills that will prepare them for a career in biological research.

Chiu received her bachelor's degree in biology and music from Mount Holyoke College, Mass., and her doctorate in molecular genetics in 2004 from New York University, New York. She trained as a postdoctoral fellow from 2004 to 2010 in molecular chronobiology at the Center for Advanced Biotechnology and Medicine, at Rutgers, the State University of New Jersey.

(See feature on Bug Squad)

Kyle Lewald, doctoral candidate in the laboratory of UC Davis molecular geneticist/physiologist Joanna Chiu, will present his exit seminar at 4:10 p.m., Wednesday, Feb. 22 in 122 Briggs and also on Zoom. The link is:
https://ucdavis.zoom.us/j/95882849672. 

His title: "Using Genomic Data to Understand and Prevent the Spread of Tuta absoluta." He will be introduced by Chiu, professor and vice chair, UC Davis Department of Entomology and Nematology. A pre-seminar coffee will take place from 3:30 to 4:10 in Briggs 158. 

T. absoluta, a species of moth in the family Gelechilidae, is a pest of tomato crops in its larval stage. It is also known as a tomato leafminer.

"Tuta absoluta is a serious agricultural pest of tomato plants," Lewald says in his abstract. "While initially discovered in Peru, it has rapidly invaded tomato fields around the world over the past century, causing widespread damage to the industry. The recent affordability of whole genome sequencing of insects opens the door to a wide number of applications to understand and control this pest."

"Using long read sequencing, we produced and annotated a highly contiguous T. absoluta genome assembly. Sequencing of individuals collected across many locations in Latin America allowed us to investigate population structure and diversity levels, as well as identify divergence times and possible migration events occurring between regions. Understanding these historical events can be key to predicting and preventing future invasion events. We also used comparative genomics between morphologically similar gelechiid species to develop efficient molecular diagnostics, allowing field researchers and stakeholders to identify Tuta absoluta rapidly to support quarantine and treatment efforts."

Lewald's research interests include studying population genetics and developing molecular diagnostics of pest insects. He received his bachelor's degree in molecular and cell biology from UC Berkeley in 2016. After studying circadian rhythms in sorghum with UC Berkeley professor Frank Harmon, he became interested in animal clock systems and joined the Chiu Lab in 2018.  

He has published his work in several journals: 

• Lewald, K. M., A. Abrieux, D. A. Wilson, Y. Lee, W. R. Conner et al., 2021 Population genomics of Drosophila suzukii reveal longitudinal population structure and signals of migrations in and out of the continental United States. G3 Genes|Genomes|Genetics jkab343.
• Lewald, K. M., and J. C. Chiu, 2020 Harnessing Transcriptomics to Study Insect Biology, in Transcriptomics in Entomological Research, CABI, Oxfordshire, UK.
• Tabuloc, C. A., K. M. Lewald, W. R. Conner, Y. Lee, E. K. Lee et al., 2019 Sequencing of Tuta absoluta genome to develop SNP genotyping assays for species identification. Journal of Pest Science. 
• Gao, J., J. Sasse, K. M. Lewald, K. Zhalnina, L. T. Cornmesser et al., 2018 Ecosystem Fabrication (EcoFAB) Protocols for The Construction of Laboratory Ecosystems Designed to Study Plant-microbe Interactions. JoVE 57170.

The UC Davis Department of Entomology and Nematology's winter seminars are held on Wednesdays at 4:10 p.m. in 122 Briggs Hall. All are virtual. A pre-seminar coffee is held from 3:30 to 4:10 p.m. in 158 Briggs. Urban landscape entomologist Emily Meineke, assistant professor, coordinates the seminars. (See schedule.) She may be reached at ekmeineke@ucdavis.edu for technical issues.

Doctoral candidate Christine Tabuloc of the laboratory of molecular geneticist and physiologist Joanna Chui, professor and vice chair of the UC Davis Department of Entomology and Nematology, will present her exit seminar at 4:10 p.m., Wednesday, Feb. 15 in 122 Briggs Hall.

Tabuloc's topic is "Environmental and Anthropogenic Impact on Insect Gene Expression and Physiology." Her seminar also will be virtual. The Zoom link:
https://ucdavis.zoom.us/j/95882849672. 

Tabuloc will be introduced by Professor Chiu, her advisor. A pre-seminar coffee session is set from 3:30 to 4:10 p.m. in Briggs 158. 

"Natural environmental factors and anthropogenic disturbances can modulate gene expression, resulting in alteration of organismal phenotype," Tabuloc says in her abstract. "In the first part of my thesis project, I used Drosophila melanogaster as an insect model to understand the mechanisms by which 24-hour light-dark cycles can regulate rhythmic changes in the chromatin to generate circadian rhythms of gene expression and orchestrate daily biological rhythms. I observed that two clock proteins, CLOCK and TIMELESS, regulate daily rhythmicity in the binding of BRAHMA, a chromatin remodeler, to DNA spanning clock-controlled genes to facilitate their rhythmic gene expression cycles. Moreover, because TIMELESS degrades in the presence of light, my results provide new insights into how light affects DNA structure and gene expression."

"In the second part of my thesis project, I investigated the impact of insecticide applications on the fruit pest Drosophila suzukii," Tabulocsaid. "Specifically, I performed RNA sequencing analysis on D. suzukii flies that are either susceptible or resistant to common insecticides to determine genetic mechanisms underlying insecticide resistance in this agricultural pest. My results revealed that enhanced metabolic detoxification confers pyrethroid resistance while spinosad resistance is the result of both metabolic and penetration resistance. Finally, we identified alternative splicing as an additional mechanism of resistance. These results will facilitate the development of efficient molecular diagnostics to identify insecticide resistance in the field and enable growers to adjust D. suzukii spray programs to control this devastating pest more effectively."

Christine received her bachelor of science degree in biochemistry and molecular biology from UC Davis in 2015. She joined the Chiu lab as an undergraduate research assistant in 2012. "Much of my work in the lab has involved different agricultural pests and investigating the molecular aspects contributing to the insect's ability to be an effective pest," she says on the Chiu lab website. "My current focus is to investigate the effects of climatic change on gene expression of an invasive pest and determine whether there is a correlation to resistance and survival. In addition to pest management research, I am also studying a kinase of a core clock protein in Drosophila melanogaster and hoping to dissect its functional contribution to the molecular oscillator."

The UC Davis Department of Entomology and Nematology's winter seminars are held on Wednesdays at 4:10 p.m. in 122 Briggs Hall. All are virtual. They are coordinated by urban landscape entomologist Emily Meineke, assistant professor. (See schedule.) She may be reached at ekmeineke@ucdavis.edu for technical issues. 

In the popular television series “Game of Thrones,” the Stark clan always knew when winter was coming. But how did they really know? 

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). 

“I am so happy for Sergio that this exciting research on animal seasonal biology has now been published,” said Chiu[ . “A long-standing question in the field has been how the circadian clock, which is important for regulating 24-hour biological rhythms such as sleep-wake and feeding-fasting cycles, also plays a role in regulating seasonal physiology and behavior. Sergio's work now convincingly shows that seasonal cues such as photoperiod and temperature can act via a clock-regulated neuropeptide to enable seasonal changes in daily activity patterns as well as reproductive status.” 

“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.” 

Their summary:

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. 

Resource:

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.