- Author: Kathy Keatley Garvey
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.
- Author: Kathy Keatley Garvey
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.
- 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.”
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.
- Author: Kathy Keatley Garvey
The seminar, set for 4:10 p.m., Pacific Time, will be virtual only, announced seminar series coordinator Emily Meineke, an urban landscape entomologist and assistant professor.
The Zoom link: https://ucdavis.zoom.us/j/95882849672.
His abstract: "Because they vector pathogens to humans, mosquitoes impact millions of people every year. The global strategy for the management of mosquito-borne diseases involves controlling vector populations, to a large extent, through insecticide application. However, vector-borne diseases are now resurgent, largely because of rising insecticide resistance in vector populations and the drug resistance of pathogens. In this context, the Vinauger Lab studies the molecular, physiological, and neural basis of mosquito behavior. We rely on a collaborative, integrative, and
multidisciplinary approach, at the intersection between data science, neuro-ethology, molecular biology, and chemical ecology. Our long-term goal is to identify targets to disrupt mosquito-host interactions and reduce mosquito-borne disease transmission."
On his website, Vinauger elaborates: "The ability of mosquitoes to detect, process, and respond to olfactory information emitted by their hosts can affect disease transmission. The magnitude of their responses to host and plant odors varies drastically throughout the day, but, despite their clear epidemiological relevance, the neural and molecular mechanisms acting at the circuit levels to control mosquito behavior remain to be determined. In the lab, we employ an interdisciplinary approach combining behavioral assays, electrophysiological recordings, transcriptomic analysis, and CRISPR/Cas9 gene editing, to characterize rhythms in odorant detection, perception, and olfactory behavior, thereby identifying the genetic basis of the temporal plasticity in mosquito-host interactions."
Molecular geneticist and physiologist Joanna Chiu, professor and vice chair of the Department of Entomology and Nematology and a Chancellor's Fellow, will serve as the host. "I have very high regard for Dr. Vinauger's integrative and multidisciplinary research into the biochemical and neurophysiological basis of insect behavior," Professor Chiu said. "His research program is innovative and rigorous, leveraging techniques in quantitative behavioral analysis, bioengineering, neurobiology, and computational methods to address exciting and important questions in mosquito biology and behavior."
The Vinauger lab "studies the molecular, physiological, and neural basis of mosquito behavior," according to its website. "We are a group of experimental biologists, relying on a collaborative, integrative, and multidisciplinary approach, at the intersection between data science, neuro-ethology, molecular biology, and chemical ecology. Our long-term goal is to identify targets to disrupt mosquito-host interactions and reduce mosquito-borne disease transmission."
The Vinauger lab's latest publication, "Visual Threats Reduce Blood-Feeding and Trigger Escape Responses in Aedes aegypti Mosquitoes," appears in the Dec. 9, 2022 edition of Scientific Reports.
The abstract:
"The diurnal mosquitoes Aedes aegypti are vectors of several arboviruses, including dengue, yellow fever, and Zika viruses. To find a host to feed on, they rely on the sophisticated integration of olfactory, visual, thermal, and gustatory cues emitted by the hosts. If detected by their target, this latter may display defensive behaviors that mosquitoes need to be able to detect and escape in order to survive. In humans, a typical response is a swat of the hand, which generates both mechanical and visual perturbations aimed at a mosquito. Here, we used programmable visual displays to generate expanding objects sharing characteristics with the visual component of an approaching hand and quantified the behavioral response of female mosquitoes. Results show that Ae. aegypti is capable of using visual information to decide whether to feed on an artificial host mimic. Stimulations delivered in a LED flight arena further reveal that landed Ae. aegypti females display a stereotypical escape strategy by taking off at an angle that is a function of the direction of stimulus introduction. Altogether, this study demonstrates that mosquitoes landed on a host mimic can use isolated visual cues to detect and avoid a potential threat."
Vinauger joined the Virginia Tech faculty in October 2017, after serving as a postdoctoral research associate at the University of Washington, Seattle. Educated in France, he received his bachelor of science degree in biology/biological sciences in 2006 from the University of Orléans; his master's degree in 2008 from the University of Tours, France; and his doctorate in 2011 from the University of Tours, Research Institute on Insect Biology.
The UC Davis Department of Entomology seminars are held on Wednesdays through March 15. (See schedule.) Eight of the 10 will be in-person in 122 Briggs Hall, and all will be virtual.
- Author: Kathy Keatley Garvey
Cai, of the laboratory of molecular geneticist and physiologist Joanna Chiu, professor and vice chair of the UC Davis Department of Entomology and Nematology, 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.
Professor Chiu, his major professor, will serve as the host.
"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 and Nematology 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.
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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.
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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.
Cai was a member of the Entomology Band, comprised of seven UC Davis graduate students who performed at Briggs Hall during the 2018 campuswide Picnic Day celebration. Cao, the drummer, dressed as a fruit fly. Entomology Today, a publication of the Entomological Society of America, featured the band in a June 2018 edition.
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.