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Molecular geneticist Joanna Chui, assistant professor of entomology, in her lab in Storer Hall. (Photo by Kathy Keatley Garvey) |
DAVIS---The UC Davis Department of Entomology’s newest faculty member is molecular geneticist Joanna Chiu, who specializes in molecular chronobiology.
She received her doctorate in molecular genetics from the Department of Biology at New York University.
In her lab in 6348 Storer Hall, Chiu is using a combination of molecular genetics, biochemical, and proteomic approaches to:
1.
study the role of posttranslational modifications of clock proteins in circadian rhythms
2.
identify new protein factors important for generating proper rhythms, and
3. dissect the molecular mechanisms connecting the oscillator to output pathways controlling animal physiology, metabolism, and behavior.
A native of Hong Kong, Chiu received her bachelor of arts degree (B.A. magna cum laude) from Mount Holyoke College, South Hadley, Mass., with double majors in biology and music. As an undergraduate, she received a number of research fellowships, including the Howard Hughes Institute Summer Research Fellowship and the New England Consortium of Undergraduate Scientific Research Summer Fellowship.
She took a brief hiatus to study 20th century music theory before begininng her graduate studies under the guidance of Gloria Coruzzi, biology chair and Carroll and Milton Petrie professor.
Chiu focused her doctoral research on understanding the function of glutamate receptor genes (GLR) in plants by using Arabidopsis thaliana as a model organism. "Until recent years, glutamate receptors were known to exist only in animal systems, in which they have been shown to function in excitatory synaptic transmission in the nervous system," she said.
After the discovery of these genes in plants by the Coruzzi lab (published in Nature), "I became interested in examining the in vivo role of glutamate receptors in an organism without a nervous system," she said.
The results of her research showed that the Arabidopsis GLR gene family (AtGLR) consists of 20 members that are divided into 3 clades based on parsimony phylogenetic analysis. Her analysis was used as the basis for establishing the nomenclature for the Arabidopsis GLR gene family (published in Science). To investigate the functional significance of AtGLR clade division, Chiu performed the first comprehensive mRNA expression analysis of the entire AtGLR gene family.
To further test whether the 3 GLR clades are functionally distinct, she generated transgenic Arabidopsis plants that are either overexpressing or underexpressing GLR genes from each of the 3 clades. Arabidopsis plants that are overexpressing a clade II or a clade III gene, she said, are hypersensitive to salt stress, suggesting a role of GLR genes in maintaining ionic homeostasis.
Her last years as a graduate student coincided with the rise of the genomic era and the explosion of genomic sequence data. In addition to working on her main thesis project, she collaborated with researchers from the American Museum of Natural History to develop OrthologID, a Web application that automates the labor-intensive process of gene orthology determination within a character-based phylogenetic framework (published in Bioinformatics). The development of OrthologID was one of the main research goals of The New York Plant Genomics Consortium, comprised of researchers from New York University, American Museum of Natural History, Cold Spring Harbor Lab, New York, and the New York Botanical Garden.
"I enjoyed my career in plant research as a graduate student, but I realized that my real passion is to study how genes and proteins regulate and control animal behavior," said Chiu, adding that she is particularly interested in the field of circadian biology. “Circadian rhythms are endogenously driven, and exist in life forms ranging from bacteria to mammals,” she said. “They drive daily oscillations of physiological states and activities, including sleep and feeding, and allow organisms to perform necessary tasks at biologically advantageous times of day.”
As a postdoctoral fellow, she studied the inner workings of circadian rhythms in the lab of Isaac Edery, Center for Advanced Biotechnology and Medicine, Rutgers University, New Jersey.
She was awarded the National Institutes of Health Pathway to Independence Award K99/R00 to continue her chronobiology research.
While a postdoctoral fellow, she lectured on "Setting the Pace of the Circadian Oscillator in Fruit Flies by Posttranslational Modifications of Clock Proteins" at a UC Davis Department of Entomology seminar on May 7, 2009.
Chiu joined the UC Davis Department of Entomology faculty on June 1.
Watch Video
Watch "Assaying Locomotor Activity to Study Circadian Rhythms and Sleep Parameters in Drosophila" on the website, Journal for Visualized Experiments
http://www.jove.com/index/details.stp?id=2157
Abstract:
Most life forms exhibit daily rhythms in cellular, physiological and behavioral phenomena that are driven by endogenous circadian (≡24 hr) pacemakers or clocks. Malfunctions in the human circadian system are associated with numerous diseases or disorders. Much progress towards our understanding of the mechanisms underlying circadian rhythms has emerged from genetic screens whereby an easily measured behavioral rhythm is used as a read-out of clock function. Studies using Drosophila have made seminal contributions to our understanding of the cellular and biochemical bases underlying circadian rhythms. The standard circadian behavioral read-out measured in Drosophila is locomotor activity. In general, the monitoring system involves specially designed devices that can measure the locomotor movement of Drosophila. These devices are housed in environmentally controlled incubators located in a darkroom and are based on using the interruption of a beam of infrared light to record the locomotor activity of individual flies contained inside small tubes. When measured over many days, Drosophila exhibit daily cycles of activity and inactivity, a behavioral rhythm that is governed by the animal's endogenous circadian system. The overall procedure has been simplified with the advent of commercially available locomotor activity monitoring devices and the development of software programs for data analysis. We use the system from Trikinetics Inc., which is the procedure described here and is currently the most popular system used worldwide. More recently, the same monitoring devices have been used to study sleep behavior in Drosophila. Because the daily wake-sleep cycles of many flies can be measured simultaneously and only 1 to 2 weeks worth of continuous locomotor activity data is usually sufficient, this system is ideal for large-scale screens to identify Drosophila manifesting altered circadian or sleep properties.
Citation:
Chiu JC, Low KH, Pike DH, Yildirim E, Edery I (2010). Assaying Locomotor Activity to Study Circadian Rhythms and Sleep Parameters in Drosophila. J Vis Exp. 43. http://www.jove.com/index/details.stp?id=2157, doi: 10.3791/2157 |
--Kathy Keatley Garvey
Communications specialist
UC Davis Department of Entomology
(530) 754-6894
