Her topic is "How Does the Time of Eating Affecting Our Circadian Physiology?" Access this form for the Zoom link.
The abstract: "The integration of circadian and metabolic signals is essential for maintaining robust circadian rhythms and ensuring efficient metabolism and energy use. Using Drosophila as an animal model, we showed that clock-controlled feeding-fasting cycles is strongly correlated to daily protein O-GlcNAcylation rhythms, which may represent a key post-translational mechanism that regulates circadian physiology. Our results could shed light on the benefits of TRE (or intermittent fasting) and the extent to which modern human lifestyles contribute to the current epidemic of metabolic disorders."
The host is her major professor, Joanna Chiu, a molecular geneticist and physiologist, vice chair of the UC Davis Department of Entomology and Nematology and a Chancellor's Fellow. Liu is currently working in the Chiu lab as a postdoctoral fellow.
For her thesis, Liu explored the interplay between circadian clock and metabolism in maintaining animal health using Drosophila melanogaster as a model. Specifically, she investigated the regulation of cellular protein O-GlcNAcylation by circadian clock and metabolic signals. O-GlcNAcylation is a nutrient senstive post-translational modification that can alter the structure and function of thousands of cellular proteins. She is fascinated by how circadian biology can be shaped by multiple factors through complex mechanisms. Her long-term goal is to understand how molecular pathways are coordinated temporally to maintain animal health and wellness.
Liu received her bachelor's degree in biological sciences in 2014 from Beijing Forestry University, China. She was a recipient of a CSC-UC Davis Joint Fellowship.
Coordinating the fall seminars is Cooperative Extension specialist and agricultural entomologist Ian Grettenberg, assistant professor, UC Davis Department of Entomology and Nematology. He may be reached at imgrettenberger@ucdavis for any technical issues.
The seminar takes place from 4:10 to 5 p.m., Wednesday, Oct. 28. Access this site for the Zoom link. Host is Cooperative Extension specialist and agricultural entomologist Ian Grettenberger, assistant professor, UC Davis Department of Entomology and Nematology. He is coordinating the department's fall seminars.
"The research in our lab focuses on understanding how chemical compounds mediate interactions among microbes, plants, herbivores, and herbivore natural enemies," Helms says. "We combine analytical chemistry and behavioral ecology in laboratory and field-based research to investigate how organisms use chemistry to navigate, communicate, and defend themselves. This seminar will discuss some of our ongoing projects examining how plants and insect herbivores use chemical information from their environment to assess their risk of attack and how herbivore natural enemies use such information to find potential prey."
Helms, an assistant professor, holds two degrees from Pepperdine University, Malibu, Calif., both awarded in 2009: a bachelor of science degree in biology and a bachelor of arts degree in biochemistry. She received her doctorate in ecology in 2015 from The Pennsylvania State University, State College, Penn. While in the John Tooker lab, Helms studied the chemical ecology of plant-insect interactions, especially how plants defend themselves against insect herbivores. She investigated how plants use olfactory cues to predict impeding herbivore attacks and the molecular mechanisms involved.
In addition to the general field of chemical ecology, Helms' research interests include plant-insect interactions, tritrophic interactions, belowground chemical ecology, chemical communication, and plant defense.
Her most recent publications:
Helms, A.M., Ray, S., Matulis, N.L.*, Kuzemchak, M.C.*, Grisales, W.*, Tooker, J.F., Ali, J.G. Chemical cues linked to risk: Cues from belowground natural enemies enhance plant defences and influence herbivore behaviour and performance. Functional Ecology. 33, 798-808 (2019). DOI: 10.1111/1365-2435.13297
Acevedo, F.E., Smith, P., Peiffer, M., Helms, A.M., Tooker, J.T., Felton, G.W. Phytohormones in fall armyworm saliva modulate defense responses in plants. Journal of Chemical Ecology. (2019). https://doi.org/10.1007/s10886-019-01079-z
Yip, E.C., Sowers, R.P.*, Helms, A.M., Mescher, M.C., De Moraes, C.M., Tooker, J.F. Tradeoffs between defenses against herbivores in goldenrod (Solidago altissima). Arthropod-Plant Interactions. 13, 279-287 (2019). DOI: 10.1007/s11829-019-09674-3
For any technical issues regarding the seminar, contact Grettenberger at email@example.com.
The article, “Genome-Enabled Insights into the Biology of Thrips as Crop Pests,” is published in the journal BMC Biology. It is the work of 57 scientists on five continents.
“This project represents over eight years of work by at least 17 laboratories across the globe,” said Professor Ullman, a former chair of the entomology department and a fellow of the Entomological Society of America and the American Association for the Advancement of Science. Her laboratory worked closely with project leader and first author Dorith Rotenberg of North Carolina State University. Project scientist Sulley Ben-Mahmoud of the Ullman lab is the paper's third author.
The western flower thrips, Frankliniella occidentalis, causes billions of dollars a year in damage worldwide. Native to Western North America and about the size of a pinhead, the insect feeds on a wide array of food, fiber, and ornamental crops and transmits plant viruses that cause significant economic damage.
“The western flower thrips and the viruses it transmits, including tomato spotted wilt virus, is important to California agriculture, causing serious problems for tomato growers, pepper growers and growers of leafy greens,” Ullman said. The tomato spotted wilt virus infects more than 1000 plant species, ranging from tomatoes, tobacco and peanuts to pansies and chrysanthemums.
“This system has been a central element of my research program for over 30 years," Ullman said, "and I am extremely excited to see this important resource made available as a tool to help us understand and control these important pests.”
In their abstract, the authors wrote that the publication should lead to “understanding the underlying genetic mechanisms of the processes governing thrips pest and vector biology, feeding behaviors, ecology, and insecticide resistance.”
“Attaining a tool to unlock the mysteries of western flower thrips biology and interactions with plant viruses in the family Tospoviridae has been a dream of mine through over 30 years of working on this system,” Ullman commented. “The genome project enabled the discovery of salivary gland-enriched genes in this tiny insect that is now guiding work that Sulley Ben-Mahmoud and I are doing with collaborators Dorith Rotenberg, Joshua Benoit, Samuel Bailey and Priya Rajarapu to identify salivary proteins acting as effectors.”
Rotenberg launched the project in 2011 after delivering a lecture at the 5th Annual Arthropod Genomics Symposium in Kansas City, Mo. “At the time, I was very naïve about what it would take to steward a thrips genome project, but was excited about what a genome sequence could mean for those of us interested in the molecular basis of thrips vector competence and thrips pest biology.”
The team worked with the i5k initiative, an international effort to sequence and analyze 5,000 arthropod genomes. This includes insects, crustaceans, spiders and other creatures with exoskeletons, segmented bodies and pairs of jointed legs.
The Rotenberg-led thrips genome project team first developed an inbred line of thrips. Baylor College of Medicine's Human Genome Sequencing Center sequenced and assembled the genome. The Rotenberg team then verified the location of 10 percent of the nearly 17,000 genes and annotated them to better understand what they do.
The authors report that some genes are associated with the thrips' ability to develop and reproduce, to find plant hosts through taste and smell, to protect against pathogens, and to detoxify plant-produced chemicals and insecticides. The latter is of special interest because thrips are known for rapidly building up resistance to chemicals.
Said Rotenberg: “I discovered over the course of eight years that the thrips genome consortium created something much greater than the sum of its parts. I was fortunate to recruit 17 international groups with expertise in arthropod genomics, evolution and development, thrips vector biology and microbe (and virus)-insect interactions to volunteer their time not only to manually correcting and annotating gene models, but to use expression evidence to explore with me new frontiers in thrips innate immunity, lateral gene transfers of bacterial origin, thrips-plant interactions, thrips development and reproduction. These world-renowned experts helped shape the landscape for contemporary molecular and evolutionary studies of Thysanoptera and in my opinion, as important, helped shape the careers of several undergraduates, grad students and postdoctoral scholars involved in the process. I am excited and proud of what we accomplished together.”
Ben-Mahmoud described the research as “a monumental feat, and I am proud of my contributions to it. I have no doubt that the paper will inform and benefit the studies of many other international insect-vector research groups, not only those who work directly with the western flower thrips.”
Persimmons, asparagus, figs and other crops distantly related to native California plants attract fewer pests and diseases than the closer kin, and thus receive fewer pesticide treatments, according to a newly published article by two UC Davis-linked scientists in the Proceedings of the Natural Academy of Sciences (PNAS).
Co-authors Ian Pearse, research ecologist with the U.S. Geological Survey and a UC Davis alumnus, and Jay Rosenheim, UC Davis distinguished professor of entomology, analyzed the 2011-2015 state records of pesticide applications of 93 major California crops.
“We hypothesized that California crops that lack close relatives in the native flora will be attacked by fewer herbivores and pathogens and require less pesticide use,” said Rosenheim, a 32-year member of the UC Davis Department of Entomology and Nematology faculty and a newly elected fellow of the Entomological Society of America.
Rosenheim and Pearse examined the pesticide applications against arthropods, pathogens, and weed plants and compiled the data into a comprehensive analysis.
Their findings appear in the PNAS article, “Phylogenetic Escape from Pests Reduces Pesticides on Some Crop Plants,” published Oct. 12. “Phylogenetic relationship” refers to the relative times in the past that species shared common ancestors.
“In contrast, our study focuses on the roughly half of all herbivores and diseases that attack California crops and that are actually native to California. These organisms originally attacked members of the native California flora, but have now shifted to attack a novel host: the crop plant.”
However, “host shifts aren't always easy,” Rosenheim said. “It's relatively easy to shift to attack a close relative of a native host plant, but it's relatively hard to shift to attack a very different host plant.”
Said Pearse: “Our study shows that crops like dates, asparagus, figs, kiwis, or persimmons that are distantly related to native California plants--and thus separated by many million years of independent evolution-- are colonized by fewer pests and diseases.”
"The crops that require the most pesticide applications, Pearse said, "are those, like artichokes, blackberries, and sweet corn, that have close relatives in the Californian flora and are of high economic value per acre."
California's top agricultural crops include almonds, grapes, lettuce, strawberries, tomatoes and walnuts.
Rosenheim said persimmons are a good example “of the phenomenon we've studied: they have very, very few pests--almost zero in my experience--and that's probably because persimmons have no close relatives in the California native plant community.”
Pearse, a 2005 Fulbright scholar who received his doctorate in ecology from UC Davis in 2011, studying with Professor Rick Karban, joined the U.S. Geological Survey in Fort Collins in 2016. He focuses his research on invasive species and plant-insect interactions. Rosenheim researches insect ecology, with a focus on host-parasitoid, predator-prey, and plant-insect interactions, with direct applications to biological control.
“Pesticides are a ubiquitous (found everywhere) component of conventional crop production but come with considerable economic and ecological costs. We tested the hypothesis that variation in pesticide use among crop species is a function of crop economics and the phylogenetic relationship of a crop to native plants, because unrelated crops accrue fewer herbivores and pathogens. Comparative analyses of a dataset of 93 Californian crops showed that more valuable crops and crops with close relatives in the native plant flora received greater pesticide use, explaining roughly half of the variance in pesticide use among crops against pathogens and herbivores. Phylogenetic escape from arthropod and pathogen pests results in lower pesticides, suggesting that the introduced status of some crops can be leveraged to reduce pesticides.”
Global change ecologist Amanda Koltz, a senior scientist with the Department of Biology, Washington University, St. Louis, will speak on "Species Interactions and Ecosystems in a Changing World" at the UC Davis Department of Entomology and Nematology's virtual seminar at 4:10 p.m., Wednesday, Oct. 14.
"Biological communities and species interactions are changing rapidly as a result of global change," she says in her abstract. "These changes are likely to have cascading effects on ecosystems, but we still have limited understanding of the extent to which organismal responses to global change may also drive ecosystem responses to it. In this talk, I will present some of my work on the potential feedbacks between global change, communities, and ecosystem functioning from two different study systems. First, I will discuss how warming can alter the cascading effects of spiders in the Arctic tundra, and then I will discuss my recent efforts at characterizing the potential consequences of shifting interactions among ruminant hosts and their parasites. The common theme throughout the talk will be the importance of considering species interactions in efforts to understand ecosystem responses to global change."
Koltz describes herself as a "global change ecologist interested in how species interactions influence community composition and ecosystem function in the context of environmental change. I use common, widespread organisms that are sensitive to change-- like wolf spiders, mosquitoes and gut worms--to better understand how the animals in our everyday lives impact the ecosystems we live in. My recent work focuses on two fundamental questions: (1) How do biological communities respond to changes in the environment? and (2) What are the consequences of changes in species interactions for the cycling of energy and nutrients within ecosystems?"
Cooperative Extension specialist and agricultural entomologist Ian Grettenberger, assistant professor, UC Davis Department of Entomology and Nematology, coordinates the fall series of virtual seminars. They are held on Wednesdays at 4:10 p.m.
Host for the Koltz seminar is Emily Meineke, assistant professor of urban landscape entomology, who researches insect-plant interactions.
Grettenberger announced that this is the form to obtain the zoom link:
Koltz's research has appeared in a number of recent publications:
- Small but Mighty: Measuring Parasites' Footprints
- Wolf Spiders May Turn to Cannibalism in a Warming Arctic
- Warming Alters Predator-Prey Interactions in the Arctic
- Bugged Out by Climate Change
- Higher Education Channel: Arctic Wolf Spider's Changing Diet May Help Keep Arctic Cool & Lessen Some Impact of Global Warming