- Author: Kathy Keatley Garvey
That's true for assistant professor Katie Thompson-Peer of the Department of Developmental and Cell Biology, UC Irvine, who will speak on "Cellular Mechanisms of Dendrite Regeneration after Neuron Injury” at the UC Davis Department of Entomology and Nematology seminar on Wednesday, May 24.
She uses the larvae and adult fruit fly, Drosophila melanogaster, as a model to study dendrite regeneration.
Thompson-Peer will present her seminar at 4:10 p.m. in Room 122, Briggs Hall. Her seminar also will be virtual. The Zoom link: https://ucdavis.zoom.us/j/95882849672
Her abstract: “Neurons have two types of cellular projections, that are essential for how they function in circuits: they have a single axon and a highly branched network of dendrites. These dendrites are the cellular structures that allow neurons to receive input from the environment or from other neurons. While much is known about how axons respond to injury, almost nothing is known about how neurons respond to dendrite injury. We have found that after dendrite injury, peripheral nervous system neurons are able to mount a reliable, reproducible process of dendrite regeneration. In this talk, I present our recent work to determine how neurons detect injury to their dendrites, using the larvae and adult fruit fly Drosophila melanogaster as a model to study dendrite regeneration.”
Thompson-Peer, who joined UC Irvine in April 2019, received her bachelor's degree in biology from the University of Pennsylvania, and then followed with a two-year stint at the Johns Hopkins University with Alex Kolodkin. She earned her doctorate from Harvard University, working with Josh Kaplan, and was a postdoctoral fellow with Yuh-Nung and Lily Jan at UC San Francisco and the Howard Hughes Medical Institute. Her postdoctoral work drew financial support from the National Institute of Neurological Disorders and Stroke F32 and K99/R00 fellowships, as well as a UC Office of the President's Postdoctoral Fellowship.
The Thompson-Peer lab explores how neurons recover from injury in vivo, and how this process is similar to and different from normal development. (See her work showcased on YouTube)
"At the most fundamental level, a neuron receives information along dendrites, and sends information down an axon to synaptic contacts," she writes on her website. "Dendrites can be injured by traumatic brain injury, stroke, and many forms of neurodegeneration, yet while the factors that control axon regeneration after injury have been extensively studied, we know almost nothing about dendrite regeneration. Our long-term research goal is to understand the cellular mechanisms of dendrite regeneration after injury."
"Our previous work found that the sensory neurons in the fruit fly Drosophila peripheral nervous system exhibit robust regeneration of dendrites after injury and used this system to explore central features of dendrite regeneration in developing animals, young adults, and aging adults. We have observed that after injury, neurons regrow dendrites that recreate some features of uninjured dendrites, but are unable to reconstruct an entire arbor that perfectly mimics an uninjured neuron. Moreover, there are mechanistic differences between the outgrowth of uninjured neurons versus the regeneration of dendrites after injury: dendrite regeneration is uniquely dependent on neuronal activity, ignores cues that constrain and pattern normal dendrite outgrowth, and confronts a mature tissue environment that is different from what a developing neuron would encounter. These challenges are significantly exacerbated when neurons in aging animals attempt to recover from injury."
Department seminar coordinator is urban landscape entomologist Emily Meineke, assistant professor. For technical issues regarding Zoom connections, she may be reached at ekmeineke@ucdavis.edu. (See complete list of spring seminars.)
- Author: Kathy Keatley Garvey
She will present her seminar at 4:10 p.m. in Room 122, Briggs Hall. Her seminar also will be virtual. The Zoom link: https://ucdavis.zoom.us/j/95882849672
Her abstract: “Neurons have two types of cellular projections, that are essential for how they function in circuits: they have a single axon and a highly branched network of dendrites. These dendrites are the cellular structures that allow neurons to receive input from the environment or from other neurons. While much is known about how axons respond to injury, almost nothing is known about how neurons respond to dendrite injury. We have found that after dendrite injury, peripheral nervous system neurons are able to mount a reliable, reproducible process of dendrite regeneration. In this talk, I present our recent work to determine how neurons detect injury to their dendrites, using the larvae and adult fruit fly Drosophila melanogaster as a model to study dendrite regeneration.”
A pre-seminar coffee takes place from 3:30 to 4:10 in Briggs 158.
Thompson-Peer, who joined UC Irvine in April 2019, received her bachelor's degree in biology from the University of Pennsylvania, and then followed with a two-year stint at the Johns Hopkins University with Alex Kolodkin. She earned her doctorate from Harvard University, working with Josh Kaplan, and was a postdoctoral fellow with Yuh-Nung and Lily Jan at UC San Francisco and the Howard Hughes Medical Institute. Her postdoctoral work drew financial support from the National Institute of Neurological Disorders and Stroke F32 and K99/R00 fellowships, as well as a UC Office of the President's Postdoctoral Fellowship.
The Thompson-Peer lab explores how neurons recover from injury in vivo, and how this process is similar to and different from normal development. (See her work on YouTube)
"At the most fundamental level, a neuron receives information along dendrites, and sends information down an axon to synaptic contacts," she writes on her website. "Dendrites can be injured by traumatic brain injury, stroke, and many forms of neurodegeneration, yet while the factors that control axon regeneration after injury have been extensively studied, we know almost nothing about dendrite regeneration. Our long-term research goal is to understand the cellular mechanisms of dendrite regeneration after injury."
"Our previous work found that the sensory neurons in the fruit fly Drosophila peripheral nervous system exhibit robust regeneration of dendrites after injury and used this system to explore central features of dendrite regeneration in developing animals, young adults, and aging adults. We have observed that after injury, neurons regrow dendrites that recreate some features of uninjured dendrites, but are unable to reconstruct an entire arbor that perfectly mimics an uninjured neuron. Moreover, there are mechanistic differences between the outgrowth of uninjured neurons versus the regeneration of dendrites after injury: dendrite regeneration is uniquely dependent on neuronal activity, ignores cues that constrain and pattern normal dendrite outgrowth, and confronts a mature tissue environment that is different from what a developing neuron would encounter. These challenges are significantly exacerbated when neurons in aging animals attempt to recover from injury."
Department seminar coordinator is urban landscape entomologist Emily Meineke, assistant professor. For technical issues regarding Zoom connections, she may be reached at ekmeineke@ucdavis.edu. (See complete list of spring seminars.)
- Author: Randall Oliver
Results help inform best practices for managing the disease-causing beetle
The University of California, Irvine campus is home to a vast urban forest consisting of approximately 30,000 trees located in a mix of landscape, riparian and open space settings. In the mid-2010s, that forest came under threat from an invasive species of beetle that arborists and pest researchers were just learning about – the polyphagous shothole borer.
The tiny beetles, which may have arrived in California from their native Southeast Asia via infested shipping materials, tunnel into trees and introduce a fungus that serves as food for adult beetles and their larva.
As the fungus grows, it colonizes the tree's vascular system, blocking transport of water and nutrients. This causes a disease called Fusarium dieback that can kill branches or entire trees.
One reason the beetles were such a threat at UCI was the high number of sycamores on campus, especially in Aldrich Park at the campus center. Hundreds of cottonwoods, native willows, golden rain and coral trees also were affected. In total, the beetles attacked more than 2,000 trees, including 75 different tree species.
A variety of approaches to controlling beetle
To better understand and tackle this problem, UCI's Facilities Management department and Office of Environmental Planning and Sustainability collaborated with researchers affiliated with UC Agriculture and Natural Resources and UC Cooperative Extension. In addition, pesticide-manufacturing companies, pest control advisers and arborists provided materials and labor to help offset the cost of research.
“UCI was the perfect testing ground to determine integrated pest management strategies for this beetle/disease complex,” said John Kabashima, UCCE environmental horticulture advisor emeritus. “Our research was multifaceted, delving into early detection, monitoring and sampling, and cultural and chemical management.”
Kabashima said UCI provided the researchers with “a lot of freedom” to try a variety of approaches and study the results over time.
“We could cut down and sample trees or leave selected infested trees alone; we explored a variety of pesticide/fungicide combinations and application techniques,” he said. “That freedom resulted in many of the management solutions that are used today to effectively control this pest.”
UCI and the researchers also established a full inventory of affected trees on campus, evaluating severity of infestation by the number of entry/exit holes and signs of dieback. One important key to management is getting rid of “amplifiers” – heavily infested trees that are both hazardous and a source of beetles to spread to other trees.
“Typically, shothole borer infestations begin with just a few trees that for some reason are highly attractive to the beetles – perhaps based on tree species, tree spacing, irrigation conditions or other factors,” Kabashima said. “Over time, the beetles and fungus multiply largely undetected in those few trees. When the beetle population reaches a critical point and the trees begin to die, the female beetles fly to adjacent trees in a secondary invasion, eventually infesting many trees over a large area.”
An opportunity to diversify UCI's urban forest
At UCI, that initial invasion took place in landscaped areas containing many large, majestic sycamores that were planted when the campus began operations in the mid-1960s.
Over several years, UCI removed 700 heavily infested trees, including many of those historic sycamores, and replaced them with other tree species.
Today, the forest at UCI is very different than it was in 2015. While shothole borers have not been eliminated completely, their presence is reduced significantly, and UCI now has the tools to manage them effectively. Reforestation efforts resulted in a diverse treescape that is not only more sustainable but also beautiful.
“Managing a 1,500-acre campus with 30,000 trees is a never-ending process,” said Richard Demerjian, UCI's assistant vice chancellor, Campus Physical & Environmental Planning. “Our forest continues to evolve, with an ongoing focus on increasing diversity and plant health.”
Demerjian also noted that UCI is now starting to consider planting new sycamore trees on a limited basis.
A primer on effective shothole borer management
Whether managing a forest of thousands of trees or just a few trees, landscape managers and residents can apply many of the lessons learned at UCI to control invasive shothole borers and other tree pests.
- Avoid monocultures. Tree diversity provides beauty and resiliency.
- Keep trees healthy. Proper irrigation and maintenance will keep trees strong and help protect them from shothole borers and other pests.
- Check trees. Look for the common signs and symptoms of infestation such as beetle entry/exit holes. Regular monitoring ensures that infestations are managed early, before they cause dieback or tree death.
- Confirm suspected infestations. Use the detection tool at www.ishb.org.
- Review management options. For trees with low infestation, prune the infested branches and monitor the tree's health over time. In non-riparian, urban settings, consider treating low and moderately infested trees with pesticides/fungicides demonstrated to be effective against the pest-disease complex (A licensed professional will be needed to apply the treatments). Severely infested trees may require removal.
- Call in a professional. A certified arborist or pest control professional would be able to provide recommendations based on the tree's condition. The local county Agricultural Commissioner's Office and UC Cooperative Extension office may have additional knowledge about current shothole borer monitoring and management programs in your area.
- Take care of green waste. The beetles can survive in cut wood for weeks or even months. Proper disposal of green waste includes chipping infested wood, followed by solarizing or composting the chips.
- Replant wisely. Begin planting new trees only after removing all amplifiers and establishing an ongoing monitoring program. Consider the current concentration of tree species when deciding what type of trees to plant.
- Author: Kathy Keatley Garvey
Hammer, assistant professor of ecology and evolutionary biology, UC Irvine, will give the in-person and virtual seminar, hosted by the UC Davis Department of Entomology and Nematology, at 4:10 p.m. in 122 Briggs Hall. The Zoom link: https://ucdavis.zoom.us/j/99515291076.
Community ecologist Rachel Vannette, associate professor, UC Davis Department of Entomology and Nematology, is hosting the seminar.
"How do insects and microbes form symbioses, and why do these partnerships often break down?" Hammer asks in his abstract. "We are addressing these questions with the gut microbiomes of social corbiculate bees. Despite an ancient association with their bee hosts, these symbionts are surprising dynamic over developmental, ecological and macroevolutionary time scales. I will discuss our recent discoveries of symbiont loss in bees, and efforts to understand why and how these losses occur."
Hammer received his bachelor's degree in general biology from UC San Diego in 2009 and his doctorate in evolutionary biology in 2018 from the University of Colorado, Boulder. He served as a postdoctoral researcher at the University of Texas, Austin, from 2018 to 2021.
Hammer's research interests include microbiomes, symbiosis, microbial ecology and evolution, bees, biodiversity, insect-plant interactions and tropical biology.
"We are a new research group at UC Irvine studying the ecology and evolution of symbioses between hosts (especially bees) and microbes," he writes on his lab website.
Nematologist Shahid Siddique, assistant professor, UC Davis Department of Entomology and Nematology, is coordinating the spring seminars. For Zoom technical issues, contact him at ssiddique@ucdavis.edu.
- Author: Kathy Keatley Garvey
Hammer will speak at 4:10 p.m. in 122 Briggs Hall. The Zoom link:
https://ucdavis.zoom.us/j/99515291076.
Community ecologist Rachel Vannette, associate professor, UC Davis Department of Entomology and Nematology, is hosting the seminar.
"How do insects and microbes form symbioses, and why do these partnerships often break down?" Hammer asks in his abstract. "We are addressing these questions with the gut microbiomes of social corbiculate bees. Despite an ancient association with their bee hosts, these symbionts are surprising dynamic over developmental, ecological and macroevolutionary time scales. I will discuss our recent discoveries of symbiont loss in bees, and efforts to understand why and how these losses occur."
Hammer received his bachelor's degree in general biology from UC San Diego in 2009 and his doctorate in evolutionary biology in 2018 from the University of Colorado, Boulder. He served as a postdoctoral researcher at the University of Texas, Austin, from 2018 to 2021.
Hammer's research interests include microbiomes, symbiosis, microbial ecology and evolution, bees, biodiversity, insect-plant interactions and tropical biology.
"We are a new research group at UC Irvine studying the ecology and evolution of symbioses between hosts (especially bees) and microbes," he writes on his lab website. His mission:
- To boldly venture into uncharted waters of symbiosis and bee biology, asking—and doing our best to answer—new questions about how they tick.
- To create a culture where lab members follow their curiosity, have fun, and regularly enjoy homemade baked goods.
- To contribute to making the academic community better reflect the diversity of society, and be a more welcoming, supportive place for historically marginalized scientists.
- To help wild bees, and connect people outside academia to insect biodiversity.
Hammer's most recent publications include
- Hammer, T.J., Le, E., Martin, A.N., Moran, N.A. 2021. The gut microbiome of bumblebees. Insectes Sociaux 68, 287-301.
- Silva Cerqueira, A.E., Hammer, T.J., Moran, N.A., Cristiano Santana, W., Megumi Kasuya, M.C., Canêdo da Silva, C. 2021. Extinction of anciently associated gut bacterial symbionts in a clade of stingless bees. The ISME Journal 15, 2813-2816.
- Hammer, T.J., Le, E., Moran, N.A. 2021. Thermal niches of specialized gut symbionts: the case of social bees. Proceedings of the Royal Society B 288, 20201480.
- Hammer, T.J., De Clerck-Floate, R., Tooker, J.F., Price, P.W., Miller, D.G., Connor, E.F. 2021. Are bacterial symbionts associated with gall induction in insects? Arthropod-Plant Interactions 15, 1-12.
- Hammer, T.J., Dickerson, J.C., McMillan, W.O., Fierer, N. 2020. Heliconius butterflies host characteristic and phylogenetically structured adult-stage microbiomes. Applied and Environmental Microbiology 86, e02007-20.
Nematologist Shahid Siddique, assistant professor, UC Davis Department of Entomology and Nematology, is coordinating the spring seminars. For Zoom technical issues, contact him at ssiddique@ucdavis.edu.