- Author: Kathy Keatley Garvey
Her seminar takes place at 3:30 in 366 Briggs Hall, and also will be on Zoom.
Mack studies Aedes aegypti with a focus on analysis of transcriptomic datasets and 3D imaging datasets. "Throughout my time in graduate school, my projects have considered pyrethroid resistance in Aedes aegypti ;examining the genetic response to this insecticide. As I finish up my dissertation, I hope to pursue a career in industry using the skills I've developed to continue to analyze large datasets!"
Insecticide resistance is a global issue, Mack says in her exit seminar abstract. Ae. aegypti, known as "the yellow fever mosquito," can transmit dengue fever, chikungunya, Zika fever, Mayaro and yellow fever viruses, and other disease agents. The mosquito was first colonized California in 2013 and arrived resistant to pyrethroids. "The pyrethroid target site genotype differs geographically in California and partially infers resistance phenotype, indicating that other mechanisms are at play as well."
"Since their detection in 2013, Aedes aegypti has become a widespread urban pest in California," the co-authors wrote in the abstract. "The availability of cryptic larval breeding sites in residential areas and resistance to insecticides pose significant challenges to control efforts. Resistance to pyrethroids is largely attributed to mutations in the voltage gated sodium channels (VGSC), the pyrethroid site of action. However, past studies have indicated that VGSC mutations may not be entirely predictive of the observed resistance phenotype."
"To investigate the frequencies of VGSC mutations and the relationship with pyrethroid insecticide resistance in California, we sampled Ae. aegypti from four locations in the Central Valley, and the Greater Los Angeles area. Mosquitoes from each location were subjected to an individual pyrethrum bottle bioassay to determine knockdown times. A subset of assayed mosquitoes from each location was then analyzed to determine the composition of 5 single nucleotide polymorphism (SNP) loci within the VGSC gene."
The conclusion:
"Resistance associated VGSC SNPs are prevalent, particularly in the Central Valley. Interestingly, among mosquitoes carrying all 4 resistance associated SNPs, we observe significant heterogeneity in bottle bioassay profiles suggesting that other mechanisms are important to the individual resistance of Ae. aegypti in California."
Mack, who holds a bachelor of science degree (2018) in biology from Creighton University, Omaha, Neb., enrolled in the UC Davis graduate school program in 2018.
Active in the Entomological Society of America, Mack scored second place in student competition at the 2022 joint meeting of the Entomological Societies of America, Canada, and British Columbia, held last November in Vancouver, British Columbia. She entered her presentation, "Three Dimensional Analysis of Vitellogenesis in Aedes aegypi Using Synchrotron X-Ray MicroCT,” in the category, "Graduate School Physiology, Biochemistry and Toxicology: Physiology.
Her abstract: "Traditional methods of viewing the internal anatomy of insects require some degree of tissue manipulation and/or destruction. Using synchrotron-based x-ray phase contrast microCT (pcMicroCT) avoids this issue and has the capability to produce high contrast, three dimensional images. Our lab is using this technique to study the morphological changes occurring in the mosquito Aedes aegypti during its reproductive cycle. Ae. aegypti is the primary global arbovirus vector, present on all continents except Antarctica. Their ability to spread these viruses is tightly linked with their ability to reproduce, as the production of eggs in this species is initiated by blood feeding. Amazingly, this species produces a full cohort of eggs (typically 50-100) in just 3 days' time following a blood meal. This rapid development represents dramatic shifts in physiological processes that result in massive volumetric changes to internal anatomy over time. To explore these changes thoroughly, a time course of microCT scans were completed over the vitellogenic period. This dataset provides a virtual representation of the volumetric, conformational, and positional changes occurring in tissues important for reproduction across the vitellogenic period. This dataset provides the field of vector biology with a detailed three-dimensional internal atlas of the processes of vitellogenesis in Ae. aegypti."
"As for career plans, I am applying to computational biology positions in industry," Mack said. "I'm not filing my dissertation until July so I am still working on this."
- Author: Kathy Keatley Garvey
Her major professor Jason Bond, then a professor and administrator at Auburn University, Alabama, described and named what is commonly called "The Barack Obama Trapdoor Spider" in 2012.
The article, published in the journal Ecology and Evolution and part of Newton's 2022 doctoral dissertation, is titled "Phylogeography and Cohesion Species Delimitation of California Endemic Trapdoor Spiders within the Aptostichus icenoglei Sibling Species Complex (Araneae: Mygalomorphae: Euctenizidae)."
Co-authors are Professor Bond, who is the Evert and Marion Schlinger Endowed Chair in the UC Davis Department of Entomology and Nematology, and associate dean, College of Agricultural and Environmental Sciences; and Bond lab members, project scientist James Starrett and doctoral candidate Emma Jochim.
"Species delimitation in mygalomorph spiders using only traditional morphological approaches has underestimated species diversity," Newton said, "yet molecular approaches have been shown to overestimate species diversity due to the local population structuring seen as 'species divergence.' Specifically, the Aptostichus icenoglei complex, which comprises the three sibling species, A. barackobamai, A. isabella, and A. icenoglei, exhibits evidence of cryptic mitochondrial DNA diversity throughout their ranges across the California Floristic Province."
The researchers sampled 62 individuals overall for the three species within the complex, using both specimens from Bond (2012) and new records. "A. barackobamai was collected across its geographic range in northern California for a total of 21 samples, and A. icenoglei was collected throughout its range in southern California for a total of 40 samples," they wrote. "Only one specimen of A. isabella was included in this study due to collecting constraints (i.e., only one individual of this species has ever been collected and a burrow has not yet been found containing this species; Bond, (2012)
Next steps? "We hope to use whole genomes for both reconstructing evolutionary relationships as well as identifying genes that contribute to potential adaptive divergence across the landscape," Newton said. "We also hope to gather more natural history data for each of the species, especially A. icenoglei populations, for general ecological information that may aid in species delimitation."
Born and raised in Eupora, Miss., and a first-generation college student in her family, Lacie holds a bachelor of science degree in biological sciences (2016) from Millsaps College, Jackson, Miss. She then enrolled in the graduate school program at Auburn University, studying with Professor Bond. When he accepted the Schlinger Endowed Chair in 2018, Lacie, along with other lab members, transferred to UC Davis. Newton completed her dissertation on species delimitation in two trapdoor spider groups, Antrodiaetus unicolor complex and Aptostichus icenoglei sister species complex, and evaluation of interspecific relationships within the genus Aptostichus.
The research drew support from a National Science Foundation Grant awarded to Bond and Starrett; the McBeth Memorial Scholarship awarded to Newton; and the Evert and Marion Schlinger Foundation.
- Author: Kathy Keatley Garvey
Postema studies the role of animal coloration in predator-prey interatctions with a special focus on color-changing species. She works with both live and artificial swallowtail caterpillars (family Papilionidae) in the field.
She is the lead author of a review article, "Color Under Pressure: How multiple Factors Shape Defensive Coloration," published in June 2022 in the journal, Behavioral Ecology.
The abstract: Behavioral ecologists have long studied the role of coloration as a defense against natural enemies. Recent reviews of defensive coloration have emphasized that these visual signals are rarely selected by single predatory receivers. Complex interactions between signaler, receiver, and environmental pressures produce a striking array of color strategies—many of which must serve multiple, sometimes conflicting, functions. In this review, we describe six common conflicts in selection pressures that produce multifunctional color patterns, and three key strategies of multifunctionality. Six general scenarios that produce conflicting selection pressures on defensive coloration are: (1) multiple antagonists, (2) conspecific communication, (3) hunting while being hunted, (4) variation in transmission environment, (5) ontogenetic changes, and (6) abiotic/physiological factors. Organisms resolve these apparent conflicts via (1) intermediate, (2) simultaneous, and/or (3) plastic color strategies. These strategies apply across the full spectrum of color defenses, from aposematism to crypsis, and reflect how complexity in sets of selection pressures can produce and maintain the diversity of animal color patterns we see in nature. Finally, we discuss how best to approach studies of multifunctionality in animal color, with specific examples of unresolved questions in the field."
On the Yang lab website, Postema says: "After growing up in Ann Arbor, MI, I relocated to Denison University in Granville, OH to pursue my undergraduate degree. Though I began my college career as a studio art major, I quickly found that biology was my calling. I studied a wide range of systems throughout college, from lemon sharks and rock iguanas to deciduous shrubs. I am now conducting research on insect color and behavior in the Animal Behavior program at UC Davis. When I'm not obsessing over bugs, I can usually be found spoiling my pet chickens, drawing sketches for The Ethogram, or writing poetry."
At UC Davis, Postema is a member of the Animal Behavior Graduate Group.
"Elizabeth will be starting a great postdoc position studying beetle coloration at the Field Museum in Chicago," Professor Yang announced.
- 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: Kathy Keatley Garvey
Alison Coomer, Pallavi Shakya and Ching-Jung Lin are among the record 18 students given travel awards by SON, thanks to industry sponsors. All travel award recipients will deliver a presentation or provide a poster at the international meeting.
Bayer Crop Science will sponsor 10 travel awards, and Microbes, Inc., Certis Biologicals and Corteva, will each sponsor two awards. In addition, the United Soybean Board will provide two travel awards to students presenting nematode research in soybean production.
Alison Coomer
Alison, a third-year graduate student in the Department of Plant Pathology, is focusing her research on plant parasitic nematodes, specifically root-knot nematodes, and their molecular mechanisms to defend against plant immune systems. "I am also working to gain more understanding in the defense mechanism in plants towards plant parasitic nematodes."
Alison, originally from the St. Louis, Mo., region, received two undergraduate degrees from Concordia University, Neb.: a bachelor's degree in biology and a bachelor's degree in chemistry.
"I am very thankful to Cobb Foundation and Mai-Ferries-Bird for receiving one of the most prestigious student awards: Cobb Foundation/Mai-Ferris-Bird Student Travel Award," she said.
In her leisure time, Alison enjoys "the outdoors, animals of all varieties, and serving my community."
Pallavi Shakya
Pallavi is a second-year doctoral student in Siddique lab. "I come from Nepal, the land of Himalayas and I am interested in exploring plant parasitic nematodes from a combination of plant pathology and bioinformatics viewpointism," she related. Pallavi received her master's degree in plant biotechnology from Wageningen University in the Netherlands where she was introduced to transcriptomics of potato cyst nematodes.
"Working with these nematodes showed me the importance of understanding plants along with the parasites they have co-evolved with," she said. "In the Siddique lab, I plan to learn about the genomics and transcriptomics aspects of plant-nematode interaction."
"I am very thankful to Bayer Crop Science for my student travel award, and I am looking forward to meeting all the amazing nematologists in the meeting."
Ching-Jung Lin
Ching-Jung is a doctoral student in the Department of Plant Pathology with a designated emphasis in biotechnology. "I am fascinated by plant-microbe interaction," she said. "Currently I am interested in the development of functional genetic tools in plant-parasitic nematodes and the characterization of nematode-induced plant immunity. Originally from Taiwan, she holds a bachelor of science degree in agronomy from National Chung-Hsing University, and a master's degree in plant biology from National Taiwan University.
"I am very thankful to Bayer Crop Science for funding my student award and I look forward to delivering my presentation at the SON conference," she said. Outside of the lab, Ching-Jung enjoys "reading, jogging, playing badminton, and going to the gym." And, she added, "I am a coffee and dog person."
Research in Shahid Siddique Lab
Research in the Siddique lab focuses on basic as well as applied aspects of interaction between parasitic nematodes and their host plants. "The long-term object of our research," he says, "is not only to enhance our understanding of molecular aspects of plant–nematode interaction but also to use this knowledge to provide new resources for reducing the impact of nematodes on crop plants in California."
SON is an international organization formed to advance the science of nematology in both its fundamental and economic aspects.
"Nematodes are the most abundant multicellular animals on the face of the earth," SON relates on its website. "They occur literally everywhere--in soil and decaying matter from the poles to the tropics, in all forms of plant life, in the bodies of almost all animals, including humans, and in insects. Living in such diverse environments as the sand and mud of the ocean bottom, stony mountain soils, and arid polar deserts are thousands to millions of nematodes per square meter."
SON defintes nematodes as "nonsegmented roundworms with complete sensory, digestive, excretory, and reproductive systems. Most, but not all, are microscopic. The variety of nematode forms and habitats is almost unbelievable: they range from the minute inhabitant of your favorite mushroom to the 27-foot-long parasite in the placenta of a sperm whale."
"Nematodes are essential elements of ecosystems, but most have no direct effect on humans," the SON website points out. "Those that do, however, can be devastating. In many places, people still suffer from diseases such as elephantiasis, river blindness, and hookworm, caused by nematodes. In most places, the effect on humans is indirect. For example, in the United States, plant-parasitic nematodes cause more than $3 billion worth of crop losses each year, and cause similar losses in cattle, sheep, and swine." (See more information about nematodes on its website.)
