“This is the first paper documenting induction/stimulation of pollen germination by non-plants,” said Christensen, a doctoral candidate in the Microbiology Graduate Group who joined the Vannette lab in January 2019. “Nectar-dwelling Acinetobacter bacteria, commonly found in flowers, stimulate protein release by inducing pollen to germinate and burst, benefitting Acinetobacter.”
The article, “Nectar Bacteria Stimulate Pollen Germination and Bursting to Enhance Microbial Fitness,” is online July 28 and will be in print in the Oct. 11th edition of the journal Current Biology.
Christensen, who co-authored the paper with community ecologist and associate professor Vannette, and former Vannette lab member Ivan Munkres, collected California poppies, Eschscholzia californica, from the UC Davis Arboretum and Public Garden, and Acinetobacter primarily from the Stebbens Cold Canyon Reserve, a unit the UC Natural Reserve System that encompasses the Blue Ridge Berryessa Natural Area in Solano and Napa counties.
The question—“How do organisms actually eat pollen?”--has been a long-standing one, Vannette said, “because pollen is well-protected by a layers of very resistant biopolymers and it's unclear how pollen-eaters get through those protective layers.”
“The finding that bacteria--in this case a specific genus of bacteria-- can cause premature pollen germination and release of nutrients-- is cool for a number of reasons,” said Vannette, a UC Davis Hellman Fellow. “First, Shawn's results are very novel--no one has described this phenomenon before! Second, Acinetobacter is a genus of bacteria that are very common in flowers. They are usually among the most abundant bacteria in nectar and are often found on other floral tissues, including pollen, stigmas etc.”
Christensen, an evolutionary biologist turned microbiologist, studies Acinetobacter and other nectar microbes and their potential influences on pollen for nutrient procurement, as well as the metabolomics of solitary bee pollen provisions.
The UC Davis doctoral student is a recipient of two research awards: the Maurer-Timm Student Research Grant, a UC Davis award for research conducted in the Natural Reserves; and a Davis Botanical Society research award, specifically for this project.
Shawn holds a bachelor of science degree in evolutionary biology from University of Wisconsin-Madison. “I studied reducing ecological impacts of phosphorus runoff, ethnobotany and domestication traits in Brassica rapa, botanical field excursions of all kinds, the evolution of chemical sets in the early origins of life, and now plant-microbe-pollinator interactions."
The honor is awarded to those scholars “whose work has been internationally recognized and acclaimed and whose teaching performance is excellent.”
The UC Davis Department of Entomology now has a total of nine distinguished professors: six current faculty--Bruce Hammock, Frank Zalom, Lynn Kimsey, James R. Carey, Jay Rosenheim, and Richard Karban--and three emeriti faculty--Harry Kaya, Howard Ferris and Thomas Scott. (In addition, emeritus professor/chair Robert E. Page Jr. is a UC Davis distinguished emeritus professor, as was the late Robbin Thorp, who died in 2019.)
Karban, whose research interests include the population regulation of animal species and the interactions between herbivores and their host plants, currently focuses his research on two main projects: volatile communication between sagebrush plants that affects resistance to herbivory and factors that control the abundance and spatial distribution of wooly bear caterpillars.
Karban has researched plant communication in sagebrush (Artemisia tridentata) on the east side of the Sierra since 1995. His groundbreaking research on plant communication among kin, published in February 2013 in the Proceedings of the Royal Society B: Biological Sciences, drew international attention. In that study, Karban and his co-researchers found that kin have distinct advantages when it comes to plant communication, just as “the ability of many animals to recognize kin has allowed them to evolve diverse cooperative behaviors.”
On his website, he explains his research on volatile communication: “When sagebrush is experimentally clipped, it releases volatile cues that undamaged branches on the same plant, on different sagebrush plants, and on some other plant species respond to. These volatile cues cause many changes in neighboring plants and some of these changes make the undamaged neighbors better defended against their herbivores. We currently know little about the nature of these cues.
“Blocking air contact between branches makes responses undetectable, indicating the involvement of airborne cues. Methyl jasmonate has the ability to serve as the signal although it remains unclear if it acts in this capacity in nature. I would like to understand the costs and benefits of releasing volatiles cues and of responding to them. I am examining the multiple consequences of emitting cues. For example, cues affect neighboring plants, nearby herbivores, as well as predators and parasites of those herbivores. I am currently examining the long-term fitness consequences for sagebrush of responding to volatile cues.”
On his research on the abundance and distribution of caterpillars, Karban writes: “Many workers define ecology as the science that explains the abundance and distribution of species. Despite a century of work on these questions, our field has only a rudimentary grasp on the factors that are important. I have been censusing populations of wooly bear caterpillars at Bodega Bay for 30 years and have relatively little understanding of the factors that produce patterns in abundance and distribution. The ‘usual suspects' all have relatively little explanatory power: weather, food limitation, and parasitoids all fail to provide much insight. Indeed, caterpillars often recover from the attacks of their tachinid parasitoids and alter their diets when parasitized to increase their chances of surviving. Including a more complete food web in our analysis does not appear to provide more resolution although ants may be unappreciated as predators and food quality may also be important. I am collaborating with Perry de Valpine to attempt to develop new analytical techniques that will account for more of the variance in abundance data. I am collaborating as well with Marcel Holyoak to examine spatial patterns of abundance.”
Karban is the author of landmark book, Plant Sensing and Communication. He is a fellow of the Ecological Society of America (ESA) and the American Association for the Advancement of Science, and the recipient of the 1990 George Mercer Award from ESA for outstanding research.
The UC Davis ecologist is featured in the Dec. 23-30, 2013 edition of The New Yorker in Michael Pollan's piece, The Intelligent Plant: Scientists Debate a New Way of Understanding Plants. Zoe Schlanger featured him in a Nov. 21, 2020 Bloomberg Quint article titled The Botanist Daring to Ask: Do Plants Have Personalities?
Karban received his bachelor's degree in environmental studies from Haverford (Penn.) College in 1977 and his doctorate in biology from the University of Pennsylvania, Philadelphia, in 1982. He served as a lecturer at Haverford College for six months before joining the UC Davis faculty in May 1982 as an assistant professor. He advanced to associate professor in 1988 and to full professor in 1994.
Niño, known internationally for her expertise on honey bee queen biology, chemical ecology, and genomics, joined the faculty in September of 2014 and maintains laboratories and offices in Briggs Hall and at the Harry H. Laidlaw Jr. Honey Bee Research Facility.
Niño serves as the director of the California Master Beekeeper Program (CAMBP), which she launched in 2016. The California Master Beekeeper Program is a continuous train-the-trainer effort. CAMBP's vision is to train beekeepers to effectively communicate the importance of honey bees and other pollinators within their communities, serve as mentors for other beekeepers, and become the informational conduit between the beekeeping communities throughout the state and UCCE staff.
Niño is also the faculty director of the Häagen-Dazs Honey Bee Haven, the department's half-acre educational bee garden located next to the Laidlaw facility, which serves as the outdoor classroom for the Pollinator Education Program, lovingly known as PEP.
“My research interests are fluid and designed to address immediate needs of various agriculture stakeholder groups,” she writes on her website. “Projects encompass both basic and applied approaches to understanding and improving honey bee health and particularly honey bee queen health. Ongoing research projects include understanding queen mating and reproductive processes, discovery and evaluation of novel biopesticides for efficacy against varroa mites, and evaluating orchard management practices with a goal of improving honey bee health. Some of our more fun projects revolve around precision beekeeping and investigate the use of cutting edge technologies to make beekeeping more efficient and sustainable.”
Niño says she “greatly enjoys working with the community and especially with children. To ensure that our future researchers, agriculture leaders and innovators and future voters understand the importance of honey bees and other pollinators to our agroecosystems.”
“Our Pollinator Education Program at the Häagen Dazs Honey Bee Haven garden has been working with the Farms of Amador County to serve third grade students and we are planning on expanding our efforts in the near future and as the pandemic hopefully resolves.”
Niño received her bachelor's degree in animal science from Cornell University in 2003; her master's degree in entomology at North Carolina State University in 2006; and her doctorate at Pennsylvania State University (PSU) in 2012. She served as a postdoctoral fellow, funded by the U.S. Department of Agriculture's National Institute of Food and Agriculture (USDA-NIFA), as a member of the PSU Center for Pollinator Research.
Niño has a varied entomology background. While working on her bachelor's degree at Cornell, she was involved in studies on darkling beetle control in poultry houses, pan-trapped horse flies, and surveyed mosquitoes in New York state. While working toward her master's degree at North Carolina State University, she studied dung beetle nutrient cycling and its effect on grass growth, effects of methoprene (insect grown regular) on dung beetles in field and laboratory settings, and assisted in a workshop on forensic entomology.
Two UC Davis Department of Entomology and Nematology faculty members are now full professors, and a third faculty member has achieved tenure as associate professor.
Molecular geneticist and physiologist Joanna Chiu, vice chair of the department, and community ecologist Louie Yang were promoted from associate professors to professors, effective July 1. Community ecologist Rachel Vannette was promoted from assistant professor to associate professor.
Professor Chiu joined the Department of Entomology and Nematology in 2010 as an assistant professor and advanced to associate professor and vice chair in 2016. She received her bachelor's degree in biology and music from Mount Holyoke College, Mass., and her doctorate in molecular genetics in 2004 from New York University, New York. She served as a postdoctoral fellow from 2004 to 2010 in chronobiology (biological rhythms and internal clocks)--molecular genetics and biochemistry--at the Center for Advanced Biotechnology and Medicine, at Rutgers, the State University of New Jersey.
Chiu's research expertise includes molecular genetics of biological timing and posttranslational regulation of proteins. She uses animal models including Drosophila melanogaster and mice to study the mechanisms that regulate circadian and seasonal physiology and behavior. Major grants from the National Institutes of Health and the National Science Foundation fund her biological rhythms research. In addition to her research in biological rhythms, Chiu also aims to leverage her expertise in genomics to address key issues in global food security.
In 2019, she was named one of 10 UC Davis Chancellor's Fellows, an honor awarded to associate professors who excel in research and teaching.
Chiu and Yang co-founded and co-direct (with Professor Jay Rosenheim) the campuswide Research Scholars Program in Insect Biology, launched in 2011 to provide undergraduates with a closely mentored research experience in biology. The program crosses numerous biological fields, including population biology; behavior and ecology; biodiversity and evolutionary ecology; agroecology; genetics and molecular biology; biochemistry and physiology; entomology; and cell biology. The goal is to provide academically strong and highly motivated undergraduates with a multi-year research experience that cultivates skills that will prepare them for a career in biological research.
Professor Yang, who holds a bachelor's degree (ecology and evolution) from Cornell University, 1999, received his doctorate from UC Davis in 2006, and joined the UC Davis faculty in 2009. In 2013, he received a prestigious National Science Foundation Faculty Early Career Development Award of $600,000. He was named a UC Davis Hellman Fellow in 2012; the Hellman Family Foundation contributes funds to support and encourage the research of promising assistant professors who exhibit potential for great distinction in their research. He was promoted to associate professor in 2015.
Yang won the 2018 Outstanding Faculty Academic Advising Award from NACADA, also known as the Global Community for Academic Advising; and the 2017 Faculty Advisor Award of Excellence in NACADA's Pacific Region 9, comprised of California, Nevada and Hawaii.
Yang says of the research underway in his lab: “We study how species interactions change over time. We apply a diversity of approaches and perspectives to a diversity of systems and questions. We do experimental community ecology. We also use observational methods, meta-analysis, conceptual synthesis, ecosystem perspectives, and theoretical models. We like data, and we like learning new things.”
Associate Professor Vannette joined the UC Davis Department of Entomology and Nematology in 2015 after serving as a postdoctoral fellow at Stanford University's biology department, where she was a Gordon and Betty Moore Foundation Postdoctoral Fellow from 2011 to 2015 and examined the role of nectar chemistry in community assembly of yeasts and plant-pollinator interactions.
Vannette received her bachelor of science degree, summa cum laude, in 2006 from Calvin College, Grand Rapids,Mich., and her doctorate from the University of Michigan's Department of Ecology and Evolutionary Biology, Ann Arbor, in 2011. She received a Hellman Fellowship grant in 2018 and a National Science Foundation Faculty Early Career Development Award in 2019 to study microbial communities in flowers and a National Science Foundation grant to support work on solitary bee microbiomes.
Of her research, Vannette says: “ All plants are colonized by microorganisms that influence plant traits and interactions with other species, including insects that consume or pollinate plants. I am interested in the basic and applied aspects of microbial contributions to the interaction between plants and insects. I also use these systems to answer basic ecological questions, such as what mechanisms influence plant biodiversity and trait evolution.”
“The Vannette lab is a team of entomologists, microbiologists, chemical ecologists, and community ecologists trying to understand how microbial communities affect plants and insects (sometimes other organisms, too),” she says. “We often study microbial communities in flowers, on insects or in soil. We rely on natural history observations, and use techniques from chemical ecology, microbial ecology and community ecology. In some cases, we study applied problems with an immediate application including pathogen control or how to support pollinators. Other questions may not have an immediate application but are nonetheless grounded in theory and will contribute to basic knowledge and conservation (e.g. how can dispersal differences among organisms affect patterns of abundance or biodiversity?)”
By Lisa Howard
UC Davis Health
See Video on YouTube (includes segment with Bruce Hammock, UC Davis distinguished professor)
Researchers at UC Davis are developing a new type of pain medication from an unusual source — tarantula venom.
The project is part of the NIH Helping to End Addiction Long-Term (HEAL) Initiative, aimed at ending opioid addiction and creating non-addictive therapies to treat pain.
Vladimir Yarov-Yarovoy, a professor of physiology and membrane biology, and Heike Wulff, a professor of pharmacology, are leading the 20-person team using computational biology to turn a poisonous peptide into one that can relieve pain. Peptides are smaller versions of proteins.
“Spiders and scorpions have millions of years of evolution optimizing peptide, protein and small-molecule poisons in their venom, which we can take advantage of,” said Bruce Hammock, a distinguished professor of entomology, who is working on the new pain reliever. “The same venoms that can cause pain and neurological dysfunction can also help nerves work better and reduce pain.”
Approximately 20 percent of adults in the U.S., around 50 million, are affected by chronic pain. About 11 million are affected by high-impact chronic pain, defined as pain that lasts three months or longer and restricts a significant activity, like being unable to work outside the home, go to school or do household chores.
A few non-opioid medications are available to help those with chronic pain, and complementary or integrative health approaches can help. In general, though, people with chronic pain have limited options for pain relief.
“For strong pain, drugs like ibuprofen or aspirin are just not strong enough. Opioids are strong enough, but they have the problem of tolerance development and addiction,” said Wulff.
Opioid addiction and misuse in the United States surged in recent years, leading to a significant health crisis. In 2019, nearly 50,000 people in the United States died from opioid-involved overdoses.
“What we need are new medications, new therapies with improved risk profiles,” said David Copenhaver, a member of the team and director of Cancer Pain Management and Supportive Care at UC Davis Health. “There's been a push to develop other, better, safer, less addictive — or zero addictive — medication and therapeutics for pain management,” said Copenhaver, who is also the associate director for the Center for Advancing Pain Relief at UC Davis.
“Channels” key to new pain reliever
To create a non-addictive but strong pain medication, the researchers are focused on pain signals traveling on sensory neurons. To stop these signals, they have targeted a particular type of protein “channel” found on the cell membranes of neurons and muscles.
These channels, called voltage-gated sodium channels, play a crucial role in generating signals to nerves and muscles.
Nine different types of these channels have been identified in humans. The sodium symbol is Na, so the voltage-gated channels are referred to as Nav1.1 through Nav1.9.
The Nav1.7 channel is the one that interests pain scientists the most because it is a key source of pain transmission.
That's where the tarantula venom comes in. A peptide — a type of protein — found in the venom of the Peruvian green velvet tarantula blocks Nav1.7, preventing it from transmitting signals, including those for pain.
“The promise of a Nav1.7 inhibitor is that we would have something that is as effective as an opioid, but not addictive,” said Wulff, who specializes in preclinical therapeutics development targeting ion channels.
The challenge with the protein in the tarantula venom is that it doesn't just block Nav1.7 channels in the sensory nerves. In its natural form, the peptide blocks all Nav1.7 channels, including those in the muscles and the brain, meaning that it could cause terrible side effects.
Engineering a non-toxic protein
To solve this problem, the researchers are using an approach known as “toxineering.” They are trying to engineer — modify — the toxin in the venom to block pain signals but not create unwanted side effects.
To do this, they are using a computer program developed by the University of Washington called Rosetta. The complex modeling software lets the team create many different iterations of the tarantula peptide, which they can then synthesize and test in the lab.
“Using the Rosetta software, we can take a natural peptide and then redesign it and make it into a therapeutic,” said Yarov-Yarovoy, an expert in computational structural modeling of peptide toxins. “Our lead peptides already show efficacy at the level of morphine, but without the side effects of opioids.”
Their preliminary results are extremely promising, but a lot of work remains to be done. The potential therapeutic candidates will need to be tested in animals, and if found safe, carefully tested in humans. The researchers estimate any new medication is at least five years away.
“What Vladimir has put together is really fantastic because no one scientist could have any hope of tackling a project that is this hard,” Hammock said about the 20-person team. “But having a collection of people makes it fun and exciting, and I think it gives us a real chance at relieving pain.”
Additional team members include Karen Wagner, Jon T. Sack, Theanne Griffith, Scott Fishmann, Hai Nguyen, Daniel J. Tancredi, Nieng Yan, William Schmidt, Andre Ghetti, Neil Castle, Michael Pennington, Phuong Tran Nguyen, Brandon Harris, Diego Lopez Mateos, Robert Stewart and Parashar Thapa.
The tarantula venom research at UC Davis is funded by a $1.5 million grant from NIH initiative Helping to End Addiction Long-Term (HEAL). FOA Number: RFA-NS-19-010
Lisa Howard, Health News Office
UC Davis Health
4900 Broadway, Suite 1200
Sacramento, CA 95820