It did: their research revealed how TSWV (family Tospoviridae, order Bunyavirales) packages its RNA genome, a crucial step in virus infection.
Their newly published research, “The Genome of a Bunyavirus Cannot be Defined at the Level of the Viral Particle But Only at the Scale of the Viral Population,” appears in the current edition of the Proceedings of the National Academy of Sciences (PNAS).
The 18-member research team included scientists primarily from the French National Research Institute for Agriculture, Food and Environment (INRAE) at the Campus International de Baillarguet, Montpellier; Department of Entomology, University of Wisconsin; and the Department of Entomology and Nematology, University of California, Davis.
“Our work showed the genome of TSWV can only be defined at the population level, pointing at emerging properties when viral particles infect plants in groups,” said a key author Stéphane Blanc, research director of INRAE's Biology and Genetics of Plant-Pathogen Interactions. “As most virions contain an incomplete genome, TSWV is a multi-component viral system, where co-infection and complementation are key in the life cycle. These findings open a myriad of possibly distinct properties depending on the genetic composition of the group of virions co-infecting a cell.”
“The most challenging part of this work was to create a protocol reliably quantifying the two polarities of each segment,” said lead author Michel Yvon of INRAE. “The next important advance will be to demonstrate that co-infection of cells by a group of particles is key to the spread of infection.”
Ullman, an international authority on orthotospoviruses and one of the four main authors, took a sabbatical to work on the project. “My interest was in understanding how TSWV packaged its RNA genome,” she said. “While this sounds like a simple goal, it is quite complex because TSWV has negative sense and ambisense viral strands and many research tools common to studying other viruses, such as infectious clones were not available.”
“It was a delight to work with the fantastic team of scientists that Stéphane assembled, all very talented with skills in virology, cryoelectron microscopy and nanopore PCR,” Ullman commented. “I cannot imagine a more talented and diverse group of people to conduct this difficult work. I learned a great deal about virus purification from Michel Yvon, whose leadership, skills in virology, and patient teaching really moved our project forward."
German, professor emeritus and former chair of both the Departments of Plant Pathology and Entomology at the University of Wisconsin, died Aug. 27, 2023 at age 82.
“I am indebted to my husband, Jean-Marc Leininger who frequently drove me to the laboratory in Avignon where I was able to rear thousands of virus-infected plants and to store TSWV isolate,” Ullman added. “Jean-Marc not only transported me and my virus specimens, but also learned to mechanically inoculate plants and helped with every inoculation and virus harvest.”
UC Davis postdoctoral scholar Sulley Ben-Mahmoud of the Ullman lab was among the co-authors.
Funding was provided by grants from Montpellier University of Excellence (MUSE); Floriculture and Nursery Research Initiative, U.S. Department of Agriculture, Agricultural Research Service (USDA-ARS); and the Fulbright Scholar Program. The authors also acknowledged support from
- Santé des Plantes et Environnementor Plant Health and Environment (SPE)
- Centre National de la Recherche Scientifique (CNRS)
- Institute of Research for Development (IRD)
- Institut national de la santé et de la recherche médicale (INSERM)
- Centre for International Cooperation in Agronomic Research for Development (CIRAD)
- Plant Health Institute of Montpelier (PHIM)
Ullman noted the importance of the research in her Fulbright application: “Sustainable management of insect-transmitted pathogens is a key concern for food production in France and the United States. Both countries grow many of the same crops and growers face similar challenges from insect-transmitted plant viruses. Current management strategies rely heavily on pesticides that may cause significant health and environmental concerns, including damage to bees and other pollinators, as shown with neonicotinoid pesticides. Clearly, better knowledge about these insect-transmitted viral systems…has potential to reduce pesticide use by providing novel and innovative technologies to manage orthotospoviruses and thrips in France and the United States.”
Ullman, a former chair of the Department of Entomology and a former associate dean of the UC Davis College of Agricultural and Environmental Sciences, anticipates strong research relationships between UC Davis and Montpellier that will lead to grant applications for international research and scholarly exchange opportunities for scientists, students, and post-doctoral scholars.
In their significance statement, the authors wrote: “Bunyaviruses infect animals, plants, fungi, and protists. Despite their importance, fundamental aspects of their biology as basic as the definition of their genome remain elusive. The viral genome consists of several negative or ambisense RNA segments, and virions often miss segments and/or package complementary strands. We formally quantify this heterogeneity on the species Tomato spotted wilt orthotospovirus. Within individual virus particles, the number, the identity, and the polarity of the segments are widely variable. In contrast, we show that a stable genetic composition is an emerging property of the viral population, each of the RNA segments/polarities accumulating reproducibly at a specific frequency. This resembles the genome formula of multipartite viruses, suggesting that bunyaviruses may also function as multicomponent viral systems.”
Their abstract: “Bunyaviruses are enveloped negative or ambisense single-stranded RNA viruses with a genome divided into several segments. The canonical view depicts each viral particle packaging one copy of each genomic segment in one polarity named the viral strand. Several opposing observations revealed nonequal ratios of the segments, uneven number of segments per virion, and even packaging of viral complementary strands. Unfortunately, these observations result from studies often addressing other questions, on distinct viral species, and not using accurate quantitative methods. Hence, what RNA segments and strands are packaged as the genome of any bunyavirus remains largely ambiguous. We addressed this issue by first investigating the virion size distribution and RNA content in populations of the tomato spotted wilt virus (TSWV) using microscopy and tomography. These revealed heterogeneity in viral particle volume and amount of RNA content, with a surprising lack of correlation between the two. Then, the ratios of all genomic segments and strands were established using RNA sequencing and qRT-PCR. Within virions, both plus and minus strands (but no mRNA) are packaged for each of the three L, M, and S segments, in reproducible nonequimolar proportions determined by those in total cell extracts. These results show that virions differ in their genomic content but together build up a highly reproducible genetic composition of the viral population. This resembles the genome formula described for multipartite viruses, with which some species of the order Bunyavirales may share some aspects of the way of life, particularly emerging properties at a supravirion scale.”
The 10 x 6-foot mural, which graces an outer wall of the Matthiasson Winery on Dry Creek Road, Napa, depicts more than 80 arthropods (insects, spiders and centipedes), several bird species, mammals (bobcat, deer, rabbits, squirrels, a pocket gopher), a gopher snake, mycorrhizal fungi and even earthworms, according to the three project leaders, UC Davis distinguished professor Diane Ullman and assistant professor Emily Meineke, both of the Department of Entomology and Nematology, and retired lecturer Gale Okumura of the Department of Design.
The project is the culmination of a spring quarter class, Entomology 001, “Art, Science and the World of Insects,” taught by Professors Ullman and Meineke. Ullman, founding co-director of the UC Davis Art/Science Fusion Program, described the project as “a collaboration between students and instructors in ENT 001; community members from Davis, Woodland, and Napa, and Matthiasson Winery; and the UC Davis Art/Science Fusion Program."
Praising the Arts/Science Fusion Program, the chancellor said the program "helps advance some of UC Davis' key goals, which are outlined in the university's 10-year strategic plan, titled 'To Boldly Go.' That first goal is to provide an educational experience that prepares all our students to address the needs and challenges of a diverse and changing world. The type of course that produced this mural helps advance this goal, by connecting art and science to enhance student learning in a truly innovative way. Another key goal is for UC Davis to be a role model for diversity. This program's strategy for teaching always includes community engagement, which attracts diverse students and fosters inclusivity through hands-on learning and collaborative teamwork. I also appreciate how the Arts/Science Fusion Program fosters community engagement."
Ullman noted that the general education class, "Art, Science and the World of Insects," was founded in 1996. It's been taught ever year since, "attracting students from every major offered on the UC Davis campus," she said.
The course--"taught with the notion that patterns, harmonies, symbols, and perceptions are shared across borders and disciplines--creates accessibility and inclusion for people that would otherwise fear science, or fear art," Ullman told the crowd. "Not only does this paradigm provide a new and innovative classroom learning experience, it creates collaborations between different kinds of students and the community."
The concept of an art/science paradigm "opened the door for students and community members to interpret the scientific endeavors of the campus and science of entomology," said Ullman, praising the College of Agricultural and Environmental Sciences "that supports this innovative method of teaching and extending knowledge to the public."
After advancing from research to a primary design, "the next step was to translate our research into visual narratives using design principles we learned from Gale," Ullman said. "With our designs in hand, the process of fabricating the artwork from clay began. Clay is a rich material with great memory, coming from the earth near Davis. In our classroom, every piece is used, recycled and carried forward."
"Once all the pieces of have been sculpted, glazed and fired in a kiln, assembly of the mosaic begins," Ullman related. "Everyone, students and community members contributed to assembly and grouting of the mosaic—truly a mosaic of human intention, creativity and will. We mixed our own grout and each color is custom designed after experimentation and consideration. Most artists would ask for 6 months to a year to complete a project of this size and scope. We completed the process in a mere 10 weeks, the scope of a quarter at UC Davis."
Ullman said that the 83 UC Davis students involved in the project "worked hard, learned about entomology, and the interactions between insects and people."
Meineke, an urban landscape entomologist, was unable to attend the Aug. 16th unveiling. Meineke and her husband Joe Kwon just "brought our newest Aggie, Genevieve Se Hwa Kwon into the world," Ullman told the gathering.
In a joint statement, Ullman and Meineke related that The Secret Life of Vineyards was designed to reflect the ecosystem within and around an organic vineyards as it progresses from early spring to harvest. A Cabernet Sauvignon vine is the centerpiece of the mural, shown from the first bud in the spring to harvest time in the autumn...The work is an ode to the importance of biodiversity and balance in the ecosystem in which wine vines are grown and reflects the passion of the Matthiasson Winery for sustainable viticulture.”
The professors credited artist Amanda Larson of Half Moon Bay "with the engineering and building of the hanging system, as well as the installation."
A familiar figure at UC Davis, he served as an associate of the Bohart Museum of Entomology and a scientific collaborator, identifying scores of insects and attending many of the Lepidopterist Society meetings there.
Plans call for dedicating the Bohart Museum's "Night at the Museum" (formerly known as "Moth Night") to him. The open house, free and open to the public, is set from 7 to 11 p.m., Saturday, July 22. The museum is located in Room 1124 of the Academic Surge Building, 455 Crocker Lane, UC Davis, campus.
Born May 23, 1933 in Glendale, Calif., Jerry received his bachelor's degree in entomology at UC Berkeley in 1955 and his doctorate there in 1961. One of his most-read books, co-authored with Charles Hogue, is California Insects, Volume 44, published in 1980. The second edition, co-authored by Kip Will, Daniel Rubinoff and Powell was published in October, 2020. Powell and Paul Opler 1938-2023) co-authored Moths of Western America, published in 2009.
In a tribute to Powell on its website, the Essig Museum posted in part:
"In his teen years he was heavily influenced by Charles 'Harbie' Harbison, who ran the Junior Naturalist Program at the San Diego Museum of Natural History, and sparked an interest in Jerry for butterflies and moths. Seeing his potential, Harbie recommended Jerry for the Entomology program at UC Berkeley, where he received his BS in 1955 and his PhD in 1961. While climbing through the ranks of Junior Entomologist (1961-62), Assistant Entomologist (1962-67), Associate Entomologist (1967-73), Entomologist (1973-94), Lecturer in Entomology (1964-69), Associate Professor (1969-73), and Professor (1973-94) at UC Berkeley, Jerry also became Curator (1972-2018) and Director (1993-1999) of the Essig Museum of Entomology (1972-1999) and Project Leader for the California Insect Survey (1963-1999). Although he retired as Director in 1999, Jerry remained a professor of the Graduate School until 2012 and maintained an active research program in Lepidoptera life histories and systematics until 2018, advising many students along the way. (See more on Essig website.)
"Jerry's rearing program was the most extensive in the history of the study of New World Microlepidoptera," according to the Essig post. "For over 50 years he and his students processed more than 15,000 collections of larval or live adult Lepidoptera. Resulting data encompass more than 1,000 species of moths, through rearing either field-collected larvae or those emerging from eggs deposited by females in confinement. This total includes more than 60% of an estimated 1,500 species of Microlepidoptera occurring in California."
Powell gained international recognition when he detected the agricultural pest, the light brown apple moth, Epiphyas postvittana, in a ultralight (UV) trap on July 19, 2006 in his backyard in Berkeley.
"Yet Powell's casual discovery that morning was just the beginning of something more serious: a moth infestation, a quarantine program and an all-out effort by state and federal authorities to stop a nasty creature that they concluded could threaten California's $38 billion agricultural market and--if unchecked--farms across the nation," wrote San Francisco Chronicle reporter Matthew B. Stannard in a June 3, 2007 piece, "Little Moth, Big Problem/Bay Area quarantine tries to halt the spread of ravenous pest."
In an email to colleagues on July 9, Peter Oboyski, executive director of the Essig Museum of Entomology, wrote in part: "With a heavy heart I am sad to report that professor Jerry Powell passed away this weekend. His contributions to our knowledge of California entomology, microlepidoptera, and insect life histories are inestimable, as is the value of the training he provided to his students. As one of those students, I am eternally grateful for the time, energy, and knowledge Jerry shared with me in the museum and the field."
"A consummate field biologist, Jerry's knowledge and interests were broad, allowing him to read landscapes and discover the most interesting and cryptic of species interactions," Oboyski wrote. "This is well documented in over 220 publications, but also in the 60+ years of his field notes and rearing records that we are currently digitizing. He is the collector of over 400 holotypes of various insect orders, described over 170 species and 14 genera of moths, and honored by 41 patronyms. He also published papers on Hymenoptera, Coleoptera, Diptera, Dermaptera, and a Nematode. His legacy is impressive and will long be remembered."
Powell described himself as a "MothNut" on his vehicle license plate, and also displayed a sticker, "Larvae on Board."
Winokur delivered her presentation on “Thermal Preferences of Aedes aegypti Mosquitoes.”
Her abstract: “Mosquito-borne pathogen transmission models used to inform control decisions are only applicable if we incorporate the temperatures mosquitoes experience. However, mosquito thermal preferences are not well resolved. We studied Aedes aegypti thermal preferences and found that female Ae. aegypti generally avoided temperatures >30°C on a gradient in the lab, and chose relatively cooler microhabitats in the field as ambient temperature increased. Incorporating these preferences could improve the accuracy of transmission models for Ae. aegypti-borne viruses.”
The Hollandsworth Prize memorializes Gerald Hollandsworth, a past president of the West Central Mosquito and Vector Control Association.
A UC Davis alumna, Winokur received her doctorate in entomology, with a designated emphasis in the biology of vector-borne diseases, in November 2022, studying with Professor Barker of the Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine.
She delivered her exit seminar, as part of the UC Davis Department of Entomology and Nematology weekly seminars, in October on "Temperature Drives Transmission of Mosquito-borne Pathogens: Improving Entomological Estimates for Aedes aegypti-borne Virus Transmission Risk."
"The mosquito Aedes aegypti is the primary vector of a range of viruses that cause a major burden on human health worldwide, including dengue, Zika, chikungunya, and yellow fever viruses," Winokur related in her abstract. "As the Zika epidemic emerged in 2016, estimates for Zika risk were based on proxy evidence from closely related dengue virus. To improve risk estimates, we studied how temperature affects Zika virus extrinsic incubation period. We sought to further improve risk estimates by studying thermal preferences of Ae. aegypti mosquitoes in the laboratory and in the field. Current mosquito-borne pathogen risk models primarily use temperatures from weather stations or thermal imagery as a proxy for the temperatures mosquitoes experience, however such approaches do not account for local environments or microclimates available to adult mosquitoes. Taken together, the results of these studies can be used to improve prediction of mosquito-borne pathogen risk and inform mosquito control decisions." (See information on the mosquito on the California Department of Public Health website)
As a postdoc in the Barker lab, Winokur is working with VectorSurv (https://vectorsurv.org/), and has a fellowship from Pacific Southwest Center of Excellence in Vector-Borne Diseases (https://pacvec.us/), working on "Enriching Practical Learning Resources for Entomological, Medical, and One-Health Curricula."
Olivia received her bachelor's degree in May of 2015 from Cornell University where she was an interdisciplinary studies major (environmental effects on human health). She enrolled in the UC Davis graduate program in 2016.
At UC Davis, Winokur served as the 2019-2020 president of the Entomology Graduate Student Association and as a 2020-2022 committee member of the UC Davis Entomology Diversity, Equity, Inclusion, & Belonging. She co-founded the Girls' Outdoor Adventure in Leadership and Science (GOALS) in 2017 and continues to serve in leadership roles. GOALS is a free two-week summer science program for high school girls and gender expansive youth from backgrounds underrepresented in STEM fields. They learn science, outdoors skills, and leadership hands-on while backpacking in Sequoia National Park.
There's still time--and room--to register to attend virtually the New Emeriti Distinguished Lecture on Wednesday, Feb. 15 by UC Davis distinguished professor emeritus Geerat Vermeij, an evolutionary biologist and paleoecologist with the UC Davis Department of Earth and Planetary Sciences.
Vermeij will speak in-person at 3 p.m. to a capacity crowd in the Putah Creek Lodge on "The Evolution of Power."
Putah Creek Lodge reservations are closed, but folks can watch the seminar virtually on Zoom, announced coordinator Walter Leal, UC Davis distinguished professor of the Department of Molecular and Cellular Biology, and former chair of the Department of Entomology and Nematology.
The lecture will be live-streamed on Zoom; registration is underway at https://bit.ly/3BXh0zA.
The program will include a poem by Andy Jones, continuing lecturer in the University Writing Program and a former poet laureate of the city of Davis. Leal also said that some "of our newest emeriti" will be honored.
In a pre-recorded video, Vermeij told Leal: "I'm going to talk about power. And I'm using power in the sense of physics and engineering, that is to say, energy per unit time. All kinds of biological phenomenon can be expressed in terms of power, so for example, productivity, even fitness, the use of force with respect to time and so on. And it turns out that if you think about various biological functions and interactions in terms of power, you rapidly come to see that the most powerful organisms have the greatest effect on their surroundings, in fact, they modify their own surroundings, often to their own benefit."
Vermeij is known for his work on coevolutionary telationships between predator and prey organisms, with a focus on marine mollusks. A native of The Netherlands, he lost his sight to glaucoma at age three, but did not let that deter him. Majoring in biology and geology, he graduated summa cum laudefrom Princeton University in 1968, and obtained his doctorate in biology and geology from Yale University in 1971. In 1992, Vermeij received a MacArthur Fellowship, the “genius” grant, and in 2000, was awarded the Daniel Giraud Elliot Medal from the National Academy of Sciences. (See The Shape of Life.)
The three-part New Emeriti Distinguished Lecture series "is a platform to celebrate the accomplishments of retiring colleagues,” Leal said last fall. “They have dedicated their lives to laying the foundation for UC Davis to grow into a premiere academic institution. We are very thankful for their contributions to the university's missions and for making UC Davis a better place for us to succeed."
First speaker in the series was UC Davis distinguished professor emeritus Harris Lewin, renowned for his research in comparative mammalian genomics and immunogenetics. He spoke Dec. 7 on “From Chickens to Cows to Everything: Perspectives from 40 Years in Science."
The last speaker in the series is Sharon Strauss, distinguished professor emerita, Department of Evolution and Ecology, College of Biological Sciences. She will speak at 3 p.m. Monday, April 17.
Leal released a “Tribute to Our New Emeriti" video last fall, spotlighting 24 faculty members who retired in 2021-22.