1980 Folwell Ave
St. Paul, MN 55108
United States
PhD, Biology, Queen's University, Kingston, Ontario, Canada 1976
MS, Biology Yale, 1974
BA, U Connecticut, 1972
Minnesota Mycological Society, North American Mycological Society, American Association of University Professors (AAUP), and Dragon Divas Cancer survivors' group
Areas of Interest
Cell culture, genetic transformation, microbiology, and insect reproduction
Biography
I study the reproductive physiology of insects. My undergrad work with Henry Hagedorn at the University of Connecticut focused on hormonal control of egg production in the mosquito Aedes aegypti. Using a radioimmunoassay to quantify yolk protein synthesis, we discovered that the insect steroid hormone, 20-hydroxyecdysone, is secreted by the ovary after a blood meal and activates expression of the vitellogenin gene in the fat body. During PhD research at Queens University in Ontario, Canada with Jerry Wyatt I investigated cyclic nucleotide metabolism in the house cricket, Acheta domesticus. High levels of this second messenger molecule in crickets suggested that insects use cGMP in processes where mammals use cAMP. However, I found that high levels of cGMP are restricted to the male accessory reproductive glands of a specific subfamily of crickets and are not characteristic of insects in general. I developed a biochemical assay for cGMP using a binding protein from silkmoth pupae, and explored enzymes involved in cyclic nucleotide metabolism. My postdoctoral work included molecular studies with ribosomal proteins in E. coli (Madison, WI), lepidopteran cell culture and baculoviruses (Texas A & M) and arboviruses in mosquito cell lines (Rutgers). Student projects have focused on molecular aspects of mosquito reproduction, gene amplification in cultured cells, cell cycle synchronization, and DNA-mediated gene transfer. Most recently, PhD student John Beckmann identified the toxin/antitoxin module encoding proteins responsible for Wolbachia-mediated cytoplasmic incompatibility in Culex pipiens. My current efforts focus on development of cell culture protocols to improve manipulation of Wolbachia in vitro, directed towards eventual genetic transformation.
Teaching
ENT 3275/5275: Insect-transmitted diseases of humans
ENT 1903: Toxins, Venoms and Drugs from Bugs
Research
My current research focuses on Wolbachia, an obligate intracellular bacterium that affects insect reproduction. Wolbachia was discovered in reproductive tissues of the mosquito Culex pipiens about 100 years ago, and is now known to occur in many insect species. It is a bacterium that has long-term applications to control of insect pests. In mosquitoes, Wolbachia causes a reproductive distortion called cytoplasmic incompatibility. In the testes, the bacteria produce a toxin that binds to the sperm of infected males. If the sperm fertilize an infected egg, the effects of the toxin are reversed, and the egg hatches. Eggs of uninfected females fail to develop when fertilized by an infected male because they lack the rescue factor. By increasing the reproductive success of infected females, which produce infected progeny, the overall abundance of Wolbachia in a host population increases. Wolbachia derives nutrients from the mosquito, and infected mosquitoes have reduced ability to vector pathogens. Ongoing applications of cytoplasmic incompatibility include suppression and/or replacement of mosquito populations in regions where humans are at risk for infection with dengue virus, and in Hawaii, to reduce transmission of malaria among endangered birds. Wolbachia normally lives in insect ovaries and testes; in a few cases, it can be grown in mosquito cell lines. I am exploring conditions to infect cells with Wolbachia from ovaries, and to improve manipulation of Wolbachia in vitro. My goal is to explore the metabolic interactions of Wolbachia with host cells and to develop systems in which Wolbachia can be genetically engineered to expand its applications to control of pest populations.
Outreach
Faculty representative to University Senate and various senate subcommittees
Select Publications
Fallon, AM, Leen LG, Kurtti, TJ. Establishment of a new cell line from embryos of the mosquito, Culex pipiens. In vitro cell dev biol-animal 2023, 59(5) 313-315. https://doi.org/10.1007/s11626-023-00771-5.
Ward, MCE, Barrios, MC, Fallon, AM. 2023. Paraquat is toxic to the soil-dwelling arthropod, Folsomia candida (Collembola: Isotomidae), and has potential effects on its Wolbachia endosymbiont. J Invert. Pathol. 2023, 198, 107936. https://doi.org/10.1016/j.jip.2023.107936
Fallon, AM, Carroll, EM. Virus-like particles from Wolbachia-infected cells may include a gene transfer agent. Insects 2023, 14, 516. https://doi.org/10.3390/insects14060516
Fallon, AM. Mitotically inactivated mosquito cells support robust Wolbachia infection and replication. In Vitro Cell. Dev. Biol. – Animal 2022. https://doi.org/10.1007/s11626-022-00726-2
Fallon, AM. From mosquito ovaries to ecdysone; from ecdysone to Wolbachia: one woman’s career in insect biology. Insects 2022, 13,756. https://doi.org/10.3390/ insects13080756
Fallon, AM. Muramidase, nuclease, or hypothetical protein genes intervene between paired genes encoding DNA packaging terminase and portal proteins in Wolbachia phages and prophages. Virus Genes 2022, 58(4):327-349. doi: 10.1007/s11262-022-01907-7.
Fallon, AM. Growth and maintenance of Wolbachia in insect cell lines. Insects 2021, 12, 706. doi.org/10.3390/insects12080706.
Fallon, AM. Assessment of mitotically inactivated mosquito cell feeder layers produced with mitomycin C. In Vitro Cell. Dev. Biol. – Animal 2021, 57:583–586. doi.org/10.1007/s11626-021-00597-z
Fallon, AM. DNA recombination and repair in Wolbachia: RecA and related proteins, Mol. Genet. Genomics 2021, 296(2):437-456. doi 10.1007/s00438-020-01760-z.
Fallon, AM: Computational evidence for antitoxins associated with RelE/ParE, RatA, Fic and AbiEii-family toxins in Wolbachia genomes. Mol. Genet. Genomics, 2020, 295, 891-909; doi 10.1007/s00438-020-01662-0
Fallon, AM: Conditions facilitating infection of mosquito cell lines with Wolbachia, an obligate intracellular bacterium, In Vitro Cell Dev Biol Animal 2019, 55 (2), 120-129. https://doi.org. 10.1007/s11626-019-00319-6
Graber, LC Fallon, AM. Tetracycline reduces feeding and reproduction of the parthenogenetic springtail, Folsomia candida. Symbiosis 2019, 77(3), 257-264. https://doi.org/10.1007/s13199-018-00593-0
Todey, SA, Fallon AM, Arnold, WS: Neonicotinoid insecticide hydrolysis and photolysis: rates and residual toxicity. Environmental Toxicology and Chemistry 2018, 37 (11):2797-2809. doi 10.1002/etc.4256.
Fallon, AM: Strain-specific response to ampicillin in Wolbachia-infected mosquito cell lines. In Vitro Cell Dev Biol Animal 2018, 454: 580-588. doi.org/10.1007/s11626-018-0279-x
Baldridge, GD, Higgins, LA, Witthuhn, BA, Markowski, TW, Baldridge, AS, Armien, AG, Fallon, AM. Proteomic analysis of a mosquito host response to persistent Wolbachia infection. Research in Microbiol 2017, 168, 609-625. https://doi.org/10.1016/j.resmic.2017.04.005.
Baldridge, GD, Li, YG, Witthuhn, BA, Higgins, LA, Markowski, TW, Baldridge, AS and Fallon, AM. Mosaic composition of ribA and wspB genes flanking the virB8-D4 operon in the Wolbachia supergroup B strain, wStr. Archs. Microbiol 2016, 198, 53-69. https://DOI 10.1007/s00203-015-1154-8.
Baldridge, GD, Markowski, TW, Witthuhn, BA Witthuhn, Higgins, LA, Baldridge AS and Fallon, AM. The Wolbachia WO bacteriophage proteome in the Aedes albopictus C/wStr1 cell line: Evidence for lytic activity? In Vitro Cell Dev. Biol--Animal 2016, 52, 77-88. https://DOI 10.1007/s11626-015-9949-0.
Li, G and Fallon, AM. Rearing the soil arthropod Folsomia candida (Collembola: Isotomidae) on agar plates and estimating biomass by protein staining with Ponceau S. Applied Entomol. Zool. 2016, 51(3) 489-494. DOI 10.1007/s13355-016-0405-8.
Fallon AM. Effects of mimosine on Wolbachia in mosquito cells: Cell cycle suppression reduces bacterial abundance. In Vitro Cell Dev. Biol Animal 2015, 51, 958-963. https://DOI 10.1007/s11626-015-9918-7.
Baldridge, GD, Baldridge, AS, Higgins, LA, Witthuhn, BA, Markowski, TW, Fallon, AM. Proteomic profiling of a robust Wolbachia infection in an Aedes albopictus mosquito cell line. Mol Microbiol 2014, 94, 537-556. doi:10.1111.mmi12768.
Fallon, AM, Baldridge, GD, Carroll, EM, Kurtz, CM. Depletion of host cell riboflavin reduces Wolbachia levels in cultured mosquito cells. In Vitro Cell. Dev. Biol Animal 2014, 50, 707-713.
Fallon, AM. Flow cytometric evaluation of the intracellular bacterium, Wolbachia pipientis, in mosquito cells. J Microbiological Methods 2014, 107, 119-125.
Beckmann, JF, Markowski, TW, Witthuhn, BA, Fallon, AM. Detection of the Wolbachia encoded DNA binding protein, HU-beta, in mosquito gonads. Insect Biochem Mol. Biol 2013, 43, 272-279.
Beckmann, JF and Fallon, AM. Detection of a Wolbachia Protein in Mosquito Spermathecae: Implications for Cytoplasmic Incompatibility. Insect Biochem. Mol. Biol. 2013, 43, 867-878.
Fallon, AM, Baldridge, GD, Higgins, LA, Witthuhn, BA. Wolbachia from the planthopper Laodelphax striatellus establishes a robust, persistent, streptomycin-resistant infection in clonal mosquito cells. In Vitro Cell Dev Biol Animal 2013, 49, 66-73.
Fallon, AM, Kurtz, CM, Carroll, EM. The oxidizing agent, paraquat, is more toxic to Wolbachia than to mosquito host cells. In Vitro Cell Dev Biol Animal, 2013, 49, 501-507.
Beckmann, J. F. and Fallon, A. M. Decapitation improves detection of Wolbachia pipientis (Rickettsiales: Anaplasmataeae) in Culex pipiens Linnaeus (Diptera: Culicidae) mosquitoes by the polymerase chain reaction. J. Med. Entomol 2012, 49, 1103-1108.
Honors and Awards
University of Minnesota Distinguished McKnight University Professor, 1999
Invited Visiting Professor, Central China Normal University, Wuhan, PRC, 1999
Semester leave: University of Texas Medical Branch, Department of Pathology, Galveston, TX; Fall, 2005
University of Minnesota, Distinguished Women Scholars Award in Science and Engineering, 2009
FAME (Faculty Award for Mentorship in Entomology) Award, U. Minnesota, 2014
Rosetta Briegel Barton Seminar, University of Oklahoma: Wolbachia and Mosquitoes: Prospects for Disease Reduction by Population Control, April 15, 2016, Norman, OK
Department of Entomology Special Recognition award for outstanding contributions to entomology, 2019 Sigma Xi, full member, Scientific Research Honor Society, 2019
Students Advised
At Rutgers
- 1982-1987 Joan E. Durbin, PhD 1987, MD, 1989
- 1983-1986 Mary Ann Fritz, PhD 1986
- 1985-1988 Yang-Ja Park, PhD 1988
- 1985-1986 Irawathy Chalikonda, MS 1986
- 1986-1987 Cuong Lam, MS 1987
- 1984-1988 Nassim Nouri, MS 1988
- 1986-1989 Steve Young, MS 1989
At University of Minnesota
- 1988-1992 Karl Kjer, PhD 1992
- 1988-1993 Que Lan, PhD 1993
- 1988-1992 Frank Shotkoski, PhD 1992
- 1989-1997 Christina Wu, MS 1992; PhD 1997;
- 1990-1995 Celeste Mazzacano, PhD 1995
- 1992-1997 Zhonghui Wang, PhD 1997
- 1992-2001 Ling Ling Niu Visiting Scholar/PhD, 1999
- 1993-1997 Jun Liu, MS 1996
- 1995-2000 Xiaogang Li, PhD 2000
- 1995-1998 Vida Hernandez, MS 1998
- 1996-2007 Karen Moline Shih, MS 1999; PhD 2007.
- 1996-2001 Dongxu Sun, PhD 2001
- 1998-2002 Nadia Nasr, PhD 2002
- 2000-2003 Melinda Schwientek, MS 2003
- 2001-2005 Abeer Yakout, MS 2006
- 2001-2005 Lingzhi Ma, Research Specialist, 2002; MS 2005
- 2001-2005 Yongjiao Zhai, Research Specialist, 2002; MS 2005
- 2002-2005 Lei Li, MS 2005
- 2009-2014 John Beckmann, PhD 2014
- 2011-2016 Grace Li, PhD 2016
Post Doctoral Associates:
- 1983-1987 Anne M. Johnston, Postdoctoral (Rutgers)
- 1984-1986 Phyllis G. Hotchkin, Postdoctoral (Rutgers)
- 1989-1989 Judy Helgen, Postdoctoral (Minnesota)
- 1989-1994 Gerald Baldridge, Postdoctoral (Minnesota)
- 1990-1994 Yang-Ja Park, Postdoctoral (Minnesota)
- 1999-2001 Ling Ling Niu, Postdoctoral (Minnesota)
- 1995-2003 Gitanjali Jayachandran, Postdoctoral (Minnesota)
Others:
- 1995, 1996, 1997 Huazhu Hong, Visiting Scientist (Central China Normal University)
- 1995-1999 Youxin Gao (Research Fellow, Minnesota)
- 2008-2008 Dr. Anita Bellie, Associate Professor, Government of India BioTechnology, Overseas Associate
- 2009-2010 Dr. Debby Filler, Professor, Anoka Ramsey Community College, Sabbatical
- 2010-2016 Gerald Baldridge, Senior Research Associate