University of Georgia
Generic selectors
Exact matches only
Search in title
Search in content
Post Type Selectors

Tag: Michael Strand

Trainee Spotlight: Benjamin Phipps

Donna Huber on November 16, 2021

Benjamin Phipps

Benjamin Phipps is an NIH T32 trainee in Michael Strand‘s laboratory. Originally from Woodland, California, Benjamin earned his bachelor’s degrees in Spanish and biology and a minor in chemistry from the University of North Texas in May 2019. While at UNT, he studied the influence of mixed vehicle emissions on regulation of the renin-angiotensin system with Dr. Amie Lund and programmed translational frameshifts in Streptomyces bacteriophages with Dr. Lee Hughes. Benjamin earned research support and two travel grants to report his findings for his undergraduate projects. In August 2019, he enrolled in the Integrated Life Sciences (ILS) program at UGA and completed several laboratory rotations in parasitology before joining the Strand Research Group. He has served as treasurer of the Genetics Graduate Student Association and currently serves in that role for the CTEGD GSA.

Why did you choose UGA?

I chose UGA for its strong track record in research and breadth of research topics. I enrolled at UGA through Integrated Life Sciences, a gateway Ph.D. program that allows incoming students to explore several life sciences departments before choosing one for their dissertation home. This allowed me to experience a greater range of research topics than if I had enrolled directly in a single department. I also developed an interest in parasitology in the last year of my undergraduate program and therefore was drawn to CTEGD, one of the largest and most active centers for parasitology research in the world.

What is your research focus/project and why are you interested in the topic?

Many mosquito species must feed on vertebrate blood to produce eggs, and thereby can transmit several blood-borne pathogens of humans. Malaria is by far the deadliest of these, killing hundreds of thousands of people each year. Suppressing mosquito populations is an attractive approach to curbing transmission of malaria. Two promising targets for limiting mosquito reproductive capacity are the communities of microorganisms that reside in the mosquito gut, which are thought to influence fecundity by aiding blood digestion, and hormones mobilized in response to the blood meal that regulate egg formation. Malaria parasites have an antagonistic relationship with mosquito gut microbes and exploit resources generated for egg production after the blood meal. My dissertation project focuses on how mosquito gut microbes influence malaria infection by modulating reproductive signaling. This research has the potential to identify microbial species that might be exploited for malaria control, as well as elucidate important functions of gut microbes in preventing infections in animals.

What are your future professional plans?

I am presently most interested in a career in academia because I enjoy mentorship and science writing, but I remain open to other opportunities.

What do you hope to do for your capstone experience? 

For my capstone experience, I would like to draw on my training in both parasitology and Spanish language to travel to Colombia or Venezuela, where malaria is declining but still endemic. Potential activities there would involve characterizing endemic anopheline populations and their vectorial capacity.

What is your favorite thing about UGA?

I really enjoy the collaborative atmosphere of life sciences at UGA. Groups such as CTEGD provide many opportunities to interact with students and faculty from diverse departments.

Any advice for a student interested in this field? 

Be sure to get involved in research as soon as possible, preferably early in your undergraduate program. Reach out to professors whose work interests you, as well as members of their team. It’s fine not to know what specific topics you want to pursue right away; your initial research experience will help you determine what interests you most, and there will be many opportunities to explore diverse fields in graduate school and beyond.

 

Support trainees like Benjamin by giving today to the Center for Tropical & Emerging Global Diseases.

[button size=’large’ style=” text=’Give Now’ icon=” icon_color=’BA0C2F’ link=’https://ctegd.uga.edu/give/’ target=’_self’ color=” hover_color=” border_color=” hover_border_color=” background_color=” hover_background_color=” font_style=” font_weight=” text_align=’center’ margin=”]

Evolutionary genomics of APSE: a tailed phage that lysogenically converts the bacterium Hamiltonella defensa into a heritable protective symbiont of aphids

Donna Huber on November 10, 2021

Background: Most phages infect free-living bacteria but a few have been identified that infect heritable symbionts of insects or other eukaryotes. Heritable symbionts are usually specialized and isolated from other bacteria with little known about the origins of associated phages. Hamiltonella defensa is a heritable bacterial symbiont of aphids that is usually infected by a tailed, double-stranded DNA phage named APSE.

Methods: We conducted comparative genomic and phylogenetic studies to determine how APSE is related to other phages and prophages.

Results: Each APSE genome was organized into four modules and two predicted functional units. Gene content and order were near-fully conserved in modules 1 and 2, which encode predicted DNA metabolism genes, and module 4, which encodes predicted virion assembly genes. Gene content of module 3, which contains predicted toxin, holin and lysozyme genes differed among haplotypes. Comparisons to other sequenced phages suggested APSE genomes are mosaics with modules 1 and 2 sharing similarities with Bordetella-Bcep-Xylostella fastidiosa-like podoviruses, module 4 sharing similarities with P22-like podoviruses, and module 3 sharing no similarities with known phages. Comparisons to other sequenced bacterial genomes identified APSE-like elements in other heritable insect symbionts (Arsenophonus spp.) and enteric bacteria in the family Morganellaceae.

Conclusions: APSEs are most closely related to phage elements in the genus Arsenophonus and other bacteria in the Morganellaceae.

Bret M Boyd, Germain Chevignon, Vilas Patel, Kerry M Oliver, Michael R Strand. Virol J. 2021 Nov 10;18(1):219. doi: 10.1186/s12985-021-01685-y.

Diet-Microbiota Interactions Alter Mosquito Development

Donna Huber on June 8, 2021

Gut microbes and diet can both strongly affect the biology of multicellular animals, but it is often difficult to disentangle microbiota-diet interactions due to the complex microbial communities many animals harbor and the nutritionally variable diets they consume. While theoretical and empirical studies indicate that greater microbiota diversity is beneficial for many animal hosts, there have been few tests performed in aquatic invertebrates. Most mosquito species are aquatic detritivores during their juvenile stages that harbor variable microbiotas and consume diets that range from nutrient rich to nutrient poor. In this study, we produced a gnotobiotic model that allowed us to examine how interactions between specific gut microbes and diets affect the fitness of Aedes aegypti, the yellow fever mosquito. Using a simplified seven-member community of bacteria (ALL7) and various laboratory and natural mosquito diets, we allowed larval mosquitoes to develop under different microbial and dietary conditions and measured the resulting time to adulthood and adult size. Larvae inoculated with the ALL7 or a more complex community developed similarly when fed nutrient-rich rat chow or fish food laboratory diets, whereas larvae inoculated with individual bacterial members of the ALL7 community exhibited few differences in development when fed a rat chow diet but exhibited large differences in performance when fed a fish food diet. In contrast, the ALL7 community largely failed to support the growth of larvae fed field-collected detritus diets unless supplemented with additional protein or yeast. Collectively, our results indicate that mosquito development and fitness are strongly contingent on both diet and microbial community composition.

Vincent G Martinson, Michael R Strand. Front Microbiol. 2021 Jun 8;12:650743. doi: 10.3389/fmicb.2021.650743. eCollection 2021.

Toll9 from Bombyx mori functions as a pattern recognition receptor that shares features with Toll-like receptor 4 from mammals

Donna Huber on May 10, 2021

Toll/Toll-like receptors (TLRs) are key regulators of the innate immune system in both invertebrates and vertebrates. However, while mammalian TLRs directly recognize pathogen-associated molecular patterns, the insect Toll pathway is thought to be primarily activated by binding Spätzle cytokines that are processed from inactive precursors in response to microbial infection. Phylogenetic and structural data generated in this study supported earlier results showing that Toll9 members differ from other insect Tolls by clustering with the mammalian TLR4 group, which recognizes lipopolysaccharide (LPS) through interaction with myeloid differentiation-2 (MD-2)-like proteins. Functional experiments showed that BmToll9 from the silkmoth Bombyx mori also recognized LPS through interaction with two MD-2-like proteins, previously named BmEsr16 and BmPP, that we refer to in this study as BmMD-2A and BmMD-2B, respectively. A chimeric BmToll9-TLR4 receptor consisting of the BmToll9 ectodomain and mouse TLR4 transmembrane and Toll/interleukin-1 (TIR) domains also activated LPS-induced release of inflammatory factors in murine cells but only in the presence of BmMD-2A or BmMD-2B. Overall, our results indicate that BmToll9 is a pattern recognition receptor for LPS that shares conserved features with the mammalian TLR4-MD-2-LPS pathway.

Ruonan Zhang, Xiaofeng Li, Jie Zhang, Yanjun Li, Yuan Wang, Yuhang Song, Feifei Ren, Huiyu Yi, Xiaojuan Deng, Yangjin Zhong, Yang Cao, Michael R Strand, Xiao-Qiang Yu, Wanying Yang. Proc Natl Acad Sci U S A. 2021 May 11;118(19):e2103021118. doi: 10.1073/pnas.2103021118.

Riboflavin instability is a key factor underlying the requirement of a gut microbiota for mosquito development

Donna Huber on April 9, 2021

We previously determined that several diets used to rear Aedes aegypti and other mosquito species support the development of larvae with a gut microbiota but do not support the development of axenic larvae. In contrast, axenic larvae have been shown to develop when fed other diets. To understand the mechanisms underlying this dichotomy, we developed a defined diet that could be manipulated in concert with microbiota composition and environmental conditions. Initial studies showed that axenic larvae could not grow under standard rearing conditions (27 °C, 16-h light: 8-h dark photoperiod) when fed a defined diet but could develop when maintained in darkness. Downstream assays identified riboflavin decay to lumichrome as the key factor that prevented axenic larvae from growing under standard conditions, while gut community members like Escherichia coli rescued development by being able to synthesize riboflavin. Earlier results showed that conventional and gnotobiotic but not axenic larvae exhibit midgut hypoxia under standard rearing conditions, which correlated with activation of several pathways with essential growth functions. In this study, axenic larvae in darkness also exhibited midgut hypoxia and activation of growth signaling but rapidly shifted to midgut normoxia and arrested growth in light, which indicated that gut hypoxia was not due to aerobic respiration by the gut microbiota but did depend on riboflavin that only resident microbes could provide under standard conditions. Overall, our results identify riboflavin provisioning as an essential function for the gut microbiota under most conditions A. aegypti larvae experience in the laboratory and field.

Yin Wang, Jai Hoon Eum, Ruby E. Harrison, Luca Valzania, Xiushuai Yang, Jena A. Johnson, Derek T. Huck, Mark R. Brown, Michael R. Strand Proceedings of the National Academy of Sciences Apr 2021, 118 (15) e2101080118; DOI: 10.1073/pnas.2101080118

Whole blood and blood components from vertebrates differentially affect egg formation in three species of anautogenous mosquitoes

Donna Huber on February 24, 2021

Background: Most female mosquitoes are anautogenous and must blood feed on a vertebrate host to produce eggs. Prior studies show that the number of eggs females lay per clutch correlates with the volume of blood ingested and that protein is the most important macronutrient for egg formation. In contrast, how whole blood, blood fractions and specific blood proteins from different vertebrates affect egg formation is less clear. Since egg formation is best understood in Aedes aegypti, we examined how blood and blood components from different vertebrates affect this species and two others: the malaria vector Anopheles gambiae and arbovirus vector Culex quinquefasciatus.

Methods: Adult female mosquitoes were fed blood, blood fractions and purified major blood proteins from different vertebrate hosts. Markers of reproductive response including ovary ecdysteroidogenesis, yolk deposition into oocytes and number of mature eggs produced were measured.

Results: Ae. aegypti, An. gambiae and C. quinquefasciatus responded differently to meals of whole blood, plasma or blood cells from human, rat, chicken and turkey hosts. We observed more similarities between the anthropophiles Ae. aegypti and An. gambiae than the ornithophile C. quinquefasciatus. Focusing on Ae. aegypti, the major plasma-derived proteins (serum albumin, fibrinogen and globulins) differentially stimulated egg formation as a function of vertebrate host source. The major blood cell protein, hemoglobin, stimulated yolk deposition when from pigs but not humans, cows or sheep. Serum albumins from different vertebrates also variably affected egg formation. Bovine serum albumin (BSA) stimulated ovary ecdysteroidogenesis, but more weakly induced digestive enzyme activities than whole blood. In contrast, BSA-derived peptides and free amino acids had no stimulatory effects on ecdysteroidogenesis or yolk deposition into oocytes.

Conclusions: Whole blood, blood fractions and specific blood proteins supported egg formation in three species of anautogenous mosquitoes but specific responses varied with the vertebrate source of the blood components tested.

Harrison, R.E., Brown, M.R. & Strand, M.R. Whole blood and blood components from vertebrates differentially affect egg formation in three species of anautogenous mosquitoes. Parasites Vectors 14, 119 (2021). https://doi.org/10.1186/s13071-021-04594-9

MdBVe46 is an envelope protein that is required for virion formation by Microplitis demolitor bracovirus

Donna Huber on February 16, 2021

Bracoviruses (BVs) are endogenized nudiviruses that braconid parasitoid wasps have coopted for functions in parasitizing hosts. Microplitis demolitor is a braconid wasp that produces Microplitis demolitor bracovirus (MdBV) and parasitizes the larval stage of the moth Chrysodeixis includens. Some BV core genes are homologs of genes also present in baculoviruses while others are only known from nudiviruses or other BVs. In this study, we had two main goals. The first was to separate MdBV virions into envelope and nucleocapsid fractions before proteomic analysis to identify core gene products that were preferentially associated with one fraction or the other. Results indicated that nearly all MdBV baculovirus-like gene products that were detected by our proteomic analysis had similar distributions to homologs in the occlusion-derived form of baculoviruses. Several core gene products unknown from baculoviruses were also identified as envelope or nucleocapsid components. Our second goal was to functionally characterize a core gene unknown from baculoviruses that was originally named HzNVorf64-like. Immunoblotting assays supported our proteomic data that identified HzNVorf64-like as an envelope protein. We thus renamed HzNVorf64-like as MdBVe46, which we further hypothesized was important for infection of C. includens. Knockdown of MdBVe46 by RNA interference (RNAi) greatly reduced transcript and protein abundance. Knockdown of MdBVe46 also altered virion morphogenesis, near-fully inhibited infection of C. includens, and significantly reduced the proportion of hosts that were successfully parasitized by M. demolitor.

Michael J Arvin, Ange Lorenzi, Gaelen R Burke, Michael R Strand. J Gen Virol. 2021 Feb 16. doi: 10.1099/jgv.0.001565.

Gene content evolution in the arthropods

Donna Huber on January 23, 2020

Abstract

BACKGROUND:

Arthropods comprise the largest and most diverse phylum on Earth and play vital roles in nearly every ecosystem. Their diversity stems in part from variations on a conserved body plan, resulting from and recorded in adaptive changes in the genome. Dissection of the genomic record of sequence change enables broad questions regarding genome evolution to be addressed, even across hyper-diverse taxa within arthropods.

RESULTS:

Using 76 whole genome sequences representing 21 orders spanning more than 500 million years of arthropod evolution, we document changes in gene and protein domain content and provide temporal and phylogenetic context for interpreting these innovations. We identify many novel gene families that arose early in the evolution of arthropods and during the diversification of insects into modern orders. We reveal unexpected variation in patterns of DNA methylation across arthropods and examples of gene family and protein domain evolution coincident with the appearance of notable phenotypic and physiological adaptations such as flight, metamorphosis, sociality, and chemoperception.

CONCLUSIONS:

These analyses demonstrate how large-scale comparative genomics can provide broad new insights into the genotype to phenotype map and generate testable hypotheses about the evolution of animal diversity.

Thomas GWC, Dohmen E, Hughes DST, Murali SC, Poelchau M, Glastad K, Anstead CA, Ayoub NA, Batterham P, Bellair M, Binford GJ, Chao H, Chen YH, Childers C, Dinh H, Doddapaneni HV, Duan JJ, Dugan S, Esposito LA, Friedrich M, Garb J, Gasser RB, Goodisman MAD, Gundersen-Rindal DE, Han Y, Handler AM, Hatakeyama M, Hering L, Hunter WB, Ioannidis P, Jayaseelan JC, Kalra D, Khila A, Korhonen PK Lee CE, Lee SL, Li Y, Lindsey ARI, Mayer G, McGregor AP, McKenna DD, Misof B, Munidasa M, Munoz-Torres M, Muzny DM, Niehuis O, Osuji-Lacy N, Palli SR, Panfilio KA, Pechmann M, Perry T, Peters RS, Poynton HC, Prpic NM, Qu J, Rotenberg D, Schal C, Schoville SD, Scully ED, Skinner E, Sloan DB, Stouthamer R, Strand MR, Szucsich NU, Wijeratne A, Young ND, Zattara EE, Benoit JB, Zdobnov EM, Pfrender ME, Hackett KJ, Werren JH, Worley KC, Gibbs RA, Chipman AD, Waterhouse RM, Bornberg-Bauer E, Hahn MW, Richards S. Genome Biol. 2020 Jan 23;21(1):15. doi: 10.1186/s13059-019-1925-7.

Predaceous Toxorhynchites mosquitoes require a living gut microbiota to develop

Donna Huber on January 22, 2020

Most species of mosquitoes are detritivores that feed on decaying plant and animal materials in their aquatic environment. Studies of several detritivorous mosquito species indicate that they host relatively low diversity communities of microbes that are acquired from the environment while feeding. Our recent results also indicate that detritivorous species normally require a living gut microbiota to grow beyond the first instar. Less well known is that some mosquitoes, including those belonging to the genus Toxorhynchites, are predators that feed on other species of mosquitoes and nektonic prey. In this study, we asked whether predaceous Toxorhynchites amboinensis larvae still require living microbes in their gut in order to develop. Using the detritivorous mosquito Aedes aegypti as prey, we found that T. amboinensis larvae harbour bacterial communities that are highly similar to that of their prey. Functional assays showed that T. amboinensis first instars provided axenic (i.e. bacteria-free) prey failed to develop, while two bacterial species present in gnotobiotic (i.e. colonized by one or more known bacterial species) prey successfully colonized the T. amboinensis gut and rescued development. Axenic T. amboinensis larvae also displayed defects in growth consistent with previously identified roles for microbe-mediated gut hypoxia in nutrient acquisition and assimilation in A. aegypti. Collectively, these results support a conserved role for gut microbes in regulating the development of mosquitoes with different feeding strategies.

Kerri L. Coon, Luca Valzania, Mark R. Brown and Michael R. Strand. Proc Biol Sci. 2020 Jan 29;287(1919):20192705. doi: 10.1098/rspb.2019.2705