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Author: Donna Huber

The good, the bad, and the ugly: From planarians to parasites

Platyhelminthes can perhaps rightly be described as a phylum of the good, the bad, and the ugly: remarkable free-living worms that colonize land, river, and sea, which are often rife with color and can display extraordinary regenerative ability; parasitic worms like schistosomes that cause devastating disease and suffering; and monstrous tapeworms that are the stuff of nightmares. In this chapter, we will explore how our research expanded beyond free-living planarians to their gruesome parasitic cousins. We start with Schistosoma mansoni, which is not a new model; however, approaching these parasites from a developmental perspective required a reinvention that may hold generalizable lessons to basic biologists interested in pivoting to disease models. We then turn to our (re)establishment of the rat tapeworm Hymenolepis diminuta, a once-favorite model that had been largely forgotten by the molecular biology revolution. Here we tell our stories in three, first-person narratives in order to convey personal views of our experiences. Welcome to the dark side.

Tania Rozario, James J Collins 3rd, Phillip A Newmark. Curr Top Dev Biol. 2022;147:345-373. doi: 10.1016/bs.ctdb.2021.12.015.

Trainee Spotlight: Justine Shiau

Justine Shiau

Justine Shiau, an NIH T32 fellow in Dr. Dennis Kyle’s laboratory, is originally from Taipei, Taiwan, and moved to the states after elementary school. She received her bachelor’s degree in Biology from the Pennsylvania State University, where she became interested in disease transmission, disease ecology, and parasitology while working with Dr. Ashutosh Pathak. Upon graduation, she moved to Athens to continue her training with Dr. Pathak, who at that time was working in the transmission ecology of vector-borne diseases with Dr. Courtney Murdock. Over the next two years, she took part in research projects revolving around vector biology and mosquito-transmitted pathogens. She was accepted by the UGA Integrated Life Science graduate program in Fall 2018.

In the Kyle lab, Justine is currently working on the transmission stages of Plasmodium falciparum, a human malaria parasite that causes significant mortality worldwide, specifically on the biology of the parasite transitioning from the vector to the human and the early stages within the human, prior to disease onset. She aims to complete the parasite’s life cycle in a laboratory setting, which would be a powerful tool to help further our understanding of the host-parasite interactions. She hopes to better understand the parasite biology and the transmission dynamic that the mosquitoes could have on the downstream infection in humans, which can potentially help us better understand and combat this horrible disease.

Why did you choose UGA?

UGA has one of the finest insectary facilities that allows the transmission of Plasmodium falciparum. Additionally, the Center of Tropical and Emerging Global Diseases (CTEGD) is the hub for parasitologists. The Center provides state-of-the-art infrastructure, research equipment, and, most of all, a supportive environment to cultivate and train graduate students to meet our goals.

What is your research focus?

Plasmodium falciparum is a parasite that causes malaria, which 50% of the world’s population is at risk of getting. Many children die from malaria every year; we cannot effectively prevent diseases and transmissions without a well-rounded understanding of the parasite’s biology and the essential players (mosquitoes) to complete its life cycle. My overarching goal is to complete the parasite’s life cycle in the lab. Currently, we are focusing on the biology of the parasite and its transition from mosquito back to human and within the human: from liver-to-blood stage infections. While doing this, there are two primary objectives that I would like to meet. First, I want to better understand the important factors for the parasites to establish infection in the human liver cells. Second, I am curious whether the mosquito stage infection can also impact the parasite’s efficiency in establishing infection in the human liver.

What are your future professional plans?

After graduate school, I hope to continue my postdoctoral training. I would like to pursue interdisciplinary research, with crosstalk between disease-ecology, parasitology, and vector biology.

Any advice for a student interested in this field?

Be open-minded and respectful to people with different expertise and people with diverse backgrounds.

 

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

Differential Growth Rates and In Vitro Drug Susceptibility to Currently Used Drugs for Multiple Isolates of Naegleria fowleri

The free-living amoeba Naegleria fowleri, which typically dwells within warm, freshwater environments, can opportunistically cause primary amoebic meningoencephalitis (PAM), a disease with a mortality rate of >97%. The lack of positive treatment outcomes for PAM has prompted the discovery and development of more effective therapeutics, yet most studies utilize only one or two clinical isolates. The inability to assess possible heterogenic responses to drugs among isolates from various geographical regions hinders progress in the discovery of more effective drugs. Here, we conducted drug efficacy and growth rate determinations for 11 different clinical isolates by applying a previously developed CellTiter-Glo 2.0 screening technique and flow cytometry. We found significant differences in the susceptibilities of these isolates to 7 of 8 drugs tested, all of which make up the cocktail that is recommended to physicians by the U.S. Centers for Disease Control and Prevention. We also discovered significant variances in growth rates among isolates, which draws attention to the differences among the amoeba isolates collected from different patients. Our results demonstrate the need for additional clinical isolates of various genotypes in drug assays and highlight the necessity for more targeted therapeutics with universal efficacy across N. fowleri isolates. Our data establish a needed baseline for drug susceptibility among clinical isolates and provide a segue for future combination therapy studies as well as research related to phenotypic or genetic differences that could shed light on mechanisms of action or predispositions to specific drugs.

IMPORTANCE Naegleria fowleri, also known as the brain-eating amoeba, is ubiquitous in warm freshwater and is an opportunistic pathogen that causes primary amoebic meningoencephalitis. Although few cases are described each year, the disease has a case fatality rate of >97%. In most laboratory studies of this organism, only one or two well-adapted lab strains are used; therefore, there is a lack of data to discern if there are major differences in potency of currently used drugs for multiple strains and genotypes of the amoeba. In this study, we found significant differences in the susceptibilities of 11 N. fowleri isolates to 7 of the 8 drugs currently used to treat the disease. The data from this study provide a baseline of drug susceptibility among clinical isolates and suggest that new drugs should be tested on a larger number of isolates in the future.

A Cassiopeia Russell, Dennis E Kyle. Microbiol Spectr. 2022 Feb 9;e0189921. doi: 10.1128/spectrum.01899-21

Insulin-like peptide 3 stimulates hemocytes to proliferate in anautogenous and facultatively autogenous mosquitoes

Most mosquito species are anautogenous, which means they must blood feed on a vertebrate host to produce eggs, while a few are autogenous and can produce eggs without blood feeding. Egg formation is best understood in the anautogenous mosquito Aedes aegypti where insulin-like peptides (ILPs), ovary ecdysteroidogenic hormone (OEH) and 20-hydroxyecdysone (20E) interact to regulate gonadotrophic cycles. Circulating hemocytes also approximately double in abundance in conjunction with a gonadotrophic cycle but the factors responsible for stimulating this increase remain unclear. Focusing on Ae. aegypti, we determined that hemocyte abundance similarly increased in intact blood-fed females and decapitated blood-fed females that were injected with ILP3, whereas OEH, 20E, or heat-killed bacteria had no stimulatory activity. ILP3 upregulated insulin-insulin growth factor signaling in hemocytes but few genes, including almost no transcripts for immune factors, were differentially expressed. ILP3 also stimulated circulating hemocytes to increase in two other anautogenous (Anopheles gambiae and Culex quinquefasciatus) and two facultatively autogenous mosquitoes (Aedes atropalpus and Culex pipiens molestus), but had no stimulatory activity in the obligately autogenous mosquito Toxorhynchites amboinensis. Altogether, our results identify ILPs as the primary regulators of hemocyte proliferation in association with egg formation, but also suggest this response has been lost in the evolution of obligate autogeny.

Ellen O Martinson, Kangkang Chen, Luca Valzania, Mark R Brown, Michael R Strand. J Exp Biol. 2022 Feb 7;jeb.243460. doi: 10.1242/jeb.243460.

CRISPR/Cas9-induced disruption of Bodo saltans paraflagellar rod-2 gene reveals its importance for cell survival

Developing transfection protocols for marine protists is an emerging field that will allow the functional characterization of protist genes and their roles in organism responses to the environment. We developed a CRISPR/Cas9 editing protocol for Bodo saltans, a free-living kinetoplastid with tolerance to both marine and freshwater conditions, and a close non-parasitic relative of trypanosomatids. Our results show that SaCas9/sgRNA ribonucleoprotein (RNP) complex-mediated disruption of the paraflagellar rod 2 gene (BsPFR2) was achieved using electroporation-mediated transfection. The use of CRISPR/Cas9 genome editing can increase the efficiency of targeted homologous recombination when a repair DNA template is provided. Based on sequence analysis, two mechanisms for repairing double-strand breaks (DSB) in B. saltans are active; homologous directed repair (HDR) utilizing an exogenous DNA template that carries an antibiotic resistance gene, and non-homologous end joining (NHEJ). However, HDR was only achieved when a single (vs. multiple) SaCas9 RNP complex was provided. Further, the biallelic knockout of BsPFR2 was detrimental for the cell, highlighting its essential role for cell survival because it facilitates the movement of food particles into the cytostome. Our Cas9/sgRNA RNP complex protocol provides a new tool for assessing gene functions in B. saltans, and perhaps similar protists with polycistronic transcription. This article is protected by copyright. All rights reserved.

Fatma Gomaa, Zhu-Hong Li, David J Beaudoin, Heba Alzan, Peter R Girguis, Roberto Docampo, Virginia P Edgcomb. Environ Microbiol. 2022 Jan 31. doi: 10.1111/1462-2920.15918.

Jessica Kissinger elected as AAAS Fellow

Jessica Kissinger with student
Dr. Jessica Kissinger with student

Three University of Georgia faculty have been named Fellows of the American Association for the Advancement of Science.

In a tradition stretching back to 1874, these individuals are elected annually by the AAAS Council for their extraordinary achievements leading to the advancement of science. Fellows must have been AAAS members for at least four years.

“Researchers are elected Fellows of the AAAS by their peers in recognition of significant contributions to their field,” said Karen Burg, vice president for research. “As we expand our research and innovation ecosystem, it’s exciting to see our faculty continue to be honored for their superb scholarship. I congratulate all of them on this wonderful achievement.”

The 2021 class of AAAS Fellows includes 564 scientists, engineers and innovators spanning 24 scientific disciplines who are being recognized for their scientifically and socially distinguished achievements. The new Fellows will be honored at the annual AAAS meeting in Philadelphia, Feb. 17-20.  Along with the rest of their 2021 class, UGA’s three new Fellows will receive an official certificate and a gold and blue rosette pin whose colors represent science and engineering.

Including these three, 37 faculty at UGA are Fellows of the American Association for the Advancement of Science.

UGA’s 2021 AAAS Fellows are:

James E. Byers: Meigs Distinguished Teaching Professor and associate dean for research and operations in the Odum School of Ecology, Byers was selected for distinguished contributions to the field of ecology, particularly in invasion biology, parasite ecology, ecosystem engineering and range boundaries in marine environments, as well as excellence in teaching.

Jessica Kissinger: Distinguished Research Professor of genetics in the Franklin College of Arts and Sciences and a member of the Center for Tropical and Emerging Global Diseases, Kissinger was selected for distinguished contributions to the field of the evolution of infectious diseases, particularly for bioinformatics approaches.

Patricia Yager: Professor of marine science in the Franklin College, Yager was selected for outstanding work on climate-driven processes and their impact on marine ecosystems.

To view a list of all AAAS Fellows from UGA, visit the Office of Research website.

 

The story by Ian Bennet first appeared on UGA Today.

Cytometry Shared Resource Lab expands capabilities with new instrument

Julie Nelson
Julie Nelson, CSRL manager, is available to train users on the newly acquire CYTEK Aurora flow cytometer. (photo credit: Donna Huber)

With the generous financial support of The Office of Research, Cytometry Shared Resource Lab, Center for Tropical and Emerging Global Diseases, Department of Infectious Diseases, and UGA faculty members Rick Tarleton, Mark Tompkins, Chet Joyner, and Sam Kurup, the CTEGD Cytometry Shared Resource Laboratory (CSRL) recently added the Cytek Aurora Spectral Cytometer to its facility. This new instrument provides a high level of flexibility to the researcher and complements the other instruments available at the facility.

“It’s great to be able to bring this exciting new resource to campus in support of the incredible research UGA members are conducting,” said Julie Nelson, CSRL manager.

Flow cytometry is a technique for measuring characteristics of cells or particles using laser excitation and innate fluorescence emission or emission from dyes added to identify cells or particles and their function in experimental biology.  In the past 30 years, this technology has revolutionized many areas of cell biology research including the study of viruses, bacteria, infectious diseases, and cancer.  This technology has also proven useful in genetic studies of plants.

The Aurora Spectral Cytometer delivers high-resolution data at the single-cell level to resolve the most challenging cell populations, such as cells with high autofluorescence or low levels of expression of key biomarkers, regardless of assay complexity. With 64 emission detectors and 5 lasers for excitation, the Aurora can resolve almost any fluorescent marker currently on the market. It can also evaluate dyes under development that can be excited by one or more of the 5 lasers available.

“This cytometer expands our capabilities from a limit of 24 parameters to 64 making it ideal for high dimensional immunophenotyping,” said Nelson. “But because of its unique spectral emission detection, it is also the best instrument for looking at highly autofluorescent cells, such as macrophages and liver cells, regardless of how many markers are needed for the assay.”

For more than 20 years, the CSRL has provided access to state-of-the-art flow cytometry analyzers to researchers at the University of Georgia and across the scientific community. In addition to the instruments, the facility also provides expert advice and consultation for the design and analysis of flow experiments.

The CSRL is hosting a free webinar on the CYTEK Aurora on Friday, January 28 at 1:00 pm with Christopher Fleming, Ph.D. To register: https://register.gotowebinar.com/register/2294357931236562192

webinar flyer

Structure-activity and structure-property relationship studies of spirocyclic chromanes with antimalarial activity

Malaria is a prevalent and lethal disease. The fast emergence and spread of resistance to current therapies is a major concern and the development of a novel line of therapy that could overcome, the problem of drug resistance, is imperative. Screening of a set of compounds with drug/natural product-based sub-structural motifs led to the identification of spirocyclic chroman-4-one 1 with promising antimalarial activity against the chloroquine-resistant Dd2 and chloroquine-sensitive 3D7 strains of the parasite. Extensive structure-activity and structure-property relationship studies were conducted to identify the essential features necessary for its activity and properties.

Iredia D Iyamu, Yingzhao Zhao, Prakash T Parvatkar, Bracken F Roberts, Debora R Casandra, Lukasz Wojtas, Dennis E Kyle, Debopam Chakrabarti, Roman Manetsch. Bioorg Med Chem. 2022 Jan 14;57:116629. doi: 10.1016/j.bmc.2022.116629.

The complete genome of Chelonus insularis reveals dynamic arrangement of genome components in parasitoid wasps that produce bracoviruses

Bracoviruses (BVs) are endogenized nudiviruses in parasitoid wasps of the microgastroid complex (family Braconidae). Microgastroid wasps have coopted nudivirus genes to produce replication-defective virions that females use to transfer virulence genes to parasitized hosts. The microgastroid complex further consists of six subfamilies and ∼50,000 species but current understanding of BV gene inventories and organization primarily derives from analysis of two wasp species in the subfamily Microgastrinae (Microplitis demolitor and Cotesia congregata) that produce M. demolitor BV (MdBV) and C. congregata BV (CcBV). Notably, several genomic features of MdBV and CcBV remain conserved since divergence of M. demolitor and C. congregata ∼53 million years ago (MYA). However, it is unknown whether these conserved traits more broadly reflect BV evolution, because no complete genomes exist for any microgastroid wasps outside of the Microgastrinae. In this regard, the subfamily Cheloninae is of greatest interest because it diverged earliest from the Microgastrinae (∼85 MYA) after endogenization of the nudivirus ancestor. Here, we present the complete genome of Chelonus insularis, which is an egg-larval parasitoid in the Cheloninae that produces C. insularis BV (CinsBV). We report that the inventory of nudivirus genes in C. insularis is conserved but are dissimilarly organized when compared to M. demolitor and C. congregata. Reciprocally, CinsBV proviral segments share organizational features with MdBV and CcBV but virulence gene inventories exhibit almost no overlap. Altogether, our results point to the functional importance of a conserved inventory of nudivirus genes and a dynamic set of virulence genes for the successful parasitism of hosts. Our results also suggest organizational features previously identified in MdBV and CcBV are likely not essential for BV virion formation.

Significance Bracoviruses are a remarkable example of virus endogenization, because large sets of genes from a nudivirus ancestor continue to produce virions that thousands of wasp species rely upon to parasitize hosts. Understanding how these genes interact and have been coopted by wasps for novel functions is of broad interest in the study of virus evolution. This manuscript characterizes bracovirus genome components in the parasitoid wasp Chelonus insularis, which together with existing wasp genomes captures a large portion of the diversity among wasp species that produce bracoviruses. Results provide new information about how bracovirus genome components are organized in different wasps while also providing additional insights on key features required for function.

Meng Mao, Michael R Strand, Gaelen R Burke. J Virol. 2022 Jan 5;JVI0157321. doi: 10.1128/JVI.01573-21.