Biology subjects

Goodman, A. G.

Publications and source records attributed to Goodman, A. G..

10 recordsLinked to original sources

bioRxiv2024

Elevational and Oceanic Barriers Shape the Distribution, Dispersal and Diversity of Aotearoa's Kapokapowai (Uropetala) Dragonflies

Mountains and islands provide an opportunity for studying the biogeography of diversification and population fragmentation. Aotearoa (New Zealand) is an excellent location to investigate both phenomena due to alpine emergence and oceanic separation. While it would be expected that separation across oceanic and elevation gradients are major barriers to gene flow in animals, including aquatic insects, such hypotheses have not been thoroughly tested in these taxa. By integrating population genomic from sub-genomic Anchored-Hybrid Enrichment sequencing, ecological niche modeling, and morphological analyses from scanning-electron microscopy, we show that tectonic uplift and oceanic vicariance are implicated in speciation and population structure in Kapokapowai (Uropetala) dragonflies. Although Te Moana o Raukawa (Cook Strait), is likely responsible for some of the genetic structure observed, speciation has not yet occurred in populations separated by the strait. We find that the altitudinal gradient across K[a] Tiritiri-o-te-Moana (the Southern Alps) is not impervious but it significantly restricts gene flow between aforementioned species. Our data support the hypothesis of an active colonization of K[a] Tiritiri-o-te-Moana by the ancestral population of Kapokapowai, followed by a recolonization of the lowlands. These findings provide key foundations for the study of lineages endemic to Aotearoa.

evolutionary biology↗

bioRxiv2024

Drosophila melanogaster Toll-9 elicits antiviral immunity against Drosophila C virus.

The Toll pathway plays a pivotal role in innate immune responses against pathogens. The evolutionary conserved pathogen recognition receptors (PRRs), including Toll like receptors (TLRs), play a crucial role in recognition of pathogen associated molecular patterns (PAMPs). The Drosophila genome encodes nine Toll receptors that are orthologous to mammalian TLRs. While mammalian TLRs directly recognize PAMPs, most Drosophila Tolls recognize the proteolytically cleaved ligand Spatzle to activate downstream signaling cascades. In this study, we demonstrated that Toll-9 is crucial for antiviral immunity against Drosophila C virus (DCV), a natural pathogen of Drosophila. A transposable element insertion in the Toll-9 gene renders the flies more susceptible to DCV. The stable expression of Toll-9 in S2 cells confers resistance against DCV infection by upregulation of the RNAi pathway. Toll-9 promotes the dephosphorylation of AKT, resulting in the induction of antiviral RNAi genes to inhibit DCV replication. Toll-9 localizes to the endosome where it binds dsRNA, suggesting its role to detect viral dsRNA. Toll-9 also induces apoptosis during DCV infection, contributing to its antiviral role. Together, this work identifies the role of Toll-9 in antiviral immunity against DCV infection through its ability to bind dsRNA and induce AKT-mediated RNAi antiviral immunity. IMPORTANCEInsects rely on innate immunity and RNA interference (RNAi) to combat viral infections. Our study underscores the pivotal role of Drosophila Toll-9 in antiviral immunity, aligning with findings in Bombyx mori, where Toll-9 activation upregulates the RNAi component Dicer2. We demonstrate that Drosophila Toll-9 functions as a pattern recognition receptor (PRR) for double-stranded RNA (dsRNA) during Drosophila C virus (DCV) infection, akin to mammalian TLRs. Toll-9 activation leads to the upregulation of key RNAi components, Dicer2 and Argonaute2, and dephosphorylation of AKT triggers apoptosis via induction of proapoptotic genes Hid and Reaper. This study also reveals that Toll-9 localizes in endosomal compartments where it interacts with dsRNA. These insights enhance our understanding of Drosophila innate immune mechanisms, reflecting the evolutionary conservation of immune responses across diverse species and providing impetus for further research into the conserved roles of TLRs across the animal kingdom.

immunology↗

bioRxiv2024

Antiviral insulin signaling during West Nile virus infection results in viral mutations

Arthropod-borne viruses or arboviruses, including West Nile virus (WNV), dengue virus (DENV), and Zika virus (ZIKV) pose significant threats to public health. It is imperative to develop novel methods to control these mosquito-borne viral infections. We previously showed that insulin/insulin-like growth factor-1 signaling (IIS)-dependent activation of ERK and JAK-STAT signaling has significant antiviral activity. Continuous immune pressure can lead to adaptive mutations of viruses during infection. We aim to elucidate how IIS-signaling in mosquitoes selects for West Nile virus escape variants, to help formulate future transmission blocking strategies. We hypothesize that passage of WNV under activation of IIS will induce adaptive mutations or escape variants in the infecting virus. To test our hypothesis, WNV was serially passaged through Culex quinquefasciatus Hsu cells in the presence or absence of bovine insulin to activate IIS antiviral pressure. We sequenced WNV genes encoding for E, NS2B, NS3, and NS5 and identified variants in E and NS5 arising from IIS antiviral pressure. In parallel to the genetic analyses, we also report differences in the levels of virus replication and Akt activation in human cells using virus passaged in the presence or absence of insulin. Finally, using adult Culex quinquefasciatus, we demonstrated the enhancement of immune response gene expression in virus-infected mosquitoes fed on insulin, compared to control. Notably, virus collected from insulin-fed mosquitoes contained a non-synonymous mutation in NS3. These results contribute towards achieving our long-term goal of manipulating mosquito IIS-dependent antiviral immunity to reduce WNV or other flavivirus transmission to mammalian hosts.

immunology↗

bioRxiv2024

Pathogenic diversification of the gut commensal Providencia alcalifaciens via acquisition of a second type III secretion system

Providencia alcalifaciens is a Gram-negative bacterium found in a wide variety of water and land environments and organisms. It has been isolated as part of the gut microbiome of animals and insects, as well as from stool samples of patients with diarrhea. Specific P. alcalifaciens strains encode gene homologs of virulence factors found in other pathogenic members of the same Enterobacterales order, such as Salmonella enterica serovar Typhimurium and Shigella flexneri. Whether these genes are also pathogenic determinants in P. alcalifaciens is not known. Here we have used P. alcalifaciens 205/92, a clinical isolate, with in vitro and in vivo infection models to investigate P. alcalifaciens-host interactions at the cellular level. Our particular focus was the role of two type III secretion systems (T3SS) belonging to the Inv-Mxi/Spa family. T3SS1b is widespread in Providencia spp. and encoded on the chromosome. T3SS1a is encoded on a large plasmid that is present in a subset of P. alcalifaciens strains, which are primarily isolates from diarrheal patients. Using a combination of electron and fluorescence microscopy and gentamicin protection assays we show that P. alcalifaciens 205/92 is internalized into eukaryotic cells, rapidly lyses its internalization vacuole and proliferates in the cytosol. This triggers caspase-4 dependent inflammasome responses in gut epithelial cells. The requirement for the T3SS1a in entry, vacuole lysis and cytosolic proliferation is host-cell type specific, playing a more prominent role in human intestinal epithelial cells as compared to macrophages. In a bovine ligated intestinal loop model, P. alcalifaciens colonizes the intestinal mucosa, inducing mild epithelial damage with negligible fluid accumulation. No overt role for T3SS1a or T3SS1b was seen in the calf infection model. However, T3SS1b was required for the rapid killing of Drosophila melanogaster. We propose that the acquisition of two T3SS by horizontal gene transfer has allowed P. alcalifaciens to diversify its host range, from a highly virulent pathogen of insects to an opportunistic gastrointestinal pathogen of animals.

microbiology↗

bioRxiv2024

Caspase-8 activity mediates TNFα production and restricts Coxiella burnetii replication during murine macrophage infection

Coxiella burnetii is an obligate intracellular bacteria which causes the global zoonotic disease Q Fever. Treatment options for infection are limited, and development of novel therapeutic strategies requires a greater understanding of how C. burnetii interacts with immune signaling. Cell death responses are known to be manipulated by C. burnetii, but the role of caspase-8, a central regulator of multiple cell death pathways, has not been investigated. In this research, we studied bacterial manipulation of caspase-8 signaling and the significance of caspase-8 to C. burnetii infection, examining bacterial replication, cell death induction, and cytokine signaling. We measured caspase, RIPK, and MLKL activation in C. burnetii-infected TNF/CHX-treated THP-1 macrophage-like cells and TNF/ZVAD-treated L929 cells to assess apoptosis and necroptosis signaling. Additionally, we measured C. burnetii replication, cell death, and TNF induction over 12 days in RIPK1-kinase-dead, RIPK3-kinase-dead, or RIPK3-kinase-dead-caspase-8-/- BMDMs to understand the significance of caspase-8 and RIPK1/3 during infection. We found that caspase-8 is inhibited by C. burnetii, coinciding with inhibition of apoptosis and increased susceptibility to necroptosis. Furthermore, C. burnetii replication was increased in BMDMs lacking caspase-8, but not in those lacking RIPK1/3 kinase activity, corresponding with decreased TNF production and reduced cell death. As TNF is associated with the control of C. burnetii, this lack of a TNF response may allow for the unchecked bacterial growth we saw in caspase-8-/- BMDMs. This research identifies and explores caspase-8 as a key regulator of C. burnetii infection, opening novel therapeutic doors.

microbiology↗

bioRxiv2023

Insulin-mediated endothelin signaling is antiviral during West Nile virus infection

West Nile virus (WNV) is the most prevalent mosquito-borne virus in the United States with approximately 2,000 cases each year. There are currently no approved human vaccines and a lack of prophylactic and therapeutic treatments. Understanding host responses to infection may reveal potential intervention targets to reduce virus replication and disease progression. The use of Drosophila melanogaster as a model organism to understand innate immunity and host antiviral responses is well established. Previous studies revealed that insulin-mediated signaling regulates WNV infection in invertebrates by regulating canonical antiviral pathways. Because insulin signaling is well-conserved across insect and mammalian species, we sought to determine if results using D. melanogaster can be extrapolated for the analysis of orthologous pathways in humans. Here, we identify insulin-mediated endothelin signaling using the D. melanogaster model and evaluate an orthologous pathway in human cells during WNV infection. We demonstrate that endothelin signaling reduces WNV replication through the activation of canonical antiviral signaling. Taken together, our findings show that endothelin-mediated antiviral immunity is broadly conserved across species and reduces replication of viruses that can cause severe human disease. IMPORTANCEArboviruses, particularly those transmitted by mosquitoes, pose a significant threat to humans and are an increasing concern because of climate change, human activity, and expanding vector-competent populations. West Nile virus is of significant concern as the most frequent mosquito-borne disease transmitted annually within the continental United States. Here, we identify a previously uncharacterized signaling pathway that impacts West Nile virus infection, namely endothelin signaling. Additionally, we demonstrate that we can successfully translate results obtained from D. melanogaster into the more relevant human system. Our results add to the growing field of insulin-mediated antiviral immunity and identifies potential biomarkers or intervention targets to better address West Nile virus infection and severe disease.

microbiology↗

bioRxiv2021

Coupled small molecules target RNA interference and JAK/STAT signaling to reduce Zika virus infection in Aedes aegypti

The recent global Zika epidemics have revealed the significant threat that mosquito-borne viruses pose. There are currently no effective vaccines or prophylactics to prevent Zika virus (ZIKV) infection. Limiting exposure to infected mosquitoes is best way to reduce disease incidence. Recent studies have focused on targeting mosquito reproduction and immune responses to reduce transmission. In particular, previous work evaluated the effect of insulin signaling on antiviral JAK/STAT and RNAi in vector mosquitoes. In this work, we demonstrate that targeting insulin signaling through the repurposing of small molecule drugs results in the activation of both of these antiviral pathways. Activation of this coordinated response additively reduced ZIKV levels in Aedes aegypti mosquitoes. This effect included a quantitatively greater reduction in salivary gland ZIKV levels relative to single pathway activation, indicating the potential for field delivery of these small molecules to substantially reduce virus transmission.

microbiology↗

bioRxiv2020

Natural Genetic Variation in Drosophila melanogaster Reveals Genes Associated with Coxiella burnetii Infection

The gram-negative bacterium Coxiella burnetii is the causative agent of Query (Q) fever in humans and coxiellosis in livestock. Association between host genetic background and Coxiella burnetii pathogenesis has been demonstrated both in humans and animals; however, specific genes associated with severity of infection remain unknown. We employed the Drosophila Genetics Reference Panel to perform a genome-wide association study and identify host genetic variants that affect Coxiella burnetii infection outcome. The analysis resulted in 64 genome-wide suggestive (P < 10-5) single nucleotide polymorphisms or gene variants in 25 unique genes. We examined the role of each gene in Coxiella burnetii infection using flies carrying a null mutation or RNAi knockdown of each gene and monitoring survival. Of the 25 candidate genes, 15 validated using at least one method. For many, this is the first report establishing involvement of these genes or their homologs with Coxiella burnetii susceptibility in any system. Among the validated genes, FER and tara play roles in the JAK-STAT, JNK, and decapentaplegic/TGF-{beta} signaling pathways that are associated with the innate immune response to Coxiella burnetii infection. Two other two validated genes, CG42673 and DIP-{varepsilon}, play roles in bacterial infection and synaptic signaling but no previous association with Coxiella burnetii pathogenesis. Furthermore, since the mammalian ortholog of CG13404 (PLGRKT) is an important regulator of macrophage function, CG13404 could play a role in Coxiella burnetii susceptibility through hemocyte regulation. These insights provide a foundation for further investigation of genetics of Coxiella burnetii susceptibility across a wide variety of hosts.

genetics↗

bioRxiv2019

Insulin potentiates JAK/STAT signaling to broadly inhibit flavivirus replication in insect vectors

The World Health Organization estimates that over half of the worlds population is at risk for vector-borne diseases, such as those caused by arboviral infection. Because many arboviruses are mosquito-borne, investigation of the insect immune response will help identify targets that could reduce the spread of these viruses by the mosquito. In this study, we used a genetic screening approach to identify insulin-like receptor as a novel component of the immune response to arboviral infection. We determined that vertebrate insulin reduces West Nile virus (WNV) replication in Drosophila melanogaster as well as WNV, Zika, and dengue virus titers in mosquito cells. Mechanistically, we showed that insulin signaling activates the JAK/STAT, but not RNAi, pathway to control infection. Finally, we validated that insulin priming of adult female Culex mosquitoes through a blood meal reduces WNV infection, demonstrating an essential role for insulin signaling in insect antiviral responses to emerging human pathogens.

microbiology↗

bioRxiv2019

Natural genetic variation screen in Drosophila identifies Wnt signaling, mitochondrial metabolism, and redox homeostasis genes as modifiers of apoptosis

Apoptosis is the primary cause of degeneration in a number of neuronal, muscular, and metabolic disorders. These diseases are subject to a great deal of phenotypic heterogeneity in patient populations, primarily due to differences in genetic variation between individuals. This creates a barrier to effective diagnosis and treatment. Understanding how genetic variation influences apoptosis could lead to the development of new therapeutics and better personalized treatment approaches. In this study, we examine the impact of the natural genetic variation in the Drosophila Genetic Reference Panel (DGRP) on two models of apoptosis-induced retinal degeneration: overexpression of p53 or reaper (rpr). We identify a number of known apoptotic, neural, and developmental genes as candidate modifiers of degeneration. We also use Gene Set Enrichment Analysis (GSEA) to identify pathways that harbor genetic variation that impact these apoptosis models, including Wnt signaling, mitochondrial metabolism, and redox homeostasis. Finally, we demonstrate that many of these candidates have a functional effect on apoptosis and degeneration. These studies provide a number of avenues for modifying genes and pathways of apoptosis-related disease.

genetics↗