Biology subjects

Kelly, S. E.

Publications and source records attributed to Kelly, S. E..

5 recordsLinked to original sources

bioRxiv2026

AP-1 activation in Drosophila neuropil ensheathing glia improves traumatic brain injury survival

Traumatic brain injury (TBI) impacts millions of individuals annually causing death, disability, and a heightened risk for long-term neurological and neuropsychiatric disorders. In recent years the fruit fly, Drosophila melanogaster has become a valuable model organism to study the cellular and molecular responses following TBI. AP-1 mediated transcriptional responses to TBI have previously been identified in Drosophila using pan-glial approaches. Fruit flies possess multiple glial subtypes which vary greatly in both cellular morphology and function, including glia of the blood hemolymph barrier, cortex, astrocyte-like, and ensheathing glia. By generating and utilizing a nuclear localized AP-1 transcriptional reporter, we identified glial subtype-specific differences in the extent of AP-1 activation following injury. Our findings identify a strong AP-1 response in the blood hemolymph barrier and ensheathing glia, a moderate response in cortex glia and little to no AP-1 activation in astrocyte-like glia. In addition, we inhibited AP-1 signaling in each glial subtype and tested the effect on acute survival. We found that inhibition of the AP-1 response in neuropil ensheathing glia leads to increased mortality following mild and moderate TBI. These results show that AP-1 activation levels vary across glial subtypes after TBI, with activation in neuropil ensheathing glia having a particularly important role in promoting post-injury survival. ARTICLE SUMMARYUsing Drosophila as a model organism, we investigated the early molecular and cellular response to traumatic brain injury. Our findings substantiate the requirement of a functional glial associated AP-1 transcriptional activation response for survival. Using colocalization studies, we characterized the AP-1 glial response in six morphologically and functionally distinct glia subtypes. After TBI, we find high levels of AP-1 activation in glia of the hemolymph brain barrier, cortex glia, and ensheathing glia. We further show the importance of AP-1 transcription within the neuropil ensheathing glia subtype for optimal survival following TBI.

neuroscience↗

bioRxiv2026

Limited horizontal transmission of an obligate, free-living bacterial symbiont

Nutritional symbionts can be essential for their animal hosts. The bacterial symbiont of the leaffooted bug, Leptoglossus zonatus, Caballeronia, is acquired from the environment each generation in the 2nd instar. The symbiont is critical for L. zonatus: aposymbiotic bugs are unable to reproduce. We hypothesized that symbiotic bugs excrete Caballeronia where juveniles might find and consume them. We inoculated L. zonatus with GFP-labelled Caballeronia and examined feces of each life stage. We found that Caballeronia is excreted almost exclusively in the adult stage. We then asked if 2nd instar nymphs could acquire Caballeronia from feces. Nymphs were provided with a) feces from adults fed GFP-labelled Caballeronia, b) GFP-Caballeronia in culture, or c) water only. We found that feces-fed bugs had similar rates of symbiont acquisition to those fed Caballeronia in culture, indicating that feces can be a source of Caballeronia for L. zonatus. However, compared to culture-fed individuals, bugs fed feces had reduced survivorship and required longer to develop, and surviving adults had reduced mass. Bacterial motility assays showed that in contrast to cultured Caballeronia cells, Caballeronia in feces were non-motile. These results suggest that feces can be a source of Caballeronia, at least in some environments. However, transmission mode can influence the success of the offspring.

ecology↗

bioRxiv2026

Identification of cytoplasmic incompatibility effectors of the reproductive manipulator Cardinium hertigii

Cytoplasmic incompatibility (CI), a widespread symbiont-induced reproductive manipulation phenotype in arthropods, selectively kills embryonic offspring produced when infected males mate with uninfected females. Most knowledge on CI comes from studying the Pseudomonadota symbiont Wolbachia and their CI effector (cif) genes, and little is known about CI mechanisms of symbionts without cif genes. We identify two putative CI effectors of Cardinium hertigii cEper1, a Bacteroidota symbiont of the parasitoid wasp Encarsia suzannae, using a combined proteomics and heterologous expression approach. We show that these genes, CAHE_0406 and CAHE_p0043, have no homology to known cif genes, yet impair yeast growth similar to known cifs and that CAHE_p0043 localizes to diffuse and fragmented yeast nuclei. These results suggest that CAHE_0406 and/or CAHE_p0043 could play a role in cEper1-induced CI, expanding our current understanding of the diversity of proteins involved in cytoplasmic incompatibility across symbiont lineages.

microbiology↗

bioRxiv2025

The facultative intracellular symbiont Lariskella is neutral for lifetime fitness and spreads through cytoplasmic incompatibility in the leaffooted bug, Leptoglossus zonatus

The maternally-inherited, intracellular bacterium Lariskella (Alphaproteobacteria: Midichloreaceae) has been widely detected in arthropods including true bugs, beetles, a wasp, a moth, and pathogen-vectoring fleas and ticks. Despite its prevalence, its role in the biology of its hosts has been unknown. We set out to determine the role of this symbiont in the leaffooted bug, Leptoglossus zonatus (Hempitera: Coreidae). To examine the effects of Lariskella on bug performance and reproduction as well as in possible interactions with the bugs obligate nutritional symbiont, Caballeronia, bugs were reared in a factorial experiment with both Lariskella and Caballeronia positive and negative treatments. Lifetime survival analysis ([~]120 days) showed significant developmental delays and decrease in survival for bugs that lacked Caballeronia, and Caballeronia-free bugs did not reproduce. However, among the Caballeronia carrying treatments, there were no significant differences in lifetime survival or reproduction in treatments with and without Lariskella, suggesting this symbiont is neutral for overall bug fitness. To test for reproductive manipulation, crossing among Lariskella-positive and negative individuals was performed. When Lariskella-negative females were mated with Lariskella positive males, fewer eggs survived early embryogenesis, consistent with a cytoplasmic incompatibility (CI) phenotype. Wild L. zonatus from California and Arizona showed high but not fixed Lariskella infection rates. Within individuals, Lariskella titer was low during early development (1st-3rd instar), followed by an increase that coincided with development of reproductive tissues. Our results reveal Lariskella to be among a growing number of microbial symbionts that cause CI, a phenotype that increases the relative fitness of females harboring the symbiont. Understanding the mechanism of how Lariskella manipulates reproduction can provide insights into the evolution of reproductive manipulators and may eventually provide tools for management of hosts of Lariskella, including pathogen-vectoring ticks and fleas. Author SummaryArthropods are a highly diverse group of animals with ancient relationships with bacteria. Some maternally-inherited, intracellular bacterial symbionts have evolved strategies to manipulate arthropod host reproduction, ensuring their own spread and persistence. One such strategy is cytoplasmic incompatibility (CI), where symbionts in males prevent viable offspring when these males mate with uninfected females. However, reproduction is rescued in crosses with both mates infected, promoting bacterial transmission within host populations. In the leaffooted bug Leptoglossus zonatus, crossing experiments revealed a significant reduction in egg survival rates when Lariskella-negative females mated with Lariskella-positive males, a typical CI phenotype discovered anew for this symbiont. Additional experiments included measuring performance and fitness of bugs with combinations of Lariskella and Caballeronia (the primary nutritional symbiont of L. zonatus). While Caballeronia-negative treatments caused developmental delays and mortality, the presence of Lariskella had no effect on development or reproduction. Lariskella has been frequently found in pathogen-vectoring arthropods, but its specific role remained unclear. Understanding the role that Lariskella plays in L. zonatus can potentially help us find future pest control measures against blood-sucking pathogen-vectors by exploiting novel CI mechanism to suppress host populations and hence the transmission of human diseases.

ecology↗

bioRxiv2022

Sex-based de novo transcriptome assemblies of the parasitoid wasp Encarsia suzannae, a host of the manipulative heritable symbiont Cardinium hertigii

Minute parasitoid wasps in the genus Encarsia are commonly used as biological pest control agents of whiteflies and armored scale insects in greenhouses or in the field. They are also a key host of the bacterial endosymbiont Cardinium hertigii which can cause a suite of reproductive manipulation phenotypes, including parthenogenesis, feminization, and cytoplasmic incompatibility; the last being most thoroughly studied in Encarsia suzannae. Despite their biological and economic importance, there are currently no published Encarsia genomes and only one public transcriptome. In this study, we applied a mapping-and-removal approach to eliminate known contaminants from previously-obtained Illumina sequencing data. We generated de novo transcriptome assemblies for both female and male E. suzannae which contain 45,986 and 54,762 final coding sequences, respectively. Benchmarking Single-Copy Orthologs (BUSCO) results indicate both assemblies are highly complete. Preliminary analyses revealed the presence of homologs of sex-determination genes characterized in other insects and putative venom proteins. These transcriptomes will be valuable tools to better understand the biology of Encarsia wasps and their evolutionary relatives. Furthermore, the separate male and female assemblies will be particularly useful references for studies involving insects of only one sex.

genomics↗