Biology subjects

Carolan, J. C.

Publications and source records attributed to Carolan, J. C..

4 recordsLinked to original sources

bioRxiv2025

Bacterial supplementation shapes honey bee gut microbiota, metabolism and proteome under controlled and field conditions

Gut bacteria are essential to honey bee (Apis mellifera) health, supporting digestion, immunity, and resilience against stressors. Probiotic-based strategies have been proposed to enhance core gut symbionts, yet the underlying mechanisms and influences of environmental context on these effects are not fully understood. This study examined the influence of gut-derived bacterial supplementation on the honey bee gut microbiome, proteome, and metabolome across three conditions: (i) controlled cages, (ii) semi-controlled cages allowing contact with nestmates, and (iii) field conditions. Treatment groups received a bacterial supplement containing Lactobacillus helsingborgensis, Lactobacillus apis, Bifidobacterium choladohabitans, and Bifidobacterium polysaccharolyticum, while control groups received only a sucrose solution. Gut samples from 10-day-old bees were analyzed. Supplemented bees showed strong gut colonization by Bifidobacterium and Lactobacillus, especially under controlled and semi-controlled conditions. In the field, L. helsingborgensis remained significantly enriched in the treatment group, indicating ecological resilience. Proteomic changes in supplemented bees included an increased abundance of major royal jelly protein precursors and mitochondrial proteins, alongside the decreased abundance of ribosomal and translation-related proteins involved in peptide biosynthesis and cellular protein quality control. Metabolomic analysis revealed reproducible shifts across all three conditions. Treatment groups showed higher concentrations of microbial fermentation products (acetate, succinate) and neuroactive compounds (ornithine, {gamma}-aminobutyrate), while sucrose, N-acetylglucosamine, and uridine that were constantly lower compared to controls. No significant changes were observed in body or gut weight. These findings highlight reproducible, context-dependent effects of bacterial supplementation on honey bee gut physiology and provide mechanistic insights for microbiome-based interventions in pollinator health. ImportanceHoney bees are essential pollinators whose health is influenced by their gut microbiome. Probiotic applications aimed at improving gut health have been proposed, yet outcomes remain inconsistent and vary across settings. Results from laboratory experiments often differ from those observed under field conditions, making it difficult to understand the complex dynamics of eusocial insect colonies. Here, we evaluate honey bee gut-derived bacterial supplementation across controlled, semi-controlled, and field settings using bacterial profiling, proteomic, and metabolomic analyses. We demonstrate that bacterial supplemented groups consistently reshape gut community composition and modulate host physiological processes, but in a context-dependent manner. These results provide a unified understanding of how microbial interventions function at colony and individual levels, guiding the rational design of probiotic strategies to support honey bee health under realistic conditions.

microbiology↗

bioRxiv2025

A novel chitinase-like family of candidate effectors unique to aphids

Molecular interactions between aphids and plants include delivery of salivary effector proteins into host cells, acting as virulence factors to suppress host immunity, or as avirulence functions triggering immune activation. However, understanding of virulence and avirulence mechanisms in aphid-plant systems is currently limited. Here, we report discovery of an effector candidate family that is unique to aphids. Using functional genomics data on divergent pea aphid (Acyrthosiphon pisum) genotypes and their F1 progeny, we filtered for differentially expressed saliva proteins that co-segregated with virulence or avirulence phenotypes. LOC100575698 (ACPISUM_029930), annotated as an uncharacterized protein, was the sole candidate effector for which RNA-Seq and saliva proteomics data showed significantly different expression both between avirulent and virulent parents and between their segregating F1 progeny, with this gene upregulated in avirulent genotypes. BLASTP searches revealed multiple divergent homologs only in genomes of the Aphidomorpha infra-order, suggesting a hitherto undefined ancient aphid-specific gene family. AlphaFold models indicate strong structural similarities but weak sequence homology to chitinases. Because the aphid-specific clade all lack canonical DxxDxDxE motifs for catalytic activity, we designate the proteins as a novel CHitinase-Like (CHL) family. Association of ACPISUM_029930 (ApCHL1) with avirulence was further supported by co-segregating SNPs and a genotype-specific alternatively spliced isoform. We hypothesise that CHL proteins may function similarly to phylogenetically unrelated chitin-binding fungal effectors that sequester chitin, also present in aphid stylets, potentially preventing defence activation through plant chitin receptors and/or blocking chitin degradation by host-secreted chitinases.

molecular biology↗

bioRxiv2024

Multi-omics approaches define novel aphid effector candidates associated with virulence and avirulence phenotypes

BackgroundCompatibility between plant parasites and their hosts is genetically determined by both interacting organisms. For example, plants may carry resistance (R) genes or deploy chemical defences. Aphid saliva contains many proteins that are secreted into host tissues. Subsets of these proteins are predicted to act as effectors, either subverting or triggering host immunity. However, associating particular effectors with virulence or avirulence outcomes presents challenges due to the combinatorial complexity. Here we use defined aphid and host genetics to test for co-segregation of expressed aphid transcripts and proteins with virulent or avirulent phenotypes. ResultsWe compared virulent and avirulent pea aphid parental genotypes, and their bulk segregant F1 progeny on Medicago truncatula genotypes carrying or lacking the RAP1 resistance quantitative trait locus. Differential gene expression analysis of whole body and head samples, in combination with proteomics of saliva and salivary glands, enabled us to pinpoint proteins associated with virulence/avirulence phenotypes. There was relatively little impact of host genotype, whereas large numbers of transcripts and proteins were differentially expressed between parental aphids, likely a reflection of their classification as divergent biotypes within the pea aphid species complex. Many fewer transcripts intersected with the equivalent differential expression patterns in the bulked F1 progeny, providing an effective filter for removing genomic background effects. Overall, there were more upregulated genes detected in the F1 avirulent dataset compared with the virulent one. Some genes were differentially expressed both in the transcriptome and in the proteome datasets, with aminopeptidase N proteins being the most frequent differentially expressed family. In addition, a substantial proportion (27%) of salivary proteins lack annotations, suggesting that many novel functions remain to be discovered. ConclusionsEspecially when combined with tightly controlled genetics of both insect and host, multi-omics approaches are powerful tools for revealing and filtering candidate lists down to plausible genes for further functional analysis as putative aphid effectors.

genomics↗

bioRxiv2021

Global protein responses of multi-drug resistant plasmid containing Escherichia coli to ampicillin, cefotaxime, imipenem and ciprofloxacin.

Antimicrobial resistance (AMR) and multi-drug resistance (MDR) in pathogenic bacteria are frequently mediated by plasmids. However, plasmids do not exist in isolation but rather require the bacterial host interaction in order to produce the AMR phenotype. This study aimed to utilise mass spectrometry-based proteomics to reveal the plasmid and chromosomally derived protein profile of Escherichia coli under antimicrobial stress. This was achieved by comparing the proteomes of E. coli containing the MDR pEK499 plasmid, under ampicillin, cefotaxime, imipenem or ciprofloxacin stress with the proteomes of these bacteria grown in the absence of antimicrobial. Our analysis identified statistically significant differentially abundant proteins common to groups exposed to the {beta}-lactam antimicrobials but not ciprofloxacin, indicating a {beta}-lactam stress response to exposure from this class of drugs, irrespective of {beta}-lactam resistance or susceptibility. These include ecotin and free methionine-R-sulfoxide reductase. These data also identified distinct differences in the cellular response to each {beta}-lactam. Data arising from comparisons of the proteomes of ciprofloxacin-treated E. coli and controls detected an increase in the relative abundance of proteins associated with ribosomes, translation, the TCA-cycle and several proteins associated with detoxification and a decrease in the relative abundances of proteins associated with stress response, including oxidative stress. We identified changes in proteins associated with persister formation in the presence of ciprofloxacin but not the {beta}-lactams. The plasmid proteome differed across each treatment and did not follow the pattern of antimicrobial - AMR protein associations. For example, a relative increase in the amount of blaCTX-M-15 in the presence of cefotaxime and ciprofloxacin but not the other {beta}-lactams, suggesting regulation of the blaCTX-M-15 protein production. The proteomic data from the this study provided novel insights into the proteins produced from the chromosome and plasmid under different antimicrobial stresses. These data also identified novel proteins not previously associated with AMR or antimicrobials responses in pathogens, which may well represent potential targets of AMR inhibition.

microbiology↗