Biology subjects

Eamonn Mallon

Publications and source records attributed to Eamonn Mallon.

3 recordsLinked to original sources

bioRxiv2014

Antimicrobial peptides play a functional role in bumblebee anti-trypanosome defense

Bumblebees, amongst the most important of pollinators, are under enormous population pressures. One of these is disease. The bumblebee and its gut trypanosome Crithidia bombi are one of the fundamental models of ecological immunology. Although there is previous evidence of increased immune gene expression upon Crithidia infection, recent work has focussed on the bumblebees gut microbiota. Here, by knocking down gene expression using RNAi, we show for the first time that antimicrobial peptides (AMPs) have a functional role in anti-Crithidia defense.

Immunology↗

bioRxiv2014

Differential gene expression and alternative splicing in insect immune specificity

Ecological studies routinely show genotype-genotype interactions between insects and their parasites. The mechanisms behind these interactions are not clearly understood. Using the bumblebee Bombus terrestris / trypanosome Crithidia bombi model system, we have carried out a transcriptome-wide analysis of gene expression and alternative splicing in bees during C. bombi infection. We have performed four analyses, 1) comparing gene expression in infected and non-infected bees 24 hours after infection by Crithidia bombi, 2) comparing expression at 24 and 48 hours after C.bombi infection, 3) searching for differential gene expression associated with the host-parasite genotype-genotype interaction at 24 hours after infection and 4) searching for alternative splicing associated with the host-parasite genotype-genotype interaction at 24 hours post infection. We found a large number of genes differentially regulated related to numerous canonical immune pathways. These genes include receptors, signaling pathways and effectors. We discovered a possible interaction between the peritrophic membrane and the insect immune system in defense against Crithidia. Most interestingly we found differential expression and alternative splicing of Dscam related transcripts and a novel immunoglobulin related gene Twitchin depends on the genotype-genotype interactions of the given bumblebee colony and Crithidia strain.

Evolutionary Biology↗

bioRxiv2014

Immune stimulation reduces sleep and memory ability in Drosophila melanogaster

Psychoneuroimmunology studies the increasing number of connections between neurobiology and immunology. We establish Drosophila melanogaster as a tractable model in this field by demonstrating the effects of the immune response on two fundamental behaviours: sleep and memory ability.\n\nWe used the Geneswitch system to upregulate peptidoglycan receptor protein (PGRP) expression, thereby stimulating the immune system in the absence of infection. Geneswitch was activated by feeding the steroid RU486, to the flies. Importantly, by stimulating the immune system of adult flies in the absence of infection we have avoided the added complications of developmental and disease effects that have confounded other studies. We used an aversive classical conditioning paradigm to quantify memory and measures of activity to infer sleep.\n\nImmune stimulated flies exhibited reduced levels of sleep, which could not be explained by a generalised increase in waking activity. The effects on sleep were more pronounced for day compared to night sleep. Immune stimulated flies also showed a reduction in memory abilities.\n\nThese are important results as they establish Drosophila as a model for immune-neural interactions and provide a possible role for sleep in the interplay between the immune response and memory.

Zoology↗