Unraveling the Bombus terrestris hemolymph, a readout of the immune response to microbial infections, through complementary mass spectrometry approaches

ABSTRACT: Pollinators are of crucial importance for maintaining biodiversity in ecosystems and for agriculture, including the Buff-tailed bumblebee Bombus terrestris. The health decline in these populations is thought to be linked to various abiotic and biotic stressors. In the hope of protecting these populations, deciphering their immune response in stress conditions represent a critical issue. To assess this metric, we analysed the bumblebee hemolymph, as a readout of the immune status. Here, we show in laboratory conditions that bacterial infections with two entomopathogenic strains and a well-recognised inducer of defence reactions in insects, impact the systemic immune response. Analysis of the hemolymph was carried out using a two-stage approach of mass spectrometry that combines MALDI molecular mass fingerprinting (MALDI MFP or MALDI-BeeTyping®) for its effectiveness in assessing the immune status of the bumblebee through a basic “blood” test and LC-ESI-MS/MS to measure the impact of our infectious models on the “haemoproteome”. By carrying out three different types of bacterial infections, we found that the bumblebee reacts in a specific way to bacterial attacks. Indeed, bacteria impact mortality and stimulate an immune response in infected individuals that is visible through changes in the molecular composition of their hemolymph. The characterisation and label-free quantification of proteins involved in specific signalling pathways in bumblebees by LC-ESI-MS/MS revealed differences in the protein expression between the non-experimentally infected and the infected bumblebees. Our results highlights differences in the molecular composition of their hemolymph to distinguish these different infections from non-experimentally infected bumblebees, and an alteration of pathways involved in (i) immunity and defences, (ii) the metabolism of carbohydrates (glycolysis), (iii) oxidative stress and (iv) amino acid biosynthesis. To conclude, we established bioinformatics models based on molecular markers reflecting the health status of these pollinators to enable diagnosis/prognosis at the population level in response to environmental stress.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Bombus Terrestris (buff-tailed Bumblebee) (apis Terrestris)

TISSUE(S): Hemolymph

DISEASE(S): Bacterial Infectious Disease

SUBMITTER: Sebastien Voisin  

LAB HEAD: Philippe Bulet

PROVIDER: PXD035224 | Pride | 2023-05-10

REPOSITORIES: Pride