# Capillary Electrophoresis Electrospray Ionization Mass Spectrometry Reveals Metabolic Perturbations During Nematode Infection in Drosophila melanogaster

## TL;DR

This study uses a sensitive mass spectrometry method to identify metabolic changes in fruit fly larvae infected with nematodes and their bacterial partners.

## Contribution

The novel use of CE-ESI-MS reveals specific metabolic perturbations in Drosophila during nematode infection.

## Key findings

- Infection alters amino acid biosynthesis and metabolism, including arginine, phenylalanine, and tryptophan.
- Signaling molecules like glutamate and pyridoxine show significant changes during nematode infection.
- CE-ESI-MS effectively profiles small polar metabolites, detecting 50 molecules with high confidence.

## Abstract

Drosophila melanogaster is broadly used to model host–pathogen interactions. Entomopathogenic nematodes are excellent research tools for dissecting the molecular and functional basis of parasitism and the host’s anti-parasitic response. In this work, we used discovery metabolomics to explore the differences in the metabolome composition of wild type D. melanogaster larvae that were infected with symbiotic nematodes (Steinernema carpocapsae carrying Xenorhabdus nematophila mutualistic bacteria) or axenic nematodes (S. carpocapsae lacking their bacterial partners). Benefiting from their high separation power, sensitivity, and compatibility with low amounts of the starting metabolome, we leveraged microanalytical capillary electrophoresis electrospray ionization mass spectrometry (CE-ESI-MS) to profile the small (<500 Da) polar portion of the metabolome among these experimental treatments. We detected and quantified 122 different small molecules, of which 50 were identified with high confidence. Supervised multivariate analysis revealed that the infection was paralleled with changes in amino acid biosynthesis (arginine, phenylalanine, tryptophan, and tyrosine), metabolism (alanine, arginine, aspartate, glutamate, glycine, proline, serine, and threonine), and classical signalling (aspartate, γ-aminobutyrate, glutamate, and pyridoxine). This study demonstrates the ability of high-sensitivity CE-ESI-MS to uncover metabolic perturbations during infection. The results from the metadata may facilitate the design of targeted studies to explore small biomolecules and their functions during host–pathogen interaction.