Elucidating the exposome: can GC/Q-TOF save the bees?

Genomics is a widely recognized field and is arguably one of the most well-researched ’omics applications. It is continuously expanding, however, and the field of exposomics within genomics is receiving an increasing amount of attention for the understanding of disease pathology and progression. The exposome represents the interaction between an organism’s environment (exposure), and its genes. It encompasses all the exposures throughout the organism lifetime and unlike the genome, it is highly variable and dynamic, making it extremely challenging to study. Increasingly sophisticated technology, such as quadrupole time-of-flight (QTOF) gas chromatography/mass spectrometry (GC/MS), is enabling researchers to gain deeper insights into the exposome.

Environmental exposures are known to play an important role in common chronic diseases, such as cancer, diabetes, and vascular and neurodegenerative conditions. Until relatively recently, the nature of the exposome has remained under researched. Scientists now understand the relationship between the environment and genetic susceptibility more than ever.

Understanding the exposome

Although they may have low penetrance, genetic variations – also known as single nucleotide polymorphisms (SNPs) – have a high prevalence and are known to contribute to global health burdens [1]. Most SNPs cause disease in the presence of specific environmental exposures but, despite this knowledge, the associations between exposure and disease are unclear. Large cohort studies rely on biobanks to show the complexity of the exposome. The development of biomarkers can improve the measurement of exposure, susceptibility, and disease in population studies. Exposure biomarkers are useful for infectious disease epidemiology.

Exposome profiling of honey bees

Recent research by scientists in the U.S. and Turkey has linked the exposome with the decline of pollinating insects, using innovative technology for discovery-based exposome profiling of honey bees. The group used GC/Q-TOF to reveal novel mechanisms of infection, biochemical feedback, and increased susceptibility to disease, in particular to the fungal gut parasite Nosema ceranae [2]. Samples were taken from infected and uninfected hives across seven different geographical locations, and analyzed using an Agilent 7200B GC/Q-TOF system to collect exposome profiles. The raw data obtained on this system were analyzed using Agilent MassHunter software for chemical feature extraction. Statistical associations were made between chemical profiles of bees infected with N. Ceranae and noninfected bees, using Agilent Mass Profiler Professional (MPP) bio-informatics software.

The group identified over 2350 chemical features in the mass spectrometry data, and the spectral library searches annotated 73 % of these compounds successfully. They observed that exposome profiles were associated with disease load, showing that chemicals and metabolites exclusive to N. Ceranae infection can be identified and even be used as biomarkers for the presence of disease.

The power of GC/Q-TOF

The Agilent 7200B Q-TOF GC/MS system delivers full-spectrum, high-resolution, accurate-mass data for screening, profiling, and identifying GC-amenable compounds. It has the ability to assign chemical formulae to unknown compounds and fragments using the MassHunter software. This has enabled researchers to profile the exposome of honey bees and gather insights into their health at the population level. As well as identifying chemical features, the system is able to elucidate chemical structures, further providing researchers, such as those working on honey bees, with discovery-based exposome analysis tools.

The future of honey bee health

Increasingly advanced analytical technologies are allowing scientists to measure and quantify new stressors and interactions among previously identified stressors, as well as new chemical biomarkers of disease to develop a ‘chemical signature’ profile. Such a profile can then provide more accurate insights and even predict the patterns of bee health decline, using a deeper understanding of how multiple environmental stressors interact with the organism.

For Research Use Only. Not for use in diagnostic procedures.

  1. Wild, C. P. (2005) Complementing the Genome with an “Exposome”: The Outstanding Challenge of Environmental Exposure Measurement in Molecular Epidemiology, Cancer Epidemiology, Biomarkers & Prevention, Vol.14(8): 1847–1850; DOI: 10.1158/1055-9965.EPI-05-0456
  2. Schick, Sassicaia J.; Broadrup, Robert L.; Mayack, Christopher; White, Helen K.; Macherone, Anthony (2018) ” Integrating GC/TOF Exposome Profiling and Genetic Disease Screening to Provide a Holistic Perspective on Honey Bee Health.” American Laboratory, 50(3): 21–23.