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Abstract

Understanding the forces that shape eco-evolutionary patterns often requires linking phenotypes to genotypes, allowing characterization of these patterns at the molecular level. DNA-based markers are less informative in this aim compared to markers associated with gene expression, and more specifically with protein quantities. The characterization of eco-evolutionary patterns also usually requires the analysis of large sample sizes to accurately estimate inter-individual variability. However, the methods used to quantify proteins are generally expensive and time consuming, which constrains the size of the produced datasets to few individuals. We present here a method that estimates the inter-individual variability of protein quantities based on a global, semi-automatic analysis of 1D electrophoretic profiles, opening the way to rapid analysis and comparison of hundreds of individuals. The main original features of the method are the in silico normalization of sample protein quantities using pictures of electrophoresis gels at different staining levels, as well as the detection of reference bands on a median profile. We demonstrate that this method can accurately discriminate between species and between geographically distant or close populations, based on inter-individual variation in venom protein profiles from three endoparasitoid wasps of two different genera (Psyttalia concolor, Psyttalia lounsburyi and Leptopilina boulardi). Finally, we discuss the experimental designs that would benefit from the development of this method.

Keywords

Non-neutral markers;Proteins;Individual 1D SDS-PAGE;Quantitative variation;Population proteomics;Parasitoid venom