title: Image Pretreatment Tools II: Normalization Techniques for 2-DE and 2-D DIGE.
abstract: Gel electrophoresis is usually applied to identify different protein expression profiles in biological samples (e.g., control vs. pathological, control vs. treated). Information about the effect to be investigated (a pathology, a drug, a ripening effect, etc.) is however generally confounded with experimental variability that is quite large in 2-DE and may arise from small variations in the sample preparation, reagents, sample loading, electrophoretic conditions, staining and image acquisition. Obtaining valid quantitative estimates of protein abundances in each map, before the differential analysis, is therefore fundamental to provide robust candidate biomarkers. Normalization procedures are applied to reduce experimental noise and make the images comparable, improving the accuracy of differential analysis. Certainly, they may deeply influence the final results, and to this respect they have to be applied with care. Here, the most widespread normalization procedures are described both for what regards the applications to 2-DE and 2D Difference Gel-electrophoresis (2-D DIGE) maps.
authors.affiliation: Department of Sciences and Technological Innovation, University of Piemonte Orientale, Viale Michel 11, 15121, Alessandria, Italy. elisa.robotti@uniupo.it.
authors.forename: Elisa
authors.initials: E
authors.lastname: Robotti
authors.affiliation: Department of Sciences and Technological Innovation, University of Piemonte Orientale, Viale Michel 11, 15121, Alessandria, Italy.
authors.forename: Emilio
authors.initials: E
authors.lastname: Marengo
authors.affiliation: Department of Sciences and Technological Innovation, University of Piemonte Orientale, Viale Michel 11, 15121, Alessandria, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Quasso
mesh_terms: D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods*; D008962:Models, Theoretical; D014176:Protein Biosynthesis; D011506:Proteins / Q000737:chemistry*; D040901:Proteomics / Q000379:methods*
chemical_list: D011506:Proteins
keywords: 2-D DIGE; Gel-electrophoresis; Normalization