title: Prefractionation methods for individual adult fruit fly hemolymph proteomic analysis.
abstract: The analysis of blood provides in depth chemical information of physiological states of organisms. Hemolymph (blood) is the fluid in the open circulatory system of Drosophila melanogaster that is the medium for molecules regulating a wide variety of physiological activities and signaling between tissues. Adult Drosophila is typically less than 3mm in length and, as a consequence, the available volume of hemolymph is usually less than 50 nL from individual flies. Proteomic analysis of volume-limited hemolymph is a great challenge for both sample handling and subsequent mass spectrometry characterization of this chemically diverse biological fluid with a wide dynamic range of proteins in concentrations. Less abundant proteins, in particular, could be easily lost during sample preparation or missed by current mass spectrometry methods. This article describes simple and customized RPLC column and IEX columns to prefractionate volume-limited hemolymph without excessive dilution. Step-gradient elution methods were developed and optimized to enhance the identification of novel proteins from an individual fruit fly hemolymph sample. Fractions from each step gradient was analyzed by an Agilent nano-RPLC chip column and then characterized by high mass resolution and high mass accuracy orbitrap mass spectrometry. As a result, both RPLC (11 proteins) and IEX fractionation approaches (9 proteins) identified more proteins than an unfractionated control approach with higher protein scores, emPAI values and coverage. Furthermore, a significant number of novel proteins were revealed by both RPLC and IEX fractionation methods, which were missed by unfractionated controls. The demonstration of this method establishes a means to deepen proteomic analysis to this commonly used, important biological model system.
authors.affiliation: Department of Chemistry, University of Illinois at Chicago, 845 W Taylor St., SES 4500, M/C 111, Chicago, IL 60607, United States.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zeng
authors.affiliation: Department of Chemistry, University of Illinois at Chicago, 845 W Taylor St., SES 4500, M/C 111, Chicago, IL 60607, United States.
authors.forename: Vitaly
authors.initials: V
authors.lastname: Avilov
authors.affiliation: Department of Chemistry, University of Illinois at Chicago, 845 W Taylor St., SES 4500, M/C 111, Chicago, IL 60607, United States; Laboratory of Integrative Neuroscience, University of Illinois at Chicago, 840 W Taylor St., SEL 4311, M/C 067, Chicago, IL 60607, United States. Electronic address: sshippy@uic.edu.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Shippy
mesh_terms: D000818:Animals; D005591:Chemical Fractionation; D002852:Chromatography, Ion Exchange / Q000379:methods; D056148:Chromatography, Reverse-Phase / Q000379:methods*; D004331:Drosophila melanogaster / Q000737:chemistry*; D005260:Female; D006458:Hemolymph / Q000737:chemistry*; D019476:Insect Proteins / Q000032:analysis* / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods; D020543:Proteome / Q000032:analysis* / Q000737:chemistry; D040901:Proteomics / Q000379:methods
chemical_list: D019476:Insect Proteins; D020543:Proteome
keywords: Drosophila melanogaster; Ion exchange chromatography; Nanoliter samples; Reverse phase liquid chromatography; Shotgun proteomics