Evolutionary Medicine and Informatics: Molecular Technologies

This approach allows us to query complex biological systems for protein content, the sum total which we refer to as the “proteome”.  Whole intact proteins within a cell cannot easily be identified as they are too large and complex for even the most powerful mass spectrometer.  However, because proteins are composed of linear polymer of amino acids coupled together through peptide bonds, large proteins can be broken down (usually using an enzyme specific for a particular amino acid in proteins) into smaller peptide fragments.  These fragments can then be identified and subsequently used to identify the protein from which it arose.  A particularly powerful tool in this effort is the “Orbitrap Mass Spectrometer” designed to rapidly and efficiently sort out these complex mixtures of peptide fragments (there are many!) and identify their respective amino acid sequences.  If enough fragments are identified they can uniquely identify the protein that contained it and therefore the gene.

Although great strides have been made in the applications of tools such as the mass spectrometer to understanding cellular structure and function, the overwhelming complexities of multicellular life limit their use.  To help overcome these limitations we have chosen a relative “simple” cell type, the spermatozoa, to begin an in depth and comprehensive analysis of the sperm proteome.  Sperm obviously play a central and indispensable role to all sexual life but surprisingly little is know about its protein makeup.  Our groups are currently working on a number of sperm proteomes that we have defined using shotgun proteomics including the model organisms Drosophila (the Fruit Fly) and the mouse.  We also have projects designed to probe the evolutionary origins of spermatozoa by defining sperm proteomes that lie at the base of all bilateral metazoans including the cnidarians (sea anemones), ctenophores (comb jellies) and polychaete worms, among others.