title: Worms from venus and mars: proteomics profiling of sexual differences in Caenorhabditis elegans using in vivo 15N isotope labeling.
abstract: Hermaphrodites of the nematode Caenorhabditis elegans produce both sperm and oocytes in the same germline. To investigate the process underlying spermatogenesis and oogenesis separately, we used a quantitative proteomics approach applied to two mutant worm lines (fem-3(q20) and fem-1(hc17)) developing only male and female germlines, respectively. We used stable isotopic labeling of whole animals by feeding them either (14)N or (15)N labeled Escherichia coli. This way, we could confidently identify and quantify 1040 proteins in two independent experiments. Of these, approximately 400 proteins showed significant differential expression between female-like and male-like animals. As expected, proteins linked to oogenesis were found to be highly upregulated in the feminized worms, whereas proteins involved in spermatogenesis were found to be highly upregulated in the masculinized worms. This was complemented by many proteins strongly enriched in either mutant. Although the function of the majority of these proteins is unknown, their expression profile indicates that they have an as yet unrecognized role in the development and/or function of the female- and male germline in C. elegans. We show that members of several protein complexes as well as functionally similar proteins show comparable abundance ratios, indicating coregulation of protein expression. Additional analysis comparing our protein data to a previously published microarray data set shows that mRNA and protein expression are poorly correlating. We provide one of the first examples of a large-scale quantitative proteomics experiment in C. elegans and show the potential and feasibility of an approach enabling system-wide accurate quantitative proteomics experiments in this model organism.
authors.affiliation: Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Centre for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
authors.forename: Bastiaan B J
authors.initials: BB
authors.lastname: Tops
authors.forename: Sharon
authors.initials: S
authors.lastname: Gauci
authors.forename: Albert J R
authors.initials: AJ
authors.lastname: Heck
authors.forename: Jeroen
authors.initials: J
authors.lastname: Krijgsveld
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D016000:Cluster Analysis; D005260:Female; D020869:Gene Expression Profiling; D007553:Isotope Labeling / Q000379:methods; D016014:Linear Models; D008297:Male; D009587:Nitrogen Isotopes / Q000737:chemistry; D009866:Oogenesis; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D040901:Proteomics / Q000379:methods*; D012737:Sex Factors; D013091:Spermatogenesis
chemical_list: D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins; C115306:FEM-1 protein, C elegans; D009587:Nitrogen Isotopes; C097435:Fem-2 protein, C elegans; D010749:Phosphoprotein Phosphatases