title: Specification of germ cell fates by FOG-3 has been conserved during nematode evolution.
abstract: Rapid changes in sexual traits are ubiquitous in evolution. To analyze this phenomenon, we are studying species of the genus Caenorhabditis. These animals use one of two different mating systems-male/hermaphroditic, like the model organism Caenorhabditis elegans, or male/female, like C. remanei. Since hermaphrodites are essentially females that produce sperm for self-fertilization, elucidating the control of cell fate in the germ line in each species could provide the key to understanding how these mating systems evolved. In C. elegans, FOG-3 is required to specify that germ cells become sperm. Thus, we cloned its homologs from both C. remanei and C. briggsae. Each species produces a single homolog of FOG-3, and RNA-mediated interference indicates that FOG-3 functions in each species to specify that germ cells develop as sperm rather than as oocytes. What factors account for the different mating systems? Northern analyses and RT-PCR data reveal that the expression of fog-3 is always correlated with spermatogenesis. Since the promoters for all three fog-3 genes contain binding sites for the transcription factor TRA-1A and are capable of driving expression of fog-3 in C. elegans hermaphrodites, we propose that alterations in the upstream sex-determination pathway, perhaps acting through TRA-1A, allow spermatogenesis in C. elegans and C. briggsae XX larvae but not in C. remanei.
authors.affiliation: Department of Biology, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Chen
authors.forename: S
authors.initials: S
authors.lastname: Cho
authors.forename: S W
authors.initials: SW
authors.lastname: Jin
authors.forename: R E
authors.initials: RE
authors.lastname: Ellis
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D005075:Biological Evolution; D015152:Blotting, Northern; D002107:Caenorhabditis / Q000145:classification / Q000235:genetics* / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins; D019070:Cell Lineage; D005260:Female; D015801:Helminth Proteins / Q000235:genetics* / Q000502:physiology*; D008297:Male; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D010375:Pedigree; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D019849:Sex Determination Processes; D013045:Species Specificity; D013091:Spermatogenesis
chemical_list: D029742:Caenorhabditis elegans Proteins; C403465:FOG-3 protein, C elegans; D015801:Helminth Proteins; D012313:RNA