Sex and the single worm: sex determination in the nematode C. elegans.
The study of sex determination in model organisms has been especially fruitful in increasing our understanding of developmental biology, gene regulation and evolutionary mechanisms. The free living nematode, Caenorhabditis elegans, can develop as one of two sexes; male or self-fertilizing hermaphrodite. Here we discuss the progress toward a genetic and molecular understanding of that decision. Numerous genetic loci have been identified that affect sexual fate, and epistasis analysis of these genes has led to a model of a regulatory hierarchy with stepwise negative interactions. It is becoming evident that many of the genes have numerous levels of regulation. We also discuss the apparent rapid rate of evolution that many of the sex determination proteins have undergone. Protein sequences of homologues from closely related species are more divergent than homologues of proteins involved in other developmental processes. Rapid evolution of sex determination genes may be a common theme throughout the animal kingdom.
Hansen
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Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9 Canada.
Pilgrim
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D000818:Animals; D017173:Caenorhabditis elegans / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins / Q000235:genetics; D004268:DNA-Binding Proteins; D004303:Dosage Compensation, Genetic; D029721:Drosophila Proteins; D019143:Evolution, Molecular; D015801:Helminth Proteins / Q000235:genetics; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D008957:Models, Genetic; D010749:Phosphoprotein Phosphatases; D012261:Ribonucleoproteins / Q000235:genetics; D019849:Sex Determination Processes; D015398:Signal Transduction; D014157:Transcription Factors
D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C115306:FEM-1 protein, C elegans; D015801:Helminth Proteins; D008565:Membrane Proteins; D012261:Ribonucleoproteins; D014157:Transcription Factors; C121025:tra-1 protein, C elegans; C066174:tra2 protein, Drosophila; C097435:Fem-2 protein, C elegans; D010749:Phosphoprotein Phosphatases