title: Revisiting Suppression of Interspecies Hybrid Male Lethality inCaenorhabditisNematodes.
abstract: Within the nematode genusCaenorhabditis,Caenorhabditis briggsaeandC. nigoniare among the most closely related species known. They differ in sexual mode, withC. nigoniretaining the ancestral XO male-XX female outcrossing system, whileC. briggsaerecently evolved self-fertility and an XX-biased sex ratio. Wild-typeC. briggsaeandC. nigonican produce fertile hybrid XX female progeny, but XO progeny are either 100% inviable (whenC. briggsaeis the mother) or viable but sterile (whenC. nigoniis the mother). A recent study provided evidence suggesting that loss of theCbr-him-8meiotic regulator inC. briggsaehermaphrodites allowed them to produce viable and fertile hybrid XO male progeny when mated toC. nigoniBecause such males would be useful for a variety of genetic experiments, we sought to verify this result. Preliminary crosses with wild-typeC. briggsaehermaphrodites occasionally produced fertile males, but they could not be confirmed to be interspecies hybrids. Using an RNA interference (RNAi) protocol that eliminates any possibility of self-progeny inCbr-him-8hermaphrodites, we found sterile males bearing theC. nigoniX chromosome, but no fertile males bearing theC. briggsaeX, as in wild-type crosses. Our results suggest that the apparent rescue of XO hybrid viability and fertility is due to incomplete purging of self-sperm prior to mating.
authors.affiliation: Department of Biology, University of Maryland, College Park, Maryland 20740.|Biological Sciences Program, University of Maryland, College Park, Maryland 20742.
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Ryan
authors.affiliation: Department of Biology, University of Maryland, College Park, Maryland 20740 ehaag@umd.edu.|Biological Sciences Program, University of Maryland, College Park, Maryland 20742 ehaag@umd.edu.
authors.forename: Eric S
authors.initials: ES
authors.lastname: Haag
mesh_terms: D000818:Animals; D002107:Caenorhabditis / Q000235:genetics*; D005260:Female; D006824:Hybridization, Genetic; D008297:Male; D010641:Phenotype; D013045:Species Specificity; D013489:Suppression, Genetic
keywords: Genetics of Sex; Haldane’s rule; X chromosome; hybrids