title: The Goddard and Saturn Genes Are Essential for Drosophila Male Fertility and May Have Arisen De Novo.
abstract: New genes arise through a variety of mechanisms, including the duplication of existing genes and the de novo birth of genes from noncoding DNA sequences. While there are numerous examples of duplicated genes with important functional roles, the functions of de novo genes remain largely unexplored. Many newly evolved genes are expressed in the male reproductive tract, suggesting that these evolutionary innovations may provide advantages to males experiencing sexual selection. Using testis-specific RNA interference, we screened 11 putative de novo genes in Drosophila melanogaster for effects on male fertility and identified two, goddard and saturn, that are essential for spermatogenesis and sperm function. Goddard knockdown (KD) males fail to produce mature sperm, while saturn KD males produce few sperm, and these function inefficiently once transferred to females. Consistent with a de novo origin, both genes are identifiable only in Drosophila and are predicted to encode proteins with no sequence similarity to any annotated protein. However, since high levels of divergence prevented the unambiguous identification of the noncoding sequences from which each gene arose, we consider goddard and saturn to be putative de novo genes. Within Drosophila, both genes have been lost in certain lineages, but show conserved, male-specific patterns of expression in the species in which they are found. Goddard is consistently found in single-copy and evolves under purifying selection. In contrast, saturn has diversified through gene duplication and positive selection. These data suggest that de novo genes can acquire essential roles in male reproduction.
authors.affiliation: Department of Biology, College of the Holy Cross, Worcester, MA.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Gubala
authors.affiliation: Evolutionary Bioinformatics Group, Institute for Evolution and Biodiversity, University of Münster, Münster, Germany.
authors.forename: Jonathan F
authors.initials: JF
authors.lastname: Schmitz
authors.affiliation: Department of Biology, College of the Holy Cross, Worcester, MA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Kearns
authors.affiliation: Department of Biology, College of the Holy Cross, Worcester, MA.
authors.forename: Tery T
authors.initials: TT
authors.lastname: Vinh
authors.affiliation: Evolutionary Bioinformatics Group, Institute for Evolution and Biodiversity, University of Münster, Münster, Germany.
authors.forename: Erich
authors.initials: E
authors.lastname: Bornberg-Bauer
authors.affiliation: Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY.
authors.forename: Mariana F
authors.initials: MF
authors.lastname: Wolfner
authors.affiliation: Department of Biology, College of the Holy Cross, Worcester, MA.|Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY.
authors.forename: Geoffrey D
authors.initials: GD
authors.lastname: Findlay
mesh_terms: D000818:Animals; D005075:Biological Evolution; D004330:Drosophila / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics*; D019143:Evolution, Molecular; D005298:Fertility / Q000235:genetics*; D020440:Gene Duplication / Q000235:genetics; D055785:Gene Knockdown Techniques / Q000379:methods; D008297:Male; D013091:Spermatogenesis / Q000235:genetics*; D013094:Spermatozoa / Q000378:metabolism; D013737:Testis / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins
keywords: Drosophila; de novo gene; fertility; sexual selection; sperm