title: Phylum-Level Conservation of Regulatory Information in Nematodes despite Extensive Non-coding Sequence Divergence.
abstract: Gene regulatory information guides development and shapes the course of evolution. To test conservation of gene regulation within the phylum Nematoda, we compared the functions of putative cis-regulatory sequences of four sets of orthologs (unc-47, unc-25, mec-3 and elt-2) from distantly-related nematode species. These species, Caenorhabditis elegans, its congeneric C. briggsae, and three parasitic species Meloidogyne hapla, Brugia malayi, and Trichinella spiralis, represent four of the five major clades in the phylum Nematoda. Despite the great phylogenetic distances sampled and the extensive sequence divergence of nematode genomes, all but one of the regulatory elements we tested are able to drive at least a subset of the expected gene expression patterns. We show that functionally conserved cis-regulatory elements have no more extended sequence similarity to their C. elegans orthologs than would be expected by chance, but they do harbor motifs that are important for proper expression of the C. elegans genes. These motifs are too short to be distinguished from the background level of sequence similarity, and while identical in sequence they are not conserved in orientation or position. Functional tests reveal that some of these motifs contribute to proper expression. Our results suggest that conserved regulatory circuitry can persist despite considerable turnover within cis elements.
authors.affiliation: Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, Illinois, United States of America.
authors.forename: Kacy L
authors.initials: KL
authors.lastname: Gordon
authors.affiliation: Department of Ecology and Evolution, The University of Chicago, Chicago, Illinois, United States of America.
authors.forename: Robert K
authors.initials: RK
authors.lastname: Arthur
authors.affiliation: Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, Illinois, United States of America; Department of Ecology and Evolution, The University of Chicago, Chicago, Illinois, United States of America.
authors.forename: Ilya
authors.initials: I
authors.lastname: Ruvinsky
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics; D017124:Conserved Sequence / Q000235:genetics*; D019143:Evolution, Molecular; D005786:Gene Expression Regulation; D014644:Genetic Variation; D009348:Nematoda / Q000235:genetics; D059372:Nucleotide Motifs / Q000235:genetics; D010802:Phylogeny; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*