Genetics and Genomics Commons^™

Morphogenetic Defects Underlie Superior Coloboma, A Newly Identified Closure Disorder Of The Dorsal Eye, Jennifer C. Hocking, Jakub K. Famulski, Kevin H. Yoon, Sonya A. Widen, Cassidy S. Bernstein, Sophie Koch, Omri Weiss, Forge Canada Consortium, Canada, Seema Agarwala, Adi Inbal, Ordan J. Lehmann, Andrew J. Waskiewicz

Biology Faculty Publications

The eye primordium arises as a lateral outgrowth of the forebrain, with a transient fissure on the inferior side of the optic cup providing an entry point for developing blood vessels. Incomplete closure of the inferior ocular fissure results in coloboma, a disease characterized by gaps in the inferior eye and recognized as a significant cause of pediatric blindness. Here, we identify eight patients with defects in tissues of the superior eye, a congenital disorder that we term superior coloboma. The embryonic origin of superior coloboma could not be explained by conventional models of eye development, leading us to …

Origin Of Amphibian And Avian Chromosomes By Fission, Fusion, And Retention Of Ancestral Chromosomes, Stephen R. Voss, D. Kevin Kump, Srikrishna Putta, Nathan Pauly, Anna Reynolds, Rema J. Henry, Saritha Basa, John A. Walker, Jeramiah J. Smith

Biology Faculty Publications

Amphibian genomes differ greatly in DNA content and chromosome size, morphology, and number. Investigations of this diversity are needed to identify mechanisms that have shaped the evolution of vertebrate genomes. We used comparative mapping to investigate the organization of genes in the Mexican axolotl (Ambystoma mexicanum), a species that presents relatively few chromosomes (n = 14) and a gigantic genome (>20 pg/N). We show extensive conservation of synteny between Ambystoma, chicken, and human, and a positive correlation between the length of conserved segments and genome size. Ambystoma segments are estimated to be four to 51 times longer than homologous …

Genic Regions Of A Large Salamander Genome Contain Long Introns And Novel Genes, Jeramiah J. Smith, Srikrishna Putta, Wei Zhu, Gerald M. Pao, Inder M. Verma, Tony Hunter, Susan V. Bryant, David M. Gardiner, Timothy T. Harkins, S. Randal Voss

Biology Faculty Publications

BACKGROUND: The basis of genome size variation remains an outstanding question because DNA sequence data are lacking for organisms with large genomes. Sixteen BAC clones from the Mexican axolotl (Ambystoma mexicanum: c-value = 32 x 10(9) bp) were isolated and sequenced to characterize the structure of genic regions.

RESULTS: Annotation of genes within BACs showed that axolotl introns are on average 10x longer than orthologous vertebrate introns and they are predicted to contain more functional elements, including miRNAs and snoRNAs. Loci were discovered within BACs for two novel EST transcripts that are differentially expressed during spinal cord regeneration and skin …

Gene Order Data From A Model Amphibian (Ambystoma): New Perspectives On Vertebrate Genome Structure And Evolution, Jeramiah J. Smith, S. Randal Voss

Biology Faculty Publications

BACKGROUND: Because amphibians arise from a branch of the vertebrate evolutionary tree that is juxtaposed between fishes and amniotes, they provide important comparative perspective for reconstructing character changes that have occurred during vertebrate evolution. Here, we report the first comparative study of vertebrate genome structure that includes a representative amphibian. We used 491 transcribed sequences from a salamander (Ambystoma) genetic map and whole genome assemblies for human, mouse, rat, dog, chicken, zebrafish, and the freshwater pufferfish Tetraodon nigroviridis to compare gene orders and rearrangement rates.

RESULTS: Ambystoma has experienced a rate of genome rearrangement that is substantially lower than mammalian …