title: Coelacanth genomes reveal signatures for evolutionary transition from water to land.
abstract: Coelacanths are known as "living fossils," as they show remarkable morphological resemblance to the fossil record and belong to the most primitive lineage of living Sarcopterygii (lobe-finned fishes and tetrapods). Coelacanths may be key to elucidating the tempo and mode of evolution from fish to tetrapods. Here, we report the genome sequences of five coelacanths, including four Latimeria chalumnae individuals (three specimens from Tanzania and one from Comoros) and one L. menadoensis individual from Indonesia. These sequences cover two African breeding populations and two known extant coelacanth species. The genome is ∼2.74 Gbp and contains a high proportion (∼60%) of repetitive elements. The genetic diversity among the individuals was extremely low, suggesting a small population size and/or a slow rate of evolution. We found a substantial number of genes that encode olfactory and pheromone receptors with features characteristic of tetrapod receptors for the detection of airborne ligands. We also found that limb enhancers of bmp7 and gli3, both of which are essential for limb formation, are conserved between coelacanth and tetrapods, but not ray-finned fishes. We expect that some tetrapod-like genes may have existed early in the evolution of primitive Sarcopterygii and were later co-opted to adapt to terrestrial environments. These coelacanth genomes will provide a cornerstone for studies to elucidate how ancestral aquatic vertebrates evolved into terrestrial animals.
authors.affiliation: Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8501, Japan;
authors.forename: Masato
authors.initials: M
authors.lastname: Nikaido
authors.forename: Hideki
authors.initials: H
authors.lastname: Noguchi
authors.forename: Hidenori
authors.initials: H
authors.lastname: Nishihara
authors.forename: Atsushi
authors.initials: A
authors.lastname: Toyoda
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Rei
authors.initials: R
authors.lastname: Kajitani
authors.forename: Hikoyu
authors.initials: H
authors.lastname: Suzuki
authors.forename: Miki
authors.initials: M
authors.lastname: Okuno
authors.forename: Mitsuto
authors.initials: M
authors.lastname: Aibara
authors.forename: Benjamin P
authors.initials: BP
authors.lastname: Ngatunga
authors.forename: Semvua I
authors.initials: SI
authors.lastname: Mzighani
authors.forename: Hassan W J
authors.initials: HW
authors.lastname: Kalombo
authors.forename: Kawilarang W A
authors.initials: KW
authors.lastname: Masengi
authors.forename: Josef
authors.initials: J
authors.lastname: Tuda
authors.forename: Sadao
authors.initials: S
authors.lastname: Nogami
authors.forename: Ryuichiro
authors.initials: R
authors.lastname: Maeda
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Iwata
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Abe
authors.forename: Koji
authors.initials: K
authors.lastname: Fujimura
authors.forename: Masataka
authors.initials: M
authors.lastname: Okabe
authors.forename: Takanori
authors.initials: T
authors.lastname: Amano
authors.forename: Akiteru
authors.initials: A
authors.lastname: Maeno
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Shiroishi
authors.forename: Takehiko
authors.initials: T
authors.lastname: Itoh
authors.forename: Sumio
authors.initials: S
authors.lastname: Sugano
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kohara
authors.forename: Asao
authors.initials: A
authors.lastname: Fujiyama
authors.forename: Norihiro
authors.initials: N
authors.lastname: Okada
mesh_terms: D000220:Adaptation, Biological; D000349:Africa; D000818:Animals; D059001:Aquatic Organisms / Q000235:genetics; D001483:Base Sequence; D044822:Biodiversity; D055419:Bone Morphogenetic Protein 7 / Q000235:genetics; D019143:Evolution, Molecular; D005121:Extremities / Q000254:growth & development; D005399:Fishes / Q000145:classification* / Q000235:genetics*; D049810:Genetic Speciation; D014644:Genetic Variation; D016678:Genome; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics; D010802:Phylogeny; D018035:Receptors, Odorant / Q000235:genetics; D043563:Receptors, Pheromone / Q000235:genetics; D017422:Sequence Analysis, DNA; D014714:Vertebrates / Q000145:classification / Q000235:genetics; D014867:Water
chemical_list: D055419:Bone Morphogenetic Protein 7; D009419:Nerve Tissue Proteins; D018035:Receptors, Odorant; D043563:Receptors, Pheromone; D014867:Water