RESUMEN
Seahorses have a specialized morphology that includes a toothless tubular mouth, a body covered with bony plates, a male brood pouch, and the absence of caudal and pelvic fins. Here we report the sequencing and de novo assembly of the genome of the tiger tail seahorse, Hippocampus comes. Comparative genomic analysis identifies higher protein and nucleotide evolutionary rates in H. comes compared with other teleost fish genomes. We identified an astacin metalloprotease gene family that has undergone expansion and is highly expressed in the male brood pouch. We also find that the H. comes genome lacks enamel matrix protein-coding proline/glutamine-rich secretory calcium-binding phosphoprotein genes, which might have led to the loss of mineralized teeth. tbx4, a regulator of hindlimb development, is also not found in H. comes genome. Knockout of tbx4 in zebrafish showed a 'pelvic fin-loss' phenotype similar to that of seahorses.
Asunto(s)
Evolución Biológica , Proteínas de Peces/genética , Genoma/genética , Smegmamorpha/anatomía & histología , Smegmamorpha/genética , Aletas de Animales/anatomía & histología , Aletas de Animales/metabolismo , Animales , Secuencia Conservada/genética , Proteínas de Peces/deficiencia , Eliminación de Gen , Genómica , Miembro Posterior/anatomía & histología , Miembro Posterior/metabolismo , Masculino , Anotación de Secuencia Molecular , Familia de Multigenes/genética , Tasa de Mutación , Filogenia , Reproducción/fisiología , Proteínas de Dominio T Box/deficiencia , Proteínas de Dominio T Box/genética , Factores de Tiempo , Proteínas de Pez Cebra/deficiencia , Proteínas de Pez Cebra/genéticaRESUMEN
The iconic phenotype of seadragons includes leaf-like appendages, a toothless tubular mouth, and male pregnancy involving incubation of fertilized eggs on an open "brood patch." We de novo-sequenced male and female genomes of the common seadragon (Phyllopteryx taeniolatus) and its closely related species, the alligator pipefish (Syngnathoides biaculeatus). Transcription profiles from an evolutionary novelty, the leaf-like appendages, show that a set of genes typically involved in fin development have been co-opted as well as an enrichment of transcripts for potential tissue repair and immune defense genes. The zebrafish mutants for scpp5, which is lost in all syngnathids, were found to lack or have deformed pharyngeal teeth, supporting the hypothesis that the loss of scpp5 has contributed to the loss of teeth in syngnathids. A putative sex-determining locus encoding a male-specific amhr2y gene shared by common seadragon and alligator pipefish was identified.