Dataset Information

The draft genomes of soft-shell turtle and green sea turtle yield insights into the development and evolution of the turtle-specific body plan.

ABSTRACT: The unique anatomical features of turtles have raised unanswered questions about the origin of their unique body plan. We generated and analyzed draft genomes of the soft-shell turtle (Pelodiscus sinensis) and the green sea turtle (Chelonia mydas); our results indicated the close relationship of the turtles to the bird-crocodilian lineage, from which they split ?267.9-248.3 million years ago (Upper Permian to Triassic). We also found extensive expansion of olfactory receptor genes in these turtles. Embryonic gene expression analysis identified an hourglass-like divergence of turtle and chicken embryogenesis, with maximal conservation around the vertebrate phylotypic period, rather than at later stages that show the amniote-common pattern. Wnt5a expression was found in the growth zone of the dorsal shell, supporting the possible co-option of limb-associated Wnt signaling in the acquisition of this turtle-specific novelty. Our results suggest that turtle evolution was accompanied by an unexpectedly conservative vertebrate phylotypic period, followed by turtle-specific repatterning of development to yield the novel structure of the shell.

SUBMITTER: Wang Z

PROVIDER: S-EPMC4000948 | biostudies-literature | 2013 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

The draft genomes of soft-shell turtle and green sea turtle yield insights into the development and evolution of the turtle-specific body plan.

Wang Zhuo Z Pascual-Anaya Juan J Zadissa Amonida A Li Wenqi W Niimura Yoshihito Y Huang Zhiyong Z Li Chunyi C White Simon S Xiong Zhiqiang Z Fang Dongming D Wang Bo B Ming Yao Y Chen Yan Y Zheng Yuan Y Kuraku Shigehiro S Pignatelli Miguel M Herrero Javier J Beal Kathryn K Nozawa Masafumi M Li Qiye Q Wang Juan J Zhang Hongyan H Yu Lili L Shigenobu Shuji S Wang Junyi J Liu Jiannan J Flicek Paul P Searle Steve S Wang Jun J Kuratani Shigeru S Yin Ye Y Aken Bronwen B Zhang Guojie G Irie Naoki N

Nature genetics 20130428 6

The unique anatomical features of turtles have raised unanswered questions about the origin of their unique body plan. We generated and analyzed draft genomes of the soft-shell turtle (Pelodiscus sinensis) and the green sea turtle (Chelonia mydas); our results indicated the close relationship of the turtles to the bird-crocodilian lineage, from which they split ∼267.9-248.3 million years ago (Upper Permian to Triassic). We also found extensive expansion of olfactory receptor genes in these turtl ...[more]

PMID: 23624526

Similar Datasets

Project description:After gastrulation, oviductal hypoxia maintains turtle embryos in an arrested state prior to oviposition. Subsequent exposure to atmospheric oxygen upon oviposition initiates recommencement of embryonic development. Arrest can be artificially extended for several days after oviposition by incubation of the egg under hypoxic conditions, with development recommencing in an apparently normal fashion after subsequent exposure to normoxia. To examine the transcriptomic events associated with embryonic arrestAfter gastrulation, oviductal hypoxia maintains turtle embryos in an arrested state prior to oviposition. Subsequent exposure to atmospheric oxygen upon oviposition initiates recommencement of embryonic development. Arrest can be artificially extended for several days after oviposition by incubation of the egg under hypoxic conditions, with development recommencing in an apparently normal fashion after subsequent exposure to normoxia. To examine the transcriptomic events associated with embryonic arrest, RNA-sequencing analysis was performed on embryos from freshly laid eggs and eggs incubated in either normoxia (oxygen tension ~159 mmHg) or hypoxia (<8 mmHg) for 36 hours (h) after oviposition (n = 5 per group). The patterns of gene expression differed markedly among the three experimental groups. Normal embryonic development in normoxia was associated with up-regulation of genes involved in DNA replication, the cell cycle, and mitosis, but these genes were commonly down-regulated after incubation in hypoxia. Many target genes of hypoxia inducible factors, including insulin-like growth factor binding protein 1, were down-regulated by normoxic incubation but upregulated by incubation in hypoxia. Notably, some of the transcriptomic effects of hypoxia in green turtle embryos resembled those reported by others to be associated with hypoxia-induced embryonic arrest in diverse taxa, including budding yeast (Saccharomyces cerevisiae), the annelid Caenorhabditis elegans, and zebrafish (Danio rerio). Thus, while among oviparous species, hypoxia-induced pre-ovipositional embryonic arrest appears to be a unique adaptation of turtles, mechanisms underlying hypoxia-induced embryonic arrest per se may be highly conserved across the diverse taxa in which this mechanism operates. We report the transciptional changes in Chelonia mydas embryos incubated in either normoxia or hypoxia comapred to freshly laid eggs.

Project description:The characterization of mitochondrial genome has been evidenced as an efficient field of study for phylogenetic and evolutionary analysis in vertebrates including turtles. The aim of this study was to distinguish the structure and variability of the Trionychidae species mitogenomes through comparative analysis. The complete mitogenome (16796 bp) of an endangered freshwater turtle, Nilssonia nigricans was sequenced and annotated. The mitogenome encoded for 37 genes and a major non-coding control region (CR). The mitogenome was A + T biased (62.16%) and included six overlapping and 19 intergenic spacer regions. The Relative synonymous codon usage (RSCU) value was consistent among all the Trionychidae species; with the exception of significant reduction of Serine (TCG) frequency in N. nigricans, N. formosa, and R. swinhoei. In N. nigricans, most of the transfer RNAs (tRNAs) were folded into classic clover-leaf secondary structures with Watson-Crick base pairing except for trnS1 (GCT). The comparative analysis revealed that most of the tRNAs were structurally different, except for trnE (TTC), trnQ (TTG), and trnM (CAT). The structural features of tRNAs resulted ≥ 10 mismatched or wobble base pairings in 12 tRNAs, which reflects the nucleotide composition in both H- and L-strands. The mitogenome of N. nigricans also revealed two unique tandem repeats (ATTAT)8, and (TATTA)20 in the CR. Further, the conserved motif 5'-GACATA-3' and stable stem-loop structure was detected in the CRs of all Trionychidae species, which play an significant role in regulating transcription and replication in the mitochondrial genome. Further, the comparative analysis of Ka/Ks indicated negative selection in most of the protein coding genes (PCGs). The constructed Maximum Likelihood (ML) phylogeny using all PCGs showed clustering of N. nigricans with N. formosa. The resulting phylogeny illustrated the similar topology as described previously and consistent with the taxonomic classification. However, more sampling from different taxonomic groups of Testudines and studies on their mitogenomics are desirable for better understanding of the phylogenetic and evolutionary relationships.

Dataset Information

The draft genomes of soft-shell turtle and green sea turtle yield insights into the development and evolution of the turtle-specific body plan.

Publications

The draft genomes of soft-shell turtle and green sea turtle yield insights into the development and evolution of the turtle-specific body plan.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets