Large scale gene duplication affected the European eel (<i>Anguilla anguilla</i>) after the 3R teleost duplication

Rozenfeld, C.; Blanca, José; Gallego,; García-Carpintero,; Jg, Herranz-Jusdado; Pérez, Luz; Asturiano, Juan F.; Cañizares, Joaquı́n; Peñaranda, David S.

doi:10.1101/232918

Cited by 2 publications

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References 103 publications

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“…Differences in peak range across teleost groups may suggest a higher conservation of TS-WGD duplications in Osteoglossomorpha and Elopomorpha lineages than in Clupeocephala. Interestingly, an even more recent peak ( K s =0.85), with a wide range, was specifically observed in the European eel, which could support a recent hypothesis of a likely fourth WGD event in this species ( Rozenfeld et al. 2017 ), however, we do not discard that such peak could be an artefact resulted from wrong fitting assumptions or due to sequencing or annotation faults.…”

Section: Resultssupporting

confidence: 56%

Whole Genome Sequencing of the Pirarucu (Arapaima gigas) Supports Independent Emergence of Major Teleost Clades

Vialle

Souza

Lopes

et al. 2018

Genome Biology and Evolution

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The Pirarucu (Arapaima gigas) is one of the world’s largest freshwater fishes and member of the superorder Osteoglossomorpha (bonytongues), one of the oldest lineages of ray-finned fishes. This species is an obligate air-breather found in the basin of the Amazon River with an attractive potential for aquaculture. Its phylogenetic position among bony fishes makes the Pirarucu a relevant subject for evolutionary studies of early teleost diversification. Here, we present, for the first time, a draft genome version of the A. gigas genome, providing useful information for further functional and evolutionary studies. The A. gigas genome was assembled with 103-Gb raw reads sequenced in an Illumina platform. The final draft genome assembly was ∼661 Mb, with a contig N50 equal to 51.23 kb and scaffold N50 of 668 kb. Repeat sequences accounted for 21.69% of the whole genome, and a total of 24,655 protein-coding genes were predicted from the genome assembly, with an average of nine exons per gene. Phylogenomic analysis based on 24 fish species supported the postulation that Osteoglossomorpha and Elopomorpha (eels, tarpons, and bonefishes) are sister groups, both forming a sister lineage with respect to Clupeocephala (remaining teleosts). Divergence time estimations suggested that Osteoglossomorpha and Elopomorpha lineages emerged independently in a period of ∼30 Myr in the Jurassic. The draft genome of A. gigas provides a valuable genetic resource for further investigations of evolutionary studies and may also offer a valuable data for economic applications.

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Section: Resultssupporting

confidence: 56%

Whole Genome Sequencing of the Pirarucu (Arapaima gigas) Supports Independent Emergence of Major Teleost Clades

Vialle

Souza

Lopes

et al. 2018

Genome Biology and Evolution

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Cold seawater induces early sexual developmental stages in the BPG axis of European eel males

et al. 2019

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Background The impossibility of closing the life cycle of the European eel ( Anguilla anguilla ) in captivity troubles the future of this critically endangered species. In addition, the European eel is a highly valued and demanded resource, thus the successful closing of its life cycle would have a substantial economic and ecological impact. With the aim of obtaining the highest gamete quality, the study of the effects of environmental factors, such as temperature, on reproductive performance may prove valuable. This is especially true for the exposure to cold water, which has been reported to improve sexual development in multiple other Actinopterygii species. Results European eel males treated with cold seawater (10 °C, T10) for 2 weeks showed an increase in the proliferation and differentiation of spermatogonial cells until the differentiated spermatogonial type A cell stage, and elevated testosterone and 11-ketotestosterone plasma levels. Transcriptomes from the tissues of the brain-pituitary-gonad (BPG) axis of T10 samples revealed a differential gene expression profile compared to the other experimental groups, with clustering in a principal component analysis and in heat maps of all differentially expressed genes. Furthermore, a functional analysis of differentially expressed genes revealed enriched gene ontology terms involved in the regulation of circadian rhythm, histone modification, meiotic nuclear division, and others. Conclusions Cold seawater treatment had a clear effect on the activity of the BPG-axis of European eel males. In particular, our cold seawater treatment induces the synchronization and increased proliferation and differentiation of specific spermatogonial cells. In the transcriptomic results, genes related to thermoception were observed. This thermoception may have caused the observed effects through epigenetic mechanisms, since all analysed tissues further revealed differentially expressed genes involved in histone modification. The presented results support our hypothesis that a low temperature seawater treatment induces an early sexual developmental stage in European eels. This hypothesis is logical given that the average temperature experienced by eels in the early stages of their oceanic reproductive migration is highly similar to that of this cold seawater treatment. Further studies are needed to test whether a cold seawater treatment can improve the response of European eels to artificial hormonal treatment, as the results suggest. Electronic supplementary material The online version of this article (10.1186/s12864-019-5969-6) contains supplementary material, which is available to authorized users.

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Large scale gene duplication affected the European eel (Anguilla anguilla) after the 3R teleost duplication

Abstract: 3 6

Cited by 2 publications

References 103 publications

Whole Genome Sequencing of the Pirarucu (Arapaima gigas) Supports Independent Emergence of Major Teleost Clades

Whole Genome Sequencing of the Pirarucu (Arapaima gigas) Supports Independent Emergence of Major Teleost Clades

Cold seawater induces early sexual developmental stages in the BPG axis of European eel males

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