Search

Contaminants of emerging concern have been increasingly associated with the modulation of the epigenome, leading to potentially inherited and persistent impacts on apical endpoints. Here, we address the performance of the OECD Test No. 236 FET (fish embryo acute toxicity) in the identification of chemicals able to modulate the epigenome. Using zebrafish (Danio rerio) embryos, acute and chronic exposures were performed with the pharmaceutical, simvastatin (SIM), a widely prescribed hypocholesterolemic drug reported to induce inter and transgenerational effects. In the present study, the epigenetic effects of environmentally relevant concentrations of SIM (from 8 ng/L to 2000 ng/L) were addressed following (1) an acute embryo assay based on OECD Test No. 236 FET, (2) a chronic partial life-cycle exposure using adult zebrafish (90 days), and (3) F1 embryos obtained from parental exposed animals. Simvastatin induced significant effects in gene expression of key epigenetic biomarkers (DNA methylation and histone acetylation/deacetylation) in the gonads of exposed adult zebrafish and in 80 hpf zebrafish embryos (acute and chronic parental intergenerational exposure), albeit with distinct effect profiles between biological samples. In the chronic exposure, SIM impacted particularly DNA methyltransferase genes in males and female gonads, whereas in F1 embryos SIM affected mostly genes associated with histone acetylation/deacetylation. In the embryo acute direct exposure, SIM modulated the expression of both genes involved in DNA methylation and histone deacetylase. These findings further support the use of epigenetic biomarkers in zebrafish embryos in a high throughput approach to identify and prioritize epigenome-modulating chemicals.

The Mammalia skin exhibits a rich spectrum of evolutionary adaptations. The pilosebaceous unit, composed of the hair shaft, follicle, and the sebaceous gland, is the most striking synapomorphy. The evolutionary diversification of mammals across different ecological niches was paralleled by the appearance of an ample variety of skin modifications. Pangolins, order Pholidota, exhibit keratin-derived scales, one of the most iconic skin appendages. This formidable armor is intended to serve as a deterrent against predators. Surprisingly, while pangolins have hair on their abdomens, the occurrence of sebaceous and sweat glands is contentious. Here, we explore various molecular modules of skin physiology in four pangolin genomes, including that of sebum production. We show that genes driving wax monoester formation -Awat1/2, show patterns of inactivation in the stem pangolin branch; while the triacylglycerol synthesis geneDgat2l6seems independently eroded in the African and Asian clades. In contrast,Elovl3implicated in the formation of specific neutral lipids required for skin barrier function, is intact and expressed in the skin. An extended comparative analysis shows that genes involved in skin pathogen defense and structural integrity of keratinocyte layers also show inactivating mutations: associated with both ancestral and independent pseudogenization events. Finally, we deduce that the suggested absence of sweat glands is not paralleled by the inactivation of the ATP-binding cassette transporterAbcc11, as previously described in Cetacea. Our findings reveal the sophisticated, convergent and complex history of gene retention and loss as key mechanisms in the evolution of the highly modified mammalian skin phenotypes.

The development of Next-Generation Sequencing (NGS) technologies has revolutionized multiple fields of Biology. The ability to sequence DNA and RNA in an automated, parallel and low-cost approach, was key to boost the applicability and acquisition efficiency of omics resources. In this context, the availability of these tools has become indispensable towards our understanding of biodiversity, deepening our knowledge on the distinct complexity levels, from cells to ecosystems. In this study we comprehensively characterised and annotated a whole-body transcriptome of Hediste diversicolor. This annelid worm species belongs to the family Nereididae and inhabits estuarine and lagoon areas on the Atlantic coasts of Europe and North America. Ecologically, this species plays an important role in benthic food webs. The ability of rework sediments through bioturbation activity makes this species essential to the estuarine mechanisms. Here, we used Illumina next-generation sequencing technology, to sequence a total 105 million (M) paired-end (PE) raw reads and produce the first multi-tissue transcriptome assembly of an adult of H. diversicolor. This transcriptome contains 69,335 transcripts with a N50 transcript length of 2,313 bp and a BUSCO gene completeness of 97.7% and 96% (S: 88.2%; D: 7.8%) in Eukaryota and Metazoa lineage-specific profile libraries. Our findings offer a valuable resource for multiple biological studies using this species., This research was partially supported by the ERA-NET BlueBio COFUND Project SIDESTREAM [Grant ID 68], co-funded through national funds provided by FCT [BLUEBIO/0005/2019]; Agencia Estatal de Investigación [PCI2020-111960], NRC – Norwegian Research Council [#311701]. A.G.S. was funded by the Portuguese Foundation for Science and Technology (FCT) under the Grant [SFRH/BD/137935/2018]. Additional strategic funding was provided by FCT [UIDP/04423/2020].

Three peroxisome proliferator-activated receptor paralogues (PPARα, -β and -γ) are currently recognized in vertebrate genomes. PPARγ is known to modulate nutrition, adipogenesis and immunity in vertebrates. Natural ligands of PPARγ have been proposed; however, the receptor also binds synthetic ligands such as endocrine disruptors. Two paralogues of PPARα and PPARβ have been documented in teleost species, a consequence of the 3R WGD. Recently, two PPARγ paralogue genes were also identified in Astyanax mexicanus. We aimed to determine whether the presence of two PPARγ paralogues is prevalent in other teleost genomes, through genomic and phylogenetic analysis. Our results showed that besides Characiformes, two PPARγ paralogous genes were also identified in other teleost taxa, coinciding with the teleost-specific, whole-genome duplication and with the retention of both genes prior to the separation of the Clupeocephala. To functionally characterize these genes, we used the European sardine (Sardina pilchardus) as a model. PPARγA and PPARγB display a different tissue distribution, despite the similarity of their functional profiles: they are unresponsive to tested fatty acids and other human PPARγ ligands yet yield a transcriptional response in the presence of tributyltin (TBT). This observation puts forward the relevance of comparative analysis to decipher alternative binding architectures and broadens the disruptive potential of man-made chemicals for aquatic species.