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- Transcriptomic down-regulation of immune system components in barrier and hematopoietic tissues after lipopolysaccharide injection in antarctic notothenia coriicepsPublication . Sousa, Carmen; Power, Deborah; Guerreiro, Pedro M; Louro, Bruno; Chen, Liangbiao; Canario, AdelinoThe environmental conditions and isolation in the Antarctic have driven the evolution of a unique biodiversity at a macro to microorganism scale. Here, we investigated the possible adaptation of the teleost Notothenia coriiceps immune system to the cold environment and unique microbial community of the Southern Ocean. The fish immune system was stimulated through an intraperitoneal injection of lipopolysaccharide (LPS 0111:B4 from E. coli) and the tissue transcriptomic response and plasma biochemistry were analyzed 7 days later and compared to a sham injected control. Gene transcription in the head-kidney, intestine and skin was significantly modified by LPS, although tissues showed different responsiveness, with the duodenum most modified and the skin the least modified. The most modified processes in head-kidney, duodenum and skin were related to cell metabolism (up-regulated) and the immune system (comprising 30% of differentially expressed genes). The immune processes identified were mostly down-regulated, particularly interleukins and pattern recognition receptors (PRRs), nucleotide-binding oligomerization domain-like receptors and mannose receptors, unlike the toll-like receptors response commonly described in other teleost fish. The modified transcriptional response was not mirrored by a modified systemic response, as the circulating levels of enzymes of innate immunity, lysozyme and antiproteases, were not significantly different from the untreated and sham control fish. In conclusion, while the N. coriiceps immune system shares many features with other teleosts there are also some specificities. Further studies should better characterize the PRRs and their role in Antarctic teleosts, as well as the importance of the LPS source and its consequences for immune activation in teleosts.
- A new subfamily of ionotropic glutamate receptors unique to the echinoderms with putative sensory rolePublication . Sania, Rubaiyat E.; Cardoso, João; Louro, Bruno; Marquet, Nathalie; Canario, AdelinoChemosensation is a critical signalling process in animals and especially important in sea cucumbers, a group of ecologically and economically important marine echinoderms (class Holothuroidea), which lack audio and visual organs and rely on chemical sensing for survival, feeding and reproduction. The ionotropic receptors are a recently identified family of chemosensory receptors in insects and other protostomes, related to the ionotropic glutamate receptor family (iGluR), a large family of membrane receptors in metazoan. Here we characterize the echinoderm iGluR subunits and consider their possible role in chemical communication in sea cucumbers. Sequence similarity searches revealed that sea cucumbers have in general a higher number of iGluR subunits when compared to other echinoderms. Phylogenetic analysis and sequence comparisons revealed GluH as a specific iGluR subfamily present in all echinoderms. Homologues of the vertebrate GluA (aka alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, AMPA), GluK (aka kainate) and GluD (aka delta) were also identified. The GluN (aka N-methyl-d-aspartate, NMDA) as well as the invertebrate deuterostome subfamily GluF (aka phi) are absent in echinoderms. The echinoderm GluH subfamily shares conserved structural protein organization with vertebrate iGluRs and the ligand binding domain (LBD) is the most conserved region; genome analysis indicates evolution via lineage and species-specific tandem gene duplications. GluH genes (named Grih) are the most highly expressed iGluRs subunit genes in tissues in the sea cucumber Holothuria arguinesis, with Griha1, Griha2 and Griha5 exclusively expressed in tentacles, making them candidates to have a chemosensory role in this species. The multiple GluH subunits may provide alternative receptor assembly combinations, thus expanding the functional possibilities and widening the range of compounds detected during aggregation and spawning in echinoderms.
- European marine omics biodiversity observation network: a strategic outline for the implementation of omics approaches in ocean observationPublication . Santi, Ioulia; Beluche, Odette; Beraud, Mélanie; Buttigieg, Pier Luigi; Casotti, Raffaella; Cox, Cymon J.; Cunliffe, Michael; Davies, Neil; de Cerio, Oihane Diaz; Exter, Katrina; Kervella, Anne Emmanuelle; Kotoulas, Georgios; Lagaisse, Rune; Laroquette, Arnaud; Louro, Bruno; Not, Fabrice; Obst, Matthias; Pavloudi, Christina; Poulain, Julie; Præbel, Kim; Vanaverbeke, Jan; Pade, NicolasMarine ecosystems, ranging from coastal seas and wetlands to the open ocean, accommodate a wealth of biological diversity from small microorganisms to large mammals. This biodiversity and its associated ecosystem function occurs across complex spatial and temporal scales and is not yet fully understood. Given the wide range of external pressures on the marine environment, this knowledge is crucial for enabling effective conservation measures and defining the limits of sustainable use. The development and application of omics-based approaches to biodiversity research has helped overcome hurdles, such as allowing the previously hidden community of microbial life to be identified, thereby enabling a holistic view of an entire ecosystem's biodiversity and functioning. The potential of omics-based approaches for marine ecosystems observation is enormous and their added value to ecosystem monitoring, management, and conservation is widely acknowledged. Despite these encouraging prospects, most omics-based studies are short-termed and typically cover only small spatial scales which therefore fail to include the full spatio-temporal complexity and dynamics of the system. To date, few attempts have been made to establish standardised, coordinated, broad scaled, and long-term omics observation networks. Here we outline the creation of an omics-based marine observation network at the European scale, the European Marine Omics Biodiversity Observation Network (EMO BON). We illustrate how linking multiple existing individual observation efforts increases the observational power in large-scale assessments of status and change in biodiversity in the oceans. Such large-scale observation efforts have the added value of cross-border cooperation, are characterised by shared costs through economies of scale, and produce structured, comparable data. The key components required to compile reference environmental datasets and how these should be linked are major challenges that we address.
- Transcriptomics reveals that the caudal neurosecretory system in the olive flounder (Paralichthys olivaceus) is more responsive in bold individuals and to chronic temperature changePublication . Yuan, Mingzhe; Zhang, Xueshu; Louro, Bruno; Li, Xiaoxue; Canario, Adelino; Lu, WeiqunIn farmed animals, personalities have demonstrated links to performance traits, health and welfare, disease susceptibility, and to coping with environmental stress. The teleost caudal neurosecretory system (CNSS) of the posterior spinal cord is involved in the regulation of the osmoregulatory and stress responses and can directly sense a hypothermal challenge via a transient receptor potential ion channel. Here we investigated the global transcriptomic response of the CNSS of shy and bold individuals of the olive flounder (Paralichthys olivaceus) acclimated to 18 degrees C and transferred to 12 degrees C (low temperature treatment, LT) or 24 degrees C (high temperature treatment, HT) for 2 h (acute) or 8 days (chronic) in relation to fish maintained at 18 degrees C (control). Overall, differential transcriptomic responses were stronger in bold individuals and induced by acute HT and chronic LT treatments. Acute HT induced innate immunity, circadian rhythm, and cellular stress response pathways and, specifically in bold individuals, a heightened response of molecular chaperones of cellular response to heat which may be related to the mechanisms of rescue of downregulated RNA splicing processes. Chronic LT also caused downregulation of innate immunity pathways as well as pathways related to cell division. In addition, the CNSS of bold individuals was enriched in pathways related to regulation of cell cycle, adaptive immune response, and apoptosis, while cellular metabolism pathways were downregulated in shy individuals. The putative temperature sensor genes Trpv1 and Trpa1 were upregulated, respectively, after acute HT and chronic LT treatments, but there was no indication of a specific neurosecretory response of the CNSS. While several of the observed transcriptomic responses to temperature appear to be shared by other tissues and species, it is also clear that bold and shy behavioural personalities show marked different responses, with bold individuals the most responsive. These results add to the knowledge base available on olive flounder aquaculture, indicating a differential role of the CNSS in the response to temperature change according to behavioural personalities.
- Holothurians have a reduced GPCR and odorant receptor-like repertoire compared to other echinodermsPublication . Marquet, Nathalie; Cardoso, João CR; Louro, Bruno; Fernandes, Stefan; Silva, Sandra; Canario, AdelinoSea cucumbers lack vision and rely on chemical sensing to reproduce and survive. However, how they recognize and respond to environmental cues remains unknown. Possible candidates are the odorant receptors (ORs), a diverse family of G protein-coupled receptors (GPCRs) involved in olfaction. The present study aimed at characterizing the chemosensory GPCRs in sea cucumbers. At least 246 distinct GPCRs, of which ca. 20% putative ORs, were found in a transcriptome assembly of putative chemosensory (tentacles, oral cavity, calcareous ring, and papillae/tegument) and reproductive (ovary and testis) tissues from Holothuria arguinensis (57 ORs) and in the Apostichopus japonicus genome (79 ORs). The sea cucumber ORs clustered with those of sea urchin and starfish into four main clades of gene expansions sharing a common ancestor and evolving under purifying selection. However, the sea cucumber ORs repertoire was the smallest among the echinoderms and the olfactory receptor signature motif LxxPxYxxxxxLxxxDxxxxxxxxP was better conserved in cluster OR-l1 which also had more members. ORs were expressed in tentacles, oral cavity, calcareous ring, and papillae/tegument, supporting their potential role in chemosensing. This study is the first comprehensive survey of chemosensory GPCRs in sea cucumbers, and provides the molecular basis to understand how they communicate.