VIVALDI-related articles published in 2019

Manuscript: High individual variability in the transcriptomic response of Mediterranean mussels to Vibrio reveals the involvement of myticins in tissue injury. (Magalí Rey-Campos, Rebeca Moreira, Valentina Valenzuela-Muñoz, Cristian Gallardo-Escárate, Beatriz Novoa, Antonio Figueras)

Published in Scientific Reports, 2019 DOI: 1038/s41598-019-39870-3.

VIVALDI partner involved: CSIC

The usual way to do experiments is to analyze a group of individual animals altogether. In this work, we analyzed the individual response of mussels before and after being infected with a very common pathogenic bacterium in aquaculture: Vibrio splendidus. We demonstrated a great variability in the defense response among individual mussels. Each animal showed an exclusive repertoire of genes not shared with other individuals. We also found that a simple injection without bacteria was a stimulus strong enough to mobilize immune cells. It suggests a reaction against a tissue injury and the specific involvement antimicrobial peptides to this danger signal.

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Manuscript: An Evolutionary Perspective of Dopachrome Tautomerase Enzymes in Metazoans (Umberto Rosani, Stefania Domeneghetti, Lorenzo Maso, K. Mathias Wegner and Paola Venier)

Published in Genes, 2019, doi: 10.3390/genes10070495

VIVALDI partner involved: UNIPD, AWI

The research team discovered in Crassostrea gigas an enzyme which was so far described in insects, bacteria and funghi. This enzyme seems to be impacted by an OsHV-1 infection.

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Manuscript: A needle in a haystack: tracing bivalve-associated viruses in high-throughput transcriptomic data (Rosani U, Shapiro M, Venier P, Allam B)

Published in Viruses, 2019, doi: 10.3390/v11030205

VIVALDI partner involved: UNIPD, AWI

Bivalve molluscs thrive in environments rich in microorganisms, such as estuarine and coastal waters, and they tend to accumulate various particles, including viruses. However, the current knowledge on mollusk viruses is mainly centered on few pathogenic viruses. This study was designed to explore the viral abundance and diversity in bivalve mollusks using transcriptomic datasets.  The analysis of 58 different species of bivalves has resulted in finding sequences of very diverse and often unknown viruses. These findings set the stage for targeted investigations on the specificity and dynamics of the identified viruses.

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Manuscript: Dynamics of the Pacific Oyster pathobiota during mortality episodes in Europe assessed by 16S rRNA gene profiling and a new target enrichment next-generation sequencing strategy (Aide Lasa, Andrea di Cesare, Giovanni Tassistro, Alessio Borello, Stefano Gualdi, Dolors Furones, Noelia Carrasco, Deborah Cheslett, Amanda Brechon, Christine Paillard, Adeline Bidault, Fabrice Pernet, Laura Canesi, Paolo Edomi, Alberto Pallavicini, Carla Pruzzo and Luigi Vezzulli)

Published in Environmental microbiology, 2019, doi: 10.1111/1462-2920.14750

VIVALDI partner involved: UNIGE, IRTA, MI, CNRS, IFREMER, UNITS

Infectious agents such as the bacteria Vibrio aestuarianus or Ostreid herpesvirus 1 have been repeatedly associated with dramatic disease outbreaks of Crassostrea gigas beds in Europe. Beside roles played by these pathogens, microbial infections in C.gigas may derive from the contribution of a larger number of microorganisms than previously thought, according to an emerging view supporting the polymicrobial nature of bivalve diseases. In this study, the microbial communities associated with a large number of C.gigas samples collected during recurrent mortality episodes at different European sites were investigated. This comparative analysis revealed that oyster experiencing mortality outbreaks displayed signs of microbiota disruption associated with the presence of previously undetected potential pathogenic microbial species mostly belonging to genus Vibrio and Arcobacter. The role of these species and their consortia should be targeted by future studies aiming to shed light on mechanisms underlying poly-microbial infections in C.gigas.

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Manuscript: Dual analysis of virus‐host interactions: the case of OsHV‐1 and the cupped oyster Crassostrea gigas (Rosani Umberto, Young Tim, Bai Chang‐Ming, Alfaro Andrea, Venier Paola)

Published in Evolutionary bioinformatics, 2019, doi: 10.1177/1176934319831305

VIVALDI partner involved: UNIPD

Analyses of the interactions between Ostreid herpesvirus 1 (OsHV-1) and the bivalve Crassostrea gigas during infection can unveil events that are critical to the emergence and progression of this viral disease and can provide novel strategies for mitigating and preventing oyster mortality. Among the currently used “omics” technologies, dual transcriptomics (dual RNA-seq) coupled with the analysis of viral DNA in the host tissues has greatly advanced the knowledge of genes and pathways mostly contributing to host defense responses. This review explores our current knowledge of “omics” technologies in the study of host-pathogen interactions and highlights relevant applications of these fields of expertise to the complex case of C gigas infections by OsHV-1, which currently threaten the mollusk production sector worldwide.

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Manuscript: Exposure to TiO2 nanoparticles induces shifts in the microbiota composition of Mytilus galloprovincialis hemolymph (Manon Auguste, Aide Lasa, Alberto Pallavicini, Stefano Gualdi, Luigi Vezzulli, Laura Canesi)

Published in Science of the total environment, 2019, doi.org/10.1016/j.scitotenv.2019.03.133

VIVALDI partner involved: UNIGE, UNITS

It is now recognized that the microbiome - the community of microorganisms that colonize an animal's body and their genomes - play an important role in the health status of all organisms, from nutrient processing to protection from disease. In particular, the interactions between the host innate immune system and the microbiota are crucial in maintaining the whole body's homeostasis. The development of nanotechnology is raising concern on the potential impact of nanoparticles (NPs) on human and environmental health. Titanium dioxide-nTiO2, one of the most widely NP in use, has been shown to affect the gut microbiota of mammals and fish, as well as to potentially alter microbial communities. In the marine bivalve Mytilus galloprovincialis (Mediterranean mussel), nTiO2 has been previously shown to interact with hemolymph components, thus resulting in modulating the immune response. However, no information is available on the possible impact of NPs on the microbiome of marine organisms.

Bivalves host high microbial abundance and diversity. Alteration of their microbiota in response to stressful conditions has been linked to a compromised health status and susceptibility to diseases. In this study, the effects of nTiO2 were confirmed by the increase in the bactericidal activity of the whole hemolymph. These represent the first data on the effects of NPs on the microbiome of marine invertebrates, and suggest that the shift in hemolymph microbiome composition induced by nTiO2 may result from the interplay between the microbiota and the immune system.

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Manuscript: A study of autophagy in hemocytes of the Pacific oyster, Crassostrea gigas (Picot Sandy, Morga Benjamin, Faury Nicole, Chollet Bruno, Dégremont Lionel, Travers Marie-Agnes, Renault Tristan, Arzul Isabelle)

Published in Autophagy, 2019, doi: 10.1080/15548627.2019.1596490

VIVALDI partner involved: Ifremer

Macro-autophagy is a mechanism that is involved in various cellular processes. This pathway has been described in organisms ranging in complexity from yeasts to mammals, and recent results indicate that it occurs in the mantle of the Pacific oyster, Crassostrea gigas. So far, the autophagy pathway had never been explored in the hemocytes of C. gigas, which play a key role in the defence of the Pacific oyster against pathogens. To investigate autophagy in oyster hemocytes, the same tools as those currently used to monitor this mechanism in mammals were adapted and applied to the hemocytes of the Pacific oyster. Our results demonstrated that autophagy occurs in hemocytes of C. gigas and can be modulated by molecules known to modulate autophagy in other organisms. This study describes an integrated approach that can be applied to investigate autophagy in marine bivalves at the cellular level.

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Manuscript: Detection and characterisation of Minchinia mytilii n. sp., a haplosporidian parasite of the blue mussel Mytilus edulis (Georgia M. Ward, Stephen W. Feist, Patricia Noguera, Mar Marcos-López, Stuart Ross, Matthew Green, Ander Urrutia, John P. Bignell, David Bass)

Published in Diseases of Aquatic Organisms, 2019, doi: https://doi.org/10.3354/dao03326

VIVALDI partner involved: CEFAS

The edible mussel Mytilus edulis is a major aquaculture commodity in Europe, with 168000 t produced in 2015. A number of abundant, well characterised parasites of the species are known, though none are considered to cause significant mortality. Haplosporida (Rhizaria, Endomyxa) is an order of protistan parasites of aquatic invertebrates, the best studied of which are the oyster pathogens Haplosporidium nelsoni and Bonamia ostreae. While these species are well characterised within their hosts, the diversity, life-cycle and modes of transmission of haplosporidians are very poorly understood. Haplosporidian parasites have previously been reported from Mytilus spp., however the majority of these remain uncharacterised, and no molecular data exist for any species. In this study, we identified 2 novel haplosporidian parasites of M. edulis present in the UK.