Publications by authors named "J Vidal-Dupiol"

24 Publications

Effects of elevated temperature and CO on the respiration, biomineralization and photophysiology of the giant clam .

Conserv Physiol 2021 16;9(1):coab041. Epub 2021 Jun 16.

IFREMER, IRD, Institut Louis-Malardé, Univ. Polynésie française, EIO, F-98719 Taravao, Tahiti, Polynésie française, France.

Many reef organisms, such as the giant clams, are confronted with global change effects. Abnormally high seawater temperatures can lead to mass bleaching events and subsequent mortality, while ocean acidification may impact biomineralization processes. Despite its strong ecological and socio-economic importance, its responses to these threats still need to be explored. We investigated physiological responses of 4-year-old to realistic levels of temperature (+1.5°C) and partial pressure of carbon dioxide (CO) (+800 atm of CO) predicted for 2100 in French Polynesian lagoons during the warmer season. During a 65-day crossed-factorial experiment, individuals were exposed to two temperatures (29.2°C, 30.7°C) and two CO (430 atm, 1212 atm) conditions. The impact of each environmental parameter and their potential synergetic effect were evaluated based on respiration, biomineralization and photophysiology. Kinetics of thermal and/or acidification stress were evaluated by performing measurements at different times of exposure (29, 41, 53, 65 days). At 30.7°C, the holobiont O production, symbiont photosynthetic yield and density were negatively impacted. High CO had a significant negative effect on shell growth rate, symbiont photosynthetic yield and density. No significant differences of the shell microstructure were observed between control and experimental conditions in the first 29 days; however, modifications (i.e. less-cohesive lamellae) appeared from 41 days in all temperature and CO conditions. No significant synergetic effect was found. Present thermal conditions (29.2°C) appeared to be sufficiently stressful to induce a host acclimatization response. All these observations indicate that temperature and CO are both forcing variables affecting 's physiology and jeopardize its survival under environmental conditions predicted for the end of this century.
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http://dx.doi.org/10.1093/conphys/coab041DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8208665PMC
June 2021

Environmentally Driven Color Variation in the Pearl Oyster var. (Linnaeus, 1758) Is Associated With Differential Methylation of CpGs in Pigment- and Biomineralization-Related Genes.

Front Genet 2021 19;12:630290. Epub 2021 Mar 19.

IHPE, Université de Montpellier, CNRS, IFREMER, Université de Perpignan Via Domitia, Montpellier, France.

Today, it is common knowledge that environmental factors can change the color of many animals. Studies have shown that the molecular mechanisms underlying such modifications could involve epigenetic factors. Since 2013, the pearl oyster var. has become a biological model for questions on color expression and variation in Mollusca. A previous study reported color plasticity in response to water depth variation, specifically a general darkening of the nacre color at greater depth. However, the molecular mechanisms behind this plasticity are still unknown. In this paper, we investigate the possible implication of epigenetic factors controlling shell color variation through a depth variation experiment associated with a DNA methylation study performed at the whole genome level with a constant genetic background. Our results revealed six genes presenting differentially methylated CpGs in response to the environmental change, among which four are linked to pigmentation processes or regulations (, , , and ), especially those leading to darker phenotypes. Interestingly, the genes and , both involved in the biomineralization process (deposition of aragonite and calcite crystals), also showed differential methylation, suggesting that a possible difference in the physical/spatial organization of the crystals could cause darkening (iridescence or transparency modification of the biomineral). These findings are of great interest for the pearl production industry, since wholly black pearls and their opposite, the palest pearls, command a higher value on several markets. They also open the route of epigenetic improvement as a new means for pearl production improvement.
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http://dx.doi.org/10.3389/fgene.2021.630290DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8018223PMC
March 2021

Molecular Pathways and Pigments Underlying the Colors of the Pearl Oyster var. (Linnaeus 1758).

Genes (Basel) 2021 03 15;12(3). Epub 2021 Mar 15.

IFREMER, UMR 241 Écosystèmes Insulaires Océaniens, Labex Corail, Centre Ifremer du Pacifique, BP 49, 98725 Tahiti, France.

The shell color of the Mollusca has attracted naturalists and collectors for hundreds of years, while the molecular pathways regulating pigment production and the pigments themselves remain poorly described. In this study, our aim was to identify the main pigments and their molecular pathways in the pearl oyster -the species displaying the broadest range of colors. Three inner shell colors were investigated-red, yellow, and green. To maximize phenotypic homogeneity, a controlled population approach combined with common garden conditioning was used. Comparative analysis of transcriptomes (RNA-seq) of with different shell colors revealed the central role of the heme pathway, which is involved in the production of red (uroporphyrin and derivates), yellow (bilirubin), and green (biliverdin and cobalamin forms) pigments. In addition, the Raper-Mason, and purine metabolism pathways were shown to produce yellow pigments (pheomelanin and xanthine) and the black pigment eumelanin. The presence of these pigments in pigmented shell was validated by Raman spectroscopy. This method also highlighted that all the identified pathways and pigments are expressed ubiquitously and that the dominant color of the shell is due to the preferential expression of one pathway compared with another. These pathways could likely be extrapolated to many other organisms presenting broad chromatic variation.
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http://dx.doi.org/10.3390/genes12030421DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7998362PMC
March 2021

A simple ATAC-seq protocol for population epigenetics.

Wellcome Open Res 2020 7;5:121. Epub 2021 Jan 7.

Univ. Montpellier, CNRS, IFREMER, UPVD, IHPE, F-66000 Perpignan and F-34095, Montpellier, France.

We describe here a protocol for the generation of sequence-ready libraries for population epigenomics studies, and the analysis of alignment results. We show that the protocol can be used to monitor chromatin structure changes in populations when exposed to environmental cues. The protocol is a streamlined version of the Assay for transposase accessible chromatin with high-throughput sequencing (ATAC-seq) that provides a positive display of accessible, presumably euchromatic regions. The protocol is straightforward and can be used with small individuals such as daphnia and schistosome worms, and probably many other biological samples of comparable size (~10,000 cells), and it requires little molecular biology handling expertise.
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http://dx.doi.org/10.12688/wellcomeopenres.15552.2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7814285PMC
January 2021

High temperature induces transcriptomic changes in that hinder progress of ostreid herpesvirus (OsHV-1) and promote survival.

J Exp Biol 2020 10 15;223(Pt 20). Epub 2020 Oct 15.

Ifremer, Université de Brest, CNRS, IRD, LEMAR, F-29280 Plouzané, France

Of all environmental factors, seawater temperature plays a decisive role in triggering marine diseases. Like fever in vertebrates, high seawater temperature could modulate the host response to pathogens in ectothermic animals. In France, massive mortality of Pacific oysters, , caused by the ostreid herpesvirus 1 (OsHV-1) is markedly reduced when temperatures exceed 24°C in the field. In the present study we assess how high temperature influences the host response to the pathogen by comparing transcriptomes (RNA sequencing) during the course of experimental infection at 21°C (reference) and 29°C. We show that high temperature induced host physiological processes that are unfavorable to the viral infection. Temperature influenced the expression of transcripts related to the immune process and increased the transcription of genes related to the apoptotic process, synaptic signaling and protein processes at 29°C. Concomitantly, the expression of genes associated with catabolism, metabolite transport, macromolecule synthesis and cell growth remained low from the first stage of infection at 29°C. Moreover, viral entry into the host might have been limited at 29°C by changes in extracellular matrix composition and protein abundance. Overall, these results provide new insights into how environmental factors modulate host-pathogen interactions.
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http://dx.doi.org/10.1242/jeb.226233DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7578350PMC
October 2020