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Impact of the toxic dinoflagellate Alexandriumcatenella on Pacific oyster reproductive output: application of flow cytometryassays on spermatozoa

Published online by Cambridge University Press:  17 April 2013

Nelly Le Goïc*
Affiliation:
Laboratoire des Sciences de l’Environnement Marin (LEMAR), IUEM-UBO, Technopôle Brest Iroise, Plouzané, France
Hélène Hégaret
Affiliation:
Laboratoire des Sciences de l’Environnement Marin (LEMAR), IUEM-UBO, Technopôle Brest Iroise, Plouzané, France
Caroline Fabioux
Affiliation:
Laboratoire des Sciences de l’Environnement Marin (LEMAR), IUEM-UBO, Technopôle Brest Iroise, Plouzané, France
Philippe Miner
Affiliation:
Laboratoire de Physiologie des Invertébrés (LPI), IFREMER, Technopôle Brest Iroise, Plouzané, France
Marc Suquet
Affiliation:
Laboratoire de Physiologie des Invertébrés (LPI), IFREMER, Technopôle Brest Iroise, Plouzané, France
Christophe Lambert
Affiliation:
Laboratoire des Sciences de l’Environnement Marin (LEMAR), IUEM-UBO, Technopôle Brest Iroise, Plouzané, France
Philippe Soudant
Affiliation:
Laboratoire des Sciences de l’Environnement Marin (LEMAR), IUEM-UBO, Technopôle Brest Iroise, Plouzané, France
*
a Corresponding author:nelly.legoic@univ-brest.fr
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Abstract

The toxic dinoflagellate Alexandrium catenella recurrently blooms on thecoasts of France and produces Paralytic Shellfish Toxins (PSTs) that accumulate inbivalves. These toxins can affect various physiological functions including reproduction.The present study aims to validate measurements of sperm viability, DNA content andmitochondrial membrane potential in Pacific oyster Crassostrea gigasusing flow cytometry coupled with fluorescent markers, and to use thesemeasurements to assess the cellular parameters of sperm from Pacific oysters exposed toA. catenella. These parameters may influence fertilization,embryogenesis and larval development in free-spawning shellfish. Sperm viability and DNAcontent estimation were assessed using SYBR-14, which only penetrates cells with intactmembranes. Cell mortality was measured with propidium iodide (PI), which penetrates cellswith membrane damage. Mitochondrial membrane potential, used as an estimate ofmitochondrial function, was measured using JC-1 dye, which selectively enters intomitochondria and reversibly changes colour from green to orange as the membrane potentialincreases. To assess the effect of toxic algae on oyster sperm, broodstock (ripe oysters)were fed toxic (A. catenella) or non toxic (Heterocapsatriquetra) dinoflagellates at 250 cell ml-1 for 9 days. After thisexposure period, mature oysters were stripped and cellular responses of sperm analysed.Average DNA staining, as measured by SYBR-14, appeared lower and more variable in gametesfrom A. catenella-exposed oysters than in those from control oysters fedH. triquetra. Additionally, mitochondrial membrane potential of spermfrom A. catenella-exposed oysters was significantly higher (1.5 fold)than that of sperm produced by oysters fed H. triquetra. Both theincrease of mitochondrial membrane potential and the modification of DNA structure can beexpected to impact spermatozoa ability to fertilize oocytes and could thus impact relatedreproductive processes.

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Type
Research Article
Copyright
© EDP Sciences, IFREMER, IRD 2013

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