Impact of the toxic dinoflagellate Alexandrium catenella on Pacific oyster reproductive output: application of flow cytometry assays on spermatozoa

Type Article
Date 2013-07
Language English
Author(s) Le Goic Nelly1, Hegaret Helene1, Fabioux Caroline1, Miner Philippe2, Suquet Marc2, Lambert Christophe1, Soudant Philippe1
Affiliation(s) 1 : IUEM UBO, Lab Sci Environm Marin LEMAR, Plouzane, France.
2 : IFREMER, Lab Physiol Invertebres LPI, Plouzane, France.
Source Aquatic Living Resources (0990-7440) (Edp Sciences S A), 2013-07 , Vol. 26 , N. 3 , P. 221-228
DOI 10.1051/alr/2013047
WOS© Times Cited 29
Keyword(s) Harmful algal bloom, Sperm quality, Cellular parameters, Flow cytometry, Pacific oyster, Crassostrea gigas, Alexandrium catenella
Abstract The toxic dinoflagellate Alexandrium catenella recurrently blooms on the coasts of France and produces Paralytic Shellfish Toxins (PSTs) that accumulate in bivalves. These toxins can affect various physiological functions including reproduction. The present study aims to validate measurements of sperm viability, DNA content and mitochondrial membrane potential in Pacific oyster Crassostrea gigas using flow cytometry coupled with fluorescent markers, and to use these measurements to assess the cellular parameters of sperm from Pacific oysters exposed to A. catenella. These parameters may influence fertilization, embryogenesis and larval development in free-spawning shellfish. Sperm viability and DNA content estimation were assessed using SYBR-14, which only penetrates cells with intact membranes. Cell mortality was measured with propidium iodide (PI), which penetrates cells with membrane damage. Mitochondrial membrane potential, used as an estimate of mitochondrial function, was measured using IC-1 dye, which selectively enters into mitochondria and reversibly changes colour from green to orange as the membrane potential increases. To assess the effect of toxic algae on oyster sperm, broodstock (ripe oysters) were fed toxic (A. catenella) or non toxic (Heterocapsa triquetra) dinoflagellates at 250 cell ml(-1) for 9 days. After this exposure 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 gametes from A. catenella-exposed oysters than in those from control oysters fed H. triquetra. Additionally, mitochondrial membrane potential of sperm from A. catenella-exposed oysters was significantly higher (1.5 fold) than that of sperm produced by oysters fed H. triquetra. Both the increase of mitochondrial membrane potential and the modification of DNA structure can be expected to impact spermatozoa ability to fertilize oocytes and could thus impact related reproductive processes.
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Le Goic Nelly, Hegaret Helene, Fabioux Caroline, Miner Philippe, Suquet Marc, Lambert Christophe, Soudant Philippe (2013). Impact of the toxic dinoflagellate Alexandrium catenella on Pacific oyster reproductive output: application of flow cytometry assays on spermatozoa. Aquatic Living Resources, 26(3), 221-228. Publisher's official version : https://doi.org/10.1051/alr/2013047 , Open Access version : https://archimer.ifremer.fr/doc/00157/26853/