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Publication de deux articles pour Sahar Mejri

Sahar Mejri, Post-Doctorat, ISMER

Supervision : Réjean Tremblay (ISMER), Céline Audet (ISMER) et Grant Vandenberg (U. Laval)

Présentement post-doctorante à « Harbor Branch Oceanographic Institute » (Florida Atlantic University) 

 

Sahar Mejri a publié tout récemment deux articles. Voici le titre et le résumé des deux articles en question :

 

Mejri, S., R. Tremblay, Y. Lambert et C. Audet. 2017. Assessing fatty acid remodelling during embryogenesis in Greenland halibut (Reinhardtius hippoglossoides) exposed to hypoxia. Marine Biology 164 :5. DOI 10.1007/s00227-016-3037-1.

Eggs of Greenland halibut (Reinhardtius hippoglossoides) are subjected to hypoxic conditions in the deep waters of the Estuary and Gulf of St. Lawrence during their development. The aim of this study was to determine whether there was potential remodelling of fatty acids (FA) during embryogenesis in eggs exposed to several levels of dissolved oxygen (DO). Fertilized eggs from three females were exposed to four DO levels: severely hypoxic (10 and 20% sat [percent saturation]), moderately hypoxic (35% sat), and normoxic (100% sat). No FA remodelling was observed in eggs submitted to the different DO levels. The most abundant FA in the polar lipid fraction were docosahexaenoic (DHA, 22: 6 n-3) and eicosapentaenoic (EPA, 20: 5 n-3) acids (26 and 22%, respectively), the latter being positively correlated with hatching success. Batches with low hatching success were characterized by eggs with decreased levels of polar EPA and DHA at the end of embryogenesis. Whatever the hatching success, the proportion of FA in the neutral fraction was always significantly lower compared to the polar fraction. Oleic acid (18: 1 n-9) (17%) was the main FA found in this fraction; together with gondoic acid (20:1 n-9), they explained most of the variation in hatching success.

 

Mejri, S., R. Tremblay, G. Vandenberg, M. Moren, I. Ben Khemis et C. Audet. 2017. Differences in nutrient content of eggs and larvae as indicators for improvement of broodstock nutrition in walleye (Sander vitreus) production. Can. J. Zoology. Disponible en ligne,  10.1139/cjz-2016-0176.

The aim of this study was to increase our knowledge about the nutritional needs of walleye (Sander vitreus (Mitchill, 1818)) broodstock. Two dietary treatments were tested: the first consisted of frozen mackerel (Scomber scombrus L., 1758) pieces with a supplement of experimental dry pellets and the second consisted of frozen mackerel pieces with a supplement of commercial trout pellets. Hatching success was highest in eggs from the wild broodstock. Eggs and larvae from wild fish were characterized by the highest levels of linoleic (LOA 18:2 n-6) and linolenic (LNA 18:3 n-3) fatty acids in the neutral lipids. They had the lowest level of docosahexaenoic acid (DHA) in both neutral and polar lipids. The results suggest the importance of the amino acids leucine, lysine, methionine, and serine for better egg survival. Vitamin A1 content was similar in eggs from wild fish and the younger broodstock from both treatment groups, but ten times lower in eggs from older broodstock. Vitamin A2 was highest in eggs from wild fish. Our results showed that neither of the two diets really resulted in egg or larval quality that were comparable to that of wild fish.