Changes in tissue concentrations of the vitamins B1 and B2 during reproductive cycle of bivalves Part 1: The scallop Pecten maximus

Vitamins Bl(thiamin) and B2. (riboflavin) in eggs of the scallop Pecten max imus are highly utilized during larval development. Possible storage of the se vitamins, for later transfer to gonads and eggs, was studied over the na tural reproductive cycle of the scallop. Vitamin concentrations were measur ed during hatchery conditioning at three periods of the year. Vitamin B1 wa s found mainly in muscle, gonad and eggs, while B2 was detected in the dige stive gland, gonad and eggs. They varied simultaneously in the three organs during the annual cycle. Two main peaks were observed for digestive,oland and gonads in spring and summer. The first peak corresponded to vitellogene sis and decreased in gonads in June as the scallops spawned and the vitamin s were lost with the eggs, The second peak was interpreted as vitamin stora ge in gonad tissue in fall. The large vitamin decrease occurring from Novem ber to February coincided with genial mitoses observed by histology. Possib le high utilisation of thiamin and riboflavin during winter was supported b y hatchery conditioning at three periods during the year: during the same w inter period, when broodstock were fed a high-vitamin diet, vitamin levels stayed low in all organs, as vitellogenesis was in progress. However, in sp ring and summer vitamin incorporation increased. We concluded that attentio n should be paid to winter-conditioning diets, as riboflavin and thiamin, e ven when provided at high levels in the food, did not accumulate in organs, suggesting intense utilisation when mitoses in the gonads take place. (C) 2001 Elsevier Science B.V. All rights reserved.