Assessing the role of vitamin C and iron in early larvae stages of Solea senegalensis fed enriched Artemia

The effect of dietary iron (Fe) and vitamin C (Ascorbic acid, AA) supplementation on development, gene expression and antioxidant status of Senegalese sole (Solea senegalensis Kaup, 1858) larvae was investigated. Larvae were reared from 7 to 28 days post hatching (dph) in triplicate using a recirculation system. Three experimental groups were established: The control group was fed Artemia enriched with the microalgae Tisochrysis lutea (T. lutea), the F group, T. lutea supplemented with Fe and the FP group, T. lutea supplemented with Fe and ascorbyl palmitate (AP). Enriched Artemia of F and FP groups displayed a significantly higher content of Fe than the control (850 μg Fe g⁻¹ DW and 350 μg Fe g⁻¹ DW, respectively). In addition, enriched Artemia of the FP group also showed a significantly higher content of AA than the control (3.5 μg AA mg⁻¹ DW and 0.8 μg AA mg⁻¹ DW, respectively). At 28 dph, Fe content in larvae from F and FP groups was 1.4- and 1.7-fold higher than the control, respectively. Moreover, larvae from FP group showed the highest AA content throughout the whole experiment (p < 0.05). Larvae from FP group grew faster and completed metamorphosis earlier than the other groups (p < 0.05). Moreover, antioxidant enzymatic activities, lipid peroxidation and total antioxidant content (TAC) at the end of the experiment (p < 0.05) indicated a positive iron-vitamin C interaction with better antioxidant status in FP group. Similar skeletal typology and histological pattern in the development of tissues was observed at 28 dph for larvae under all feeding regimes assayed. Nevertheless, an increasing collagen fibre was evidenced in larvae of FP group The gene expression pattern during the experimental period revealed that different levels of iron and vitamin C modified the expression levels of genes involved in stress (crh, pomca2 and hsc70-4l), glycolytic pathway (pkm), antioxidative defence (slc23a1), osmoregulation (aqp3a, aqp12 and nppc1) and iron homeostasis (hamp1, fpn, tf). The present study is the first report about the potential effect of iron and vitamin C during the first stages of development in S. senegalensis larvae.