For an analysis of growth, the standard length (SL) and width of
5 thawed larvae per tank and time point was noted, followed by
analyses of RNA:DNA ratio, tryptic activity and gene expression.
Assessing the ratio of RNA to DNA is a well-accepted index in larval
research for nutritional condition [36]. To do so, five 11 dph turbot
larvae were freeze dried for 24 h to a constant weight (Alpha1-4
freeze dryer, Christ GmbH, Germany) and subsequently weighed
with a microbalance (SC2, Sartorius AG, Germany). Quantification
of RNA and DNA was performed according to Malzahn et al. [37]
with modifications, where whole individual larva were analysed
instead of only muscle tissue. RNA:DNA-ratio was subsequently
calculated of individual larvae.