Summary: | In an attempt to better understand the problems in weaning larval fish to artificial diets, our lab has begun toinvestigate the role of the digestive hormone cholecystokinin (CCK). While there are a number of other labs alsoinvestigating CCK and other digestive hormones such as bombesin, PPY, and gastrin; research into the roles of thesehormones in fish is still in its infancy. Previous research with red drum larvae suggests that some component ofrotifers and algae enable red drum larvae to more efficiently utilize microparticulate diets than when these are notincluded in the culture system. The current study investigated the impact of soluble components of rotifers and algaeon the CCK and trypsin responses of larval red drum at 6 and 10 days post hatch (DPH). Introduction ofhomogenized rotifers was shown to significantly increase whole body CCK levels, CCK mRNA, and trypsin activityin 6 DPH red drum larvae, but not in 10 DPH larvae. Homogenates of Isochrysis galbana did not significantly affectCCK or trypsin at either age. This research suggests that there is a soluble component of rotifers that can upregulatedigestive function in larval red drum, at least in 6 DPH larvae.
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