Data from: Diet-dependent induction of life-history changes in Daphnia: 5α-cyprinol sulfate is not the kairomone

Daphnia responds to chemical cues released by fish with adaptive changes
in behavior (DVM), morphology, and life history traits, e. g. a reduction
in size at first reproduction (SFR). For cyprinid fish, it has been
revealed that DVM and changes in morphology of Daphnia are induced by the
bile salt 5α-cyprinolsulfate (CPS), while the substance that induces
life-history changes is unknown. Here we show that C18-solid phase
extracts from fish incubation water of roach (Rutilus rutilus) that have
fed Daphnia (RfD) induce a reduction of SFR in D. magna while similar
extracts with chironomid larvae as prey do not. Subsequent fractionation
of RfD by HPLC revealed that the major bile salts of cyprinid fish, CPS
and taurochenodeoxycholic acid, eluted outside the active fractions, while
taurocholic acid (TCA) had its peak within the active fractions. A
dose-response experiment revealed that up to 2 µM TCA did not reduce SFR,
which excludes TCA as a potential kairomone. In conclusion, we show that
all major bile salts of cyprinid fish do not cause the observed reduction
in SFR, which points to an unknown kairomone that proves to be negatively
charged.