Starvation induced changes in nucleic acids and protein contents of crustacean zooplankton

We compared changes in nucleic acids (DNA and RNA) and protein (PRO) contents of crustacean zooplankton (Calanus sinicus and Artemia sp.) to starving exposure. We measured a reduction in the individual DNA, RNA and PRO of meta-naupliar stage of Artemia sp. following 2-days of starvation, while such response was not clear for starved copepodite stage 5 of C. sinicus. We measured a significantly reduced RNA:DNA ratio for the starved individuals of both species after 2 days, whereas there was no significant difference in the RNA:PRO ratios of fed and starved individuals of both species. Although DNA, RNA and PRO of individuals were slightly reduced for C. sinicu following prolonged starvation (6-days), the declines of RNA:DNA and RNA:PRO ratios were disappeared due to the relative decrease of DNA and PRO to RNA. These results demonstrate significant negative responses of RNA:DNA ratio to starving exposure and highlight these biochemical measurements as useful proxies of physiological responses to food limited conditions for crustacean zooplankton. However, we also note that RNA:DNA ratio is representative of short-term feeding history (i.e., short starvation) for crustacean zooplankton.