Light‐induced release of Artemia dried embryos from diapause: Analysis of metabolic status

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Abstract
Commercially obtained Artemia cysts were hydrated and incubated for prolonged periods in aerobic conditions, but deprived from light. A part of these cysts refused to hatch and remained in diapause until they were activated by illumination. During a dark incubation period of 20 days, the light‐induced hatchability remained constant, while the respiration rate and the ATP concentrations slowly decreased to the very low values of 0.01 μl O2/hour mg WW and 0.3 nmol ATP/mg protein, respectively. The endogenous trehalose reserves did not measurably decrease and glycerol was not synthesized during this treatment.Furthermore, we have demonstrated that light, acting as a diapause breaker, induced, in an irreversible manner, an enhancement of respiration and a concomitant breakdown of trehalose. The fact that a very short period of illumination was sufficient to induce hatching and that the induction was irreversible demonstrated that we were definitely not dealing with an exogeneous dormancy, whereby the environment causes the arrest of development. Light acted as a transient signal suspending diapause and triggering development.
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