The proteomics of dormancy: lessons from encysted hydrated embryos of an aquatic invertebrate

Dormancy is displayed by several organisms when environmental conditions cannot support their regular life activities. Numerous aquatic invertebrates survive for decades in a hydrated state as encysted embryos. In search for functional pathways that are associated with this form of dormancy, we used label-free quantitative proteome profiling and compared the proteomes of encysted dormant embryos (“resting eggs”; RE) with non-dormant embryos (amictic eggs; AM) of the rotifer Brachionus plicatilis. We also compared resting eggs (RE) before and after an obligatory dormant period (E0). A total of 2,631 proteins were identified in AM, RE and E0 eggs. Significantly lower numbers of proteins were determined for RE and E0, compared with AM. About 80% of the proteins were upregulated in AM, in the comparisons of AM vs. RE and AM vs. E0. The differentially expressed proteins were assigned to a large number of putative functional pathways, demonstrating the dramatic changes occurring during dormancy.