BRIAN, B.K.*; SCHILL, R.O.; TUNNACLIFFE, A; Univ. of Cambridge, UK; Univ. of T�bingen, Germany ; Univ. of Cambridge, UK: Hydrophilic proteins in invertebrate anhydrobiosis

Over the last 30 years, much attention has been focused on the role of trehalose in anhydrobiosis. However, desiccation tolerant bdelloid rotifers Philodina roseola and Adineta vaga lack trehalose or other disaccharides, suggesting that other biostabilisers are used. Candidates include hydrophilic proteins like the late embryogenesis abundant (LEA) proteins associated with desiccation tolerance in plant seeds. Given the recent discovery of LEA proteins in nematodes, we tested for their presence in other anhydrobiotic and dehydration-tolerant invertebrates, including rotifers. A polyclonal antiserum against the AavLEA1 protein from anhydrobiotic nematode Aphelenchus avenae was used in Western blots of protein extracts from other organisms. Clear signals were observed in P. roseola, tardigrade Macrobiotus hufelandi, stress resistant gemmules of sponge Spongilla lacustris, larvae of the beetle Tenebrio molitar, and in cysts and larvae of brine shrimp Artemia franciscana. The regulation of putative A. franciscana LEA proteins is consistent with a role in desiccation tolerance: they are present at high levels in dry anhydrobiotic cysts, but after rehydration the level declines; no signal is seen in the non-anhydrobiotic adult. Expression of LEA protein in P. roseola is also linked to desiccation tolerance, since it is upregulated by dehydration. Proof of the identity of these proteins will require sequencing, but the data suggest that LEA proteins are widespread in invertebrates and are associated with resistance to water stress.