Dehydrating cells can lead to massive damage in molecular organization, often resulting in cell death and, consequently, death of the organism. In anhydrobionts, several bioprotectants, e.g. sugars and stress proteins, play a role in avoiding these damages. In tardigrades (micrometazoans able to perform anhydrobiosis in any stage of their life cycle), bioprotectants are certainly involved, but their nature and role is only understood in part. We evaluated the Hsp70 and Hsp90 levels in hydrated and desiccated animals of two eutardigrade species: Macrobiotus richtersi and Amphibolus volubilis. For both species, we found no significant differences in the level of both Hsps between hydrated and anhydrobiotic specimens.Also, DNA can be damaged by dehydration. In several unicellular organisms, even though characterized by desiccation tolerance, dramatic DNA damages can occur during desiccation or in the dry state that follows. It has been hypothesized that DNA damages could also occur in anhydrobiotic tardigrades. To verify this hypothesis, we evaluated tardigrade survival and DNA desiccation-induced double (DSBs) and single (SSBs) strand breaks in specimens of M. richtersi naturally dried within leaf litter as well as experimentally desiccated in our lab under controlled conditions. Dry specimens were also exposed to thermal stress (37°C) at different values of air humidity (RH). An inverse relationship between M. richtersi survival and RH levels was found. Moreover, tardigrades dried within leaf litter, when re-hydrated had a faster recovery of active movement than those dehydrated on paper. No visible DNA DSBs were observed, but preliminary data on SSBs seems to bring different results, which need to be confirmed.
|Data di pubblicazione:||2008|
|Autori:||R. Guidetti; T. Altiero; R. Bertolani; L. Rebecchi|
|Titolo:||Hsp levels and DNA integrity in anhydrobiotic tardigrades|
|Appare nelle tipologie:||Abstract in Atti di Convegno|
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