Ultraviolet radiation tolerance in hydrated and desiccated eutardigrades; Tolleranza alle radiazioni ultraviolette in eutardigradi essiccati e idratati

Abstract So far, most studies on tardigrade resistance to extreme stresses have focused on their responses to several chemical and physical extremes, but there is still a paucity of data regarding the tardigrade responses to ultraviolet radiation. Considering also the future perspectives offered by...

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Published in:Journal of zoological systematics and evolutionary research 2011-05, Vol.49, p.104
Main Authors: Altiero, Tiziana, Guidetti, Roberto, Caselli, Valentina, Cesari, Michele, Rebecchi, Lorena
Format: Article
Language:English
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Summary:Abstract So far, most studies on tardigrade resistance to extreme stresses have focused on their responses to several chemical and physical extremes, but there is still a paucity of data regarding the tardigrade responses to ultraviolet radiation. Considering also the future perspectives offered by space flights, we compared the biological responses of two eutardigrade species (Paramacrobiotus richtersi and Ramazzottius oberhaeuseri) to UV irradiation, alone or in combination with multiple stressors (temperature and air relative humidity) in two different physiological conditions (desiccated and hydrated states). Tardigrades were exposed to seven different UV doses (from 10.32 up to 87.72kJm-2) in a controlled climatic chamber. The results showed that active and anhydrobiotic tardigrades were able to withstand high doses of ultraviolet radiations. The survival rate of hydrated or desiccated specimens of both species was inversely related to the UV doses, with P. richtersi that better tolerated the increase of UV dose than R. oberhaeuseri. Surprisingly, the tolerance to physical and chemical extreme stresses is not an exclusive property of desiccated tardigrades; in certain environmental conditions (high air humidity level or low temperature), desiccated tardigrades have a lower or similar ability to withstand UV irradiation than hydrated ones. This represents a further demonstration of the uniqueness of this animal group in tolerating extreme stresses. In addition, we demonstrated that high temperatures have a strong impact on tardigrade survival during UV exposition both in hydrated and desiccated animals. Riassunto La maggior parte degli studi sulla resistenza dei tardigradi agli stress estremi hanno portato ad analizzare la loro tolleranza a diversi stress chimici e fisici, ma molto poco è stato fatto sulla tolleranza dei tardigradi alle radiazioni ultraviolette. Considerando anche le future prospettive offerte dai voli spaziali, in questo lavoro abbiamo confrontato le risposte di esemplari essiccati (in anidrobiosi) o idratati (attivi) di due specie di eutardigradi (Paramacrobiotus richtersi e Ramazzottius oberhaeuseri) alle sole radiazioni ultraviolette (UV), o alla combinazione delle radiazioni UV con altri fattori di stress (temperatura e umidità relativa dell'aria, RH). I tardigradi sono stati esposti a sette diverse dosi di radiazioni UV (da 10.32 a 87.72kJm-2) in una camera climatica controllata. I risultati evidenziano che sia itardigradi idrata
ISSN:0947-5745
1439-0469
DOI:10.1111/j.1439-0469.2010.00607.x