Abstract Reactive oxygen species (ROS) are crucial signalling molecules, but their excessive accumulation under stress can lead to oxidative damage. In this study, we investigated the influence of age, sex, and duration of anhydrobiosis on the ROS levels in intact tardigrades (Paramacrobiotus experimentalis) and their released coelomocytes (storage cells). The determination of ROS levels, based on confocal microscopy and the quantification of 2,7-dichlorodihydrofluorescein diacetate (DCFH2-DA) fluorescence, was performed 48 h after rehydration following short or long anhydrobiosis (tun duration of 3 or 30 days, respectively), for females and males assigned to three distinct age classes of adult animals (young, mature, and old). ROS levels were influenced differently by the age and sex of animals, in addition to tun duration, and differed distinctly between intact animals and released storage cells, suggesting an important effect of the extracellular environment. Furthermore, although the ROS level could serve as a survival indicator, its predictive power is dependent on age. Thus, the ROS-mediated response to anhydrobiosis is shaped by its duration, in addition to the age and sex of the animal. Moreover, the response differs between cellular and whole-organism levels.
Nagwani et al. (Thu,) studied this question.