Sea cucumbers have adopted strategies that lead to the development of hypometabolism and involuntary non-pathological response. The first occurs by reduction of aerobic scope, which in turn determines physiological responses that generate dormancy and aestivation. Involuntary non-pathological responses, such as skin ulceration and evisceration, occurs as extreme control mechanisms to seek to reset organismal physiological condition at the expense of anatomical modification. In these organisms,
pH and temperature represent two of the most important key factors that produces these responses . Evisceration and autotomy, reinforces the hypothesis that the mechanism involved in temperature perception remains similar throughout the life cycle.
T he detachment of the sensory fibres of collagen from the body walls suggest that coelomocytes play a greater role in perception. A plausible mechanism that explains how coelomocytes might respond to temperature could involve the adjustment of their affinity to Ca+2 , which activates transient receptor proteins, an important kind of membrane protein that constitutes a primary mechanism for detecting heat. With regard to pH, this affect antioxidant activity , especially when it is
accompanied
by changes in temperature. Temperature and pH produce molecular and physiological response that generate stress and might influence survival. As seen during aestivation, these parameters increased the presence of reactive oxygen species (ROS) and produce and imbalance in the proportion of antioxidants, which causes oxidative stress. The response might be
regulated through adjustment of electron transport in mitochondria, with production of superoxide anions (O2-· ) as minor by-products. As high concentration of ROS modifies protein structure, antioxidant enzyme activity regulates their concentration in mitochondria and cytosol. Enzymes such as superoxide (SOD), glutathione peroxidase (GPx), catalases (CAT), and thioredoxins-peroxiredoxin (Trx-Prx ) participate in the elimination of O2-· by converting it into hydrogen peroxide and water. Some experiment performed with sea cucumbers showed that constant increase of temperature increased the initial SOD activity of the body wall tissues from 45.2 to 128.2 U mg-1 of protein, while the increase of the exposure time to 25°C for 72h and 168h did not produce significant c hanges in antioxidant activity. Furthermore, in these organisms, the
reduction of pH from 8.1 to 7.7 increase
GPx activity of the coelomic fluid. Although the effect of temperature and pH are important in oxidative stress, few studies have addressed their interaction. From the publications, the evidence shows that at least in the short term, pH rather than temperature appears to be more important when antioxidant activity is considered. Here we present a hypothesis that explained the interaction of these factors
and resume the main results of the articles that have been addressed for the topic.