Mechanisms and evolution of resistance to environmental extremes in animals

Abstract

When animals are exposed to an extreme environmental stress, one of three possible outcomes takes place: the animal dies, the animal avoids the environmental stress and survives, or the animal tolerates the environmental stress and survives. This review is concerned with the third possibility, and will look at mechanisms that rare animals use to survive extreme environmental stresses including freezing, desiccation, intense heat, irradiation, and low-oxygen conditions (hypoxia). In addition, an increasing understanding of the molecular mechanisms involved in environmental stress tolerance allows us to speculate on how these tolerances arose. Uncovering the mechanisms of extreme environmental stress tolerance and how they evolve has broad implications for our understanding of the evolution of early life on this planet, colonization of new environments, and the search for novel forms of life both on Earth and elsewhere, as well as a number of agricultural and health-related applications.

Tardigrade CAHS Proteins Act as Molecular Swiss Army Knives to Mediate Desiccation Tolerance Through Multiple Mechanisms

“…With a molecular understanding of how to induce or prevent gelation of CAHS D, we set out to determine how CAHS D gelation influences robust protection of biological material during desiccation. Extreme drying can impart a number of stresses on biological systems, 19,21,43 with protein dysfunctions being a major set of common perturbations. 19,21,43 The two prevalent, and non-mutually exclusive, forms of protein dysfunction during desiccation are protein unfolding and protein aggregation.…”

Low-dose ionizing radiation as a hormetin: experimental observations and therapeutic perspective for age-related disorders

“…Extrapolation of effects from the high to low exposure doses is not founded as any other extrapolation. Moreover, such extrapolation neglects the fact that all organisms were always exposed to ionizing radiation and that multiple mechanisms to repair radiation damage evolved during the evolution (Boothby et al 2019 ). The model of radiation hormesis is based on the assumption that repair mechanisms, triggered by the LDIR, might be efficacious not only against the radiation-induced damage, but also against damage from other stressors.…”

Comparative Oncology: New Insights into an Ancient Disease

“…In addition to the mammals highlighted above, another extraordinary animal with incredible resistance to DNA damage is the nearly indestructible, microscopic tardigrade. Tardigrades have multiple protective mechanisms, such as desiccation and temperature tolerance ( Boothby, 2019 ), that allow them to survive in extreme, radioactive environments ( Jönsson, 2019 ). Interestingly, one particular mechanism tardigrades use to protect their DNA from environmental damage is absent in humans.…”