Looking to the past to predict the future : Tardigrades - a model example

Abstract

It is well known that Tardigrades are extremotolerant, earning them the title of one of the toughest animals on Earth. Such tolerance means that they are able to survive in space and are capable of withstanding lunar and Martian conditions. Their resistance to extreme high and low temperatures and pressures, absence of food, water and oxygen, exposure to radiation, and survival in the vacuum of space itself allows them to withstand such inhospitable environments. In the absence of water, which is essential for life, they undergo anhydrobiosis and reduce their metabolic rate to negligible levels, allowing them to go into a dormant tun state. Once exposed to water again however, they are reactivated. While most studies on Tardigrades are mainly focused on quantifying and determining the extent of their resistance, little knowledge is present on which genes confer such resistance to each stressor, and why such resistance arose or is even required. Our current research aims to investigate whether the presumed ancestors of Tardigrades were equally resistant to extreme conditions, or whether the current resistance of the Tardigrada was the result of a particular genetic event. We also hope to determine which gene/s confer resistance to different environmental extremes by exposing Tardigrades to various types and levels of extreme conditions and identifying their responses. If this is achieved, the various genes for different types of resistance may in future be used as a knock-in gene using CRISPR. This also begs the question...WHY these organisms require genes for such extreme environmental resistance on a planet in which such conditions are not present.