The Tardigrade Ramazzottius varieornatus as a Model Animal for Astrobiological Studies

Abstract

Tardigrades are invertebrate animals, some of which can enter into an ametabolic desiccated state called anhydrobiosis. In this state, tardigrades are extremotolerant and able to survive open space environments characterized by severe vacuum and intense radiation. For these reasons, tardigrades are expected to serve as important model organisms for astrobiological studies, particularly those focusing on how multicellular organisms can withstand the extreme environments of space and the possibility of extraterrestrial multicellular life forms. To develop tardigrades as model organisms, we established a culture system for the tardigrade species Ramazzottius varieornatus, a species that is tolerant to several types of extreme physical and chemical environmental conditions while in an anhydrobiotic, or "tun", state. Based on studies using this culture system and the extremotolerance of this tardigrade in connection with its anhydrobiotic capacity, R. varieornatus is a suitable model organism for astrobiological studies and will provide new insight into the mechanisms underlying the ability of multicellular organisms to tolerate extreme environments.

Crystal structure of secretory abundant heat soluble protein 4 from one of the toughest “water bears” micro‐animals Ramazzottius Varieornatus

“…Secretory abundant heat soluble (SAHS) protein is one of them and is constantly expressed at high levels in Ramazzottius varieornatus . This tardigrade can enter an anhydrobiotic state in a shorter time than other species such as Hypsibius dujardini , . Although the expression levels of SAHS proteins are low in active H .…”

Structural insights into a secretory abundant heat‐soluble protein from an anhydrobiotic tardigrade,Ramazzottius varieornatus

“…Moreover, two tardigrades Richtersius coronifer and Milnesium tardigradum in dehydrated states can survive in space (low Earth orbit) for 10 days . Anhydrobiotic tardigrades therefore have a potential as model animals for studies on long‐term preservation of organs and astrobiology .…”

“… and Tanaka et al . took molecular biological approaches using a tardigrade Ramazzottius varieornatus , which can enter anhydrobiosis in a shorter time than other tardigrades such as Hypsibius dujardini . Consequently, four new heat‐soluble protein families named secretory abundant heat‐soluble (SAHS) proteins, cytoplasmic abundant heat‐soluble (CAHS) proteins, mitochondrial abundant heat‐soluble (MAHS) proteins, and Rv LEAM were discovered.…”

The wealth of shared resources: Improving molecular taxonomy using eDNA and public databases

“…These sequences were recovered in a single clade, sister to a calibration Ramazzottius varieornatus. Ramazzottius is one of the more widely studied genera of Tardigrada (Horikawa, 2008, Tanaka et al, 2015, Yoshida et al, 2017; Fukuda & Inoue, 2018; Neves et al, 2020,) and whilst these sequences likely represent further sampling of R. varieornatus , they may additionally belong to a new sister species within the genus. Here, this methodology reveals its potential application to direct future work, suggesting that further sampling and collection of voucher specimens in Edinburgh (from which all these sequences originate) may reveal a new species of Ramazzottius .…”