title: Tolerance of anhydrobiotic eggs of the Tardigrade Ramazzottius varieornatus to extreme environments.
abstract: Tardigrades are tiny (less than 1 mm in length) invertebrate animals that have the potential to survive travel to other planets because of their tolerance to extreme environmental conditions by means of a dry ametabolic state called anhydrobiosis. While the tolerance of adult tardigrades to extreme environments has been reported, there are few reports on the tolerance of their eggs. We examined the ability of hydrated and anhydrobiotic eggs of the tardigrade Ramazzottius varieornatus to hatch after exposure to ionizing irradiation (helium ions), extremely low and high temperatures, and high vacuum. We previously reported that there was a similar pattern of tolerance against ionizing radiation between hydrated and anhydrobiotic adults. In contrast, anhydrobiotic eggs (50% lethal dose; 1690 Gy) were substantially more radioresistant than hydrated ones (50% lethal dose; 509 Gy). Anhydrobiotic eggs also have a broader temperature resistance compared with hydrated ones. Over 70% of the anhydrobiotic eggs treated at either -196°C or +50°C hatched successfully, but all the hydrated eggs failed to hatch. After exposure to high-vacuum conditions (5.3×10(-4) Pa to 6.2×10(-5) Pa), the hatchability of the anhydrobiotic eggs was comparable to that of untreated control eggs.
authors.affiliation: NASA Ames Research Center, Moffett Field, California, USA. horikawadd@gmail.com
authors.forename: Daiki D
authors.initials: DD
authors.lastname: Horikawa
authors.forename: Ayami
authors.initials: A
authors.lastname: Yamaguchi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Sakashita
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tanaka
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Hamada
authors.forename: Fumiko
authors.initials: F
authors.lastname: Yukuhiro
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Kuwahara
authors.forename: Takekazu
authors.initials: T
authors.lastname: Kunieda
authors.forename: Masahiko
authors.initials: M
authors.lastname: Watanabe
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Nakahara
authors.forename: Seiichi
authors.initials: S
authors.lastname: Wada
authors.forename: Tomoo
authors.initials: T
authors.lastname: Funayama
authors.forename: Chihiro
authors.initials: C
authors.lastname: Katagiri
authors.forename: Seigo
authors.initials: S
authors.lastname: Higashi
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Yokobori
authors.forename: Mikinori
authors.initials: M
authors.lastname: Kuwabara
authors.forename: Lynn J
authors.initials: LJ
authors.lastname: Rothschild
authors.forename: Takashi
authors.initials: T
authors.lastname: Okuda
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Hashimoto
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kobayashi
mesh_terms: D000818:Animals; D004307:Dose-Response Relationship, Radiation; D008855:Microscopy, Electron, Scanning; D011829:Radiation Dosage; D011836:Radiation Tolerance; D058467:Tardigrada / Q000378:metabolism* / Q000528:radiation effects; D013696:Temperature