No abstract

No abstract

The Tardigrade Resistance to Space Effects (TARSE) project, part of the mission LIFE on FOTON-M3, analyzed the effects of the space environment on desiccated and active tardigrades. Four experiments were conducted in which the eutardigrade Macrobiotus richtersi was used as a model species. Desiccated (in leaf litter or on paper) and hydrated tardigrades (fed or starved) were flown on FOTON-M3 for 12 days in September 2007, which, for the first time, allowed for a comparison of the effects of the space environment on desiccated and on active animals. In this paper, we report the experimental design of the TARSE project and data on tardigrade survival. In addition, data on survival, genomic DNA integrity, Hsp70 and Hsp90 expressions, antioxidant enzyme contents and activities, and life history traits were compared between hydrated starved tardigrades flown in space and those maintained on Earth as a control. Microgravity and radiation had no effect on survival or DNA integrity of active tardigrades. Hsp expressions between the animals in space and the control animals on Earth were similar. Spaceflight induced an increase of glutathione content and its related enzymatic activities. Catalase and superoxide dismutase decreased with spaceflight, and thiobarbituric acid reactive substances did not change. During the flight mission, tardigrades molted, and females laid eggs. Several eggs hatched, and the newborns exhibited normal morphology and behavior.

For many years, Paramacrobiotus richtersi was reported to consist of populations with different chromosome numbers and reproductive modes. To clarify the relationships among different populations, the type locality of the species (Clare Island, Ireland) and several Italian localities were sampled. Populations were investigated with an integrated approach, using morphological (LM, CLSM, SEM), morphometric, karyological, and molecular (18S rRNA, cox1 genes) data. Paramacrobiotus richtersi was redescribed and a neotype designed from the Irish bisexual population. Animals of all populations had very similar qualitative and quantitative characters, apart from the absence of males and the presence of triploidy in some of them, whereas some differences were recorded in the egg shell. All populations examined had the same 18S haplotype, while 21 haplotypes were found in the cox1 gene. In four cases, those qualitative characters were correlated with clear molecular (cox1) differences (genetic distance 14.6–21.8%). The integrative approach, which considered the morphological differences in the eggs, the reproductive biology and the wide genetic distances among putative species, led to the description of four new species (Paramacrobiotus arduus sp. n., Paramacrobiotus celsus sp. n., Paramacrobiotus depressus sp. n., Paramacrobiotus spatialis sp. n.) and two Unconfirmed Candidate Species (UCS) within the P. richtersi complex. Paramacrobiotus fairbanksi, the only ascertained parthenogenetic, triploid species, was redescribed and showed a wide distribution (Italy, Spain, Poland, Alaska), while the amphimictic species showed limited distributions. The difference in distribution between apomictic and amphimictic populations can be explained by the difference in the dispersal potentials associated with these two types of reproduction.Electronic supplementary materialThe online version of this article (10.1186/s40851-018-0113-z) contains supplementary material, which is available to authorized users.

Tardigrades often colonise extreme habitats, in which they survive using both types of dormancy: quiescence and diapause.

No abstract

SUMMARYAnhydrobiosis is a highly stable state of suspended animation in an organism due to its desiccation, which is followed by recovery after rehydration. Changes occurring during drying could damage molecules, including DNA. Using the anhydrobiotic tardigrade Paramacrobiotus richtersi as a model organism, we have evaluated the effects of environmental factors, such as temperature and air humidity level (RH), on the survival of desiccated animals and on the degradation of their DNA. Tardigrades naturally desiccated in leaf litter and tardigrades experimentally desiccated on blotting paper were considered. Replicates were kept at 37°C and at different levels of RH for 21 days. RH values and temperature, as well as time of exposure to these environmental factors, have a negative effect on tardigrade survival and on the time required by animals to recover active life after desiccation. DNA damages (revealed as single strand breaks) occurred only in desiccated tardigrades kept for a long time at high RH values. These results indicate that during the anhydrobiotic state, damages take place and accumulate with time. Two hypotheses can be formulated to explain the results: (i) oxidative damages occur in desiccated specimens of P. richtersi, and (ii) high temperatures and high RH values change the state of the disaccharide trehalose, reducing its protective role. Supplementary material available online at

A complete understanding of the feeding structures is fundamental in order to study how animals survive. Some birds use long and protrusible tongues as the main tool to collect their central caloric source (e.g. woodpeckers and nectarivores). Hummingbirds are the oldest and most diverse clade of nectarivorous vertebrates, being a perfect subject to study tongue specializations. Their tongue functions to intraorally transport arthropods through their long bills and enables them to exploit the nectarivorous niche by collecting small amounts of liquid, therefore it is of vital importance to study its anatomy and structure at various scales. I focused on the portions of the hummingbird tongue that have been shown to be key for understanding their feeding mechanisms. I used histology, transmission and scanning electron microscopy, microCT, and ex-vivo experiments in order to advance the comprehension of the morphology and functioning of the hummingbird feeding apparatus. I found that hummingbird tongues are composed mainly of thin cornified epithelium, lack papillae, and completely fill the internal cast of the rostral oropharyngeal cavity. Understanding this puzzle-piece match between bill and tongue will be essential for the study of intraoral transport of nectar. Likewise, I found that the structural composition and tissue architecture of the tongue groove walls provide the rostral portion of the tongue with elastic properties that are central to the study of tongue-nectar interactions during the feeding process. Detailed studies on hummingbirds set the basis for comparisons with other nectar-feeding birds and contribute to comprehend the natural solutions to collecting liquids in the most efficient way possible. PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.2986v1 | CC BY 4.0 Open Access | rec Abstract 12 A complete understanding of the feeding structures is fundamental in order to study how 13 animals survive. Some birds use long and protrusible tongues as the main tool to collect their 14 central caloric source (e.g. woodpeckers and nectarivores). Hummingbirds are the oldest and 15 most diverse clade of nectarivorous vertebrates, being a perfect subject to study tongue 16 specializations. Their tongue functions to intraorally transport arthropods through their long bills 17 and enables them to exploit the nectarivorous niche by collecting small amounts of liquid, 18 therefore it is of vital importance to study its anatomy and structure at various scales. I focused 19 on the portions of the hummingbird tongue that have been shown to be key for understanding 20 their feeding mechanisms. I used histology, transmission and scanning electron microscopy, 21 microCT, and ex-vivo experiments in order to advance the comprehension of the morphology and 22 functioning of the hummingbird feeding apparatus. I found that hummingbird tongues are 23 composed mainly of thin cornified epithelium, lack papillae, and completely fill the internal cast 24 of the rostral oropharyngeal cavity. Understanding this puzzle-pie...