Biology subjects

Kmita, H.

Publications and source records attributed to Kmita, H..

5 recordsLinked to original sources

bioRxiv2023

Recovery from anhydrobiosis in the tardigrade Paramacrobiotus experimentalis: better to be young than old and in a group than alone

Desiccation-tolerant organisms can survive dehydration in a state of anhydrobiosis. Tardigrades can recover from anhydrobiosis at any life stage and are considered among the toughest animals on Earth. However, the factors that influence recovery from anhydrobiosis are not well understood. The study aimed to evaluate the effect of sex, age, the presence of other individuals and the combination of the number and duration of anhydrobiosis episodes on the recovery of Paramacrobiotus experimentalis. The activity of 1,200 individuals for up to 48 hours after rehydration was evaluated using ANOVA. Age was the main factor influencing return to activity, followed by the combination of number and duration of anhydrobiosis episodes, influence of the presence of other individuals, and sex. More individuals returned to activity after repeated short than repeated long anhydrobiosis episodes and older individuals were less likely to recover than younger individuals. In addition, when compared to single animals, the presence of other individuals resulted in higher number of active animals after dehydration and rehydration. The effect of sex was significant, but there was no general tendency for one sex to recover from anhydrobiosis better than the other one. The results contribute to a better understanding of the anhydrobiosis ability of Pam. experimentalis and provide background for full explanation of molecular, cellular and environmental mechanisms of anhydrobiosis.

physiology↗

bioRxiv2022

How long can tardigrades survive in anhydrobiotic state? Searching on tardigrade anhydrobiosis patterns

Anhydrobiosis is a desiccation tolerance that denotes the ability to survive almost complete dehydration without sustaining damage. However, knowledge on the survival capacity of anhydrobiosis in various species of tardigrades is still very limited. Our research has compared anhydrobiotic capacities of four tardigrade species: Echiniscus testudo, Paramacrobiotus experimentalis, Pseudohexapodibius degenerans and Macrobiotus pseudohufelandi, which differ in feeding behaviour, habitats occupied, and which belong to different genera. Moreover, in the case of Ech. testudo two populations-from urban and natural habitats-were analysed. Clear differences in the anhydrobiotic capacity were observed among different tardigrade species. These differences appear to be determined by the habitat, but not by the nutritional behaviour of the species sharing the habitat type. Moreover, the results indicated that the longer tun state duration, the more time was necessary for the animals to return to activity.

physiology↗

bioRxiv2021

Verification of Hypsibius exemplaris Gasiorek et al., 2018 (Eutardigrada; Hypsibiidae) application in anhydrobiosis research

Anhydrobiosis is considered to be an adaptation of important applicative implications because it enables resistance to the lack of water. The phenomenon is still not well understood at molecular level. Thus, a good model invertebrate species for the research is required. The best known anhydrobiotic invertebrates are tardigrades (Tardigrada), considered to be toughest animals in the world. Hypsibius. exemplaris is one of the best studied tardigrade species, with its name "exemplaris" referring to the widespread use of the species as a laboratory model for various types of research. However, available data suggest that anhydrobiotic capability of the species may be overestimated. Therefore, we determined anhydrobiosis survival by Hys. exemplaris specimens using three different anhydrobiosis protocols. We also checked ultrastructure of storage cells within formed dormant structures (tuns) that has not been studied yet for Hys. exemplaris. These cells are known to support energetic requirements of anhydrobiosis. The obtained results indicate that Hys. exemplaris appears not to be a good model species for anhydrobiosis research.

zoology↗

bioRxiv2020

The tardigrade Hypsibius exemplaris as an emerging model to study the mitochondrial alternative oxidase at animal organismal level

Mitochondrial alternative oxidase (AOX) is present in mitochondria of many invertebrates. Independently of the reason concerning the enzyme occurrence in animal mitochondria, expression of AOX in human mitochondria is regarded as a potential therapeutic strategy. Till now, relevant data were obtained due to heterologous AOX expression in cells and animals without natively expressed AOX. Application of animals natively expressing AOX importantly contribute the research. Thus, we investigated Hypsibius exemplaris as a model for AOX activity analysis. We observed that H. exemplaris tolerance to the blockage of the MRC complexes was diminished in the presence of AOX inhibitor and the inhibitor-sensitive respiration enabled the tardigrade respiration under condition of the blockage. Furthermore, although detection of AOX at protein level and pronounced oxygraphic registration of its activity required the MRC complex blockage, the obtained data indicated that AOX clearly contributed animal functioning. We demonstrated that AOX activity in tardigrades, can be monitored by measurement of intact specimen whole-body respiration. Furthermore, it was also possible to monitor the impact of the MRC complex IV blockage on AOX expression and AOX inhibition in the absence of the blockage on animal functioning. Thus, H. exemplaris is applied as a whole-animal model suitable to study AOX.

molecular biology↗

bioRxiv2020

Mitochondrial alternative oxidase contributes to successful tardigrade anhydrobiosis

Anhydrobiosis can be described as an adaptation to lack of water. This adaptation provides some organisms including tardigrades with a set of capabilities allowing them to survive extreme conditions that even do not exist on Earth. However, the underlying cellular mechanisms are still not explained. Available data assumes important contribution of mitochondrial proteins. Since mitochondrial alternative oxidase (AOX) described as a drought response element has recently been proposed for various invertebrates including tardigrades, we have decided to check if AOX is involved in successful anhydrobiosis of tardigrades. Milnesium inceptum was used as a model for the study. We confirmed functionality of M. inceptum AOX and estimated its activity contribution to anhydrobiosis of different duration. We observed that AOX activity was particularly important for M. inceptum revival after longer-term anhydrobiosis but did not affect rehydration stage. The results may contribute to explanation and then application of anhydrobiosis underlying mechanisms.

cell biology↗