Cryptobiosis Research Articles

Inducing the Entry of Third Stage Dispersal Juveniles of Bursaphelenchus xylophilus into Cryptobiosis Through Osmotic Regulation.

Cryptobiosis is a state where organisms lose nearly all their internal water and enter anhydrobiosis under extreme environmental stress. The dispersal third-stage juveniles (pre-dauer juveniles, ) of Bursaphelenchus xylophilus can enter cryptobiosis through dehydration and revive upon rehydration when environmental conditions improve. Osmotic regulation is crucial for their survival in this process. In this study, specimens of B. xylophilus were collected from dead Pinus massoniana due to pine wilt disease in Ningbo, Zhejiang Province, China. Following immersion in 8% potassium chloride (KCl) solution, B. xylophilus entered a cryptobiotic state after gradual dehydration due to increased external osmotic pressure by natural water evaporation. B. xylophilus could resist low-temperature stress at -20 °C. B. xylophilus could revive upon rehydration, with a survival rate of 92.1%. This process can regulate the entry of B. xylophilus into cryptobiosis, enabling them to resist extreme environments. This method described in our study is simple and reliable, providing technical support for studying the stress resistance mechanisms of B. xylophilus.

An experimental study on tolerance to hypoxia in tardigrades.

Introduction: Tardigrades are small aquatic invertebrates with well documented tolerance to several environmental stresses, including desiccation, low temperature, and radiation, and an ability to survive long periods in a cryptobiotic state under arrested metabolism. Many tardigrade populations live in habitats where temporary exposure to hypoxia is expected, e.g., benthic layers or substrates that regularly undergo desiccation, but tolerance to hypoxia has so far not been thoroughly investigated in tardigrades. Method: We studied the response to exposure for hypoxia (<1ppm) during 1-24h in two tardigrade species, Richtersius cf. coronifer and Hypsibius exemplaris. The animals were exposed to hypoxia in their hydrated active state. Results: Survival was high in both species after the shortest exposures to hypoxia but tended to decline with longer exposures, with almost complete failure to recover after 24h in hypoxia. R. cf. coronifer tended to be more tolerant than H. exemplaris. When oxygen level was gradually reduced from 8 to 1ppm, behavioral responses in terms of irregular body movements were first observed at 3-4ppm. Discussion: The study shows that both limno-terrestrial and freshwater tardigrades are able to recover after exposure to severe hypoxia, but only exposure for relatively short periods of time. It also indicates that tardigrade species have different sensitivity and response patterns to exposure to hypoxia. These results will hopefully encourage more studies on how tardigrades are affected by and respond to hypoxic conditions.

Rehydration of the sleeping chironomid, Polypedilum vanderplanki Hinton, 1951 larvae from cryptobiotic state up to full physiological hydration (Diptera: Chironomidae)

During desiccation the Polypedilum vanderplanki larva loses 97% of its body water, resulting in the shutdown of all metabolic and physiological processes. The larvae are able to resume active life when rehydrated. As dehydration process has already been largely understood, rehydration mechanisms are still poorly recognized. X-ray microtomograms and electron scanning microscopy images recorded during the hydration showed that the volume of the larva's head hardly changes, while the remaining parts of the body increase in volume. In the 1H-NMR spectrum, as recorded for active larvae, component characteristic of solid state matter is absent. The spectrum is superposition of components coming from tightly and loosely bound water fraction, as well as from lipids. The value of the c coefficient (0.66 ± 0.02) of the allometric function describing the hydration models means that the increase in the volume of rehydrated larvae over time is linear. The initial phase of hydration does not depend on the chemical composition of water, but the amount of ions affects the further process and the rate of return of larva’s to active life. Diffusion and ion channels play a major role in the permeability of water through the larva's body integument.

Single-Cell Nanoencapsulation: From Passive to Active Shells.

Single-cell nanoencapsulation is an emerging field in cell-surface engineering, emphasizing the protection of living cells against external harmful stresses in vitro and in vivo. Inspired by the cryptobiotic state found in nature, cell-in-shell structures are formed, which are called artificial spores and which show suppression or retardation in cell growth and division and enhanced cell survival under harsh conditions. The property requirements of the shells suggested for realization of artificial spores, such as durability, permselectivity, degradability, and functionalizability, are demonstrated with various cytocompatible materials and processes. The first-generation shells in single-cell nanoencapsulation are passive in the operation mode, and do not biochemically regulate the cellular metabolism or activities. Recent advances indicate that the field has shifted further toward the formation of active shells. Such shells are intimately involved in the regulation and manipulation of biological processes. Not only endowing the cells with new properties that they do not possess in their native forms, active shells also regulate cellular metabolism and/or rewire biological pathways. Recent developments in shell formation for microbial and mammalian cells are discussed and an outlook on the field is given.

Cell Biology of the Tardigrades: Current Knowledge and Perspectives.

The invertebrate phylum Tardigrada has received much attention for containing species adapted to the most challenging environmental conditions where an ability to survive complete desiccation or freezing in a cryptobiotic state is necessary for persistence. Although research on tardigrades has a long history, the last decade has seen a dramatic increase in molecular biological ("omics") studies, most of them with the aim to reveal the biochemical mechanisms behind desiccation tolerance of tardigrades. Several other aspects of tardigrade cell biology have been studied, and we review some of them, including karyology, embryology, the role of storage cells, and the question of whether tardigrades are eutelic animals. We also review some of the theories about how anhydrobiotic organisms are able to maintain cell integrity under dry conditions, and our current knowledge on the role of vitrification and DNA protection and repair. Many aspects of tardigrade stress tolerance have relevance for human medicine, and the first transfers of tardigrade stress genes to human cells have now appeared. We expect this field to develop rapidly in the coming years, as more genomic information becomes available. However, many basic cell biological aspects remain to be investigated, such as immunology, cell cycle kinetics, cell metabolism, and culturing of tardigrade cells. Such development will be necessary to allow tardigrades to move from a nonmodel organism position to a true model organism with interesting associations with the current models C. elegans and D. melanogaster.

A sustainable culture of tardigrades (Hypsibius dujardini) for astrobiological laboratory activities

Tardigrades are microscopic organisms that have gained importance in astrobiology in recent years. They have extreme survival ability and can enter into a state of latency for several years called cryptobiosis. Due to our interest in conducting experiments with tardigrades to complement the laboratory exercises with students in the course of astrobiology, we bought samples of tardigrades in the cryptobiotic state. A sample of these were cultured at room temperature (18oC) with an oxygenation system, and fed with Spirulina algae every week. We found that in a few weeks tardigrades were producing eggs normally. This species, H. dujardini, has been cultured before and it is a good sample for culture as we saw. This species provides a good sustainable culture and is inexpensive and easy to produce tardigrades for didactic purposes.

A molecular study of the tardigrade Echiniscus testudo (Echiniscidae) reveals low DNA sequence diversity over a large geographical area

In the present study we investigate the genetic diversity within the asexually reproducing tardigrade Echiniscus testudo. The present study is the first to sample a tardigrade species for comparison of DNA sequence diversity between widely separated samples. Echiniscus testudo was sampled at 13 localities spanning three continents. DNA sequences of the mitochondrial COI gene and the nuclear ITS2 sequence were used to investigate the genetic diversity and phylogeographic structure of the various asexual lineages. Terrestrial tardigrades with the capability of entering a cryptobiotic state are assumed to have a high passive dispersal potential through airborne transport. Our results show moderate (ITS2) to high (COI) haplotype diversity and low sequence diversity that indicate evolution of haplotypes within distinct asexual lineages and a high dispersal potential. No isolation by distance was detected by Mantel tests. Different phylogeny inference methods (neighbor-joining, maximum parsimony, maximum likelihood and Bayesian inference) revealed little topological resolution, but minimum spanning networks showed some phylogeographic patterns. The COI and ITS2 minimum spanning networks show patterns that indicate dispersal of several haplotypes from founding populations. In conclusion our data show a low genetic diversity and a relatively high haplotype diversity indicating that E. testudo is a young species with a high dispersal potential.

Reactivation of a cryptobiotic stream ecosystem in the McMurdo Dry Valleys, Antarctica: A long-term geomorphological experiment

The McMurdo Dry Valleys of Antarctica contain many glacial meltwater streams that flow for 6 to 12 weeks during the austral summer and link the glaciers to the lakes on the valley floors. Dry valley streams gain solutes longitudinally through weathering reactions and microbial processes occurring in the hyporheic zone. Some streams have thriving cyanobacterial mats. In streams with regular summer flow, the mats are freeze-dried through the winter and begin photosynthesizing with the onset of flow. To evaluate the longer term persistence of cyanobacterial mats, we diverted flow to an abandoned channel, which had not received substantial flow for approximately two decades. Monitoring of specific conductance showed that for the first 3 years after the diversion, the solute concentrations were greater in the reactivated channel than in most other dry valley streams. We observed that cyanobacterial mats became abundant in the reactivated channel within a week, indicating that the mats had been preserved in a cryptobiotic state in the channel. Over the next several years, these mats had high rates of productivity and nitrogen fixation compared to mats from other streams. Experiments in which mats from the reactivated channel and another stream were incubated in water from both of the streams indicated that the greater solute concentrations in the reactivated channel stimulated net primary productivity of mats from both streams. These stream-scale experimental results indicate that the cryptobiotic preservation of cyanobacterial mats in abandoned channels in the dry valleys allows for rapid response of these stream ecosystems to climatic and geomorphological change, similar to other arid zone stream ecosystems.

On the disparate terminological use of the concept cryptobiosis.

Journal of Fish DiseasesVolume 27, Issue 3 p. 175-176 On the disparate terminological use of the concept cryptobiosis K I Jönsson, K I Jönsson Department of Theoretical Ecology, Lund University, Lund, SwedenSearch for more papers by this author K I Jönsson, K I Jönsson Department of Theoretical Ecology, Lund University, Lund, SwedenSearch for more papers by this author First published: 08 March 2004 https://doi.org/10.1111/j.1365-2761.2004.00534.xCitations: 1 K I Jönsson, Department of Theoretical Ecology, Lund University, Ecology Building, S-223 62 Lund, Sweden (e-mail: ingemar.jonsson@teorekol.lu.se) Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume27, Issue3March 2004Pages 175-176 RelatedInformation

Causes and consequences of excess resistance in cryptobiotic metazoans.

Despite more than 200 yr of recognition that some microscopic metazoans survive environmental conditions far beyond those experienced in nature while in a cryptobiotic state, this phenomenon has received little attention from evolutionary biologists. The excess environmental resistance exhibited by cryptobiotic organisms cannot be viewed as an adaptation within current evolutionary biology. Rather, excess resistance may have evolved as a by-product of natural selection for tolerance to desiccation or other naturally occurring environmental agents. The combined effects of desiccation, metabolic arrest, effective stabilization of dry or frozen cells by protectant molecules, and efficient DNA repair mechanisms may have led to a protection of the organism against conditions far beyond those experienced in nature.

An ecological study of an Antarctic freshwater pool with particular reference to Tardigrada and Rotifera

Deep Lake Tarn is a small pool in the Vestfold Hills, Antarctica, which freezes solid seasonally. When free water is present, rotifers, tardigrades, nematodes, protozoans and bacteria are active and are mainly associated with an algal mat composed of cyanophytes, chlorophytes chrysophytes and a pyrrophyte.Hypsibius arcticus (Murray) (Tardigrada) reached a maximum density of 470 individuals per g wet weight of algal mat and individuals took about three months to reach full size. A new species ofIsohypsibius was recorded and will be described elsewhere. Tardigrades overwintered in their cryptobiotic state. The population density of bdelloid rotifers changed cyclically, peaking at three-weekly intervals during summer. They also overwintered in their cryptobiotic state.

Rapid, chloramphenicol-resistant, activation of membrane electron transport on germination of Bacillus spores

KEILIN1 observed that the life cycle of diverse organisms includes a stage when life seems to be arrested, which he termed the cryptobiotic state. As an example of this, the mature bacterial spore can remain dormant with no detectable metabolism for long periods and then on exposure to germinants, rapidly germinate and outgrow in a synchronous manner, to yield a vegetative cell. We have been particularly interested in the composition and activities of the membrane-bound electron transport chain in sporulating Bacillus megaterium KM (ref. 2) and in the unique reversed orientation which characterises the membranes surrounding the developing spore3. This report describes the rapid changes observed in the membrane of Bacillus megaterium KM spores during germination and outgrowth. A rapid chloramphenicol-resistant, activation of membrane NADH oxidase activity occurred within 5–10 min of germination. Membrane-bound DL-α-glycerol-P and L-malate oxidase activities appeared sequentially at later times and their appearance was prevented by chloramphenicol. Evidence is presented to suggest that in the dormant spore the electron transport sequence is blocked in the region between NADH dehydrogenase and the cytochromes.

The Mode of Gregarine Infection in Zygoptera (Odonata)

AbstractÅbro, A. (Institute of Anatomy, University of Bergen, N‐5000 Bergen, Norway). The mode of gregarine infection in Zygoptera (Odonata). Zool. Scr. 5 (6): 265–275, 1976.—The eugregarine Hoplorhynchus oligacanthus (Sieb.) is an intestinal parasite in imagines of the zygopterans Pyrrho‐soma nymphula (Sulz.) and Enallagma cyathigerum (Charp.). Gameto‐cysts, resulting from the union of a presumed male and a female gregarine gamont, leave the host with the faeces which drop to the woodland floor. Gametogony, zygote formation, and subsequent sporogony take place within the extrahost gametocysts. Infective sporozoites become enclosed in oocysts furnished with a highly resistent shell. When fully formed, the oocysts are released by simple rupture of the gametocyst envelopes. The oocysts, which probably disperse in the habitat by means of rain‐water, appear to enter a cryptobiotic state. Enzymic tests implied that liberation of sporozoites occurred more readily if oocysts were submitted to repeated freezing and thawing. Zygopterans consume lots of small insects; about three‐quarters of zygopteran food was found to consist of Chironomidae and Ceratopogonidae. Examination of various small insects available as prey for zygopterans revealed imagines of medium‐sized Chironomidae and Ceratopogonidae as vectors of Hoplorhynchus oocysts, which were found suspended on their tarsal bristles. An infective oocyst appears to contain 8 sporozoites. When introduced into a host, each of the sporozoites released from the oocyst will eventually develop into a gamont. Only one in a hundred chironomids and ceratopogonids was found to carry oocysts; none the less, this is considered sufficient to cause a high infection of the entire zygopteran populations. The occasional large number of non‐infective oocysts without sporozoites indicates that sporogony and formation of an oocyst capsule are independent events.

Reversible suspension of metabolism and the origin of life.

This paper is concerned to show that the capacity to tolerate a total suspension of metabolism (cryptobiosis) is a primitive characteristic of protoplasm. It is a characteristic that makes it possible to visualize a much wider range of environmental conditions for the possible origin of the first living systems. The characteristics of the cryptobiotic state are first noted, certain special features of cryptobiosis revealed by experiments on complex multicellular animals are then described, and finally the relevance of all this to theories about the origin of life are briefly noted.

The Revival of Macrobiotus areolatus Murray (Tardigrada) from the Cryptobiotic State

The purpose of this study was to investigate some physical and biological parameters affecting the revival of the tardigrade, Macrobiotus areolatus Murray, 1907, from a cryptobiotic state. The animals were dried on filter paper under controlled conditions. Based on per cent survival, optimum recovery conditions were established within experimental ranges of pH 6-8, 5-27 C, and 5-9 mgm/L dissolved oxygen. Studies of revival time over the optimum range indicate significant temperature and oxygen effects, revival time appearing to vary inversely with temperature and dissolved oxygen concentration. The pH effect on revival time is not significant. Preliminary data indicate that nutriton may have an effect on revival time. Well-fed animals revive more rapidly than starved ones. Revival time appears to be directly propor- tional to the duration of the cryptobiotic state. Possible errors and suggestions for improvement of experimental techniques are cited. Numerous animals are known to exhibit latent stages, but the most interesting are those in which a nearly complete arrest of metabolic activities occurs. Such an arrest is a cryptobiotic state. Desiccation in tardigrades, with which this paper is concerned, represents a particular kind of cryptobiosis. In the desiccated state tardigrades appear to be lifeless. Upon the addition of water they rapidly swell and resume active life. In the active tardigrade homeostatic processes regulate an organism-environ- ment interaction which is at a point far removed from chemical equilibrium, just as in any other organism. In the desiccated tardigrade, however, material and energy exchange with the surrounding environment are greatly reduced and the metabolic rate approaches zero. The adaptive significance of such a phe- nomenon appears obvious. Under environmental stress the biotic integrity of the organism is preserved when the same stress might otherwise result in its destruction. It is doubtful that metabolism in the cryptobiotic tardigrade ever reaches zero. Baumann (1922) was of the opinion that tardigrades will not survive complete desiccation, and probably carry on some metabolic activities, though at an extremely low rate, in the cryptobiotic state. Schmidt (1948) found that rotifers revive from the cryptobiotic state more slowly, and fewer survive, with an increase in the time that they are kept dry. Pigon & Weglarska (1953, 1955) detected a measurable oxygen uptake in desiccated tardigrades at high humidities. At lower humidities the measurable rate of oxygen uptake was low and unreliable. They believed that metabolic activities were carried on even at the lowest humidities, however. It is possible that oxygen uptake measured at low humidities is due not to respiratory activities of the tardigrade cells which may lead to starvation, but, instead, to abnormal oxidation which may be more harmful than slow respiration.