Life In Extreme Environments Research Articles

Biogeophysics: A new frontier in Earth science research

“Biogeophysics” is a rapidly evolving Earth science discipline concerned with the geophysical signatures of microbial interactions with geologic media. It spans the established disciplines of geomicrobiology, biogeoscience, and geophysics. Biogeophysics research in the last decade has confirmed the potential for geophysical techniques to measure not simply the physical and chemical properties of the subsurface, as already well established, but also to detect microbes, microbial growth, and microbe‐mineral interactions, thus representing a major paradigm shift in geophysical thinking. In this review we begin by defining biogeophysics and provide a historical perspective. We then consider microbial alterations of petrophysical properties as such alteration is the source of most biogeophysical signals. Our review then focuses on geophysical interrogation of microbial processes, including the direct detection of microbial cells and biofilm formation, microbial metabolic by‐products, microbe‐mediated redox processes, and biogeochemical and microbe‐mineral transformations. We conclude by discussing challenges, opportunities, and potential new applications of biogeophysics to the exploration of life in extreme environments, e.g., the deep biosphere, the cryosphere, and other planets. We find that published biogeophysics studies to date are mostly observation based, presenting only empirical relationships between microbial and geophysical variables. Future research endeavors must focus on developing theoretical and/or numerical models for predicting geophysical signals arising from microbial activity.

A Cryptoendolithic Community in Volcanic Glass

Fluorescent in situ hybridization (FISH) and 16S rDNA analysis were used to characterize the endolithic colonization of silica-rich rhyolitic glass (obsidian) in a barren terrestrial volcanic environment in Iceland. The rocks were inhabited by a diverse eubacterial assemblage. In the interior of the rock, we identified cyanobacterial and algal 16S (plastid) sequences and visualized phototrophs by FISH, which demonstrates that molecular methods can be used to characterize phototrophs at the limits of photosynthetically active radiation (PAR). Temperatures on the surface of the dark rocks can exceed 40 degrees C but are below freezing for much of the winter. The rocks effectively shield the organisms within from ultraviolet radiation. Although PAR sufficient for photosynthesis cannot penetrate more than approximately 250 mum into the solid rock, the phototrophs inhabit cavities; and we hypothesize that by weathering the rock they may contribute to the formation of cavities in a feedback process, which allows them to acquire sufficient PAR at greater depths. These observations show how pioneer phototrophs can colonize the interior of volcanic glasses and rocks, despite the opaque nature of these materials. The data show that protected microhabitats in volcanic rocky environments would have been available for phototrophs on early Earth.

The cell nuclei of skeletal muscle cells are transcriptionally active in hibernating edible dormice

BackgroundSkeletal muscle is able to react in a rapid, dynamic way to metabolic and mechanical stimuli. In particular, exposure to either prolonged starvation or disuse results in muscle atrophy. At variance, in hibernating animals muscle atrophy may be scarce or absent after bouts of hibernation i.e., periods of prolonged (months) inactivity and food deprivation, and muscle function is fully preserved at arousal. In this study, myocytes from the quadriceps muscle of euthermic and hibernating edible dormice were investigated by a combination of morphological, morphometrical and immunocytochemical analyses at the light and electron microscopy level. The focus was on cell nuclei and mitochondria, which are highly sensitive markers of changing metabolic rate.ResultsFindings presented herein demonstrate that: 1) the general histology of the muscle, inclusive of muscle fibre shape and size, and the ratio of fast and slow fibre types are not affected by hibernation; 2) the fine structure of cytoplasmic and nuclear constituents is similar in euthermia and hibernation but for lipid droplets, which accumulate during lethargy; 3) during hibernation, mitochondria are larger in size with longer cristae, and 4) myonuclei maintain the same amount and distribution of transcripts and transcription factors as in euthermia.ConclusionIn this study we demonstrate that skeletal muscle cells of the hibernating edible dormouse maintain their structural and functional integrity in full, even after months in the nest. A twofold explanation for that is envisaged: 1) the maintenance, during hibernation, of low-rate nuclear and mitochondrial activity counterbalancing myofibre wasting, 2) the intensive muscle stimulation (shivering) during periodic arousals in the nest, which would mimic physical exercise. These two factors would prevent muscle atrophy usually occurring in mammals after prolonged starvation and/or inactivity as a consequence of prevailing catabolism. Understanding the mechanisms responsible for skeletal muscle preservation in hibernators could pave the way to prevention and treatment of muscle wasting associated with pathological conditions or ageing as well as life in extreme environments, such as ocean deeps or spaceflights.

Ancient Photosynthetic Eukaryote Biofilms in an Atacama Desert Coastal Cave

Caves offer a stable and protected environment from harsh and changing outside prevailing conditions. Hence, they represent an interesting habitat for studying life in extreme environments. Here, we report the presence of a member of the ancient eukaryote red algae Cyanidium group in a coastal cave of the hyperarid Atacama Desert. This microorganism was found to form a seemingly monospecific biofilm growing under extremely low photon flux levels. Our work suggests that this species, Cyanidium sp. Atacama, is a new member of a recently proposed novel monophyletic lineage of mesophilic "cave" Cyanidium sp., distinct from the remaining three other lineages which are all thermo-acidophilic. The cave described in this work may represent an evolutionary island for life in the midst of the Atacama Desert.

The Living Cosmos: Our Search for Life in the Universe

Considering the development of life on Earth, the existence of life in extreme environments and the potential for life elsewhere in the Universe, this book gives a fascinating insight into our place in the Universe. Chris Impey leads the reader through the history, from the Copernican revolution to the emergence of the field of astrobiology – the study of life in the cosmos. He examines how life on Earth began, exploring its incredible variety and the extreme environments in which it can survive. Finally, Impey turns his attention to our Solar System and the planets beyond, discussing whether there may be life elsewhere in the Universe. Written in non-technical language, this book is ideal for anyone wanting to know more about astrobiology and how it is changing our views of life and the Universe. An accompanying website available at www.cambridge.org/9780521173841 features podcasts, articles and news stories on astrobiology.

“Hairy Blobs:” Microbial Suspects Preserved in Modern and Ancient Extremely Acid Lake Evaporites

"Hairy blobs" are unusual clumps of organic bodies and sulfate crystals that have been found in evaporite minerals grown in acid saline lakes. Here, we document modern hairy blobs in halite and gypsum from 5 modern acid saline lakes in southern Western Australia, and Permian hairy blobs trapped in halite from the mid-Permian Opeche Shale in the subsurface of North Dakota. These are among the first microbial remains described from acid saline lake environments. They give clues about the role of microorganisms in the acidity, geochemistry, and mineralogy of these extreme environments. This study also may add to the inventory of life in extreme environments and help predict possible martian life-forms and the method of preservation.

Session 39. Life in Extreme Environments

AstrobiologyVol. 8, No. 2 Session 39. Life in Extreme EnvironmentsAriel Anbar and Beth OrcuttAriel AnbarSearch for more papers by this author and Beth OrcuttSearch for more papers by this authorPublished Online:8 Apr 2008https://doi.org/10.1089/ast.2008.1263AboutSectionsPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail FiguresReferencesRelatedDetails Volume 8Issue 2Apr 2008 Information© 2008 Mary Ann Liebert, Inc.To cite this article:Ariel Anbar and Beth Orcutt.Session 39. Life in Extreme Environments.Astrobiology.Apr 2008.472-475.http://doi.org/10.1089/ast.2008.1263Published in Volume: 8 Issue 2: April 8, 2008PDF download

Life in extreme environments: survival strategy of the endolithic desert lichen Verrucaria rubrocincta

Verrucaria rubrocincta Breuss is an endolithic lichen that inhabits caliche plates exposed on the surface of the Sonoran Desert. Caliche surface temperatures are regularly in excess of 60 degrees C during the summer and approach 0 degrees C in the winter. Incident light intensities are high, with photosynthetically active radiation levels typically to 2,600 micromol/m(2) s(-1) during the summer. A cross-section of rock inhabited by V. rubrocincta shows an anatomical zonation comprising an upper micrite layer, a photobiont layer containing clusters of algal cells, and a pseudomedulla embedded in the caliche. Hyphae of the pseudomedulla become less numerous with depth below the rock surface. Stable carbon and oxygen isotopic data for the caliche and micrite fall into two sloping, well-separated arrays on a delta(13)C-delta(18)O plot. The delta(13)C(PDB) of the micrite ranges from 2.1 to 8.1 and delta(18)O(SMOW) from 25.4 to 28.9, whereas delta(13)C(PDB) of the caliche ranges from -4.7 to 0.7 and delta(18)O(SMOW) from 23.7 to 29.2. The isotopic data of the micrite can be explained by preferential fixing of (12)C into the alga, leaving local (13)C enrichment and evaporative enrichment of (18)O in the water. The (14)C dates of the micrite range from recent to 884 years b.p., indicating that "dead" carbon from the caliche is not a significant source for the lichen-precipitated micrite. The endolithic growth is an adaptation to the environmental extremes of exposed rock surfaces in the hot desert. The micrite layer is highly reflective and reduces light intensity to the algae below and acts as an efficient sunscreen that blocks harmful UV radiation. The micrite also acts as a cap to the lichen and helps trap moisture. The lichen survives by the combined effects of biodeterioration and biomineralization. Biodeterioration of the caliche concomitant with biomineralization of a protective surface coating of micrite results in the distinctive anatomy of V. rubrocincta.

Life in Extreme Environments: A Tribute to Melbourne R. Carriker, Gentleman Malacologist Introduction

Life in Extreme Environments: A Tribute to Melbourne R. Carriker, Gentleman Malacologist Introduction

Biophysiological changes observed in members of the Italian expeditions to Antarctica

The objective of this study was to investigate whether food consumed by individuals working in Antarctica is adequate and sufficient, from the nutritional viewpoint, to sustain life in extreme environments. Malnutrition can be the cause of both health impairment and reduction in psychological and physiological efficiency. The study involved individuals from two subsequent expeditions in Antarctica, namely, 34 subjects (group A) from the Italian Mario Zucchelli Base (MZB) in October–November 2002 and 30 subjects (group B) from the Italian–French Concordia Station (CS) between November 2003 and January 2004. Each group of volunteers consisted of subjects with a controlled diet as well as of subjects with a free diet. Blood and hair samples were taken just before the expeditions (with the purpose of setting the baseline) and during the last week spent in Antarctica. Samples were then shipped to Italy to be analyzed, while the body composition and the hydration status were measured on the spot by Bio-Impedentiometric Assay (BIA). Anthropometrical measurements were carried out weekly. The data obtained were statistically assessed by using the Student t-test for correlated samples and showed, in all subjects, alterations of the hypothalamic–pituitary–thyroid axis, of blood parameters and of some components of the hair along with some variations of the psychological behaviour. The variations observed can probably be ascribed to environmental conditions and a combination of factors such as isolation, atmospheric conditions and prolonged presence of daylight.

Impact cratering — fundamental process in geoscience and planetary science

Impact cratering is a geological process characterized by ultra-fast strain rates, which generates extreme shock pressure and shock temperature conditions on and just below planetary surfaces. Despite initial skepticism, this catastrophic process has now been widely accepted by geoscientists with respect to its importance in terrestrial — indeed, in planetary — evolution. About 170 impact structures have been discovered on Earth so far, and some more structures are considered to be of possible impact origin. One major extinction event, at the Cretaceous-Paleogene boundary, has been firmly linked with catastrophic impact, but whether other important extinction events in Earth history, including the so-called “Mother of All Mass Extinctions” at the Permian-Triassic boundary, were triggered by huge impact catastrophes is still hotly debated and a subject of ongoing research. There is a beneficial side to impact events as well, as some impact structures worldwide have been shown to contain significant (in some cases, world class) ore deposits, including the gold-uranium province of the Witwatersrand basin in South Africa, the enormous Ni and PGE deposits of the Sudbury structure in Canada, as well as important hydrocarbon resources, especially in North America. Impact cratering is not a process of the past, and it is mandatory to improve knowledge of the past-impact record on Earth to better constrain the probability of such events in the future. In addition, further improvement of our understanding of the physico-chemical and geological processes fundamental to the impact cratering process is required for reliable numerical modeling of the process, and also for the correlation of impact magnitude and environmental effects. Over the last few decades, impact cratering has steadily grown into an integrated discipline comprising most disciplines of the geosciences as well as planetary science, which has created positive spin-offs including the study of paleo-environments and paleo-climatology, or the important issue of life in extreme environments. And yet, in many parts of the world, the impact process is not yet part of the geoscience curriculum, and for this reason, it deserves to be actively promoted not only as a geoscientific discipline in its own right, but also as an important life-science discipline.

The cold side of life

Barren land covered with huge ice shelves, swept by merciless winds and entrapped by deadly cold seas: that is a common perception of the polar regions. However, this picture could not be more wrong, as both the Arctic and Antarctic are teeming with life that is extraordinarily adapted to the harsh conditions and which often exists at the edge of survival (Fig 1,Fig 2,Fig 3,Fig 4). There has been a growing interest in these psychrophilic organisms, and how they evolved to grow and proliferate at permanently cold temperatures (D'Amico et al , 2006). Yet, it is not only the life sciences that can gain important insights from studying biological communities at the poles. Understanding how polar ecosystems respond to rapid climate change is of global significance; there is evidence that organisms, oceans and the atmosphere in the polar regions interact strongly, influencing each other in complex ways and with potentially major consequences for climate. Figure 1. A jellyfish offshore of McMurdo Station, Ross Island. Photograph by Steve Clabuesch/US National Science Foundation. Figure 2. Chinstrap penguins are about 68 cm (27 inches) tall and weigh about 4 kg (9 pounds). They are social animals and number about 5 million. Photograph by Zee Evans/US National Science Foundation. Figure 3. A crab‐eater seal lounges on an ice floe near the Antarctic Peninsula. Crab‐eaters are the most numerous seals in the world, with a population of more than 15 million. Although they do not eat crabs, they do eat krill and other crustaceans. They will reach a length of over 8 ft (2.44 m) and a weight of up to 500 lb (227 kg). Photograph by Jeffrey Kietzmann/US National Science Foundation. Figure 4. A snailfish, Paraliparis devriesi . Common inhabitants of deeper Antarctic waters, snailfish are characterized by a layer of jelly between the muscle and the …

Microbial activity in soils frozen to below −39 °C

Recent research on life in extreme environments has shown that some microorganisms metabolize at extremely low temperatures in Arctic and Antarctic ice and permafrost. Here, we present kinetic data on CO 2 and 14CO 2 release from intact and 14C-glucose amended tundra soils (Barrow, Alaska) incubated for up to a year at 0 to −39°C. The rate of CO 2 production declined exponentially with temperature but it remained positive and measurable, e.g. 2–7 ng CO 2–C cm −3 soil d −1, at −39 °C. The variation of CO 2 release rate ( v) was adequately explained by the double exponential dependence on temperature ( T) and unfrozen water content ( W) ( r 2>0.98): v= A exp( λT+ kW) and where A, λ and k are constants. The rate of 14CO 2 release from added glucose declined more steeply with cooling as compared with the release of total CO 2, indicating that (a) there could be some abiotic component in the measured flux of CO 2 or (b) endogenous respiration is more cold-resistant than substrate-induced respiration. The respiration activity was completely eliminated by soil sterilization (1 h, 121 °C), stimulated by the addition of oxidizable substrate (glucose, yeast extract), and reduced by the addition of acetate, which inhibits microbial processes in acidic soils (pH 3–5). The tundra soil from Barrow displayed higher below-zero activity than boreal soils from West Siberia and Sweden. The permafrost soils (20–30 cm) were more active than the samples from seasonally frozen topsoil (0–10 cm, Barrow). Finding measurable respiration to −39 °C is significant for determining, understanding, and predicting current and future CO 2 emission to the atmosphere and for understanding the low temperature limits of microbial activity on the Earth and on other planets.

Cretaceous Park? A Commentary on Microbial Paleomics

AstrobiologyVol. 5, No. 2 News & ViewsCretaceous Park? A Commentary on Microbial PaleomicsTori M. HoehlerTori M. HoehlerSearch for more papers by this authorPublished Online:6 Apr 2005https://doi.org/10.1089/ast.2005.5.95AboutSectionsPDF/EPUB ToolsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail FiguresReferencesRelatedDetailsCited ByPreservation of ancestral Cretaceous microflora recovered from a hypersaline oil reservoir11 March 2016 | Scientific Reports, Vol. 6, No. 1Extreme environments in the forests of Ushuaia, Argentina20 November 2007 | Geophysical Research Letters, Vol. 34, No. 22Stratified Communities of Active Archaea in Deep Marine Subsurface SedimentsApplied and Environmental Microbiology, Vol. 72, No. 7Fossil DNA in Cretaceous Black Shales: Myth or Reality? Jaap S. Sinninghe Damsté and Marco J.L. Coolen11 May 2006 | Astrobiology, Vol. 6, No. 2Ancient DNA derived from alkenone-biosynthesizing haptophytes and other algae in Holocene sediments from the Black Sea18 February 2006 | Paleoceanography, Vol. 21, No. 1Microbial Life in Extreme Environments: Linking Geological and Microbiological Processes Volume 5Issue 2Apr 2005 InformationCopyright 2005, Mary Ann Liebert, Inc.To cite this article:Tori M. Hoehler.Cretaceous Park? A Commentary on Microbial Paleomics.Astrobiology.Apr 2005.95-99.http://doi.org/10.1089/ast.2005.5.95Published in Volume: 5 Issue 2: April 6, 2005PDF download

Terrestrial Permafrost as a Model Environment for Bioastronomy

The extent to which organisms can survive extended periods of metabolic inactivity in cold environments such as permafrost is one of the key questions in the study of life in extreme environments and for astrobiology. Viable bacteria have been cultured from million year-old Siberian permafrost samples, but the relationship between the age of the bacteria and the age of the sediments remains controversial. In this study we analyze the level of racemization of amino acids in permafrost samples collected from several sites in Northern Siberia. We have shown that even during long exposures to low temperatures (−10°C to −15°C), the bacterial cells in permafrost are not completely dormant, but continue to metabolize and at least partially control the extent of amino acid racemization.

A perspective on the importance of reproductive mode in astrobiology.

Reproduction is a vital characteristic of life, and sex is the most common reproductive mode in the eukaryotic world. Sex and reproduction are not necessarily linked mechanisms: Sexuality without reproduction exists, while several forms of asexual reproduction are known. The occurrence of sexuality itself is paradoxical, as it is very costly in evolutionary terms. Most of the hypotheses (more than 20) attempting to explain the prevalence of sex fall into two categories: Sex either creates good gene combinations for adaptation to environments or eliminates bad gene combinations counteracting the accumulation of mutations. In spite of this apparent wealth of beneficial effects of sex, asexuality is not rare. Most eukaryotic, asexual lineages are short-lived and can only persist through the presence of sexual roots, but at least two animal groups, bdelloid rotifers and darwinulid ostracods, seem to claim the status of ancient asexuals. Research on (a)sexuality is relevant to astrobiology in a number of ways. First, strong relationships between the origin and persistence of life in extreme environments and reproductive mode are known. Second, the "habitability" of nonterrestrial environments to life greatly depends on reproductive mode. Whereas asexuals can do equally well or better in harsh environments, they fail to adapt fast enough to changing abiotic and biotic environments. Third, it has been shown that plants reproduce mainly asexually in space, and sperm production and motility in some vertebrates are hampered. Both findings indicate that extraterrestrial life under conditions different from Earth might be dominated by asexual reproduction. Finally, for exchange of biological material between planets, the choice of reproductive mode will be important.

Mollusc-microbe mutualisms extend the potential for life in hypersaline systems.

Metazoans in extreme environments have evolved mutualisms with microbes that extend the physical and chemical capabilities of both partners. Some of the best examples are bivalve molluscs in evaporite and hypersaline settings. Mollusc tissue is developmentally and evolutionarily amenable to housing vast numbers of symbiotic microbes. Documented benefits to the host are nutritional. Multiple postulated benefits to the microbes are related to optimizing metabolic performance at interfaces, where heterogeneity and steep gradients that cannot be negotiated by microbes can be spanned by larger metazoan hosts. A small cockle, Fragum erugatum, and its photosymbiotic microbes provide a remarkable example of a mutualistic partnership in the hypersaline reaches of Shark Bay, Western Australia. Lucinid bivalves and their endosymbiotic chemolithotrophic bacteria provide examples in which hosts span oxic/anoxic interfaces on behalf of their symbionts at sites of seafloor venting. Multiple lines of evidence underscore the antiquity of mutualisms and suggest that they may have played a significant role in life's first experiments above the prokaryotic grade of complexity. The study of metazoan-microbe mutualisms and their signatures in extreme environments in the geologic record will provide a significant augmentation to microbial models in paleobiology and astrobiology. There are strong potential links between mutualisms and the early history of life on Earth, the persistence of life in extreme environments at times of global crisis and mass extinction, and the possibilities for life elsewhere in the universe.

極限生物圏 地球生物圏のフロンティア

The search for life on the edges (frontiers) of the global biosphere bridges earth-bound biology and exobiology. This communication reviews recent microbiological studies on selected “frontiers”, i.e., deep-sea, deep subsurface, and Antarctica. Deep-sea is characterized as the aphotic (non-photosynthetic) habitat, and the primary production is mostly due to the chemosynthetic autotrophy at the hydrothermal vents and methane-rich seeps. Formation of the chemosynthesis-dependent animal communities in the deep leads to the idea that such communities may be found in the “ocean” of the Jovian satellite, Europa. An anoxic (no-O2), as well as aphotic, condition is characteristic of the deep subsurface biosphere. Microorganisms in the deep subsurface biosphere exploit every available oxidant for anaerobic respiration. Sulfate, nitrate, iron (III) and CO2 are the representative oxidants in the deep subsurface. Below the 3000 m-thick glacier on Antarctica, >70 lakes having liquid water are entombed. One of such sub-glacial lakes, Lake Vostok, has been a target of “life in extreme environments” and is about to be drill-penetrated for microbiological studies. These biospheric frontiers will provide new knowledge about the diversity and the potential of life on Earth and facilitate the capability of astrobiologial exploration.

Special Session IV: Life in Extreme Environments

Special Session IV: Life in Extreme Environments

Students’ Pre-Instructional Beliefs and Reasoning Strategies About Astrobiology Concepts

Students’ Pre-Instructional Beliefs and Reasoning Strategies About Astrobiology Concepts