Single Celled Organism Fossils From the NeoArchean of South Africa

When you think about the basic ingredients for life to thrive on Earth, no doubt water and oxygen pop to mind. But there was a time on our planet when our atmosphere only had one-one thousandth of one percent of the amount of oxygen it has now, yet there were plenty of life forms around then too, although proof of them has been scarce. A recent discovery of fossilized bacteria dating to about 2.5 billion years ago provides long-sought-for evidence that the Earth was crawling with life even though it lacked much oxygen during a phase in our planet's development known as the Neoarchean Eon.

"These fossils represent the oldest known organisms that lived in a very dark, deep-water environment," says Andrew Czaja, the assistant professor of geology at the University of Cincinnati in the US who made the discovery. "These bacteria existed two billion years before plants and trees, which evolved about 450 million years ago. We discovered these microfossils preserved in a layer of hard silica-rich rock called chert located within the Kaapvaal craton of South Africa."

link.

Microbially Induced Sedimentary Structures From Paleoproterozoic Canada

Microbially induced sedimentary structures in the Paleoproterozoic, upper Huronian Supergroup, Canada

Authors:

Hill et al

Abstract:

The Paleoproterozoic Gordon Lake and Bar River formations, Huronian Supergroup, contain a variety of sedimentary structures in the Flack Lake area of Ontario, Canada, that have been considered of debatable origin. We identify these structures as microbially induced sedimentary structures (MISS). The preserved MISS are related to microbial mat destruction and decay, and include sand cracks, mat chips, remnant gas domes, pyrite patches, and iron laminae. A biological origin for the fossil structures is supported by their similarities to modern and ancient documented examples of MISS, the sand-dominated nature of the substrate in which they are preserved, and key microtextures identified in thin section. Microtextures include curled, frayed and layered mat chips, carbonaceous laminae, oriented grains, and concentrated heavy minerals. On outcrop scale, the presence of desiccation cracks, flaser and lenticular bedding, and ripples in association with the types of MISS identified in the Gordon Lake Formation support the interpretation of a tidal flat depositional environment. The Gordon Lake Formation contains a greater number and diversity of MISS than the overlying Bar River Formation, as a result of lower energy deposition in the former. The quartz arenite of the Bar River Formation contains fine-grained to pebbly granulestone characterized mainly by tangential and planar cross beds, which is consistent with a tidal channel or sand shoal setting. Although fossil evidence of life is rare in the rocks of the Huronian Supergroup, identification of MISS in the Flack Lake area provides a significant and convincing indication of microbial colonization at the time of deposition.

Enzymatic Antioxidant Systems in Early Anaerobes

Enzymatic Antioxidant Systems in Early Anaerobes: Theoretical Considerations

Authors:

Ireneusz et al

Abstract:

It is widely accepted that cyanobacteria-dependent oxygen that was released into Earth's atmosphere ca. 2.5 billion years ago sparked the evolution of the aerobic metabolism and the antioxidant system. In modern aerobes, enzymes such as superoxide dismutases (SODs), peroxiredoxins (PXs), and catalases (CATs) constitute the core of the enzymatic antioxidant system (EAS) directed against reactive oxygen species (ROS). In many anaerobic prokaryotes, the superoxide reductases (SORs) have been identified as the main force in counteracting ROS toxicity. We found that 93% of the analyzed strict anaerobes possess at least one antioxidant enzyme, and 50% have a functional EAS, that is, consisting of at least two antioxidant enzymes: one for superoxide anion radical detoxification and another for hydrogen peroxide decomposition. The results presented here suggest that the last universal common ancestor (LUCA) was not a strict anaerobe. O2 could have been available for the first microorganisms before oxygenic photosynthesis evolved, however, from the intrinsic activity of EAS, not solely from abiotic sources.

Monocercomonoides (eukaryote) Completely Lacks Mitochondria

Mitochondria are membrane-bound components within cells that are often described as the cells' powerhouses. They've long been considered as essential components for life in eukaryotes, the group including plants, fungi, animals, and unicellular protists, if for no other reason than that every known eukaryote had them. But researchers reporting in the Cell Press journal Current Biology on May 12, 2016 now challenge this notion. They've discovered a eukaryote that contains absolutely no trace of mitochondria at all.

"In low-oxygen environments, eukaryotes often possess a reduced form of the mitochondrion, but it was believed that some of the mitochondrial functions are so essential that these organelles are indispensable for their life," says Anna Karnkowska, a former post-doctoral fellow at Charles University in Prague who is now at the University of British Columbia in Vancouver, Canada. "We have characterized a eukaryotic microbe which indeed possesses no mitochondrion at all."

Organisms from the genus Monocercomonoides have been recognized for more than 80 years. They are related to the human pathogens Giardia and Trichomonas, all of which belong to a group known as Metamonada, which lives exclusively in low-oxygen environments.

In the new study, Karnkowska and Vladimir Hampl at Charles University in Prague and BIOCEV, along with colleagues from the Czech Republic and Canada, sequenced the Monocercomonoides genome. They were surprised to find that this organism lacks all mitochondrial proteins.

link.

paper (open access) here.

Hadesarchaea: a new Extremophile Discovered Kilometers Deep in the Earth's Crust

They live several kilometers under the surface of the earth, need no light or oxygen and can only be seen in a microscope. By sequencing genomes of a newly discovered group of microbes, the Hadesarchaea, an international team of researchers have found out how these microorganisms make a living in the deep subsurface biosphere of our planet.

Microorganisms that live below the surface of the earth remain one of the last great areas of exploration. Organisms that live there have not been grow in the laboratory and therefore their lifestyles are unknown. An international team led by microbiologists Brett Baker, Assistant Professor at The University of Texas and Thijs Ettema, senior lecturer at Uppsala University, along with scientists from UNC Chapel Hill and the University of Bremen, have discovered how microorganisms, first discovered in a South African gold mine at a depth of two miles, are able to make a living in the absence of oxygen and light. The study is published in Nature Microbiology.

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Increasing Aridity Negatively Impacts Soil Microbes in Global Drylands

Increasing aridity reduces soil microbial diversity and abundance in global drylands

Authors:

Maestre et al

Abstract:

Soil bacteria and fungi play key roles in the functioning of terrestrial ecosystems, yet our understanding of their responses to climate change lags significantly behind that of other organisms. This gap in our understanding is particularly true for drylands, which occupy ∼41% of Earth´s surface, because no global, systematic assessments of the joint diversity of soil bacteria and fungi have been conducted in these environments to date. Here we present results from a study conducted across 80 dryland sites from all continents, except Antarctica, to assess how changes in aridity affect the composition, abundance, and diversity of soil bacteria and fungi. The diversity and abundance of soil bacteria and fungi was reduced as aridity increased. These results were largely driven by the negative impacts of aridity on soil organic carbon content, which positively affected the abundance and diversity of both bacteria and fungi. Aridity promoted shifts in the composition of soil bacteria, with increases in the relative abundance of Chloroflexi and α-Proteobacteria and decreases in Acidobacteria and Verrucomicrobia. Contrary to what has been reported by previous continental and global-scale studies, soil pH was not a major driver of bacterial diversity, and fungal communities were dominated by Ascomycota. Our results fill a critical gap in our understanding of soil microbial communities in terrestrial ecosystems. They suggest that changes in aridity, such as those predicted by climate-change models, may reduce microbial abundance and diversity, a response that will likely impact the provision of key ecosystem services by global drylands.

Does Very High Dessication Tolerance Increase Radiation Resistance in Microbes?

Isolation of Radiation-Resistant Bacteria from Mars Analog Antarctic Dry Valleys by Preselection, and the Correlation between Radiation and Desiccation Resistance

Authors:

Musilova et al

Abstract:

Extreme radiation–resistant microorganisms can survive doses of ionizing radiation far greater than are present in the natural environment. Radiation resistance is believed to be an incidental adaptation to desiccation resistance, as both hazards cause similar cellular damage. Desert soils are, therefore, promising targets to prospect for new radiation-resistant strains. This is the first study to isolate radiation-resistant microbes by using gamma-ray exposure preselection from the extreme cold desert of the Antarctic Dry Valleys (a martian surface analogue). Halomonads, identified by 16S rRNA gene sequencing, were the most numerous survivors of the highest irradiation exposures. They were studied here for the first time for both their desiccation and irradiation survival characteristics. In addition, the association between desiccation and radiation resistance has not been investigated quantitatively before for a broad diversity of microorganisms. Thus, a meta-analysis of scientific literature was conducted to gather a larger data set. A strong correlation was found between desiccation and radiation resistance, indicating that an increase in the desiccation resistance of 5 days corresponds to an increase in the room-temperature irradiation survival of 1 kGy. Irradiation at −79°C (representative of average martian surface temperatures) increases the microbial radiation resistance 9-fold. Consequently, the survival of the cold-, desiccation-, and radiation-resistant organisms isolated here has implications for the potential habitability of dormant or cryopreserved life on Mars

Can Methanogenic Microbes Survive Mars' Perchlorates?

Sensitivity and Adaptability of Methanogens to Perchlorates: Implications for Life on Mars

Authors:

Krall et al

Abstract:

In 2008, the Mars Phoenix Lander discovered perchlorate at its landing site, and in 2012, the Curiosity Rover confirmed the presence of perchlorate on Mars. The research reported here was designed to determine if certain methanogens could grow in the presence of three different perchlorate salt solutions. The methanogens tested were Methanothermobacter wolfeii, Methanosarcina barkeri, Methanobacterium formicicum and Methanococcus maripaludis. Media were prepared containing 0, 0.5%, 1.0%, 2%, 5% and 10% wt/vol magnesium perchlorate, sodium perchlorate, or calcium perchlorate. Organisms were inoculated into their respective media followed by incubation at each organism’s growth temperature. Methane production, commonly used to measure methanogen growth, was measured by gas chromatography of headspace gas samples. Methane concentrations varied with species and perchlorate salt tested. However, all four methanogens produced substantial levels of methane in the presence of up to 1.0% perchlorate, but not higher. The standard procedure for growing methanogens typically includes sodium sulfide, a reducing agent, to reduce residual molecular oxygen. However, the sodium sulfide may have been reducing the perchlorate, thus allowing for growth of the methanogens. To investigate this possibility, experiments were conducted where stainless steel nails were used instead of sodium sulfide as the reducing agent. Prior to the addition of perchlorate and inoculation, the nails were removed from the liquid medium. Just as in the prior experiments, the methanogens produced methane at comparable levels to those seen with sodium sulfide as the reductant, indicating that sodium sulfide did not reduce the perchlorate to any significant extent. Additionally, cells metabolizing in 1% perchlorate were transferred to 2%, cells metabolizing in 2% were transferred to 5%, and finally cells metabolizing in 5% were transferred to 10%. All four species produced methane at 2% and 5%, but not 10% indicating some success in adapting cells to concentrations higher than 1%. The results reported here indicate that the presence of perchlorate on Mars does not rule out the possible existence of methanogens.

I think they are being very optimistic.

Using a Virus to Permanently Sterilize Animals

Caltech biologists have developed a nonsurgical method to deliver long-term contraception to both male and female animals with a single shot. The technique--so far used only in mice--holds promise as an alternative to spaying and neutering feral animals.

The approach was developed in the lab of Bruce Hay, professor of biology and biological engineering at Caltech, and is described in the October 5 issue of Current Biology. The lead author on the paper is postdoctoral scholar Juan Li.

Hay's team was inspired by work conducted in recent years by David Baltimore and others showing that an adeno-associated virus (AAV)--a small, harmless virus that is unable to replicate on its own, that has been useful in gene-therapy trials--can be used to deliver sequences of DNA to muscle cells, causing them to produce specific antibodies that are known to fight infectious diseases, such as HIV, malaria, and hepatitis C.

Li and her colleagues thought the same approach could be used to produce infertility. They used an AAV to deliver a gene that directs muscle cells to produce an antibody that neutralizes gonadotropin-releasing hormone (GnRH) in mice. GnRH is what the researchers refer to as a "master regulator of reproduction" in vertebrates--it stimulates the release of two hormones from the pituitary that promote the formation of eggs, sperm, and sex steroids. Without it, an animal is rendered infertile.

In the past, other teams have tried neutralizing GnRH through vaccination. However, the loss of fertility that was seen in those cases was often temporary. In the new study, Hay and his colleagues saw that the mice--both male and female--were unable to conceive after about two months, and the majority remained infertile for the remainder of their lives.

"Inhibiting GnRH is an ideal way to inhibit fertility and behaviors caused by sex steroids, such as aggression and territoriality," says Hay. He notes that in the study, his team also shows that female mice can be rendered infertile using a different antibody that targets a binding site for sperm on the egg. "This target is ideal when you want to inhibit fertility but want to leave the individual otherwise completely normal in terms of reproductive behaviors and hormonal cycling."

Hay's team has dubbed the new approach "vectored contraception" and says that there are many other proteins that are thought to be important for reproduction that might also be targeted by this technique.

link.

I am not at all afraid of whom might get this and the greater implications of this technology.  Nothing could possibly go wrong here!

Microbes Caused the RIse of the First MicroContinents?

Microbes, Mineral Evolution, and the Rise of Microcontinents—Origin and Coevolution of Life with Early Earth

Authors:

Grosch et al

Abstract:

Earth is the most mineralogically diverse planet in our solar system, the direct consequence of a coevolving geosphere and biosphere. We consider the possibility that a microbial biosphere originated and thrived in the early Hadean-Archean Earth subseafloor environment, with fundamental consequences for the complex evolution and habitability of our planet. In this hypothesis paper, we explore possible venues for the origin of life and the direct consequences of microbially mediated, low-temperature hydrothermal alteration of the early oceanic lithosphere. We hypothesize that subsurface fluid-rock-microbe interactions resulted in more efficient hydration of the early oceanic crust, which in turn promoted bulk melting to produce the first evolved fragments of felsic crust. These evolved magmas most likely included sialic or tonalitic sheets, felsic volcaniclastics, and minor rhyolitic intrusions emplaced in an Iceland-type extensional setting as the earliest microcontinents. With the further development of proto-tectonic processes, these buoyant felsic crustal fragments formed the nucleus of intra-oceanic tonalite-trondhjemite-granitoid (TTG) island arcs. Thus microbes, by facilitating extensive hydrothermal alteration of the earliest oceanic crust through bioalteration, promoted mineral diversification and may have been early architects of surface environments and microcontinents on young Earth. We explore how the possible onset of subseafloor fluid-rock-microbe interactions on early Earth accelerated metavolcanic clay mineral formation, crustal melting, and subsequent metamorphic mineral evolution. We also consider environmental factors supporting this earliest step in geosphere-biosphere coevolution and the implications for habitability and mineral evolution on other rocky planets, such as Mars.

Climate Change may Unleash Viruses Frozen in Arctic Tundra

Scientists said they will reanimate a 30,000-year-old giant virus unearthed in the frozen wastelands of Siberia, and warned climate change may awaken dangerous microscopic pathogens.

Reporting this week in the flagship journal of the US National Academy of Sciences, French researchers announced the discovery of Mollivirus sibericum, the fourth type of pre-historic virus found since 2003 -- and the second by this team.

Before waking it up, researchers will have to verify that the bug cannot cause animal or human disease.

To qualify as a "giant", a virus has to be longer than half a micron, a thousandth of a millimetre (0.00002 of an inch).

Mollivirus sibericum -- "soft virus from Siberia" -- comes in at 0.6 microns, and was found in the permafrost of northeastern Russia.

Climate change is warming the Arctic and sub-Arctic regions at more than twice the global average, which means that permafrost is not so permanent any more.

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Explaining Endogenous Retroviruses

What are endogenous retroviruses —backwards viruses from within?

Endogenous retroviruses originate from retroviruses, which are a distinctive family of viruses that infect vertebrates. During infection, retroviruses enter host cells, and convert their RNA genomes to DNA by reverse transcription. This is in direct opposition to the central dogma of molecular biology, which states that the flow of genetic information passes from DNA to RNA, hence the name retrovirus. After reverse transcription, the DNA copy of the viral genome is integrated into the host genome, enabling expression of viral genes via the host cellular machinery to produce more viruses. Occasionally, integration occurs in a germline cell (those that produce sperm or eggs), allowing the retroviral insertion to be inherited by host progeny as an endogenous retrovirus or ‘ERV’ for short. The term endogenous is applied since ERVs are inherited in a similar manner to genes, residing within the host genome in every nucleated cell of the organism.

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Hydrothermal Environments as Home for Early Life on Earth and Mars

A Single Cell Organism With an *EYE* Developed From Endosymbiotic Components

Eye-like ocelloids are built from different endosymbiotically acquired components

Authors:

Gavelis et al

Abstract:

Multicellularity is often considered a prerequisite for morphological complexity, as seen in the camera-type eyes found in several groups of animals. A notable exception exists in single-celled eukaryotes called dinoflagellates, some of which have an eye-like ‘ocelloid’ consisting of subcellular analogues to a cornea, lens, iris, and retina. These planktonic cells are uncultivated and rarely encountered in environmental samples, obscuring the function and evolutionary origin of the ocelloid. Here we show, using a combination of electron microscopy, tomography, isolated-organelle genomics, and single-cell genomics, that ocelloids are built from pre-existing organelles, including a cornea-like layer made of mitochondria and a retinal body made of anastomosing plastids. We find that the retinal body forms the central core of a network of peridinin-type plastids, which in dinoflagellates and their relatives originated through an ancient endosymbiosis with a red alga. As such, the ocelloid is a chimaeric structure, incorporating organelles with different endosymbiotic histories. The anatomical complexity of single-celled organisms may be limited by the components available for differentiation, but the ocelloid shows that pre-existing organelles can be assembled into a structure so complex that it was initially mistaken for a multicellular eye. Although mitochondria and plastids are acknowledged chiefly for their metabolic roles, they can also be building blocks for greater structural complexity.

1/2 of Banded Iron Formations are Microbial in Origin

Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and a half billion years ago.

That's the upshot of a study published this week in the Proceedings of the National Academy of Sciences (PNAS). The findings have meaning for fields as diverse as mining and the search for life in space.

Clark Johnson, a professor of geoscience at the University of Wisconsin-Madison, and former postdoctoral researcher Weiqiang Li examined samples from the banded iron formation in Western Australia. Banded iron is the iron-rich rock found in ore deposits worldwide, from the proposed iron mine in Northern Wisconsin to the enormous mines of Western Australia.

These ancient deposits, up to 150 meters deep, were begging for explanation, says Johnson.

Scientists thought the iron had entered the ocean from hot, mineral-rich water released at mid-ocean vents that then precipitated to the ocean floor. Now Johnson and Li, who is currently at Nanjing University in China, show that half of the iron in banded iron was metabolized by ancient bacteria living along the continental shelves.

The banding was thought to represent some sort of seasonal changes. The UW-Madison researchers found long-term swings in the composition, but not variations on shorter periods like decades or centuries.

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ACADEMIC BUN FIGHT! Potential PaleoArchean Trace Fossils Mimic Biogenic Cenozoic Microbial Corrosion

Paleoarchean trace fossils in altered volcanic glass

Authors:

Staudigel et al

Abstract:

Microbial corrosion textures in volcanic glass from Cenozoic seafloor basalts and the corresponding titanite replacement microtextures in metamorphosed Paleoarchean pillow lavas have been interpreted as evidence for a deep biosphere dating back in time through the earliest periods of preserved life on earth. This interpretation has been recently challenged for Paleoarchean titanite replacement textures based on textural and geochronological data from pillow lavas in the Hooggenoeg Complex of the Barberton Greenstone Belt in South Africa. We use this controversy to explore the strengths and weaknesses of arguments made in support or rejection of the biogenicity interpretation of bioalteration trace fossils in Cenozoic basalt glasses and their putative equivalents in Paleoarchean greenstones. Our analysis suggests that biogenicity cannot be taken for granted for all titanite-based textures in metamorphosed basalt glass, but a cautious and critical evaluation of evidence suggests that biogenicity remains the most likely interpretation for previously described titanite microtextures in Paleoarchean pillow lavas.

But are disputed!

Questioning the biogenicity of titanite mineral trace fossils in Archean pillow lavas

Authors:

Grosch et al

Abstract:

Staudigel et al. (1) compare early Archean titanite microtextures to recent microtubules in Cenozoic volcanic seafloor glass to support a biogenic origin. However, given the 3.5 billion years of Earth history since eruption of the Archean lavas, many geological processes have affected these rocks, complicating the simple case for trace fossils. Using hollow and partially mineralized microtextures in modern seafloor basalt as an analog for argued microbial alteration of Archean glass is, in our opinion, a weak line of argument and an overextrapolated interpretation in support of biogenicity. The many assumptions required in their proposed bioalteration model are not supported by microbiological experiments or geological observations. For example, Staudigel et al. (1) require that hollow microbial tunnels are filled in by some process forming titanite, but when and how this occurs is not substantiated. The authors also contradict earlier work by abandoning organic carbon linings to the microtextures as evidence in support of biogenicity. Staudigel et al. provide no new data to support a biogenic origin, and we highlight that they have further complicated their lines of argument.

And then the original authors counter!

Reply to Grosch and McLoughlin: Glass bioalteration trace fossils can be preserved by titanite in Paleoarchean greenstones

Authors:

Staudigel et al

Abstract:

Before debating the criticism that Grosch and McLoughlin (1) extend toward our paper (2), we point out that we agree on important issues, such as the difficulty of interpreting titanite textures in greenstones with complex metamorphic histories. We further agree with them that their images are too ambiguous to be certain of the presence of any biotextures.

We welcome Grosch and McLoughlin’s (1) clarification of their textural continuum of titanite textures in figure 1 of ref. 1, even though we are missing a genetic interpretation. We distinguish two types of titanite textures: (i) well-crystallized blade-like titanite crystals that have no resemblance to Cenozoic glass bioalteration and (ii) some “filamentous” textures that indeed closely resemble candidate biotextures. Lumping two visually distinct texture types into one group does not automatically give license to infer one process for their formation. Furthermore, we suggest here that none of the images conjure any simple metamorphic or biotic interpretations. In particular the candidate biotextures lack any obvious connections to glass surfaces or cracks in the glass, prohibiting a direct morphological comparison with Cenozoic biotextures.

Diverse Microbial Biota From Calymmian MesoProterozoic Siberia

Kotuikan Formation assemblage: a diverse organic-walled microbiota in the Mesoproterozoic Anabar succession, northern Siberia

Authors:

Vorob’eva et al

Abstract:

Abundant and diverse microfossils from shales of the Lower Member of the ∼1500-Ma-old Kotuikan Formation in northern Siberia document early Mesoproterozoic life along the Siberian Platform. Similar to many Meso- and Neoproterozoic microbiota, the Kotuikan assemblage is dominated by prokaryotic cyanobacteria, both filamentous (oscillatorialeans and nostocaleans, which are represented primarily by cellular trichomes and by empty sheaths) and coccoidal (chroococcaleans, including solitary and colonial specimens). However, unlike Mesoproterozoic microbiota of shallow-water settings, the Kotuikan compressed organic-walled microfossil assemblage in the open shelf facies includes diverse microscopic eukaryotes: large (up to ∼1-mm diameter) megasphaeromorph acritarchs, branched filaments that are most likely of eukaryotic algae and coccoidal monostromatic colonies of chlorococcaleans, as well as other morphologically complex microorganisms.

The Kotuikan assemblage contains numerous taxa previously recorded from Neoproterozoic successions (e.g., Elatera, Eosolena, Palaeastrum, Pterospermopsimorpha, Rugosoopsis and Navifusa), but these are long-ranging genera and no Neoproterozoic index fossils have been recorded. The microbiota is considered to be Mesoproterozoic in age because it contains a mixed assemblage of prokaryotic and eukaryotic microorganism remains including new taxa unknown in younger deposits. The Kotuikan assemblage documents the status of the marine biosphere at an early Mesoproterozoic time preceding the primary radiation of eukaryotes and representing an evolutionary stage transitional between the predominantly prokaryote-dominated Paleoproterozoic and the eukaryote-dominated Neoproterozoic microbiota.

As reported in this study, 35 taxa were identified in the Kotuikan assemblage (of which five forms are described informally) that are assigned to 18 genera of microscopic prokaryotes and eukaryotes. Two new genera and five new species are proposed: Hirudiforma lancetica gen. and sp. nov., H. simmetrica gen. and sp. nov., Lineaforma elongata gen. and sp. nov., Elatera minor sp. nov., Eosolena minuta sp. nov.

Methanoflorens stordalenmirensis: A Potentially Potent Microbial Amplipher to Anthropogenic Global Warming

Tiny soil microbes are among the world's biggest potential amplifiers of human-caused climate change, but whether microbial communities are mere slaves to their environment or influential actors in their own right is an open question. Now, research by an international team of scientists from the U.S., Sweden and Australia, led by University of Arizona scientists, shows that a single species of microbe, discovered only very recently, is an unexpected key player in climate change.

The findings, published in the journal Nature, should help scientists improve their simulations of future climate by replacing assumptions about the different greenhouse gases emitted from thawing permafrost with new understanding of how different communities of microbes control the release of these gases.

Earlier this year, the international team discovered that a single species of microbe, previously undescribed by science, was prominent in permafrost soils in northern Sweden that have begun to thaw under the effect of globally rising temperatures. Researchers suspected that it played a significant role in global warming by liberating vast amounts of carbon stored in permafrost soil close to the Arctic Circle in the form of methane, a powerful greenhouse gas trapping heat in the Earth's atmosphere. But the actual role of this microbe — assigned the preliminary name Methanoflorens stordalenmirensis, which roughly translates to "methane-bloomer from the Stordalen Mire" — was unknown.

The new research nails down the role of the new microbe, finding that the sheer abundance of Methanoflorens, as compared to other microbial species in thawing permafrost, should help to predict their collective impact on future climate change.

"If you think of the African savanna as an analogy, you could say that both lions and elephants produce carbon dioxide, but they eat different things," said senior author Scott Saleska, an associate professor in the UA's Department of Ecology and Evolutionary Biology and director of the UA's new Ecosystem Genomics Institute. "In Methanoflorens, we discovered the microbial equivalent of an elephant, an organism that plays an enormously important role in what happens to the whole ecosystem."

Significantly, the study revealed that because of these microbial activities, all wetlands are not the same when it comes to methane release.

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Pithivirus is a Monster (in size)

Chantal Abergel and Jean-Michel Claverie were used to finding strange viruses. The married virologists at Aix-Marseille University had made a career of it. But pithovirus, which they discovered in 2013 in a sample of Siberian dirt that had been frozen for more than 30,000 years, was more bizarre than the pair had ever imagined a virus could be.

In the world of microbes, viruses are small — notoriously small. Pithovirus is not. The largest virus ever discovered, pithovirus is more massive than even some bacteria. Most viruses copy themselves by hijacking their host’s molecular machinery. But pithovirus is much more independent, possessing some replication machinery of its own. Pithovirus’s relatively large number of genes also differentiated it from other viruses, which are often genetically simple — the smallest have a mere four genes. Pithovirus has around 500 genes, and some are used for complex tasks such as making proteins and repairing and replicating DNA. “It was so different from what we were taught about viruses,” Abergel said.

The stunning find, first revealed in March, isn’t just expanding scientists’ notions of what a virus can be. It is reframing the debate over the origins of life.

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How Well do Microbes Retain Water in Martian Soil Under Martian Conditions?

Water retention of selected microorganisms and Martian soil simulants under close to Martian environmental conditions

Authors:

Jänchen et al

Abstract:

Based on the latest knowledge about microorganisms resistant towards extreme conditions on Earth and results of new complex models on the development of the Martian atmosphere we quantitatively examined the water-bearing properties of selected extremophiles and simulated Martian regolith components and their interaction with water vapor under close to Martian environmental conditions. Three different species of microorganisms have been chosen and prepared for our study: Deinococcus geothermalis, Leptothrix sp. OT_B_406, and Xanthoria elegans. Further, two mineral mixtures representing the early and the late Martian surface as well as montmorillonite as a single component of phyllosilicatic minerals, typical for the Noachian period on Mars, were selected. The thermal mass loss of the minerals and bacteria-samples was measured by thermoanalysis. The hydration and dehydration properties were determined under close to Martian environmental conditions by sorption isotherm measurements using a McBain-Bakr quartz spring balance. It was possible to determine the total water content of the materials as well as the reversibly bound water fraction as function of the atmospheres humidity by means of these methods. Our results are important for the evaluation of future space mission outcomes including astrobiological aspects and can support the modeling of the atmosphere/surface interaction by showing the influence on the water inventory of the upper most layer of the Martian surface.