Evidence is growing that hydrothermal venting occurs not only along mid-ocean ridges but also on old regions of the oceanic crust away from spreading centers.Here we report the discovery of an extensive hydrothermal field at 30°N near the eastern intersection of the Mid-Atlantic Ridge and Atlantis fracture zone.The vent field-named"Lost City"-is distinctly different from all other known sea-floor hydrothermal fields in that it is located on 1.5-Ma-old crust,nearly 15 km from the spreading axis,and may be driven by the heat of exothermic serpentinization reactions between sea water and mantle rocks.It is located on a dome-like massif and is dominated by steep-sided carbonate chimneys,rather than the sulphide structures typical of"black smoker"hydrothermal fields.We found that vent fluids are relatively cool(40～75 ℃)and alkaline (pH9.0～9.8),supporting dense microbial communities that include anaerobic thermophiles.Because the geological characteristics of the Atlantis massif are similar to numerous areas of old crust along the Mid-Atlantic,Indian and Arctic ridges,these results indicate that a much larger portion of the oceanic crust may support hydrothermal activity and microbial life than previously thought.

An off-axis hydrothermal vent field near the mid-atlantic ridge at 30°n

Hydrogen gas, H2, is generated by alkaline hydrothermal vents through an ancient geochemical process called serpentinization, in which water reacts with iron-containing minerals deep within the Earth’s crust. H2 is the electron donor for the most ancient and the only energy-releasing route of biological CO2 fixation, the acetyl-CoA pathway. At the origin of metabolism, CO2 fixation by hydrothermal H2 within serpentinizing systems could have preceded and patterned biotic pathways. Here we show that three hydrothermal minerals—greigite (Fe3S4), magnetite (Fe3O4) and awaruite (Ni3Fe)—catalyse the fixation of CO2 with H2 at 100 °C under alkaline aqueous conditions. The product spectrum includes formate (up to 200 mM), acetate (up to 100 µM), pyruvate (up to 10 µM), methanol (up to 100 µM) and methane. The results shed light on both the geochemical origin of microbial metabolism and the nature of abiotic formate and methane synthesis in modern hydrothermal vents. Three iron minerals found in alkaline hydrothermal vents are shown to convert CO2 and H2 into formate, acetate and pyruvate in water, suggesting that such reactions could have paved the way for early metabolism.

/pdf/a-hydrogen-dependent-geochemical-analogue-of-primordial-48urp23u0m.pdf

A hydrogen-dependent geochemical analogue of primordial carbon and energy metabolism

Vesicles formed from single-chain amphiphiles (SCAs) such as fatty acids probably played an important role in the origin of life. A major criticism of the hypothesis that life arose in an early ocean hydrothermal environment is that hot temperatures, large pH gradients, high salinity and abundant divalent cations should preclude vesicle formation. However, these arguments are based on model vesicles using 1–3 SCAs, even though Fischer–Tropsch-type synthesis under hydrothermal conditions produces a wide array of fatty acids and 1-alkanols, including abundant C10–C15 compounds. Here, we show that mixtures of these C10–C15 SCAs form vesicles in aqueous solutions between pH ~6.5 and >12 at modern seawater concentrations of NaCl, Mg2+ and Ca2+. Adding C10 isoprenoids improves vesicle stability even further. Vesicles form most readily at temperatures of ~70 °C and require salinity and strongly alkaline conditions to self-assemble. Thus, alkaline hydrothermal conditions not only permit protocell formation at the origin of life but actively favour it.

/pdf/promotion-of-protocell-self-assembly-from-mixed-amphiphiles-s7wkn37efk.pdf

Promotion of protocell self-assembly from mixed amphiphiles at the origin of life.

The aim of this article is to provide the reader with an overview of the different possible scenarios for the emergence of life, to critically assess them and, according to the conclusions we reach, to analyze whether similar processes could have been conducive to independent origins of life on the several icy moons of the Solar System. Instead of directly proposing a concrete and unequivocal cradle of life on Earth, we focus on describing the different requirements that are arguably needed for the transition between non-life to life. We approach this topic from geological, biological, and chemical perspectives with the aim of providing answers in an integrative manner. We reflect upon the most prominent origins hypotheses and assess whether they match the aforementioned abiogenic requirements. Based on the conclusions extracted, we address whether the conditions for abiogenesis are/were met in any of the oceanic icy moons.

/pdf/the-emergence-of-life-36u3ozm2vz.pdf

The Emergence of Life

ATP is universally conserved as the principal energy currency in cells, driving metabolism through phosphorylation and condensation reactions. Such deep conservation suggests that ATP arose at an early stage of biochemical evolution. Yet purine synthesis requires 6 phosphorylation steps linked to ATP hydrolysis. This autocatalytic requirement for ATP to synthesize ATP implies the need for an earlier prebiotic ATP equivalent, which could drive protometabolism before purine synthesis. Why this early phosphorylating agent was replaced, and specifically with ATP rather than other nucleoside triphosphates, remains a mystery. Here, we show that the deep conservation of ATP might reflect its prebiotic chemistry in relation to another universally conserved intermediate, acetyl phosphate (AcP), which bridges between thioester and phosphate metabolism by linking acetyl CoA to the substrate-level phosphorylation of ADP. We confirm earlier results showing that AcP can phosphorylate ADP to ATP at nearly 20% yield in water in the presence of Fe 3+ ions. We then show that Fe 3+ and AcP are surprisingly favoured. A wide range of prebiotically relevant ions and minerals failed to catalyse ADP phosphorylation. From a panel of prebiotic phosphorylating agents, only AcP, and to a lesser extent carbamoyl phosphate, showed any significant phosphorylating potential. Critically, AcP did not phosphorylate any other nucleoside diphosphate. We use these data, reaction kinetics, and molecular dynamic simulations to infer a possible mechanism. Our findings might suggest that the reason ATP is universally conserved across life is that its formation is chemically favoured in aqueous solution under mild prebiotic conditions. 

A prebiotic basis for ATP as the universal energy currency

Fibroblasts are known for their ability to make and modify the extracellular matrix. However, there is more to them than meets the eye. It is now clear that they help define tissue microenvironments and support immune responses in organs. As technology advances, we have started to uncover the secrets of fibroblasts. In this Essay, we present fibroblasts as not only the builders and renovators of tissue environments but also the rheostat cells for immune circuits. Although they perform location-specific functions, they do not have badges of fixed identity. Instead, they display a spectrum of functional states and can swing between these states depending on the needs of the organ. As fibroblasts participate in a range of activities both in health and disease, finding the key factors that alter their development and functional states will be an important goal to restore homeostasis in maladapted tissues.

/pdf/why-does-understanding-the-biology-of-fibroblasts-in-31g6xxbm.pdf

Why does understanding the biology of fibroblasts in immunity really matter?

Ex vivo model of functioning human lymph node reveals role for innate lymphocytes and stroma in response to vaccine adjuvant.

Two key problems concern cell membranes during the emergence and early evolution of life: what was their initial composition, and why did the membranes of archaea and bacteria diverge? The composit...

https://royalsocietypublishing.org/doi/pdf/10.1098/rsfs.2019.0067

Isoprenoids enhance the stability of fatty acid membranes at the emergence of life potentially leading to an early lipid divide.

Precision medicine in immune-mediated inflammatory diseases (IMIDs) requires an understanding of how cellular networks change following therapy. We describe a therapeutic atlas for Crohn’s disease (CD) and ulcerative colitis (UC) following anti-tumour necrosis factor (TNF) therapy. We generated ~1 million single-cell transcriptomes, organised into 109 cell states, from 216 gut biopsies from 38 patients and three controls, revealing disease- and therapy-specific differences. A systems-biology analysis identified distinct spatially-resolved cellular microenvironments: granuloma signatures in CD and interferon (IFN)-response signatures localising to T-cell aggregates and epithelial damage in CD and UC. Longitudinal comparisons demonstrated that disease progression in non-responders associated with myeloid and stromal cell perturbations in CD and increased multi-cellular IFN signalling in UC. IFN signalling was also observed in rheumatoid arthritis (RA) synovium with a lymphoid pathotype. Our therapeutic atlas informs drug positioning across IMIDs, and suggests a rationale for the use of janus kinase (JAK) inhibition following anti-TNF resistance.

/pdf/a-longitudinal-single-cell-therapeutic-atlas-of-anti-tumour-135xylpa.pdf

A longitudinal single-cell therapeutic atlas of anti-tumour necrosis factor treatment in inflammatory bowel disease

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Why does understanding the biology of fibroblasts in immunity really matter?

Ex vivo model of functioning human lymph node reveals role for innate lymphocytes and stroma in response to vaccine adjuvant.

Isoprenoids enhance the stability of fatty acid membranes at the emergence of life potentially leading to an early lipid divide.

A longitudinal single-cell therapeutic atlas of anti-tumour necrosis factor treatment in inflammatory bowel disease