biosignature Archives

Hexose sugar permeability through archaeal and hybrid membranes. Temporal dependence of average carboxyfluorescein (CF) fluorescence in the archaea-like G1PC phospholipid membrane (G1PC, filled symbols) and in the ‘hybrid’ phospholipid membrane (G3PC, open symbols) during the exposure to 1 mM of variant substrates delivered to the microfluidic coves. Mean (symbols) and standard deviation (error bars) were calculated from at least 10 single-vesicle measurements across three independent experiments. Data are processed and illustrated as described in Figure 1 legend. N is the number of single vesicles investigated for each substrate exposure and each type of vesicles. **: p-value < 0.01. Numerical values of CF fluorescence in individual vesicles for each lipid type during the delivery of each substrate are provided in S1 File and S2 File. -- biorxiv.org

Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Genomics, Proteomics, Bioinformatics, Origin & Evolution of Life, Status Report

Membrane Permeability Selection Drove the Stereochemistry of Life

by Keith CowingMay 9, 2024September 18, 2025

Early in the evolution of life a proto-metabolic network was encapsulated within a membrane compartment. The permeability characteristics of the membrane determined several key functions of this network by determining […]

(A) Schematic of assumptions concerning the outer layers of Enceladus, where H2 (and other solutes) and H2O erupt from the subsurface ocean as a plume of gas. As solutes and H2O vaporize and travel through the tiger stripes, H2O condenses onto the surrounding ice shell as it travels outward, enriching the plume in solutes. Once out of the ice shell conduit, the ratio of solutes to H2O remains the same as the gases expand into the vacuum of space and are detected by Cassini’s INMS. (B) Calculated log aqueous activities (at 273.15 K) of constrained species, resulting from the process illustrated in the left panel using data from Table 1, are displayed as functions of tiger-stripe temperatures. The dashed curve represents a hypothetical organic molecule detected at 1 ppm in the plume gas and then converted into log aqueous activity. -- chemrxiv.org

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, SETI & Technosignatures, Status Report, Tricorders & Sensors, Water/Hycean Worlds & Oceanography

Distinguishing Potential Organic Biosignatures on Ocean Worlds from Abiotic Geochemical Products using Thermodynamic Calculations

by Keith CowingMay 9, 2024May 9, 2024

The search for life in our solar system often involves efforts to detect organic molecules, which have been found on many extraterrestrial bodies, including planets, moons, meteorites, comets, and asteroids. […]

Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Mars, Status Report

Experimental Identification of Potential Martian Biosignatures in Open and Closed Systems

by Keith CowingMay 6, 2024May 6, 2024

NASA’s Perseverance and ESA’s Rosalind Franklin rovers have the scientific goal of searching for evidence of ancient life on Mars. Geochemical biosignatures that form because of microbe-mineral interactions could play […]

Reflectance spectra of all four microbes with biosignatures and wavelength regions annotated. Colors represent regions of the visible wavelength range, and the gray area represents the near-infrared region of the electromagnetic spectrum. Annotated biosignatures for black microbial mat include a chlorophyll absorption feature and a photosynthetic red edge. Orange microbial mat also has a photosynthetic red edge in addition to chlorophyll, phycocyanin, and carotenoid absorptions. Biosignatures within the Arthrobacter sp. spectrum include carotenoids, 43 and Ectothiorhodospira sp. str. BSL-9 has both carotenoid and bacteriochlorophyll-a absorptions. -- astro-ph.EP

Analog Studies, Arctic / Antarctic / Alpine, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Extremeophiles and Extreme Environments, Imaging & Spectroscopy, Microbiology & Virology, Status Report

Detectability of Surface Biosignatures for Directly-Imaged Rocky Exoplanets

by Keith CowingApril 26, 2024April 26, 2024

Modeling the detection of life has never been more opportune. With next generation space telescopes, like the currently developing Habitable Worlds Observatory (HWO) concept, we will begin to characterize rocky […]

Simulated oxygen (left; a,d,g), sulfate (middle; b,e,h), and methane (right; c,f,i) concentrations in a Proterozoic-like ocean with 10-3 PAL O2. Maps show each species in surface seawater (top; a-c) and benthic seawater (middle; d-f). Also shown are zonal average vertical profiles (bottom; g-i). Oxygen is limited to oxygen oases in surface seawater, leading to extensive SO4 2- reduction and local SO4 2- scarcity at depth, especially underlying productive regions of the surface ocean and in the oldest bottom waters. Where SO4 2- concentrations are low, methanogenesis leads to CH4 accumulation, but CH4 must evade oxidation by both SO4 2- in the ocean interior and O2 in surface waters before it may enter the atmosphere. This figure is reproduced from Reinhard et al. (2020) under Creative Commons Attribution License CCBY. Nitrous oxide (N2O -- astro-ph.EP

Analog Studies, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Fossils & Paleontology, Gaia - Planetary Perspectives, Habitable Zones, Origin & Evolution of Life, Status Report, Terraforming & Geoengineering

The Early Earth As An Analogue For Exoplanetary Biogeochemistry

by Keith CowingApril 25, 2024April 25, 2024

Planet Earth has evolved from an entirely anoxic planet with possibly a different tectonic regime to the oxygenated world with horizontal plate tectonics that we know today.

Reflectance spectra of purple and blue-green cyanobacteria (top), PNSB (N = 10) (middle), and, PSB (N = 12) (bottom) where N denotes the number of samples. Labels of main pigments identified: (a) Chl-a Soret band, (b) Carotenoids, (c) Chl-a Qx band, (d) Phycobilins, (e) Chl-a Qy band, (f) BChl-a Soret band, (g) BChl-a, b Qx band, (h) BChl-a Qy band, and (i) BChl-b Qy band. Dry samples (right) show a stronger reflectance than fresh samples (left), water absorption features at 1490 and 1900 nm are stronger in the fresh samples. The reflectance of the culture medium alone is shown as a dotted line for control.

Astrochemistry, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Imaging & Spectroscopy, Microbiology & Virology, Status Report, Water/Hycean Worlds & Oceanography

Purple Is The New Green: Biopigments And Spectra Of Earth-like Purple Worlds

by Keith CowingApril 18, 2024April 18, 2024

With more than 5,500 detected exoplanets, the search for life is entering a new era. Using life on Earth as our guide, we look beyond green landscapes to expand our […]

Using life on Earth as a guide, scientists are cataloging the colors and chemical signatures that a diverse range of organisms and minerals would present in an exoplanet’s reflected light. Credit: Ryan Young/Cornell University

Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Microbiology & Virology, Plant Biology, Press Release

In The Search For Alien Life, Purple May Be The New Green

by Keith CowingApril 16, 2024April 17, 2024

In the search for life across the cosmos, the familiar green hue we most associate with life on Earth may not be the best indicator. An Earth-like planet orbiting another […]

WATSON Testing Setup at Greenland's Summit Station NASA ID: PIA24169 Date Created:2021-04-07 larger image

Analog Studies, Arctic / Antarctic / Alpine, Away Teams & Field Reports, Biosignatures & Paleobiology, Cryobiology, Exploration Gear & Tech, Habitable Zones, Icy Worlds, Status Report, Tricorders & Sensors

Away Team Field Test Of WATSON Biosignature Tricorder In Greenland

by Keith CowingApril 11, 2024April 11, 2024

During 2019 field tests near Greenland’s Summit Station, a high-elevation remote observing station, the WATSON (Wireline Analysis Tool for the Subsurface Observation of Northern ice sheets) instrument is put through […]

Astrogeology, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Status Report

Habitability Constraints By Nutrient Availability In Atmospheres Of Rocky Exoplanets

by Keith CowingApril 7, 2024

Life as we know it requires the presence of liquid water and the availability of nutrients, which are mainly based on the elements C, H, N, O, P, and S […]

Energy-ordered resource stratification as an observable signature of life. (a) Stratified profiles of chemical resources layered by energy content are commonly observed on Earth, e.g., microbial mats, early Earth fossils (stromatolites), Winogradsky columns, and in marine environments. (b) Such profiles are generally understood to be shaped by biotic species (typically microbes) that metabolize these resources for energy. Here, we propose that energy-ordered resource stratification is a robust signature of biotic action. -- q-bio.PE

Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Status Report

Energy-ordered Resource Stratification As An Agnostic Signature Of Life

by Keith CowingApril 4, 2024April 4, 2024

The search for extraterrestrial life hinges on identifying biosignatures, often focusing on gaseous metabolic byproducts as indicators. However, most such biosignatures require assuming specific metabolic processes.

biosignature

Membrane Permeability Selection Drove the Stereochemistry of Life

Distinguishing Potential Organic Biosignatures on Ocean Worlds from Abiotic Geochemical Products using Thermodynamic Calculations

Experimental Identification of Potential Martian Biosignatures in Open and Closed Systems

Detectability of Surface Biosignatures for Directly-Imaged Rocky Exoplanets

The Early Earth As An Analogue For Exoplanetary Biogeochemistry

Purple Is The New Green: Biopigments And Spectra Of Earth-like Purple Worlds

In The Search For Alien Life, Purple May Be The New Green

Away Team Field Test Of WATSON Biosignature Tricorder In Greenland

Habitability Constraints By Nutrient Availability In Atmospheres Of Rocky Exoplanets

Energy-ordered Resource Stratification As An Agnostic Signature Of Life

Relevance of the Avalon Assemblage as an Astrobiological Analog for Icy Ocean Worlds

The Climate and Potential Habitability of a Warm and Oxygenated Mars

Variable X-ray flux May Explain Variable Helium Escape From The Habitable-zone Exoplanet LHS 1140b

Spacetime Contactability in Galactic Civilization Networks: Contact Counts and Percolation

Surprisingly Enriched CO and CH4 in Halley-type Comet 13P/Olbers: Clues to Its Interstellar Heritage