oxygenic photosynthesis Archives - Page 2 of 2 - Astrobiology

Synechococcus -- Wikipedia

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Synechococcus sp. PCC7335 Responses To Far-red Enriched Spectra and Anoxic/microoxic Atmospheres: Potential for Astrobiotechnological Applications

by Keith CowingJune 20, 2024June 20, 2024

Recently, cyanobacteria have gained attention in space exploration to support long-term crewed missions via Bioregenerative Life Support Systems. In this frame, cyanobacteria would provide biomass and profitable biomolecules through oxygenic […]

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.

Shows the CH4 production rate from ecosystem 1 for the 3.8 Ga Earth (dashed) and TRAPPIST-1e (solid) case. The CH4 production rate is split between anoxic H2 (purple) and CO (grey) consumers. the total of these is also shown (green) This plot used simulations with the reduced network. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report, TRAPPIST-1

Biosignatures From Pre-oxygen Photosynthesising Life On TRAPPIST-1e

by Keith CowingApril 18, 2024April 18, 2024

In order to assess observational evidence for potential atmospheric biosignatures on exoplanets, it will be essential to test whether spectral fingerprints from multiple gases can be explained by abiotic or […]

Schematic representation of oxygenic photosynthesis and the generation of superoxide during the day inside a Cyanobacterial cell. The thylakoid membrane contains Photosystem II (PSII) connected to phycobilisomes, Photosystem I (PSI), cytochrome b6f (cyt b6f), and electron transporters plastoquinone (PQ) and plastocyanin (PC). Phycobilisomes capture light energy and transfer it to PSII resulting in the hydrolysis of water and transfer of electrons to PQ, with the concomitant generation of molecular oxygen (O2) and protons (H+ ). PQ then transfers the electrons to PSI via cyt b6f and PC, thereby translocating two protons (2H+ ) across the thylakoid membrane, into the lumen. The resulting proton gradient powers the synthesis of adenosine triphosphate (ATP) via ATP synthase. PSI transfers electrons to ferredoxin (Fd), that in turn transfers electrons to ferredoxin NADP+ oxidoreductase (FNR) to generate reduced nicotinamide adenine dinucleotide phosphate (NADPH). Both NADPH and ATP are used to power cellular processes, such as CO2 fixation (Mullineaux, 2014). Increased light exposure may result in excess electrons being fed into the electron transport chain, resulting in the generation of superoxide (O2 •– ) (Latifi et al., 2009). Dismutation of O2 •– to hydrogen peroxide (H2O2) potentially occurs in different species via superoxide dimutases (SODs), in the cytoplasm, thylakoid lumen or periplasmic space (Herbert et al., 1992; Li et al., 2002; Napoli et al., 2021; Raghavan et al., 2013; Raghavan et al., 2015). Image generated in Biorender ©. -- biorxiv.org

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Early-branching Cyanobacteria Up-regulate Superoxide Dismutase Activity Under A Simulated Early Earth Anoxic Atmosphere

by Keith CowingMarch 17, 2024

The evolution of oxygenic photosynthesis during the Archean (4-2.5 Ga), required the presence of complementary reducing pathways to maintain the cellular redox balance.

Image of Navifusa majensis, a microfossil from the McDermott Formation in Australia. This 1.75 billion-year-old microfossil contains thylakoids, which identify it as a cyanobacterium. CREDIT Emmanuelle Javaux

Biosignatures & Paleobiology, Fossils & Paleontology, Microbiology & Virology, Origin & Evolution of Life, Plant Biology, Press Release, Space Life Science

The Evolution Of Photosynthesis Documented By Thylakoids In Fossil Cyanobacteria

by Keith CowingJanuary 6, 2024January 6, 2024

Researchers at the University of Liège (ULiège) have identified microstructures in fossil cells that are 1.75 billion years old.

General structure of the phot0 molecule. M is either Ca2+ (phot0-Ca), or Mg2+ (phot0-Mg), or Zn2+ (phot0-Zn). -- astro-ph.EP

Biophysics, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Microbiology & Virology, Plant Biology, Press Release

On The Importance And Challenges Of Modelling Extraterrestrial Photopigments Via Density-functional Theory

by Keith CowingOctober 15, 2023October 15, 2023

The emergence of oxygenic photosynthesis was a major event in Earth’s evolutionary history and was facilitated by chlorophylls (a major category of photopigments).

Bright-field optical microscopy

Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Plant Biology, Status Report, TRAPPIST-1

Oxygenic Photosynthetic Responses Of Cyanobacteria Exposed Under An M-dwarf Starlight Simulator: Implications For Exoplanet’s Habitability

by Keith CowingFebruary 20, 2023February 20, 2023

Introduction: The search for life on distant exoplanets is expected to rely on atmospheric biosignatures detection, such as oxygen of biological origin.