Origins of life from chemistry to biology

Understanding how life started on Earth is a long-standing mystery. This article explores the sequence of events that may have led a mixture of simple chemicals to transform into the first living cells; showing how, in recent years, ribonucleic acid (RNA) has emerged as an important clue to this mystery

Ladakh: Diverse, high-altitude extreme environments for off-earth analogue and astrobiology research

This paper highlights unique sites in Ladakh, India, investigated during our 2016 multidisciplinary pathfinding expedition to the region. We summarize our scientific findings and the site's potential to support science exploration, testing of new technologies and science protocols within the framework of astrobiology research. Ladakh has several accessible, diverse, pristine and extreme environments at very high altitudes (3000-5700 m above sea level). These sites include glacial passes, sand dunes, hot springs and saline lake shorelines with periglacial features. We report geological observations and environmental characteristics (of astrobiological significance) along with the development of regolith-landform maps for cold high passes. The effects of the diurnal water cycle on salt deliquescence were studied using the ExoMars Mission instrument mockup: HabitAbility: Brines, Irradiance and Temperature (HABIT). It recorded the existence of an interaction between the diurnal water cycle in the atmosphere and salts in the soil (which can serve as habitable liquid water reservoirs). Life detection assays were also tested to establish the best protocols for biomass measurements in brines, periglacial ice-mud and permafrost melt water environments in the Tso-Kar region. This campaign helped confirm the relevance of clays and brines as interest targets of research on Mars for biomarker preservation and life detection.The team would like to express its gratitude to BirbalSahni Institute of Palaeosciences, Department of Science and Technology,Office of Chief Wildlife Warden of Ladakh, Government of India for helpingarrange the requisite clearances and permits for the conducted work. Projectmentoring and guidance provided by Spaceward Bound members at NASAAmes Research Center. Financial and logistics support provided by TataMotors Ltd, Inspired Journeys Co, Pearl Travels Ltd and NationalGeographic Traveller India. Website and IT support provided by the BlueMarble Space Institute of Science. Audio-video documentation support pro-vided by Astroproject India and The H

Origins of life from chemistry to biology

Understanding how life started on Earth is a long-standing mystery. This article explores the sequence of events that may have led a mixture of simple chemicals to transform into the first living cells; showing how, in recent years, ribonucleic acid (RNA) has emerged as an important clue to this mystery

Formation of Abasic Oligomers in Nonenzymatic Polymerization of Canonical Nucleotides

Polymerization of nucleotides under prebiotically plausible conditions has been a focus of several origins of life studies. Non-activated nucleotides have been shown to undergo polymerization under geothermal conditions when subjected to dry-wet cycles. They do so by a mechanism similar to acid-catalyzed ester-bond formation. However, one study showed that the low pH of these reactions resulted in predominantly depurination, thereby resulting in the formation of abasic sites in the oligomers. In this study, we aimed to systematically characterize the nature of the oligomers that resulted in reactions that involved one or more of the canonical ribonucleotides. All the reactions analyzed showed the presence of abasic oligomers, with purine nucleotides being affected the most due to deglycosylation. Even in the reactions that contained nucleotide mixtures, the presence of abasic oligomers was detected, which suggested that information transfer would be severely hampered due to losing the capacity to base pair via H-bonds. Importantly, the stability of the N-glycosidic linkage, under conditions used for dry-wet cycling, was also determined. Results from this study further strengthen the hypothesis that chemical evolution in a pre-RNA World would have been vital for the evolution of informational molecules of an RNA World. This is evident in the high degree of instability displayed by N-glycosidic bonds of canonical purine ribonucleotides under the same geothermal conditions that otherwise readily favors polymerization. Significantly, the resultant product characterization in the reactions concerned underscores the difficulty associated with analyzing complex prebiotically relevant reactions due to inherent limitation of current analytical methods