Biofluorescent worlds: global biological fluorescence as a biosignature

O’Malley-James, Jack T.; Kaltenegger, Lisa

doi:10.1093/mnras/sty2411

Cited by 13 publications

(3 citation statements)

References 115 publications

(173 reference statements)

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“…The fluorescence flux constitutes a proportionally larger fraction of the total flux at these wavelengths (Meroni et al , 2009 ; Joiner et al , 2011 ). Fluorescence as an adaptation in response to high-UV flare events has been proposed as a potentially temporal biosignature for planets orbiting M dwarf stars (O'Malley-James and Kaltenegger, 2016 ). To detect biological fluorescence will be very challenging and would require signal-to-noise ratios higher than for most features thus far discussed.…”

Section: Surface Biosignaturesmentioning

confidence: 99%

Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life

et al. 2018

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In the coming years and decades, advanced space- and ground-based observatories will allow an unprecedented opportunity to probe the atmospheres and surfaces of potentially habitable exoplanets for signatures of life. Life on Earth, through its gaseous products and reflectance and scattering properties, has left its fingerprint on the spectrum of our planet. Aided by the universality of the laws of physics and chemistry, we turn to Earth's biosphere, both in the present and through geologic time, for analog signatures that will aid in the search for life elsewhere. Considering the insights gained from modern and ancient Earth, and the broader array of hypothetical exoplanet possibilities, we have compiled a comprehensive overview of our current understanding of potential exoplanet biosignatures, including gaseous, surface, and temporal biosignatures. We additionally survey biogenic spectral features that are well known in the specialist literature but have not yet been robustly vetted in the context of exoplanet biosignatures. We briefly review advances in assessing biosignature plausibility, including novel methods for determining chemical disequilibrium from remotely obtainable data and assessment tools for determining the minimum biomass required to maintain short-lived biogenic gases as atmospheric signatures. We focus particularly on advances made since the seminal review by Des Marais et al. The purpose of this work is not to propose new biosignature strategies, a goal left to companion articles in this series, but to review the current literature, draw meaningful connections between seemingly disparate areas, and clear the way for a path forward. Key Words: Exoplanets—Biosignatures—Habitability markers—Photosynthesis—Planetary surfaces—Atmospheres—Spectroscopy—Cryptic biospheres—False positives. Astrobiology 18, 663–708.

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Section: Surface Biosignaturesmentioning

confidence: 99%

Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life

et al. 2018

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“…The excitation by higher energy wavelengths of light (shorter wavelength)—usually blue or UV—followed by their emission at lower energy (and longer wavelength) is called fluorescence 1 , generally resulting from green to red colours. This enigmatic mechanism is long known among vertebrates, particularly bird feathers that reflect UV light 2 – 4 .…”

Section: Introductionmentioning

confidence: 99%

Fluorescence and UV–visible reflectance in the fur of several Rodentia genera

Sobral¹,

Souza-Gudinho²

2022

Sci Rep

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Mammals are generally brown in colour, but recent publications are showing that they may not be as uniform as once assumed. Monotremes, marsupials, and a handful of eutherians reflect various colours when lit with UV light, mostly purple. Because of these still scarce records, we aimed to explore UV reflectance among rodent genera, the most diverse mammalian group, and the group of eutherians with the most common records of biofluorescence. Here we report structures like nails and quills reflected green, but for most genera, it was faded. However, Hystrix, Erethizon, and Ctenomys showed intense and contrasting green glow, while Chaetomys presented a vivid orange anogenital. The main available explanation of fluorescence in mammals relies on porphyrin. This explanation applies to the cases like Chaetomys, where specimens showed anogenital orange biofluorescence, but does not apply to the green biofluorescence we observed. In our sample, because the structures that reflected green were all keratinized, we have reasons to believe that biofluorescence results from keratinization and is a structurally-based colouration. However, not all spines/quills equally biofluoresced, so we cannot rule out other explanations. Since Rodentia is the most common mammalian group with reports on biofluorescence, this trait likely serves various functions that match the species diversity of this group.

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“…For example the scattering of light by the physical structure of organisms, degradation products of biological molecules, fluorescence and bioluminescence. A description of these phenomena can be find in [22], while [73] made a description of the bioluminescence and fluorescence detectability. Observed Vis-NIR spectrum of the Earthshine obtained by [38].…”

Section: Surface and Industrial Biosignaturesmentioning

confidence: 99%

Biosignatures Search in Habitable Planets

Claudi

Alei

2019

Galaxies

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The search for life has had a new enthusiastic restart in the last two decades thanks to the large number of new worlds discovered. The about 4100 exoplanets found so far, show a large diversity of planets, from hot giants to rocky planets orbiting small and cold stars. Most of them are very different from those of the Solar System and one of the striking case is that of the super-Earths, rocky planets with masses ranging between 1 and 10 M ⊕ with dimensions up to twice those of Earth. In the right environment, these planets could be the cradle of alien life that could modify the chemical composition of their atmospheres. So, the search for life signatures requires as the first step the knowledge of planet atmospheres, the main objective of future exoplanetary space explorations. Indeed, the quest for the determination of the chemical composition of those planetary atmospheres rises also more general interest than that given by the mere directory of the atmospheric compounds. It opens out to the more general speculation on what such detection might tell us about the presence of life on those planets. As, for now, we have only one example of life in the universe, we are bound to study terrestrial organisms to assess possibilities of life on other planets and guide our search for possible extinct or extant life on other planetary bodies. In this review, we try to answer the three questions that also in this special search, mark the beginning of every research: what? where? how?

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Biofluorescent worlds: global biological fluorescence as a biosignature

Cited by 13 publications

References 115 publications

Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life

Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life

Fluorescence and UV–visible reflectance in the fur of several Rodentia genera

Biosignatures Search in Habitable Planets

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