A Search for Extraterrestrial Eukaryotes: Biological and Planetary Science Aspects

Chela-Flores, Julian (1996) A Search for Extraterrestrial Eukaryotes: Biological and Planetary Science Aspects. (Preprint)

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One pressing question in Bioastronomy is to attempt to devise assays in the search for extraterrestrial eukaryotes (SETE). In the positive case of encountering a fossil of a certain microorganism, it is not yet clear how to identify it in an unequivocal manner, even if found arrested and preserved in the midst of biological activity, as in some known Archean sediments on Earth. On the other hand, for living microorganisms the present approach may have some advantages over the straightforward probe of the morphological features of the putative eukaryote, as we argue that we are not constrained to base identification on morphological properties, such as the presence of organelles, which are known to be missing in some higher taxa. The present work suggests one possible assay to detect eukaryotes, namely, the search for cellular division with a delay in replication of heterochromatic chromosome segments; we also discuss the biological and astronomical implications of a SETE program. Further, extremophiles may inhabit deep in the silicate crust of terrestrial planets which may have been deposited with the original sediment and survived over geologic time. Comparative planetology suggests that there are common ingredients in the nature of the landscapes of the terrestrial planets, particularly gradation. Hence, a SETE program should look for indicators of the first steps towards eukaryogenesis, for instance deep in the Martian crust. Additional ingredients in the common landscape of the rocky planets, or satellites, may be volcanism and tectonics. This has led to the belief that hot springs may be present at the bottom of Europa's great ocean. Hence, eukaryotes should also be searched for in this aquatic environment. Our current work emphasising gene silencing, may suggest how to decide whether extraterrestrial microbiota may have taken the first steps towards eukaryogenesis, the process which introduced the basic cellular plan of those Earth-bound organisms that have been raised to the level of intelligent beings.

Item Type: Article
Divisions: School of Theoretical Physics > Preprints
Date Deposited: 19 Jun 2018 14:06
Last Modified: 18 Jul 2018 10:59
URI: http://dair.dias.ie/id/eprint/665

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