Astrobiology Science Conference 2015 (2015) 7328.pdf AN ESTIMATE OF THE ELEMENTAL COMPOSITION OF LUCA. Aditya Chopra1 and Charles H. Lineweaver1, 1Planetary Science Institute, Research School of Earth Sciences and Research School of Astronomy and Astrophysics, Australian National University,
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[email protected] A number of genomic and proteomic features of composition of life, we attempt to account for life on Earth, like the 16S ribosomal RNA gene, have differences in composition between species and other been highly conserved over billions of years. Genetic phylogenetic taxa (Fig. 2) by weighting datasets such and proteomic conservation translates to conservation that the result represents the root of prokaryotic life of metabolic pathways across taxa. It follows that the (LUCA). Variations in composition between data sets stoichiometry of the elements that make up some of that can be attributed to different growth stages or the biomolecules will be conserved. By extension, the environmental factors are used as estimates of the elemental make up of the whole organism is a uncertainty associated with the average abundances for relatively conserved feature of life on Earth [1,2]. each taxa. We describe how average bulk elemental Euryarchaeota 1a Methanococci, Methanobacteria, Methanopyri 7 Euryarchaeota 1b abundances in extant life can yield an indirect estimate 6 Thermoplasmata, Methanomicrobia, Halobacteria, Archaeoglobi Euryarchaeota 2 4 Thermococci of relative abundances of elements in the Last Crenarchaeota Sulfolobus, Thermoproteus ? Thaumarchaeota Universal Common Ancestor (LUCA). The results Cenarchaeum ? Korarchaeota ARMAN could give us important hints about the stoichiometry ? 2 Archaeal Richmond Mine Acidophilic Nanoorganisms Nanoarchaeota of the environment where LUCA existed and perhaps Archaea Terrabacteria clues to the processes involved in the origin and early Actinobacteria, Deinococcus-Thermus, 1 Cyanobacteria, Life Chloroflexi, 9 evolution of life [3].