| From Early Cells to Multicellularity |
LIFE is a NASA Astrobiology Program Research Coordination Network, dedicated to understanding life from early cells to multicellularity. The LIFE Research Coordination Network (RCN) is pleased to host a virtual seminar series that will showcase the research of leaders and emerging leaders in the field of astrobiology.
The LIFE RCN Seminar Series is typically held the first Monday of every month from 1-2 PM EST and will consist of live-streamed short (30-40 min) talks followed by Q&A and discussion. This seminar series is open to all who share an interest in the co-evolution of life and the Earth from the appearance of the earliest cells to the advent of multicellularity.
Click here to join the LIFE mailing list. Connect on Twitter @LIFE_RCN. |
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| Monday, March 4th at 10AM PDT / 1PM EDT / 5PM UTC |
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| Dr. Philip Donoghue Professor of Palaeobiology University of Bristol |
| The Nature of the Last Universal Common Ancestor and its Impact on the Early Earth System
The nature of the Last Universal Common Ancestor (LUCA), its age, and impact on the Earth system have been the subject of vigorous debates across diverse disciplines, often based on disparate data. Age estimates for LUCA are usually based on the fossil record, varying with every reinterpretation. The nature of LUCA’s metabolism has proven equally contentious, with some attributing all core metabolisms to LUCA, while others reconstruct a simpler life form dependent on geochemistry.
Here we show, using a set of pre-LUCA duplications under a new cross-bracing approach implemented in PAML, calibrated with microbial fossils and isotope records of metabolisms, that LUCA existed ~4.2 Ga. We use 700 prokaryotic genomes to infer a 2.59Mb+ genome encoding at least 2500 proteins, comparable to modern prokaryotes. Our results suggest LUCA was anaerobic, acetogenic and possessed an early immune system. While LUCA is sometimes perceived as living in isolation, we infer LUCA to have been part of an established ecology. The metabolism of LUCA would have provided a niche for other community members, while hydrogen recycling by atmospheric photochemistry could have supported a modestly productive early ecosystem. |
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