Palestrante
Descrição
The development and application of novel analytical techniques for the study of ancient life on Earth is an important step for establishing the most suitable framework for the search of biosignatures of deep time in samples returned from Mars. One of the main challenges in the study of early life traces in our planet is that Precambrian cellular remains have simple morphologies, micrometric dimensions and are commonly poorly preserved, imposing stringent interpretational and analytical challenges for irrefutable attestations of biogenicity. In this context, the need for high-resolution imaging approaches and the capacity of integrating different lines of evidence face technical constrains of the resolution, contrast or penetration depth of most conventional imaging approaches. Here we report the 3D nanoscale integrative description of the morphology and geochemical composition of Precambrian microfossils using ptychographic X-ray computed tomography (1), a non-invasive imaging technique that provides quantitative electron density of materials in the nanoscale. (2) We analyzed a set of Precambrian microfossils of different morphologies and states of preservation and also traces of microbial mats. Our results provide the 3D morphology and electron density of both organic and mineral phases with an average resolution of 50 nm. This approach provides novel insights into the fossils ultrastructure and geochemical composition, with implications for the understanding of their biogenicity, paleo-ecology and taphonomy. This approach also provides a significant contribution to the debate of the biogenicity criteria for morphological biosignatures, and, given its non-destructiveness, nanometric-resolution and capacity to correlate morphology and identification of the phases at the nanoscale, it has the potential to be a standard technique to be applied in samples returned from Mars in the near-future.
Referências
1 HOLLER, M. et al. X-ray ptychographic computed tomography at 16 nm isotropic 3D resolution. Scientific Reports, v. 4, p. 3857-1-3857-5, 2014. doi: 10.1038/srep03857.
2 DIAZ, A. et al. Three-dimensional mass density mapping of cellular ultrastructure by ptychographic X-ray nanotomography. Journal of Structural Biology, v. 192, n. 3, p. 461-469, Dec. 2015.
| Apresentação do trabalho acadêmico para o público geral | Não |
|---|---|
| Subárea | Biofísica |
