Publications of Emmanuelle Javaux
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See detailPhototrophic green algae in Mid-Proterozoic oceans
Sforna, Marie-Catherine ULiege; Loron, Corentin ULiege; Demoulin, Catherine ULiege et al

Poster (2020, January)

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See detailDiversification of complex life on the early Earth: the Proterozoic of Artic Canada as a case study
Loron, Corentin ULiege; Halverson, Galen; Rainbird, Rob et al

Poster (2020)

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See detailInterpreting the biological affinities of early Eukaryotes
Loron, Corentin ULiege; François, Camille; Rainbird, Rob et al

Conference (2020)

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See detailThe Proterozoic Arctic Canada as a case study for the evolution and diversity of early Eukaryotes.
Loron, Corentin ULiege; Halverson, Galen; Rainbird, Rob et al

Poster (2020)

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See detailBiodiversity of Cyanobacteria and associated microbiome in the BCCM/ULC Culture Collection
Ahn, Anne-Catherine ULiege; Cornet, Luc ULiege; Beets, Kim ULiege et al

Poster (2019, October 18)

Cyanobacteria are a phylum of photosynthetic bacteria that played an important role in the evolution of the planet by oxygenating its early atmosphere and provoking the Great Oxydation Event around 2.3 ... [more ▼]

Cyanobacteria are a phylum of photosynthetic bacteria that played an important role in the evolution of the planet by oxygenating its early atmosphere and provoking the Great Oxydation Event around 2.3 billion years ago. Early cyanobacteria were the ancestors of plastids and thus, at the origin of the highly successful algae and plants. Nowadays, they still are the basis of the food chain in many biotopes, as long as there is liquid water, light, air and some minerals. Some cyanobacterial taxa are very resistant to harsh environmental conditions, and thus, grow in polar, hypersaline, alkaline and/or arid biotopes, but also in spatial conditions. Furthermore, they are also a prolific source of secondary compounds with bioactivies. The BCCM/ULC public collection funded by the Belgian Science Policy Office since 2011 presently includes 224 cyanobacterial strains, with 140 being of Antarctic origin (catalogue: http://bccm.belspo.be/catalogues/ulc-catalogue-search). The strains are unicyanobacterial but not axenic, due to the well known difficulties of purifying them. Morphological identification showed that the strains belong to the orders of Synechococcales, Oscillatoriales, Pleurocapsales, Chroococcidiopsidales and Nostocales. Furthermore, 16S rRNA and ITS sequences of the strains are being characterized. Recent sequencing efforts increased the amount of available 16S rRNA sequences of BCCM/ULC strains to 190. Those sequences belong to 75 OTUs (groups of sequences with > 99 % 16S rRNA similarity), which represents a quite large diversity. To better characterize the microbiome of the cultures, a metagenomic analysis was performed for 12 polar or subpolar strains and three temperate ones, including three early-branching organisms that will be useful for phylogenomics. The design of a specific metagenomic pipeline enabled the easy recovery of the cyanobacterial genomes from the non-axenic cultures. In parallel, 31 genomes of co-cultivated bacteria (12 nearly complete) from the same cultures were determined. They mostly belonged to Bacteroidetes and Proteobacteria, some of them being very closely related, in spite of sometimes geographically distant sampling sites (Cornet et al. 2018). In summary, the BCCM/ULC public collection serves as a Biological Resource Centre to conserve ex situ and document the biodiversity of cyanobacteria and their microbiomes, as well as a repository for discovery of novel bioactive compounds. Cornet, L., Bertrand, A., Hanikenne, M., Javaux, E., Wilmotte, A., & Baurain, D. (2018). Metagenomic assembly of new (sub)polar Cyanobacteria and their associated microbiome from non-axenic cultures. Microbial Genomics.4. DOI 10.1099/mgen.0.000212. [less ▲]

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See detailAntarctic cyanobacteria sources of biosignatures
Lara, Yannick ULiege; Demoulin, Catherine ULiege; Lambion, Alexandre ULiege et al

Conference (2019, September 05)

The high UV intensities and extreme seasonality make some of Antarctic habitats interesting to the study life adaptive strategies in extreme conditions, and the biosignatures that can be preserved. In ... [more ▼]

The high UV intensities and extreme seasonality make some of Antarctic habitats interesting to the study life adaptive strategies in extreme conditions, and the biosignatures that can be preserved. In Antarctica, most of the surface, lacustrine and endolithic photosynthetic niches are occupied by cyanobacteria, which are well equipped to survive cold, desiccation or UV exposure. To provide a better understanding of the cyanobacteria survival strategies to extreme conditions, we used transmitted light and TEM microscopy as well as high-throughput sequencing technologies on the Antarctic lineage Phormidesmis priestleyi. We observed and characterized the production of a gloeocapsin-like UV-screening pigment and compared it to the pigment produced by Gloeocapsa alpina. Cyanobacteria are considered to be the inventors of oxygenic photosynthesis and therefore played a pivotal role in early Life and Earth evolution during the Precambrian. However, to perform photosynthesis in the UV exposure of the Early Earth unprotected by an ozone layer, their ancestors must have developed multiple molecular strategies. The presence of a gloeocapsin-like pigment in different cyanobacterial lineages may suggest its early production by their common ancestor, potentially present before the oxidation of the atmosphere. In Polar regions, low temperatures lead to the success of particular organisms featuring adaptations to molecular and cellular disturbances such as rigidity of membranes, reduction of enzyme-catalyzed reactions, and solute transport. Our results underline the importance of functional categories of genes involved in the production of key molecules for the survival of polar P. priestleyi (e.g. exopolysaccharides, chaperone proteins, fatty acids and phospholipids). The study of Antarctic cyanobacteria is promising to find new analog biosignatures for Life in rocky habitable planets. This project is supported by the mini-ARC PUMA (ULiège, Belgium). [less ▲]

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See detailCharacterization of a non-toxic pyomelanin pigment produced by the yeast Yarrowia lipolytica
Ben Tahar, Imen ULiege; Kus-Liśkiewicz, Małgorzata; Lara, Yannick ULiege et al

in Biotechnology Progress (2019)

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See detailNew insights on the paleobiology, biostratigraphy and paleogeography of the pre-Sturtian microfossil index taxon Cerebrosphaera
Cornet, Yohan ULiege; François, Camille; Compère, Philippe ULiege et al

in Precambrian Research (2019)

Important biological and geological events occurred during the early Neoproterozoic. Among diversifying eukaryotic assemblages, populations of the distinctive robust organic-walled vesicular microfossils ... [more ▼]

Important biological and geological events occurred during the early Neoproterozoic. Among diversifying eukaryotic assemblages, populations of the distinctive robust organic-walled vesicular microfossils (acritarchs) Cerebrosphaera occur as a short-lived taxon in several late Tonian to early Cryogenian worldwide successions. Here we report the first occurrence of this taxon in the Bouenza Subgroup (Republic of the Congo), enlarging its paleogeographic distribution and biostratigraphic significance. We also attempt to determine its biological affinities, using a combined analytical approach on specimens from the Kanpa and Hussar Formations, Australia, and from the Svanbergfjellet Formation, Spitsbergen. Morphological and quantitative analyses were performed using light microscopy and scanning electron microscopy, on more than 200 specimens and 9 specimens, respectively. The analyses show fine-scale morphological details and a morphological continuum between the former species Cerebrosphaera ananguae and Cerebrosphaera buickii, confirming their synonymy as proposed by a recently revised taxonomy. These observations also highlighted the presence of a previously mentioned envelope, formerly described and illustrated here for the first time. Ultrastructural analyses performed with TEM revealed two types of complex (bilayered and trilayered) wall ultrastructures. The molecular structure and thermal maturity of the organic walls estimated using Infrared and Raman microspectroscopies, reveal the highly aromatic composition of Cerebrosphaera’s wall biopolymer with short/highly branched aliphatic chains unlike known biopolymers. The complex morphology, ultrastructure and recalcitrant chemistry, combined with the large size of Cerebrosphaera confirm its eukaryotic nature. Comparison with possible modern analogues permits to suggest an affinity to stem metazoan eggs. This hypothesis is consistent with estimates from molecular clocks and, if confirmed, would provide an older evidence for stem metazoans than the Cryogenian biomarker and Ediacaran body fossil records. Our study reveals that Cerebrosphaera populations are important for the late Proterozoic biostratigraphy, but also participated to the Neoproterozoic diversification eukaryotes in connected oceans. [less ▲]

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See detailThe nitrogen-isotopic composition of 1.1 billion-year-old porphyrins reveals oceans dominated by phototrophic bacteria.
Brocks, Jochen; Gueneli, Nur; McKenna, Amy M. et al

Conference (2019, September)

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See detailChallenges in evidencing the earliest traces of life
Javaux, Emmanuelle ULiege

in Nature (2019), 572

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See detailGeoscience for understanding habitability in the solar system and beyond
Dehant, Véronique ULiege; Airo, A; Debaille, Vincianne ULiege et al

in Space Science Reviews (2019), 215

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See detailEarly traces of life: challenges and evidence
Javaux, Emmanuelle ULiege

Conference (2019, July 03)

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See detailEarly eukaryote Paleobiology and Evolution
Javaux, Emmanuelle ULiege

Scientific conference (2019, May)

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See detailFirst Traces of Life: evidence and challenges
Javaux, Emmanuelle ULiege

Conference (2019, May)

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See detailEvolution and diversity of early Eukaryotes: insights from the Proterozoic of Arctic Canada
Loron, Corentin ULiege; Halverson, Galen; Rainbird, Robert et al

Poster (2019, May)

Detailed reference viewed: 39 (7 ULiège)
See detailEarly Traces of life
Javaux, Emmanuelle ULiege

Conference (2019, April)

Detailed reference viewed: 20 (2 ULiège)