11 research outputs found
Differences in Gender Norms Between Countries: Are They Valid? The Issue of Measurement Invariance
New multi-scale perspectives on the stromatolites of Shark Bay, Western Australia
A recent field-intensive program in Shark Bay, Western Australia provides new multi-scale perspectives on the worldâs most extensive modern stromatolite system. Mapping revealed a unique geographic distribution of morphologically distinct stromatolite structures, many of them previously undocumented. These distinctive structures combined with characteristic shelf physiography define eight âStromatolite Provincesâ. Morphological and molecular studies of microbial mat composition resulted in a revised growth model where coccoid cyanobacteria predominate in mat communities forming lithified discrete stromatolite buildups. This contradicts traditional views that stromatolites with the best lamination in Hamelin Pool are formed by filamentous cyanobacterial mats. Finally, analysis of internal fabrics of stromatolites revealed pervasive precipitation of microcrystalline carbonate (i.e. micrite) in microbial mats forming framework and cement that may be analogous to the micritic microstructures typical of Precambrian stromatolites. These discoveries represent fundamental advances in our knowledge of the Shark Bay microbial system, laying a foundation for detailed studies of stromatolite morphogenesis that will advance our understanding of benthic ecosystems on the early Earth
Stromatolites in the Paratethys Sea during the Middle Miocene climate transition as witness of the Badenian salinity crisis
Active eukaryotes in microbialites from Highborne Cay, Bahamas, and Hamelin Pool (Shark Bay), Australia
Brackish to hypersaline facies in lacustrine carbonates: Purbeck Limestone Group, Upper JurassicâLower Cretaceous, Wessex Basin, Dorset, UK
Classification of the Paleoproterozoic Gulcheru Formation: Implications on Early Paleogeographic and Tectonic Evolution of the Cuddapah Basin, India
Characterization of bacterial diversity associated with microbial mats, gypsum evaporites and carbonate microbialites in thalassic wetlands: Tebenquiche and La Brava, Salar de Atacama, Chile
Inner workings of thrombolites: spatial gradients of metabolic activity as revealed by metatranscriptome profiling
Microbialites are sedimentary deposits formed by the metabolic interactions of microbes and their environment. These lithifying microbial communities represent one of the oldest ecosystems on Earth, yet the molecular mechanisms underlying the function of these communities are poorly understood. In this study, we used comparative metagenomic and metatranscriptomic analyses to characterize the spatial organization of the thrombolites of Highborne Cay, The Bahamas, an actively forming microbialite system. At midday, there were differences in gene expression throughout the spatial profile of the thrombolitic mat with a high abundance of transcripts encoding genes required for photosynthesis, nitrogen fixation and exopolymeric substance production in the upper three mm of the mat. Transcripts associated with denitrification and sulfate reduction were in low abundance throughout the depth profile, suggesting these metabolisms were less active during midday. Comparative metagenomics of the Bahamian thrombolites with other known microbialite ecosystems from across the globe revealed that, despite many shared core pathways, the thrombolites represented genetically distinct communities. This study represents the first time the metatranscriptome of living microbialite has been characterized and offers a new molecular perspective on those microbial metabolisms, and their underlying genetic pathways, that influence the mechanisms of carbonate precipitation in lithifying microbial mat ecosystems