By a News Reporter-Staff News Editor at Life Science Weekly -- Investigators publish new report on Biogeoscience. According to news reporting out of Mexico City, Mexico, by NewsRx editors, research stated, "The search for microfossils in the geological record has been a long-term challenge. Part of the problem comes from the difficulty of identifying such microfossils unambiguously, since they can be morphologically confused with abiotic biomorphs."
Our news journalists obtained a quote from the research from National Autonomous University, "One route to improve our ability to correctly identify microfossils involves studying fossilization processes affecting bacteria in modern settings. We studied the initial stages of fossilization of cyanobacterial cells in modern microbialites from Lake Alchichica (Mexico), a Mg-rich hyperalkaline crater lake (pH 8.9) hosting currently growing stromatolites composed of aragonite [CaCO3] and hydromagnesite [Mg-5(CO3)4(OH)(2)center dot 4(H2O)]. Most of the biomass associated with the microbialites is composed of cyanobacteria. Scanning electron microscopy analyses coupled with confocal laser scanning microscopy observations were conducted to co-localize cyanobacterial cells and associated minerals. These observations showed that cyanobacterial cells affiliated with the order Pleurocapsales become specifically encrusted within aragonite with an apparent preservation of cell morphology. Encrustation gradients from non-encrusted to totally encrusted cells spanning distances of a few hundred micrometers were observed. Cells exhibiting increased levels of encrustation along this gradient were studied down to the nm scale using a combination of focused ion beam (FIB) milling, transmission electron microscopy (TEM) and scanning transmission x-ray microscopy (STXM) at the C, O and N K-edges. Two different types of aragonite crystals were observed: one type was composed of needle-shaped nano-crystals growing outward from the cell body with a crystallographic orientation perpendicular to the cell wall, and another type was composed of larger crystals that progressively filled the cell interior. Exopolymeric substances (EPS), initially co-localized with the cells, decreased in concentration and dispersed away from the cells while crystal growth occurred. As encrustation developed, EPS progressively disappeared, but remaining EPS showed the same spectroscopic signature."
According to the news editors, the research concluded: "In the most advanced stages of fossilization, only the textural organization of the two types of aragonite recorded the initial cell morphology and spatial distribution."
For more information on this research see: Cyanobacterial calcification in modern microbialites at the submicrometer scale. Biogeosciences, 2013;10(8):5255-5266. Biogeosciences can be contacted at: Copernicus Gesellschaft Mbh, Bahnhofsallee 1E, Gottingen, 37081, Germany. (Copernicus Publications - www.copernicus.org; Biogeosciences - publications.copernicus.org)
Our news journalists report that additional information may be obtained by contacting E. Couradeau, National Autonomous University of Mexico, Dept. of Ecol & Recursos Nat, Mexico City 04510, DF, Mexico. Additional authors for this research include K. Benzerara, E. Gerard, I. Esteve, D. Moreira, R. Tavera and P. Lopez-Garcia (see also Biogeoscience).
Keywords for this news article include: Mexico City, Biogeoscience, North and Central America
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