18 research outputs found
Intravenous Tissue Plasminogen Activator Can Be Safely Given without Complete Blood Count Results Back
Calcium oxalates in biofilms on limestone walls of Maya buildings in Chichén Itzá, Mexico
Microbial biofilms frequently cause the esthetic and biological deterioration of stone monuments. Chichén Itzá, designated as a UNESCO World Heritage Site and as one of the seven new wonders of the world, is one Maya archeological site affected by biofilms. In the present study, we analyzed the biofilms at three different building complexes of Chichén Itzá: the Lower Temple of the Jaguars, the Temple of the Warriors, and Tzompantli. Samples of biofilms and detached rocks were taken from walls with abundant white-, green-, black-, and orange-colored biofilms. The morphology of rock fragments and dust was analyzed by electron and optical microscopy and was structurally characterized by X-ray diffraction. An HCl treatment (5% v/v) was subsequently applied to eliminate carbonates. The morphological analysis evidenced the presence of cyanobacteria, algae, and lichens. Some algae formed small nodules on orange- or black-colored rocks. Lichens were associated with a distinct mineral content on the inner surface of rocks versus on the outer surface. The presence of calcium oxalates such as weddellite (C2CaO4·2H2O) and whewellite (C2CaO4·H2O) and other minerals, including quartz and feldspars, was confirmed by X-ray diffraction. The lichens collected from the Lower Temple of the Jaguars and Tzompantli were therefore confirmed to disintegrate rock surfaces through biomineralization and the formation of oxalate crystals. At sites with greater solar radiation, a higher quantity of weddellite and a lower quantity of whewellite were observed. In conclusion, the establishment of microorganisms on the stone surfaces of Chichén Itzá causes esthetic damage and also leads to the biomineralization of these rock surfaces.Peer reviewe
The Study of Growth of Calogaya sp. PLM8 on Cyrus the Great’s Tomb, UNESCO World Heritage Site in Iran
The network of Shanghai Stroke Service System (4S): A public health-care web-based database using automatic extraction of electronic medical records
A review of the nature, role and control of lithobionts on stone cultural heritage: weighing-up and managing biodeterioration and bioprotection
Consistent changes in the taxonomic structure and functional attributes of bacterial communities during primary succession
Este artículo contiene 10 páginas, 3 figuras.Ecologists have long studied primary succession, the changes that occur in biological communities after initial colonization
of an environment. Most of this work has focused on succession in plant communities, laying the conceptual foundation for
much of what we currently know about community assembly patterns over time. Because of their prevalence and importance
in ecosystems, an increasing number of studies have focused on microbial community dynamics during succession. Here, we
conducted a meta-analysis of bacterial primary succession patterns across a range of distinct habitats, including the infant
gut, plant surfaces, soil chronosequences, and aquatic environments, to determine whether consistent changes in bacterial
diversity, community composition, and functional traits are evident over the course of succession. Although these distinct
habitats harbor unique bacterial communities, we were able to identify patterns in community assembly that were shared
across habitat types. We found an increase in taxonomic and functional diversity with time while the taxonomic composition
and functional profiles of communities became less variable (lower beta diversity) in late successional stages. In addition, we
found consistent decreases in the rRNA operon copy number and in the high-efficient phosphate assimilation process (Pst
system) suggesting that reductions in resource availability during succession select for taxa adapted to low-resource
conditions. Together, these results highlight that, like many plant communities, microbial communities also exhibit
predictable patterns during primary succession.ROA was supported through the Spanish FPI
PhD scholarships program (MINECO). Funding was provided by grants
BRIDGES, CGL2015-69043-P (ROA and EOC), and CTM2015-64728-
C2-2-R (AR) from the Spanish Office of Science (MINECO).Peer reviewe