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The study of the paleoenvironment depends upon proxies of palaeovegetation associated with chronological records. Carbon stable isotopes in soil samples provide information on the past vegetation type due to differences in mass fractionation during photosynthesis. Radiocarbon measurements on soil organic matter may also have different behaviors, given the complexity of soils as mixtures of multiple sources. With the aim of investigating how different soils, under different vegetation coverages, may affect paleoenvironmental reconstructions, we have analyzed four soil profiles collected at the Itatiaia National Park, between Rio de Janeiro and Minas Gerais states in Brazil, in the context of the Atlantic Forest biome, at altitudes between 1898m and 2457m. Different chemical fractions of the bulk soil were separately 14C dated for each sample depth. For the total soil and the non-hydrolyzable carbon, discrepancies in pMC values were mostly within 5% from the humin fraction values. Two Histosol profiles collected under forest vegetation on a hillside presented very different morphologies and chronologies, possibly related to colluvium effect, indicated by the deposition of originally older material. The results for a Histosol profile under grassland indicates that C3 plants were the dominant vegetation over most of the last 8000 years at the most distant location while a Cambisol profile under transitional vegetation shows variations, with C3 plants at ca. 2 kyr BP, switching to C4 before ca. 700 yr BP, suggesting anthropic influence. [ABSTRACT FROM AUTHOR]

We recovered 195 fungal isolates from the sediments of different lakes in the Antarctic Peninsula, which were screened to detect bioactive compounds. Forty-two taxa belonging to the phyla Ascomycota , Basidiomycota , and Mortierellomycota were identified. Thelebolus globosus , Antarctomyces psychrotrophicus , Pseudogymnoascus verrucosus , Vishniacozyma victoriae , and Phenoliferia sp. were found to be the most prevalent. The fungal assemblages showed high diversity and richness, but low dominance values. However, the diversity indices and fungal distribution ranged according to the different lake sediments. Sixty fungal extracts displayed at least one biological activity against the evaluated targets. Among them, Pseudogymnoascus destructans showed selective trypanocidal activity, Cladosporium sp. 1 and Trichoderma polysporum showed antifungal activity, and Pseudogymnoascus appendiculatus and Helotiales sp. showed high herbicidal activity. We detected a rich and diverse fungal community composed of cold cosmopolitan and psychrophilic endemic taxa recognized as decomposers, symbiotics, pathogens, and potential new species, in the sediments of Antarctic lakes. The dynamics and balance of this fungal community represents an interesting aquatic web model for further ecological and evolutionary studies under extreme conditions and potential climate changes in the regions. In addition, we detected fungal taxa and isolates able to produce bioactive compounds that may represent the source of prototype molecules for applications in medicine and agriculture. Image 1 • We access fungi present in the sediments of lakes of Antarctica. • Taxa belonging to cold cosmopolitan and psychrophilic endemic taxa. • Fungi demonstrated trypanocidal, herbicidal, and antifungal activities. • Decomposers, symbiotics, pathogens, and potential new species were detected. [ABSTRACT FROM AUTHOR]