Anais da Academia Brasileira de Ciencias最新文献

The degradation of plastic materials has led to the emergence of new forms of reduced size (≤ 5 mm); know as microplastics (MPs). The presence of microplastics is a growing concern due to their persistence and, consequently, their ability to disseminate environmental pollutants. This review, in addition to providing an overview of the accumulation of plastic waste, which poses a risk to aquatic organisms and human health, seeks alternatives to mitigate this problem. To this end, we sought to address the main causes, sources, affected sites (soil, air, water), as well as the possible harmful effects caused by the presence of MPs on aquatic organisms and humans. The circular economy system has become an alternative for effectively reducing MPs in nature. In this context, we also presented an overview of trends in MP recycling, pollution control, and how proposed legislation on single-use plastic production is being discussed. Finally, an overview of scientific publications on the subject over the last ten years was presented.

Microplastic contamination has become an urgent concern for global ecosystems, especially for wildlife health in areas under intense anthropogenic pressures. This study analyzes the presence of microplastics in fruit bats (Phyllostomidae: Stenodermatinae and Carolliinae) in two Brazilian biomes: Cerrado and Amazon. Surprisingly, bats from the Amazon presented higher levels of contamination than those from the Cerrado, challenging the idea that more open and historically modified landscapes, such as the Cerrado, would have higher contamination. Land use and land cover classifications did not influence contamination levels, indicating that habitat-specific factors play a more relevant role. Contamination varied by organ, with the stomach presenting the highest concentrations in both biomes. Interestingly, bats from the subfamily Carolliinae, with more varied diets, presented higher contamination, probably due to dietary exposure and inhalation in anthropogenically altered areas. This study is the first to record microplastics in Cerrado bats and in detoxifying organs such as the liver. Our findings highlight the vulnerability of bats to microplastic pollution and the need for further research into its impacts, as well as suggesting conservation measures in regions of rapidly changing biodiversity.

Pursuing artificial enzymes through materials engineering allows mimicking the high reactivity of natural enzymes while attaching new and desirable properties to the final material. For this, the use of biopolymers - including from waste - as precursors stands out due to their biocompatible features, harmlessness, easy handling, and low cost. Herein, we repurposed Black Wattle gum, an industrial waste from the tannin industry, into an imidazole-functionalized biocatalyst for dephosphorylation reactions. The obtained sample, GNAIMZ, was fully characterized by colorimetric assays, carbon-13 nuclear magnetic resonance, and potentiometric titrations, proving the chemical modification proposed. Then, GNAIMZ was evaluated with organophosphate simulant diethyl 2,4-dinitrophenylphosphate (DEDNPP) and real pesticide Paraoxon, unveiling rate enhancements up to 107-fold compared to the reaction in the absence of biocatalyst. At last, GNAIMZ was applied in DNA cleavage assays, unraveling a nuclease-like activity leading to total degradation of plasmid DNA at pH 7.5 for 12 hours. Overall, this study showcases the successful valorization of a waste-derived gum into a dual-function artificial enzyme for dephosphorylation reactions capable of neutralizing toxic organophosphates and promoting DNA cleavage, reinforcing the promising features of biopolymers as scaffolds for synthetic enzymes - even from byproducts - pursued to chemical security and genetic engineering.

The knowledge of diet is essential to understanding species biology and thus fostering conservation strategies. This study described and compared the diet of six species of anurans in the family Hylidae (Boana punctata, B. raniceps, Dendropsophus leucophyllatus, D. walfordi, Lysapsus bolivianus, and Sphaenorhyncus lacteus), from a floodplain environment in the Brazilian Amazon. Research was conducted in the Lake Maicá complex, in Santarém municipality, Pará state, between April and August 2023. The diet of the six species was composed mainly of arthropods, with the order Diptera being the most common prey category, except in B. raniceps (Orthoptera) and S. lacteus (Formicidae). We observed a weak correlation between individual body size and the volume of prey consumed. Overall, niche overlap between species was high, with most having a broad trophic niche and generalist diets. The exception was S. lacteus, which had a diet which specialized on ants. Additionally, these findings emphasize the ecological role of hylid frogs in regulating some arthropods populations, reinforcing their significance in maintaining trophic dynamics in floodplain ecosystems.

The persistent accumulation of microplastics from synthetic polymers threatens ecosystems and biodiversity. The use of biodegradable and compostable materials as alternatives to conventional plastics in food packaging has shown promise, particularly with the development of nanocomposites that can be tailored to meet market demands. In this study, ZnO and TiO₂ nanoparticles were combined and incorporated into a biodegradable poly(butylene adipate-co-terephthalate) (PBAT) matrix at varying concentrations, forming a novel ternary PBAT/ZnO/TiO₂ system. The films produced via melt processing were characterized using conventional and non-conventional techniques to evaluate their thermal, morphological, chemical, wettability, and biosafety properties. The results indicated that the combined addition of ZnO and TiO₂ slightly reduced the thermal stability and crystallinity of PBAT, while increasing surface hydrophilicity. These features may contribute to accelerated degradation and reduced environmental persistence. Furthermore, improvements in the elastic modulus and enhanced biosafety were observed across all tested concentrations. These findings suggest that the prepared nanocomposites, particularly at 0.75 and 1 wt%, not only possess properties suitable for food packaging applications but also demonstrate potential to mitigate environmental persistence through accelerated degradation. Therefore, this study supports the development of environmentally friendly materials for food packaging, addressing the urgent need to reduce microplastic pollution.

Microorganisms often occur in association with macroalgae, with the term "phycosphere" referring to the seaweed surface where they may be present. Phycosphere represents a poorly explored niche of marine diversity, especially in the polar regions. DNA metabarcoding provides a new and accessible method for the detection of DNA from different organisms, especially applicable for poorly known groups where taxonomic expertise is limited or unavailable. In this study we used DNA metabarcoding to provide an initial survey of eukaryotic communities associated with marine macroalgae obtained from the shores of Svalbard. Samples of Ulvaria obscura were sequenced and the DNA reads found were assigned to 75 taxa of six Kingdoms and 17 phyla: Chromista (Ciliophora, Haptophyta, Ochrophyta, Oomycota and Chrysophyta), Fungi (Ascomycota, Basidiomycota, Chytridiomycota, Mortierellomycota and Rozellomycota), Holozoa (Ichthyosporia), Metazoa (Cnidaria), Protozoa (Cercozoa, Discosea and Heterolobosea) and Viridiplantae (Bryophyta and Chlorophyta). The most abundant group was Viridiplantae, followed by Fungi. Our environmental DNA study confirmed that the phycosphere of U. obscura shelters a rich and complex microbiome, suggesting that Arctic macroalgae provide a hotspot of currently undescribed polar biodiversity. Additionally, our results were obtained during the first official Brazilian Arctic expedition, representing a historic step for the Brazilian Antarctic Program (PROANTAR).

Meta-analyses have shown modest weight loss with physical training. Low training load can be one possible cause, however this has not yet been investigated. This cross-sectional study investigated the correlation between training load parameters and the body composition of 335 individuals engaged in exercise (47.9 ± 12.7 years, 138 males). Data on exercise frequency, intensity, duration, and body composition were collected. Men showed significantly higher energy expenditure during training (632.5, 95% CI: 560.0 - 704.5) compared to women (280.4, 95% CI: 253.9- 306.8). Greater energy expenditure was inversely correlated with lower body mass index (r=-0.23; p<0.05), body fat percentage (BF%) (r=-0.53; p<0.05), fat mass (r=-0.37; p<0.05), waist-to-hip ratio (r= -0.31; p<0.05), and visceral fat (r=-0.38; p<0.05) in both sexes. Significant correlations persisted when considering confounding factors among men, except for skeletal muscle mass. For women, only BF% and skeletal muscle mass correlations remained. Linear regression analysis indicated that to attain a BF% below 20%, individuals needed to expend 9.07 kcal/kg per training session in seven weekly sessions (r2= 0.33); however, only 15.2% of the participants met this energy demand. Thus, an adequate maintenance of adequate body fat levels appears to be dependent on individuals with a high energy expenditure during training, without significant reliance on other influencing factors.

The fossil remains of Thanatosdrakon from the Plottier Formation (PS-3 quarry, Mendoza, Argentina) offer a unique opportunity to investigate the preservation of pterosaurs in fluvial environments. The objective of this study is to reconstruct the taphonomic history of the holotype (UNCUYO-LD 307) and paratype (UNCUYO-LD 350). Detailed stratigraphic analysis together with taphonomic attributes allowed defining that the specimens were preserved with a variable drainage floodplain taphonomic mode (VDF-BA). Distinct taphonomic submodes were defined for each specimen, reflecting differences in biostratinomic and fosildiagenetic processes. The holotype, which was discovered in reddish pelites interpreted as floodplain deposits, exhibits associated skeletal elements suggesting rapid burial. In contrast, the paratype, composed of only one humerus, exhibits evidence of prolonged subaerial exposure, which is evidence that it was exposed to different paleoenvironmental conditions. These findings underscore the variable preservation pathways within the same depositional setting and highlight the influence of both rapid burial and prolonged exposure on the fragile skeletons of large pterosaurs. The taphonomic submodes that have been defined contribute valuable insights into the taphonomic biases that have shaped the pterosaur fossil record in the Cretaceous Patagonian basins.

Thalassemia, an autosomal recessive genetic disorder affecting production of normal globin chains, presents varying prevalence worldwide. The frequency of global α-thalassemia remains understudied, especially in Brazil, due to its genetic diversity and large population size. This study compared α-thalassemia frequency between microcytic patients and healthy volunteers in Rio de Janeiro, stratified by self-reported skin color. DNA extracted from whole blood/EDTA underwent genotyping for α-thalassemia using multiplex PCR, targeting α3.7 kb, α4.2 kb, αSEA, αMED, αFIL, and α20.5 kb deletions. Frequency of α-thalassemia among patients was 63.6%, distributed as follows: 62.1% for α3.7 kb deletion, 0.7% for α4.2 kb deletion, and 0.8% for αSEA deletion. In healthy volunteers, the prevalence was 3.2%, distributed as 0.53% in self-declared white, 1.07% in brown, and 1.60% in black individuals, all presenting heterozygous genotype for α3.7 kb deletion. Frequency in healthy population was significantly lower than that observed in microcytosis population (p < 0.001). Determining α-thalassemia frequency in highly admixed population may enhance genetic counseling, given that asymptomatic carriers can produce offspring with combinations of Hb variants, potentially leading to severe clinical phenotypes.