Anais da Academia Brasileira de Ciencias最新文献

The objective of this study was to investigate the chemical composition of Syzygium aromaticum essential oil (SAEO), both as its toxicity and biological activities on Corynebacterium diphtheriae. The essential oil (EO) was obtained by hydrodistillation and verified by GC-MS. The main chemical components were eugenol (48.79%), caryophyllene (44.29%) and α-humulene (4.87%). In vitro tests with human red blood cells, blood compatibility. SAEO showed high toxicity for Artemia salina and the bioassay on Tenebrio molitor larvae revealed an average survival rate of 80.00%. The antioxidant activity of SAEO was moderate (40.60%) using the phosphomolybdenum method. SAEO inhibited the growth of all C. diphtheriae strains tested at minimum inhibitory concentrations of 62.5-1000 µg mL-1 (strong to moderate). The minimum bactericidal concentration of SAEO was observed in two strains. Microorganisms cultivated in the presence of subinhibitory concentrations (subMIC) do not show morphological changes. The subMIC of SAEO inhibited in some strains, but in most cases, increased biofilm formation. In conclusion, the results of this study found that SAEO has an inhibitory effect against C. diphtheriae, representing an alternative antimicrobial therapy, although more in vivo biological studies, alone or in combination with occasional antimicrobials, should be carried out to better evaluate its effects.

This article reports the development of a beer made with Baccharis dracunculifolia and its application in an experimental model of diabetes. Initially, the production of the beverage was standardized in order to incorporate the plant extract properly. Next, the beer was analyzed by the UHPLC-MS to identify the substances present. Among others, caffeic acid (5.85 mg / L), m-coumaric acid (5.16 mg / L), pinocembrin (2.99 mg / L), chrysin (10.86 mg / L), myricetin (1.73 mg / L) and spathulenol (9.30 mg / L) were found. Animal tests indicate improvement in biochemical and histological parameters of STZ-induced Wistar rats that ingested the beer made with the plant. The antidiabetic potential of this beverage was observed in the different tests that evaluated insulin resistance and the decrease of the clinical manifestations of diabetes in animals. The use of the drink as an adjunct in clinical treatments for DM2 may be useful, especially in suppressing the oxidative damage caused by the disease.

Understanding lectin-carbohydrate interactions at the structural and molecular levels is crucial to the field of lectins, as the diverse roles and biological activities exhibited by these proteins are fundamentally linked to their specific binding to target glycoconjugates. This study aimed to apply molecular dynamics to analyze the structure and binding properties of Parkia lectins. 3D structures of Parkia platycephala and P. biglobosa lectins, both unliganded and in complex with D-mannose, were used as inputs for simulations. The trajectories data enabled the study of stability, carbohydrate-binding interactions, and intermonomeric contacts for both proteins. The results revealed stable binding of D-mannose within the lectin domains and their binding mode at each of the three domains, displaying consistent binding motifs across the sites, with slight variations between the lectins and other Jacalin-related lectins. Despite these variations, the binding energies of the lectins with the ligand, as estimated using MM/GBSA, demonstrated favorable interactions in all cases. The dimeric interfaces of both lectins could be identified, and the main contacts have been mapped. These findings enhance our understanding of lectin-carbohydrate interactions and provide insights into the structural properties of Parkia lectins for potential biological and therapeutic applications.

Some Antarctic ice-free areas have been affected by changes in lacustrine zones and permafrost thawing due to rising air temperatures over the last 60 years Temperature time-series were analyzed to understand the processes leading to the changes of Boeckella and Buenos Aires lakes, north Antarctic Peninsula. Statistical calculations were applied to average, maximum, and minimum temperatures, as well as to indexes such as Positive Degrees Day, Freezing/Thaw Day, and days with temperatures ≥ 0 °C and ≥ 10 °C. Changes in the region over recent decades were observed in mean and maximum temperatures and an increase in minimum temperature since the mid-1990s. In addition, the Normalized Difference Water Index was extracted from Landsat images from 2003, 2016, 2020, and 2021. These images were used to calculate changes in the areas of Boeckella and Buenos Aires lakes. These data revealed an 87% decrease in the area (m²) of Boeckella Lake and a 60% increase in Buenos Aires Lake´s area (m²). Concern has been raised about the modifying lake areas in the Antarctic Peninsula, where the collapse of Boeckella Lake could be the first case recorded in ice-free areas of Antarctica continent.

Glaciers are sensitive to environmental climatic conditions and show their variability over time. This study investigates the environmental characteristics and variation in glacial cover of the Greenwich, Livingston, Robert and Snow islands, Antarctica, between 1956 and 2023. The glacier extension mapping was based on visual interpretation of the Landsat 4, 7 and 8 optical images and normalised difference indexes combination. The REMA 8 digital elevation model was applied to the islands' geomorphometric analysis. Results were compared to climatic series and environmental characteristics. The glacial coverage decreased by 16.9% from 1956 to 2023, equivalent to 209.95 ± 0.113 km². Snow Island, with shallow bathymetry near glacial margins and land-terminating ice-fronts, exhibited the smallest retreat rate values. The glacial coverage of Livingston Island decreased significantly (18%, equivalent to 153.2 ± 0.113 km²) from 1956-2021, representing the highest values in the study. The changes in glacial coverage of the Robert and Greenwich islands were more substantial in the 1989-2023 period than in 1956-1989. Sectors with marine-terminating glaciers, associated with high bathymetric amplitudes, exhibited more significant variations compared to other sectors, contributing to the evolution of fjord-type bays. Glacial coverage has been lost in recent decades due to regional atmospheric and oceanic warming.

Understanding the temporal dynamics of high-fat diets (HFD) effects on behavior and metabolism is crucial for comprehending their negative impact on organisms. This study investigated the short-term effects (15, 25, and 35 days) of HFD in Swiss mice. Our findings revealed distinct behavioral and metabolic changes throughout the treatment. After 15 days of HFD, mice exhibited impaired exploratory habituation and significant increases in visceral adipose mass, fasting glucose levels, and glucose intolerance. Extending the diet to 25 days intensified the metabolic effects, resulting in compromised acquisition of recognition memory, increased body mass gain, and elevated plasma total cholesterol and triglyceride levels. After 35 days of HFD, these effects were further intensified and accompanied by anxiogenic-like responses in the open field test. Additionally, we observed a positive correlation between metabolic changes and behavioral impairments alongside prefrontal cortex mitochondrial dysfunction. In conclusion, our study reveals the temporal dynamics of behavioral and metabolic changes induced by short-term HFD in Swiss mice, highlighting the relationship between metabolic dysfunction and behavioral impairments. These findings pave the way for future research to unravel the underlying mechanisms and develop strategies to counteract the detrimental effects of HFD on behavior and metabolism.

Dissolved organic carbon (DOC) is a key component of the biogeochemical carbon cycle in the Southern Ocean. However, there are still significant gaps in understanding the role of DOC in polar environments, due to the limitations of spatiotemporal sampling. In this study, we investigated the regional aspects controlling the distribution and diffusive and advective fluxes of DOC along the northern Antarctic Peninsula (NAP) during austral late summers of 1995 and between 2015 and 2019. DOC concentrations ranged from 33.1 to 157.6 μmol kg-1. The NAP showed regional differences in both its hydrographic conditions and DOC distribution. The regional variability reflected the main biogeochemical sources and fates of DOC associated with the Antarctic Circumpolar Current inflows, the Weddell Gyre transport and the meltwater input. The intensity of the advective fluxes of DOC was 106 times greater than the diffusive fluxes. However, ocean fronts along NAP environments are mesoscale structures for observations of downward and upward diffusive fluxes of DOC. This study adds insights on the role of DOC as a proxy for a better understanding of the coupling between physical and biogeochemical processes over time in an environment sensitive to climate change.

The use of agro-industrial wastes as biosorbents is a promising alternative for sustainable, economical and effective adsorption. However, few studies evaluate the use of Brazilian agro-industrial waste as biosorbents without physicochemical pre-treatment. This study explored the potential of sugarcane bagasse (SCB) and rice husk waste (RHW) as low-cost biosorbents for yellow tartrazine dye removal. Characterization of the materials were carried out using ATR-FTIR, SEM, pHPZC and lignocellulosic composition. Cellulose and hemicellulose were the major constituents of both materials. By the Box-Behnken experimental design, the response surfaces indicated maximum removal of 60.1% for SCB and 83.1% for RHW. While the qmax of SCB and RHW for tartrazine were relatively low at 2.45 ± 0.03 mg g-1 and 3.55 ± 0.02 mg g-1, respectively, the potential for achieving higher dye removals by increasing the adsorbent dosage in large-scale applications warrants further investigation. For both biosorbents, the pseudo-second-order kinetic model and Brouers-Sotolongo isotherm provided the best fit for the data, and the adsorption processes were spontaneous and exothermic. In conclusion, SCB and RHW demonstrated high tartrazine removal, promoting sustainable agro-industrial waste management.

Dark Septate Endophytic (DSE) fungi can benefit plants by optimizing nutrient uptake, biosynthesis of phytohormones-like compounds, and stress relief such as toxic metals. The objective was to characterize in vitro 57 strains of the DSE Periconia macrospinosa isolated from sugarcane roots, indicating the most promising in solubilizing phosphate sources, growing in different metal and vinasse contents, and producing molecules related to indoleacetic acid (IAA). The strains were from the Embrapa Agrobiology Fungi Collection. Over 35% of the strains solubilize calcium phosphate, highlighting A356 and A155. No strain solubilizes aluminum phosphate. Three strains did not grow in the presence of Cd (A333, A334, A163), but A226, A332, and A423 stand out showing high growth with Cd. All strains grew in the presence of Cu, Zn, and Vinasse. A163, A164, and A328 were even stimulated by Cu addition. A331 and A335 showed a marked growth decrease with Zn. All strains are highly adapted to grow in vinasse presence. A257 and A226 produced the highest amount of IAA. The most biotechnological potential strains are indicated by presenting high growth under Cd, Cu, Zn, and vinasse stress, associated with a high tolerance index to these pollutants, further calcium phosphate solubilization, or IAA production.

Shell beds, or coquinas, have a complex origin, limiting their utility in paleoecology. However, such accumulations can serve as crucial paleoenvironmental indicators, since their bioestratinomic and diagenetic properties explain the physical-chemical and biological processes of their formation, as well as the ancient environments linked to their development. In 2016, the PALEOANTAR Project sampled coquinas from the James Ross Island (Antarctic Peninsula) in Passo São José (PSJ - San José Way) and Muro do Castelo (MDC - Castle Wall), two new localities with outcrops of the lower Lachman Crags Member, Santa Marta Formation, Marambio Group, Cretaceous of Larsen Basin. The paleontological content and sedimentary structures indicate a shallow marine depositional system. The PSJ coquina are composed by gastropods bioclasts, with predominantly dense/loose packing. The MDC presents a larger variety of bioclasts with bivalve dominance on a loose packing and conglomeratic horizons, that varies from granule to pebble. Sedimentary and biostratinomic features observed in samples from both localities indicate their genesis from high-energy events, characterized as a proximal tempestite. These descriptions allow a more accurate reconstruction of the depositional environments, highlighting the importance of these rocks in the geological record during the Cretaceous of Antarctica.