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We performed qualitative and quantitative analysis of surfaces of kefir biofilms loaded with Amazon rainforest fruit extract. Scanning electron microscopy and atomic force microscopy were used to evaluate the micromorphology of the biofilms. The films surface displayed a lower density of microorganisms (∼ 0.061 microorganisms/μm 2 ) for the lowest concentration of fruit extract, however, a greater density (∼0.220 microorganisms/μm 2 ) was observed for the higher concentration. Height stereometric parameters revealed that the biofilms with the highest concentration presented the highest roughness. However, almost all the stereometric parameters related to texture showed no significant difference. Furthermore, the Hurst coefficients of the average power spectrum density were similar for all biofilms. Fractal parameters confirmed that higher concentrations of fruit extract induced a superior topographic irregularity. However, fractal lacunarity does not show any significant difference confirming the similarity of the microtextures. Moreover, fractal succolarity and surface entropy exhibited values that suggested ideal percolation and strong topographic uniformity, respectively, indicating that these films can uniformly adhere to other surfaces. Our results confirm that the stereometric and fractal parameters can be relevant for the surface characterization of microbial films, which can be of great importance to the biomedical field., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Adaptive responses of antioxidant defense systems (ADS) to changes in increased levels of activity are critical, especially in Antarctic fishes. The benthopelagic marbled notothen (Notothenia rossii) shows higher spontaneous activity than the benthonic and sluggish rockcod (N. coriiceps). Therefore, we hypothesize that species-related responses of ADS would occur to counteract different rates of reactive oxygen species formation in these two Antarctic fish. Here we evaluated ADS and oxidative damage in tissues (brain, gills, liver and white muscle) of the two Antarctic fish. Despite no significant differences in lipid and protein oxidative damage were observed, we actually found species- and tissue-specific differences in ADS. Gill metallothionein-like proteins (MTLP) and liver reduced glutathione (GSH) concentrations were higher in N. coriiceps than in N. rossii. Brain and gill antioxidant capacity against peroxyl radicals (ACAP); gill enzyme [glutamate-cysteine ligase (GSL), superoxide dismutase (SOD) and catalase (CAT)] activity; liver GCL and SOD activity; and white muscle CAT activity were higher in N. rossii than in N. coriiceps. Therefore, the more active fish (N. rossii) maintains higher activities of enzymes involved in superoxide ions (O 2 .- ) detoxification and GSH production in peripheral tissues (gills, liver and white muscle). This allows the more active fish (N. rossii) to keep levels of lipid and protein oxidative damage similar to those observed in the sluggish fish (N. coriiceps). It is worth noting that the more active fish also shows a higher brain antioxidant capacity, which could involve other non-enzymatic antioxidants like vitamins C and E. In contrast, N. coriiceps shows lower consumption of non-enzymatic antioxidants in peripheral tissues than N. coriiceps. As hypothesized, our results indicate that differences in ADS profiles between fish species are likely related to their habits and metabolic rates. This would imply in different fish abilities to deal with oxidative stress associated with increasing seawater temperature., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Antioxidant defense system (ADS) and oxidative stress parameters were evaluated in the Antarctic fish Notothenia rossii and N. coriiceps exposed to increasing temperature. Acclimated fish were kept at 0°C or exposed to 4°C for 1day (N. rossii) or to 2 and 4°C for 1 and 6 days (N. coriiceps). Measurements were assessed in brain, gills, liver, white muscle and erythrocytes. Parameters analyzed included antioxidant capacity against peroxyl radicals (ACAP); reduced glutathione (GSH) and metallothionein-like proteins (MTLP) concentration; superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutamate-cysteine ligase (GCL) activity; lipid peroxidation (LPO) level and protein carbonyl (PC) concentration. Increased liver GST activity was observed in N. rossii exposed to 4°C for 1day. Increased muscle GPx activity was observed in N. coriiceps after exposure to 2°C for 1day. Reduced gill GPx activity and increased liver SOD activity were observed after exposure to 4°C for 1day. In N. coriiceps, increased gill GCL activity and reduced gill GPx activity, as well as reduced liver MTLP were observed after exposure to 2°C for 6 days. Reduced brain SOD activity and increased brain LPO; reduced gill ACAP, GSH concentration and GPx activity, as well as increased gill GCL activity; reduced liver ACAP, MTLP, SOD activity, GST activity and increased liver and erythrocytes LPO were observed after exposure to 4°C for 6 days. These findings indicate that ADS is more responsive to short-term increasing temperature in the sluggish N. coriiceps than in the active N. rossii. However, responses of N. coriiceps to long-term increasing temperature were transient and did not prevent tissue oxidative damage. Considering the predicted increase in temperature in the Southern Ocean over the next decades, our findings suggest that Antarctic fishes are sensitive to ocean warming, displaying tissue oxidative damage associated with the thermal stress., (Copyright © 2017 Elsevier Ltd. All rights reserved.)