Coccomyxa onubensis (C. onubensis) is an acidotolerant microalga isolated from Tinto River (Huelva), which contains high levels of metal cations in solution, mainly Fe (II) and (III), and Cu (II). Fe is more bioavailable at low pH, mainly because Fe (II) and Fe (III) are far more soluble, especially Fe (III). For this reason, this study aims to evaluate both physiological and biochemical responses of C. onubensis when subjected to Fe (III)-induced stress. Changes in growth, photosynthetic viability and antioxidant responses to the induced oxidative stress were determined. The results obtained suggest that the addition of moderate Fe (III) levels to C. onubensis cultures results in improved growth and photosynthetic viability. Increases in the intracellular levels of the enzyme superoxide dismutase (SOD) and flavonoids, used as antioxidant response biomarkers, a point at Fe (III)-mediated oxidative stress induction. The apparent decrease in the content of other phenolic molecules and polyunsaturated fatty acids might be understood as a sign of antioxidant molecules' involvement in reactive oxygen species (ROS) scavenging. In conclusion, a noticeable antioxidant capacity displayed by C. onubensis allows the use of moderate Fe (III) levels to trigger the accumulation of valuable antioxidant molecules, allowing the production of cell extracts with potential anti-inflammatory activity.

Coccomyxa onubensis (C. onubensis) is an acidotolerant microalga isolated from the extremely acidic Tinto River (Huelva), which contains high levels of metals in solution, mainly Fe and Cu. This makes C. onubensis an adequate candidate to easily cope with high levels of oxidative stress by increasing the levels of certain molecules and enzymes, which helps them elicit an adequate antioxidant biochemical response. Thus, C. onubensis is a promising source of bioactive compounds which exhibit in vitro anti-inflammatory activity, including fatty acids, (poly)phenolic compounds and carotenoids. In this study, the correlations between the antioxidant response and anti-inflammatory activity of cell extracts obtained from Fe (III)-stressed microalgal cultures were analyzed. The results suggested a direct relationship between the antioxidant capacity of the microalgal extracts and Fe (III) concentration in the culture medium. Consequently, the production of some of the target antioxidant molecules, including carotenes, xanthophylls and (poly)phenols, increased. The levels of these molecules increased the most in cell extracts obtained from microalgal cultures at 0.25 mM of Fe (III), which was correlated with a 50 % increase in the anti-inflammatory activity of the microalgal extracts in THP-1 differentiated human macrophages. Fe (III)-modulated oxidative stress allowed us to define culture conditions that can enhance the anti-inflammatory activity of C. onubensis extracts, which are enriched in valuable antioxidant molecules. Overall, this study highlighted the utility of a microalgal species from a highly acidic environment as a novel, natural source of anti-inflammatory agents, based on its ability to cope with the oxidative conditions of its habitat.

The aim of this work was to compare the potential induction of oxidative stress and the antioxidant enzymatic response after a short-term waterborne exposure to copper (Cu) and arsenic (As) with that of the nanoparticles (NPs) of these elements (Cu-NPs and As-NPs) in fish larvae of the species Dicentrarchus labrax. Larvae were grouped in several tanks and exposed to different concentrations of contaminants (0 to 10 mg/L) for 24 or 96 h under laboratory conditions. Copper and arsenic concentrations were analysed in larval tissues using ICP-MS. A set of oxidative stress biomarkers, including the levels of hydroperoxides (HPs), and superoxide dismutase (SOD) and catalase (CAT) activities were assessed. The trace element concentrations (mg/kg d.w.) in larvae ranged as follows: 3.28–6.67 (Cu at 24 h) and 2.76–3.42 (Cu at 96 h); 3.03–8.31 (Cu-NPs at 24 h) and 2.50–4.86 (Cu-NPs at 96 h); 1.92–3.45 (As at 24 h) and 2.22–4.71 (As at 96 h); and 2.19–8.56 (As-NPs at 24 h) and 1.75–9.90 (As-NPs at 96 h). In Cu tests, the oxidative damage (ROOH levels) was induced from 0.1 mg/L at both exposure times, while for Cu-NPs, this damage was not observed until 1 mg/L, which was paralleled by concomitant increases in SOD activity. The CAT activity was also increased but at lower metal concentrations (0.01 mg/L and 0.1 mg/L for both chemical forms). No oxidative damage was observed for As or As-NPs after 24 h, but it was observed for As after 96 h of treatment with 0.01 mg/L. A decrease in SOD activity was observed for As after 24 h, but it turned out to be increased after 96 h. However, As-NPs did not alter SOD activity. The CAT activity was stimulated only at 96 h by As and at 24 h by As-NPs. Therefore, the two chemical forms of Cu exhibited a higher bioaccumulation and toxicity potential as compared to those of As. Importantly, the association of both Cu and As in NPs reduced the respective trace metal bioaccumulation, resulting also in a reduction in the toxic effects (mortality and biochemical). Furthermore, the assessment of oxidative stress-related biomarkers in seabass larvae appears to be a useful tool for biomonitoring environmental-occurring trace elements.

The aim of this study was to assess the ontogenetic changes in vitro in both the responsiveness of anterior pituitary tissue to growth hormone-releasing hormone (GHRH) and the critical role of GHRH in the long-term regulation of pulsatile GH secretion during perinatal porcine life. A superfusion system was used to apply three consecutive 10-min pulses of GHRH (the first of 1 nM and the other two of 10 nM) for 3 consecutive days in pituitary glands isolated from fetal (95- and 110-day) and neonatal (12-day) male pigs. In fetuses, total GHRH-induced GH release decreased progressively over the 3 days. However, in neonates, GH did not decrease until day 3, but remained higher than in fetuses. When each GH pulse was assessed individually, fetuses showed a similar pattern. GH secretion induced by the first GHRH pulse on days 1 and 2 was lower than that induced by the second and third pulses. By day 3, GH release lowered dramatically after all pulses. In contrast, in neonates no differences were observed among the GH levels induced by the three GHRH pulses at any day, although day 3 showed lower GH rates. In conclusion, during perinatal development, a desensitizing effect to long-term repetitive GHRH pulses was observed in both fetuses and neonates, but this effect was delayed in neonates. Thus, the capacity of somatotrope cells to maintain GH response to GHRH seems to be developmentally regulated during perinatal stages. Furthermore, the frequency of GHRH pulses, rather than the concentrations, might be a key factor to elicit desensitization.

Coccomyxa onubensis (C. onubensis) belongs to the extensive genus Coccomyxa, which inhabits ecosystems with high metal concentrations, generally at acidic pH. In this study, the feasibility of cultivating the acidotolerant microalga C. onubensis in raceway open ponds was investigated. Specific attention was paid to the production of lipids and carotenoids. C. onubensis was cultivated outdoors, under non-sterile conditions, in three separate ponds that differed in their nutrient concentrations and aeration rates. The results show that C. onubensis was able to grow steadily and free of photosynthetic contaminants throughout the cultivation period. The low pH of the media prevented non-extremophilic competitors from proliferating, thus allowing for the selective growth of C. onubensis. The highest productivity values for the biomass and targeted compounds were obtained in the culture supplemented with twice the amount of nutrients and aeration rate. These significant maximum productivity values were 0.223 mg of carotenoids·g⁻¹·d⁻¹, 0.139 mg of chlorophylls·g⁻¹·d⁻¹, and 0.031 g of biomass·L⁻¹·d⁻¹. A significant maximum lipid production of 9.87% in the dry biomass was reached, of which 49.92% corresponded to polyunsaturated fatty acids (PUFAs). Overall, this manuscript demonstrates that the production of acidic-habitat microalgae in open systems can be advantageous for microalgae-based production of carotenoids and PUFAs, while avoiding contamination by photosynthetic competitors.