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Efficacy of orally used of red yeast (Phaffia rhodozyma) (1.6 mg astaxanthin/g product) at 15.5 g (P1), 37.3 g (P2) and 47 (P3) g per kg diet were studied on performance, carcass composition, antioxidant activity and fillet pigmentation in rainbow trout (Oncorhynchus mykiss) weighing 208–212 g for eight weeks at 11 °C. Synthetic astaxanthin (AX) (0.5 g/kg diet) and basal diet were used as controls. With an increase in P. rhodozyma concentration in diet, weight gain and specific growth rate exhibited an increase compared to basal diet (P < 0.05%). A significant difference was seen among the treatments but only P3 diet significantly demonstrated a better growth than AX diet (P < 0.05). Activity of antioxidant enzymes; superoxidase dismutase, glutathione peroxidase, total antioxidant activity, glutathione reductase, and catalase exhibited an enhancement in serum or liver samples of fish fed P. rhodozyma compared to basal diet (P < 0.05). Protein content in fillet of fish fed P3 diet was higher than both basal and AX diets (P < 0.05), but no significant difference was seen in contents of lipid, moisture, ash and pH values either among the treatments or between treatments and basal diet (P > 0.05). Water holding capacity and lipid loss in fillets of treatments were lower than fish fed basal diet (P < 0.05). By increasing P. rhodozyma concentration in fish diets, redness value exhibited a progressive increase, and the highest value was seen in P3 diet compared to other treatments (P < 0.05). These data show application of P. rhodozyma at 47 g/kg diet in trout could provide a better performance, antioxidant activities, and fillet pigmentation.

Animal populations are increasingly forced to live in small residual natural or semi-natural areas due to habitat loss and fragmentation. Here, the viability of populations is often compromised by intrinsic threat factors typical of small and isolated populations, such as inbreeding depression, genetic drift and environmental and demographic stochasticity. Under these circumstances, organisms may have low fitness due to inadequate physiological responses needed to face environmental challenges. However, few studies have investigated the relationship between habitat fragmentation and stress defences. In this study, we aimed to test whether an increase in the level of individual inbreeding produced an increase in the antioxidant system response. To this purpose, we genotyped 151 individuals of fire salamander Salamandra salamandra (Amphibia: Urodela) within five sampling populations, located in forest landscapes with different degree of fragmentation in northern Italy. For 113 individuals we also measured the glutathione-S-transferase (GST) and catalase (CAT) enzyme activity. Results showed a significant increase in individual GST activity for increasing levels of inbreeding, whereas no relationship was found for CAT. We also measured acetylcholinesterase to test the possible confounding effects of pesticides that might have occurred in fragmented landscapes with forests interspersed with agricultural areas. However, no difference in this enzyme activity was found among sampling populations. We argue that high levels of GST activity may be symptomatic of oxidative stress derived from inbreeding. An increased frequency of homozygous deleterious alleles due to inbreeding may cause homeostatic alterations and trigger the expression of GST for protection against hydrogen peroxide reactive oxygen species. We suggest using GST as a biomarker for environmental stressors with great caution and not to underestimate that the sources of stress deriving from habitat fragmentation

Plastic ingestion is one of the main impacts of marine litter on organisms. The occurrence of microplastics (MPs < 5 mm) in the stomachs of Mediterranean species was already reported in several studies. In this context, the present study aims to develop a new approach of digestion for the identification of MPs in the gastrointestinal tracts (GITs) of marine organisms. The new approach combines two digestion protocols, including potassium hydroxide (KOH) and nitric acid (HNO), to remove most organic and inorganic materials. This digestion allows recording small MPs that are difficult to find via routinely stomach content analysis and also to minimize the overestimation of the phenomenon trough the control of airborne contamination. The new approach was tested on a voracious pelagic opportunistic predator, the common dolphinfish, a fishery resource exploited in several Mediterranean areas. The results showed that a large amount of ingested meso- and microplastics, such as fragments or sheets, was recorded in GITs (F = 65.5 %). The FTIR analysis on litter samples allowed to identify polyethylene, polypropylene and polystyrene as dominant constituent polymers of microplastics. These results confirmed that our novel combined digestion protocol represents a reliable approach to detect MPs in opportunistic pelagic predators.