Regulated autophagy is involved in the repair of renal ischemia-reperfusion injury (IRI). ω3-Polyunsaturated fatty acids (ω3-PUFAs) show protective effects against various renal injuries. It was recently reported that ω3-PUFAs regulate autophagy. We assessed whether ω3-PUFAs attenuated IR-induced acute kidney injury (AKI) and evaluated associated mechanisms. C57Bl/6 background fat-1 mice and wild-type mice (wt) were divided into four groups: wt sham (n = 10), fat-1 sham (n = 10), wt IRI (reperfusion 35 min after clamping both the renal artery and vein; n = 15), and fat-1 IRI (n = 15). Kidneys and blood were harvested 24 h after IRI. Renal histological and molecular data were collected. The kidneys of fat-1 mice showed better renal cell survival, renal function, and pathological damage than those of wt mice after IRI. In addition, fat-1 mice showed less oxidative stress and autophagy impairment; greater amounts of LC3, Beclin-1, and Atg7; lower amounts of p62; and higher levels of renal cathepsin D and ATP6E than wt kidneys. They also showed more AMPK activation, which resulted in the inhibition of phosphorylation of the mammalian target of rapamycin (mTOR). Collectively, ω3-PUFAs in fat-1 mice contributed to AMPK mediated autophagy activation, leading to a renoprotective response.

The presence of valuable bioactive compounds in European eel (Anguilla anguilla) skin was studied. For it, proximate and lipid class compositions and analysis of the fatty acid (FA) profile (individual FAs; FA groups, i.e., saturated, monounsaturated, and polyunsaturated; FA ratios, i.e., polyunsaturated/saturated, ω3/ω6) were determined and compared to the composition of the eel muscle. As a result, higher (p<0.05) levels of proteins (271.6 g·kg-1), lipids (38.0 g·kg-1), ash (27.7 g·kg-1) and ω6 FAs were observed in the skin tissue. Contrary, the muscle tissue showed higher (p<0.05) moisture, ω3 FA and ω3/ω6 values. Regarding lipid classes, a higher (p<0.05) proportion of phospholipids (111.1 g·kg-1 lipids), sterols (104.7 g·kg-1 lipids), α-tocopherol (274.0 mg·kg-1 lipids), and free fatty acids (43.6 g·kg-1 lipids) was observed in the skin tissue. No differences (p>0.05) between both tissues could be detected for triacylglycerol and FA group (saturated, monounsaturated, and polyunsaturated) values, as well as for the polyunsaturated/saturated ratio. It is concluded that eel skin, a by-product resulting from commercial processing, can be considered a valuable source to provide the food and pharmaceutical industries with useful value-added constituents such as proteins, lipids, ω3 FAs, phospholipids, and α-tocopherol.

Fatty acid desaturase 2 (Fads2) is the key enzyme of long chain polyunsaturated fatty acid (LC-PUFA) biosynthesis. Endogenous production of these biomolecules in vertebrates, if present, is insufficient to meet demand. Hence, LC-PUFA are considered as conditionally-essential. At present however, LC-PUFA are globally-limited nutrients due to anthropogenic factors. Attention of research is given therefore to find ways to maximize endogenous LC-PUFA production especially in production species, whereby deeper knowledge on molecular mechanisms of enzymatic steps involved is being generated. This review first briefly informs about the milestones in the history of LC-PUFA essentiality exploration before it focuses on the main aim – to highlight the fascinating Fads2 potential to play roles fundamental to adaptation to novel environmental conditions. Investigations are summarized, which elucidate the evolutionary history of fish Fads2 providing an explanation for the remarkable plasticity of this enzyme in fish. Further, structural implications of Fads2 substrate specificity are discussed and some relevant studies performed on organisms other than fish are mentioned in cases when such studies have so far not been conducted on fish models. The importance of Fads2 in the context of growing aquaculture demand and dwindling LC-PUFA supply is depicted and a few remedies in the form of genetic engineering to improve endogenous production of these biomolecules are outlined.

Among cephalopod discards, ink has revealed several beneficial properties regarding human health, environmental preservation and food preservation. In this study, different concentrations of an aqueous extract of cuttlefish (Sepia spp.) ink (CI) were added, respectively, to the packing medium employed during golden seabream (Sparus aurata) canning. Quality parameters of the resulting canned fish were determined and compared to the counterpart control and raw samples. As a result, an important effect of the CI concentration added to the packing medium was proved. The presence in the packing medium of a relatively low CI concentration led to lower (p<0.05) lipid oxidation development (fluorescent compound formation), lower (p<0.05) changes of colour parameters (L* and a* values) and lower (p<0.05) trimethylamine values in canned fish. Additionally, the two lowest CI concentrations tested led to higher average values of C22:6ω3 and ω3/ω6 ratios. Remarkably, higher average values of free fatty acids, polyene index and C20:5ω3 were detected in all kinds of CI-treated fish when compared to control canned samples. In agreement with environmental sustainability and circular economy requirements, the study provides a first approach to a novel and beneficial use of the present marine discard for the quality enhancement of canned fish.