Elena Coccia

n-3 LC-PUFA deposition efficiency and appetite-regulating hormones are modulated by the dietary lipid source during rainbow trout grow-out and finishing periods

Largely attributable to concerns surrounding sustainability, the utilisation of omega-3 long-chain polyunsaturated fatty acid-rich (n-3 LC-PUFA) fish oils in aquafeeds for farmed fish species is an increasingly concerning issue. Therefore, strategies to maximise the deposition efficiency of these key health beneficial fatty acids are being investigated. The present study examined the effects of four vegetable-based dietary lipid sources (linseed, olive, palm and sunflower oil) on the deposition efficiency of n-3 LC-PUFA and the circulating blood plasma concentrations of the appetite-regulating hormones, leptin and ghrelin, during the grow-out and finishing phases in rainbow trout culture. Minimal detrimental effects were noted in fish performance; however, major modifications were apparent in tissue fatty acid compositions, which generally reflected that of the diet. These modifications diminished somewhat following the fish oil finishing phase, but longer-lasting effects remained evident. The fatty acid composition of the alternative oils was demonstrated to have a modulatory effect on the deposition efficiency of n-3 LC-PUFA and on the key endocrine hormones involved in appetite regulation, growth and feed intake during both the grow-out and finishing phases. In particular, n-6 PUFA (sunflower oil diet) appeared to ‘spare’ the catabolism of n-3 LC-PUFA and, as such, resulted in the highest retention of these fatty acids, ultimately highlighting new nutritional approaches to maximise the maintenance of the qualitative benefits of fish oils when they are used in feeds for aquaculture species.

Digestive Enzymes in the Crayfish Cherax albidus: Polymorphism and Partial Characterization

We will deal with the partial characterization and the activity of the following digestive enzymes: amylase, pectinase, alginase, lipase, and protease present in the digestive tract of juvenile freshwater crayfish Cherax albidus. Gastric juices, the hepatopancreas, and the intestine were sampled for enzyme analysis. Among carbohydratases, amylase activity was the highest. It was significantly higher in the intestine than in the gastric juice and hepatopancreas. Lipase activity was significantly higher in the hepatopancreas and the intestine compared to the gastric juice. Both alkaline and acid proteases were found. Alkaline proteases were characterized by employing specific protease inhibitors. Both trypsin and chymotrypsin activity was detected. The majority of alkaline protease activity was ascribable to trypsin. Several isoforms of digestive enzymes were identified by gel electrophoresis. This work provides basic information to study the digestive abilities of crayfish.

Effects of recombinant trout leptin in superoxide production and NF-κB/MAPK phosphorylation in blood leukocytes.

Studies in mammals indicate that leptin is a multifunctional cytokine involved in regulation of energy metabolism and the modulation of the immune function. However, evidence for an immunomodulatory effect of leptin in fish is still missing. At least in part, this lack of knowledge is due to the absence of materials and models. In this study, we produced trout recombinant leptin (rt-lep) and tested its capacity to trigger cellular pathways, usually active in mammal immune system cells. STAT3, NF-κB, and the three major MAPK cascades (JNK, p38 and ERK), were activated by rt-lep in in vitro incubations with blood leucocytes of the rainbow trout Oncorhynchus mykiss. We also showed that rt-lep causes a decrease in superoxide anion production in trout blood leucocytes. Thus our data indicate that as in mammals also in teleosts leptin plays pleiotropic activities. Importantly, its actions in fishes do not always conform to the picture emerging for mammals.

Fatty Acid-Specific Alterations in Leptin, PPARα, and CPT-1 Gene Expression in the Rainbow Trout

It is known that fatty acids (FA) regulate lipid metabolism by modulating the expression of numerous genes. In order to gain a better understanding of the effect of individual FA on lipid metabolism related genes in rainbow trout (Oncorhynchus mykiss), an in vitro time-course study was implemented where twelve individual FA (butyric 4:0; caprylic 8:0; palmitic (PAM) 16:0; stearic (STA) 18:0; palmitoleic16:1n-7; oleic 18:1n-9; 11-cis-eicosenoic 20:1n-9; linoleic (LNA) 18:2n-6; α-linolenic (ALA) 18:3n-3; eicosapentenoic (EPA) 20:5n-3; docosahexaenoic (DHA) 22:6n-3; arachidonic (ARA) 20:4n-6) were incubated in rainbow trout liver slices. The effect of FA administration over time was evaluated on the expression of leptin, PPARα and CPT-1 (lipid oxidative related genes). Leptin mRNA expression was down regulated by saturated fatty acids (SFA) and LNA, and was up regulated by monounsaturated fatty acids (MUFA) and long chain PUFA, whilst STA and ALA had no effect. PPARα and CPT-1mRNA expression were up regulated by SFA, MUFA, ALA, ARA and DHA; and down regulated by LNA and EPA. These results suggest that there are individual and specific FA induced modifications of leptin, PPARα and CPT-1 gene expression in rainbow trout, and it is envisaged that such results may provide highly valuable information for future practical applications in fish nutrition.

Development of Biopolymers as Binders for Feed for Farmed Aquatic Organisms

Diets for aquatic animals are numerous. They differ from species to species and may change to meet varied nutritional requests during the life cycle, and may be designed for larvae, juveniles, adults and breeders. In this review we will focus on a particular aspect of aquaculture feed represented by binders. Binders can be liquids or solids with the capacity of forming bridges, coatings or films that make strong inter-particle bonding. Binders are used to improve feed manufacture and to stabilize diets in water. Differently from feed for livestock, feed for aquaculture requires an adequate level of processing to guarantee good stability in water, long enough for animals to consume it. For this reason the role of binder is crucial in determining variable levels of firmness adequate to specific feeding behaviour. Although the problem of feed stability is far more crucial with crustaceans than with fish, some fish are benthic and small pellets that sink rapidly to the bottom where they can be located and recognized by the chemoreceptors of the fish are highly sought. Usually commercial feed for fish is stable after extrusion and binders are not requested to improve water stability. In some recent experiments binders are included in practical diets for fish to generate firmer feces when emitted into water to reduce pollution (Brinker, 2007). Among crustaceans crayfish are slow feeders with a characteristic tendency, that they share with prawns and shrimps, to manipulate food using mouth appendages before ingestion (Holdich, 2002). Thus, in aquatic animal feed preparation, to stabilize feed pellets and to ensure minimum nutrient leaching and disintegration appear to be crucial. Feed stability is considered a crucial requirement also in the echinoculture. Indeed, sea urchin are grazers and need time to eat the offered feed, so that it must remain intact for several days, in order to limit the loss of nutrients and to make rearing structure management easier (Caltagirone et al., 1992; Mortensen et al., 2004; Pearce et al., 2004). In addition, prepared diets frequently lead to poor gonad quality in terms of texture, firmness, colour and taste (Pearce et al., 2002a), that means low marketability of the product. For these reasons research focused on the selection of appropriate binders to ensure consistence to the experimental feed must take into account their effects not only on feed stability but also on gonad yield and sensorial quality. Since a binder may not be optimal for all species, and even for the same species the

The orexinergic system in rainbow trout Oncorhynchus mykiss and its regulation by dietary lipids.

In this study, we report the distribution of orexin A (OXA), orexin B (OXB), and orexin receptor (OX2R) immunoreactive (ir) cells in the hypothalamus and gastrointestinal tract of Oncorhynchus mykiss fed diets with different dietary fatty acid compositions. Trout were fed five iso‐energetic experimental diets containing fish oil, or one of four different vegetable oils (olive, sunflower, linseed, and palm oils) as the added dietary lipid source for 12 weeks. OXA, OXB, and OX2R immunoreactive neurons and nervous fibers were identified in the lateral and ventro‐medial hypothalamus. OXA, OXB, and OX2R ir cells were found in the mucosa and glands of the stomach and in the mucosa of both the pyloric cecae and intestine. OX2R ir cells were localized in the mucosa layer of both the pyloric cecae and intestine. These immunohistochemical (IHC) results were confirmed via Western blotting. Antibodies against preproorexin (PPO) crossreacted with a band of ∼16 kDa in the hypothalamus, stomach, pyloric cecae, and intestine. Antibodies against OX2R crossreacted with a band of ∼38 kDa in the hypothalamus, pyloric cecae, and intestine. The presence and distribution of OXA, OXB, and OX2R ir cells in the hypothalamus and gastrointestinal tract did not appear to be affected by dietary oils. The presence of orexin system immunoreactive cells in the stomach, pyloric cecae, and intestine of rainbow trout, but not in the enteric nervous system, could suggest a possible role of these peptides as signaling of gastric emptying or endocrine modulation, implying a main local action played by orexins. Microsc. Res. Tech. 78:707–714, 2015.

Agar-based Biocomposites slow down Progression in the Reproductive Cycle Facilitating Synchronization of the Gonads of Reared Specimens of Paracentrotus lividus

Background: Biopolymers have many fields of application. In Echiniculture they are usually employed to bind trial diets, although a systematic study on the performances of biopolymers as feed binders is lacking.

The Olfactory Organ of the Trout Salmo trutta fario: A Novel Localization for a Progestin Receptor

A progestin receptor (PR) has been detected in the olfactory organ of the trout Salmo trutta fario. The specificity of this receptor was high for 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (17α,20β‐DP), but it also bound 17α‐hydroxy‐progesterone (17α‐OHP) and 21‐hydroxyprogesterone (21‐OHP), even when present at low concentrations (10‐fold in relative binding affinity assay). Progesterone (P) competed effectively at much higher concentrations (1,000‐fold in relative binding affinity assay). Immunohistochemical studies carried out with three different monoclonal antibodies against human progesterone receptor (hPR), chicken progesterone receptor hinge region (cPR), and chicken progesterone receptor A/B domain (PR22), revealed that immunoreactivity was present in the epithelium of the olfactory organ of females and males of the trout Salmo trutta fario only against hPR. Western blotting showed two hPR immunoreactive bands of about 62 and 66 kDa. Finally, a portion of the cDNA of about 300 nucleotides extending over the DNA binding domain and the ligand binding domain was cloned and sequenced, revealing a high degree of sequence homology of the PR in Salmo trutta fario with the PR in other teleosts. Microsc. Res. Tech., 2010.

Functional characterization of a BCL10 isoform in the rainbow trout Oncorhynchus mykiss

The complexes formed by BCL10, MALT1 and members of the family of CARMA proteins have recently been the focus of much attention because they represent a key mechanism for regulating activation of the transcription factor NF‐κB. Here, we report the functional characterization of a novel isoform of BCL10 in the troutOncorhynchus mykiss, which we named tBCL10. tBCL10 dimerizes, binds to components of the CBM complex and forms cytoplasmic filaments. Functionally, tBCL10 activates NF‐κB transcription factor and is inhibited by the deubiquitinating enzyme A20. Finally, depletion experiments indicate that tBCL10 can functionally replace the human protein. This work demonstrates the evolutionary conservation of the mechanism of NF‐κB activation through the CBM complex, and indicates that the rainbow troutO. mykiss can serve as a model organism to study this pathway.

Evaluation of metabolic changes induced by polyphenols in the crayfish Astacus leptodactylus by metabolomics using Fourier transformed infrared spectroscopy

In the present study, the effects of polyphenols on the chemical composition of the hepatopancreas of the Astacus leptodactylus, a highly sought farmed crayfish, have been investigated by attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy. The hepatopancreas spectrum was quite complex and contained several peaks arising from the contribution of different functional groups belonging to protein, lipids and carbohydrates. The PCA statistical analysis revealed that there were significant differences between crayfish fed a diet without polyphenols and crayfish fed a diet containing polyphenols. Such differences indicated an increase in lipids and proteins in the hepatopancreas of polyphenol-fed crayfish. In conclusion, the analysis of the infrared spectral profile of the hepatopancreas of Astacus leptodactylus, allowed us to elucidate the changes in different biomolecules in response to polyphenol treatment, and confirms the suitability of ATR-FTIR spectral data to analyze diet-induced metabolic effects. These considerations, coupled with the small amount of sample and no preparation needed, make ATR-FTIR a useful tool for routine analyses where the metabolic impact of substances is investigated, especially with a large number of samples.