Cytokine gene expression and prostaglandin production in head kidney leukocytes isolated from Atlantic cod (Gadus morhua) added different levels of arachidonic acid and eicosapentaenoic acid.

Primary head kidney leukocytes from Atlantic cod were isolated to evaluate the use of arachidonic acid and eicosapentaenoic acid by cyclooxygenases and the production of prostaglandins E2 and E3. The expression of cyclooxygenase genes and selected interleukin genes like Interleukin 1ß, Interleukin 6, interleukin 8 and interleukin 10 were monitored. Increasing concentrations of eicosapentaenoic acid and arachidonic acid in equal amounts increased cyclooxygenase2 transcription as well as cell secretion of prostaglandin E2. Even though the ratio of the two fatty acids was 1:1, the ratio between prostaglandin E2 and E3 was 50:1. The addition of arachidonic acid alone increased prostaglandin E2 secretion but did not induce cyclooxygenase2 transcription. However, when the concentration of eicosapentaenoic acid was increased, maintaining arachidonic acid constant, both prostaglandin E3 and prostaglandin E2 production was induced and the prostaglandin E2 production was higher than in cell cultures only added arachidonic acid. An up-regulation of cyclooxygenase2 transcription was also observed. The addition of the two fatty acids also affected the immune response by alteration of leukocytic cytokines gene expression. According to our results the Cyclooxygenase in cod seem to prefer arachidonic acid as substrate. Therefore, we suggest that the shift from marine oils (rich in n-3 fatty acids) to plant oils (higher in n-6 fatty acids) in the diet of commercially reared Atlantic cod could have negative effects on the whole organism through the increase in the production of prostaglandins belonging to those derived from n-6 fatty acids.

The metabolic effects of prolonged starvation and refeeding in sturgeon and rainbow trout.

The present study examines the particular metabolic strategies of the sturgeon Acipenser naccarii in facing a period of prolonged starvation (72 days) and subsequent refeeding (60 days) compared to the trout Oncorhynchus mykiss response under similar conditions. Plasma metabolites, endogenous reserves, and the activity of intermediate enzymes in liver and white muscle were evaluated. This study shows the mobilization of tissue reserves during a starvation period in both species with an associated enzymatic response. The sturgeon displayed an early increase in hepatic glycolysis during starvation. The trout preferentially used lactate for gluconeogenesis in liver and white muscle. The sturgeon had higher lipid-degradation capacity and greater synthesis of hepatic ketone bodies than the trout, although this latter species also showed strong synthesis of ketone bodies during starvation. During refeeding, the metabolic activity present before starvation was recovered in both fish, with a reestablishment of tissue reserves, plasmatic parameters (glucemia and cholesterol), and enzymatic activities in the liver and muscle. A compensatory effect in enzymes regarding lipids, ketone bodies, and oxidative metabolism was displayed in the liver of both species. There are metabolic differences between sturgeon and trout that support the contention that the sturgeon has common characteristics with elasmobranchs and teleosts.

Study of antioxidant defense in four species of Perloidea (Insecta, Plecoptera).

The aim of the present work is to conduct a comparative study of oxidative states in the nymphs of four species of Plecoptera belonging to the superfamily Perloidea: Perla marginata (Panzer, 1799) (family Perlidae), Guadalgenus franzi (Aubert, 1963), Isoperla curtate Navás, 1924, and lsoperla grammatica (Poda, 1761) (family Perlodidae) in relation to their ecological and biological characteristics. For this, the activity of the following antioxidant enzymes was determined: superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPX), glutathione transferase (GST), and DT-diaphorase (DTD), together with lipid peroxidation. Glucose 6-phosphate dehydrogenase (G6PDH) was also determined. The four species studied were selected based on significant ecological and biological differences. The results obtained when studying different indicative parameters of the oxidative state of the nymph of different species showed that each has an important enzymatic antioxidant potential, and that differences among species are conditioned by the duration of the nymphal development period more than by whether they come from permanent or temporary habitats. Thus, Plecoptera, although traditionally considered as typical inhabitants of permanent waters, seem to have sufficient variability in physiological mechanisms, together with behavioral and ecological adaptations, to cope with potentially unfavorable conditions that may occur in temporary waters.

Effect of starvation and refeeding on digestive enzyme activities in sturgeon (Acipenser naccarii) and trout (Oncorhynchus mykiss).

The digestive enzyme activities were determined in Adriatic sturgeon and rainbow trout during starvation and refeeding period. Overall, the digestive enzyme activities are affected in the same sense in both species. The protease and lipase activities were decreased later than amylase activity. Even after 1 month of starvation, both species would be prepared to digest protein and lipids in an effective way. After 72 days of starvation, the digestive machinery of the sturgeon and of the trout shows an altered capacity to digest macronutrients. The capacity to digest proteins and lipids, after 60 days of refeeding, begins to become re-established in sturgeon and trout. In contrast, in this period, the capacity to digest carbohydrates remains depressed in both species.