Occurrence of two NOS isoforms in the developing gut of sea bass Dicentrarchus labrax (L.).

In this work we have examined the appearance and distribution of nitric oxide synthase (NOS), with histochemical, immunohistochemical and biochemical methods, during development of the sea bass (Dicentrarchus labrax) gut. The data showed that both the calcium-calmodulin dependent neuronal isoform (nNOS) and calcium-independent inducible isoform (iNOS) are present in the larval gut of sea bass. The nNOS-immunoreactivity was present in the epithelial cells and enteric nerve cells of gut both in the 8-day-old specimens and in the 24-day-old-larvae. In the adult nNOS-immunoreactivity disappeared from epithelial cells, remaining in the wall intramural neurons and fibers. The iNOS-immunoreactivity was present in the epithelial cells of 24-day-old-larvae and was not detectable in the adult gut. Western blot analysis and determination of NOS activity also demonstrated the presence of the two NOS isoforms, nNOS and iNOS, in the gut of 24-day-old specimens. The presumably different roles played by the two isoforms of enzyme are discussed. The presence of nNOS isoform in the gut enteric neurons of the same larval stages of D. labrax in which we previously demonstrated the presence of substance P and Vasoactive Intestinal Polypeptide (VIP), may suggest that all these three components of the motility control system are already present in the larval phase. Nitric oxide (NO) may be also involved in the early immune response. The present results on the occurrence of iNOS isoform in epithelial gut cells of the same regions in which the gut-associated lymphoid tissue (GALT) will differentiate, may suggest for NO a role in early defence mechanisms, before the establishment of immune responses in GALT. Finally, the developmental and regional differences in nNOS and iNOS expression also suggest a regulatory role in development and differentiation of the sea bass gut.

Occurrence of nitric oxide synthase in Megoura viciae Buckton (Homoptera, Aphididae): an histochemical and immunohistochemical localisation.

Nitric oxide (NO) is known to be involved in many physiological reactions of insects. We analysed NOS localisation in aphids of the species Megoura viciae by means of histochemical reaction for the NADPH-diaphorase activity and immunohistochemical methods for uNOS, nNOS and iNOS. The obtained data provided a complex and peculiar pattern of NOS distribution in cells and tissue of M. viciae. The histochemical reaction for NADPH-diaphorase was an indicative, but not exact marker of NOS localisation in aphids. The use of anti uNOS antiserum (frequently applied in insects) was of limited value in our specimens, whereas more satisfactory results were obtained with anti nNOS and iNOS antisera of human origin. The results of Western blot analysis confirmed the immunohistochemical ones, showing an aphid protein that reacted strongly with the polyclonal antibody anti-iNOS and anti-nNOS while a similar protein band was weakly immunoreactive with the polyclonal antibody anti-uNOS. Our results suggest that NO, prevalently synthesised by calcium/calmodulin-dependent isoform, plays important physiological roles both in adult and embryological stages of aphids. The data of principal interest was NOS presence in bacteriocytes, cells that host symbiotic prokaryotes belonging to the species Buchnera aphidicola, and in nuclei of adipocytes and gut cells.

Effect of resveratrol and catechin on PC12 tyrosine kinase activities and their synergistic protection from beta-amyloid toxicity.

beta-Amyloid peptide (beta-AP) is the main component of amyloid deposits around the cerebral vessel and in the brain parenchyma in Alzheimer's disease and Down's syndrome. In vitro studies in neuronal cells or in PC12 and Hela cell lines have shown that the aggregate form of beta-AP is toxic. Many genetic and environmental factors including metal ions, proteoglycans, plasma proteins and antioxidants modify beta-AP toxicity. We investigated the effect of two plant polyphenols--resveratrol and catechin--on soluble and particulate tyrosine kinase activity from PC12 cells and the protective action of these compounds against beta-AP (1-41) toxicity. beta-AP (1-41) decreased PC12 viability with an IC50 value of 1.1 +/- 0.14 x 10(-8) M. Resveratrol and catechin protected PC12 cells from beta-AP (1-41) toxicity. With 25 microM resveratrol the IC50 value increased to 2.2 +/- 0.19 x 10(-7) M. In the presence of beta-AP (1-41) resveratrol showed a concentration-dependent biphasic effect, and at a concentration of up to 40 microM it protected PC12 cells from beta-AP (1-41) toxicity. At concentrations higher than 40 microM, an inhibitory activity on cell proliferation appeared. This antiproliferative effect was also seen in the absence of beta-AP (1-41). With 100 microM catechin the IC50 value increased from 1.1 +/- 0.14 x 10(-8) M to 3.2 +/- 0.25 x 10(-7) M beta-AP (1-41). The protective effect was concentration dependent. Resveratrol and catechin had a synergistic protective action. In the presence of 40 microM catechin and 10 microM resveratrol or 20 microM resveratrol and 10 microM catechin, the toxicity determined by 10(-7) M beta-AP (1-41) was almost completely removed. Resveratrol and catechin had different effects on PC12 tyrosine kinase activity. With peptide 1-17 of gastrin as substrate, resveratrol inhibited particulate tyrosine kinases while it had no effect on soluble activity. With the same substrate, catechin increased the activity of soluble fraction while it inhibited particulate activity. When peptide 6-20 of cell division kinase p34cdc2 was utilized, catechin showed an opposite effect, inhibiting soluble tyrosine kinase activity and increasing particulate activity. With peptide 6-20, resveratrol inhibited both soluble and particulate activities. These results demonstrate that resveratrol and catechin have different activities on the signal transduction pathway involving protein phosphorylation. These differences may contribute not only to the different effects of these compounds on PC12 growth but also to the synergistic effect against beta-AP (1-41) toxicity. The different activity of resveratrol and catechin on signal transduction pathways, as well as the differences in metal chelation, partition coefficient between water and lipids, hydrogen donation redox potential and enzyme inhibition may be at least in part based on synergistic protection against beta-AP (1-41) toxicity.

Relationship between iron and protein content of dishes and polyphenol content in accompanying wines.

The traditional combination of wines and dishes is highly complex, elaborated and refined. The aim of this study was to investigate the possible relationship between the chemical composition of wines and dishes that determines their combination. We determined the content of total polyphenols in 56 wines. The content of total proteins, total lipids, kilocalories, sodium, potassium, calcium, copper and zinc were determined in 44 raw foods and 44 dishes. Nine gourmets independently chose three wines for each food. We correlated the content of the chemical constituents of foods with the phenol content of wines combined with each food by the gourmets. A significant positive correlation was obtained between the phenol content of wines and iron (r = 0.81, p < 0.0001) and total protein content (r = 0.66, p < 0.0001) of foods. Nine gourmets composing a second panel chose three wines for each dish. A significant positive correlation was also obtained between the phenol content of wines and iron (r = 0.69, p < 0.0001), total protein (r = 0.50, p < 0.0006) and potassium (r = 0.45, p < 0.002) in dishes combined with wines by the second panel of gourmets. Plant phenols decrease the intestinal absorption of iron and have antioxidant activity in the intestinal tract and elsewhere in the body. These positive effects compensate the negative antinutritional activity toward protein digestion. The traditional combination of wines and dishes appears to be very favorable since wines poor in phenols are combined with dishes poor in iron and/or proteins to minimize their possible antinutritional effects, while phenol-rich wines are combined with dishes rich in iron to decrease iron absorption and prandial peroxidative stress.