Nuclear-mitochondrial interactions in the regulation of protein synthesis in Drosophila hydei salivary gland cells

Contains fulltext : mmubn000001_025224816.pdf (publisher's version ) (Open Access)Promotor : C. Kuyper63 p

Dietary protein hydrolysates vs. the intact proteins do not enhance mucosal integrity and growth performance in weaned piglets

Two separate experiments, but using the same diets, were designed to study whether the addition to the diet of protein hydrolysates or crystalline glutamine (gln) affect small intestinal integrity (experiment 1) and growth performance (experiment 2). It was hypothesized that dietary supplementation of hydrolysed proteins would increase the availability of amino acids for the gut wall and therefore result in an improved small intestinal integrity and growth performance of piglets after weaning. The five diets differed in their protein composition: soybean meal and wheat gluten (SBM+WG), SBM and hydrolysed wheat gluten (SBM +HWG), hydrolysed soybean meal and WG (HSBM+WG), SBM and potato protein (SBM+PP), 2% of gln added to SBM and PP (SBM+PP+gln). In experiment 1, 88 piglets of 8.4 kg (S.D.: 0.82) were weaned at 26 days of age (day 0). Piglets were dissected and sampled on days 0, 3, or 7 postweaning. Results showed that the protein hydrolysates did not increase villus height, did not reduce crypt depth and did not raise brush-border aminopeptidase and isomaltase-sucrase activity when compared to the diets containing the unhydrolysed proteins. In experiment 2, 165 piglets of 8.5 kg (S.D.: 1.33) were weaned at 26 days of age. Feed intake and weight gain were not enhanced by the protein hydrolysates. The addition to the diet of crystalline gln resulted in improved average daily gain and feed efficiency by 22 and 17%, respectively (

Differential modulation of enterocyte-like Caco-2 cells after exposure to short-chain fatty acids

The response of intestinal epithelial cells to short-chain fatty acids, which are increasingly used as food additives, was investigated. Human small intestinal epithelial cell model Caco-2 cells were exposed to formate, propionate and butyrate to assess their effect on cellular growth, metabolism, differentiation and protection against bacteria. The Caco-2 cells were entirely grown in the different short-chain fatty acids and respective growth patterns were determined. Differentiated cells were exposed to 0-20 mM short-chain fatty acids for 48 h and changes in DNA, RNA, (glyco)protein syntheses, sucrase isomaltase activity, transepithelial electrical resistance and protection against Salmonella enteritidis were measured. The short-chain fatty acids, altered linearly and differentially the growth pattern ranging from stimulation by formate to inhibition by butyrate. Formate inhibited cellular metabolism. Low concentrations of up to 5 mM propionate and 2 mM butyrate stimulated metabolism, while higher doses were inhibitory. Formate had no effect on sucrase isomaltase enzyme activity and transepithelial electrical resistance, whereas propionate and butyrate increased these markers of differentiation. Infection with S. enteritidis did not benefit from the short-chain fatty acid-induced transepithelial electrical resistance. It is concluded that formate, propionate and butyrate selectively and differentially modulate growth characteristics, cellular metabolism, sucrase isomaltase activity and transepithelial electrical resistance in a concentration- and carbon atom-related fashion. The short-chain fatty acid-induced transepithelial electrical resistance does not confer protection against S. enteritidis

Effects of prefermented cereals or the end products of fermentation on growth and metabolism of enterocyte-like Caco-2 cells and on intestinal health of restrictedly fed weanling pigs

To unravel the underlying mechanisms that explain the positive effects of prefermented cereals on in vivo gastrointestinal (GI) architecture and function, an in vitro experiment using a human small intestinal epithelial cell model (Caco-2) was performed. A range of dilutions (0% to 10%) of the supernatants of three liquid experimental diets, as well as Na-lactate were used in an in vitro experiment to assess their effect on cellular growth, metabolism, differentiation and mucosal integrity using Caco-2. The experimental diets contained, in addition to a protein rich basal diet (60%), (1) a liquid control diet (C) containing 40% of a mixture of barley and wheat (ratio 3 : 1) or (2) a liquid diet (F) containing 40% prefermented barley and wheat or (3) C with the addition of the fermentation end-products (organic acids and ethanol) in concentrations similar to those in the fermented diet (FP). For F, the mixture of barley and wheat was fermented at 35°C for 48 h. Parallel to the in vitro experiment, 18 groups of eight weanling pigs were assigned to one of the experimental diets during a 14-day in vivo experiment. Each group was fed restrictively. The results of the in vitro experiment showed that the lowest dose of both F- and FP-supernatants had no clear effects on the cell proliferation, but incubation with 5% and 10% of the F- and FP-supernatants decreased the cell numbers at day 19. DNA, RNA, protein and glycoprotein synthesis in differentiated Caco-2 cells were stimulated by incubation with the lower concentrations (0.5% to 2.5%) of F- and FP-supernatants whereas the higher concentrations (5% and 10%) had no effect. Both the F- and FP-supernatants decreased the specific sucrase–isomaltase activity in a dose-dependent manner, but the effects on the specific aminopeptidase activities were less clear. Mucosal integrity initially decreased after incubation with the highest F- and FP-supernatants and started to recover between 24 and 48 h. The results of the in vivo experiment showed no dietary effects (P > 0.1) on GI morphology and brush-border enzyme activities at day 5 or at day 14. Time related changes in GI characteristics followed a normal pattern. In conclusion, the supernatants of diets containing either prefermented cereals or their fermentation end-products clearly modulate cellular growth, metabolism, differentiation and mucosal integrity in an in vitro model, although these effects were not observed in the in vivo characteristics measured in weanling pig