Effect of nutritional background and exposure to Enteromyxum leei (Myxozoa) on the mucin and goblet cell pattern of the intestine of gilthead sea bream (Sparus aurata)

Poster presentado en el 15th International Conference on Diseases of Fish and Shellfish celebrado en Croacia del 12 al 16 de septiembre de 2011The aim of the present work was to determine if a practical plant protein-based diet containing vegetable oils (VO) as the major lipid source could alter the qualitative and quantitative carbohydrate pattern of the intestine of gilthead sea bream (GSB) challenged with Enteromyxum leei, a wide-spread enteric parasite in the Mediterranean basin causing heavy economic losses. GSB were fed during 9 months a fish oil (FO) based diet or a diet in which FO was 66% replaced by a blend of vegetable oils (66VO). Recipient fish (R) were challenged by exposure to E. leei-contaminated effluent for 102 days, and control (C) animals were kept unexposed[1]. Samples of anterior (AI), middle (MI) and posterior (PI) intestine were obtained for the histological study with lectin and histochemistry. Positively stained cells were counted in 10 digital fields at x 312.5 for each fish and intestine segment. As fish were periodically and non-lethally sampled to know their infection status, R fish were categorized as exposed but not infected (R-NonPAR), and infected at early, medium or late times. The number of goblet cells (GC) stained with PAS (for neutral mucins), alcian blue (AB, for acidic mucins), aldehyde fuchsine-AB (AF-AB, for carboxylated and/or sulphated acidic mucins), and with the lectin SNA (for the detection of sialic acid) were counted. A strong negative correlation was found between the number of GC positive (+) for most of the techniques applied and the intensity of infection, especially in the PI, regardless of the nutritional background. However, the decrease of the number of GC was more pronounced in R-66VO than in R-FO. The 66VO diet produced a significant decrease of GC with neutral and acidic mucins in AI and MI, and that of SNA+ GC in MI. However, the diet did not affect the intensity of staining with SNA in the brush border or the apical part of the epithelium, but the infection reduced both significantly. In all the groups, the SNA intensity was significantly lower in AI. The kinetic study showed the time-dependent effect on the GC decrease, since early infected fish had the lowest GC counts in PI with all the stainings. There were no significant differences in the number of GC+ for any of the stainings among the three intestinal sections of CTRL animals within each diet. R-NonPAR fish had higher values of AB+ and SNA+ GC in PI than R-early and intermediate infected ones.This work was funded by EU (FOOD-CT-2006-16249); AQUAMAX) and MICINN (AGL2009-13282-C02-01). Additional funding was obtained from Generalitat Valenciana (PROMETEO 2010/006). I.E. received a PhD fellowship (FPI) from MICINN, and B.S. a JAE-INTRO fellowship from CSIC.Peer Reviewe