Stock enhancement or sea ranching? Insights from monitoring the genetic diversity, relatedness and effective population size in a seeded great scallop population (Pecten maximus).

The mass release of hatchery-propagated stocks raises numerous questions concerning its efficiency in terms of local recruitment and effect on the genetic diversity of wild populations. A seeding program, consisting of mass release of hatchery-produced juveniles in the local naturally occurring population of great scallops (Pecten maximus L.), was initiated in the early 1980s in the Bay of Brest (France). The present study aims at evaluating whether this seeding program leads to actual population enhancement, with detectable effects on genetic diversity and effective population size, or consists of sea ranching with limited genetic consequences on the wild stock. To address this question, microsatellite-based genetic monitoring of three hatchery-born and naturally recruited populations was conducted over a 5-year period. Results showed a limited reduction in allelic richness but a strong alteration of allelic frequencies in hatchery populations, while genetic diversity appeared very stable over time in the wild populations. A temporal increase in relatedness was observed in both cultured stock and wild populations. Effective population size (Ne) estimates were low and variable in the wild population. Moreover, the application of the Ryman-Laikre model suggested a high contribution of hatchery-born scallops to the reproductive output of the wild population. Overall, the data suggest that the main objective of the seeding program, which is stock enhancement, is fulfilled. Moreover, gene flow from surrounding populations and/or the reproductive input of undetected sub-populations within the bay may buffer the Ryman-Laikre effect and ensure the retention of the local genetic variability.

Molecular identification and expression of differentially regulated genes of the European flounder, Platichthys flesus, submitted to pesticide exposure.

Effects of pesticide exposure on the European flounder, Platichthys flesus, were investigated using a suppression subtractive hybridization method (SSH) to identify up- and down-regulated genes after a 30-day exposure to herbicides (a cocktail of atrazine, diuron, and isoproturon, and a single herbicide, glyphosate). A total of 256 expressed gene sequences were identified as having the potential for being differentially expressed, of which 116 could be identified by homology with databased sequences. The metabolic functions with which they are associated include energy production, general metabolism, signaling, transport, immune system, and structure. Expression of 14 of these genes was analyzed in liver, muscle, and gills by reverse transcriptase-polymerase chain reaction (RT-PCR) under experimental conditions (0, 15, and 30 days of exposure) and under field conditions (sampling in two estuaries displaying different levels of pesticide contamination). This study provides a first basis for studying the response of fish to pesticide exposure and allows the characterization of new potential genetic markers of pesticide contamination in the field.

Discrepancies in phylogeographical patterns of two European anglerfishes (Lophius budegassa and Lophius piscatorius).

In order to investigate the relative importance of historical processes and life-history traits in shaping the present-day genetic structure of European anglerfishes, 382 Lophius piscatorius and 134 Lophius budegassa were sequenced on the 5' end of the mitochondrial control region. Both species showed a limited genetic structure and some evidence of a demographic expansion that probably occurred not at the end of the Last Glacial Maximum, but earlier in the Pleistocene. The main discrepancy between the two anglerfishes concerned the genetic structure between Atlantic and Mediterranean populations, with weak but significant differentiation observed only in L. budegassa. This genetic structure was congruent with the existence of a phylogeographical break previously reported in several marine species across the Almeria-Oran front. The contrast observed between both anglerfishes was supposed to be induced by a possible more ancient (re)colonisation of the Mediterranean Sea by L. budegassa. Finally, the limited genetic structure and lack of isolation by distance observed in both species suggested high larval dispersal capacities that probably overwhelm the influence of the bathymetric distribution range on migrations of adults and juveniles.

Anti-Saccharomyces cerevisiae mannan antibodies in familial Crohn's disease.

OBJECTIVE: Anti-Saccharomyces cerevisiae mannan antibodies (ASCA) are associated with Crohn's disease. The aim of this study was to determine the prevalence of ASCA in families in which at least two members were affected with Crohn's disease. METHODS: A total of 20 families including two (n=15) or more (n=5) patients with Crohn's disease were tested for ASCA with use of an ELISA method. Overall, 51 affected members, 66 healthy first degree relatives, and 163 healthy control subjects were studied. RESULTS: ASCA were detected in 35 of 51 (69%) patients with Crohn's disease and in 13 of 66 (20%) healthy relatives versus one of 163 healthy control subjects (p < 0.0001 and p < 0.001). ASCA-positive relatives were distributed in 12 of 20 families. ASCA were present in eight healthy parents and four healthy siblings. The prevalence of ASCA in relatives did not depend on the ASCA status of affected members. CONCLUSION: ASCA in 20% of healthy first degree relatives of patients with Crohn's disease suggest that these antibodies might be a subclinical marker for Crohn's disease in families. Whether ASCA reflect environmental or genetic factors or a combination of both is unknown.

Anti-Saccharomyces cerevisiae mannan antibodies combined with antineutrophil cytoplasmic autoantibodies in inflammatory bowel disease: prevalence and diagnostic role.

BACKGROUND: Perinuclear antineutrophil cytoplasmic autoantibodies (pANCA) are a well recognised marker for ulcerative colitis. Antibodies to oligomannosidic epitopes of the yeast Saccharomyces cerevisiae (ASCA) are a new marker associated with Crohn's disease. AIMS: To assess the value of detecting pANCA and/or ASCA for the diagnosis of ulcerative colitis and Crohn's disease. METHODS: Serum samples were obtained from 100 patients with Crohn's disease, 101 patients with ulcerative colitis, 27 patients with other miscellaneous diarrhoeal illnesses, and 163 healthy controls. Determination of pANCA and ASCA was performed using the standardised indirect immunofluorescence technique and an ELISA, respectively. RESULTS: The combination of a positive pANCA test and a negative ASCA test yielded a sensitivity, specificity, and positive predictive value of 57%, 97%, and 92.5% respectively for ulcerative colitis. The combination of a positive ASCA test and a negative pANCA test yielded a sensitivity, specificity, and positive predictive value of 49%, 97%, and 96% respectively for Crohn's disease. Among patients with miscellaneous non-inflammatory bowel disorders, three were ASCA positive and two were pANCA positive. One control was ASCA positive. The presence of ASCA in patients with Crohn's disease was associated with small bowel involvement. CONCLUSION: ASCA and pANCA are strongly associated with Crohn's disease and ulcerative colitis, respectively. Combination of both tests could help the diagnosis of inflammatory bowel disease.