UC (ulcerative colitis) patients have an increased risk of developing colorectal cancer compared with the normal population. The cause underlying this higher risk is not fully defined but includes nutritional and environmental factors concomitant with genetic alterations. We aimed to evaluate genetic stability in the colonic tissue of UC patients in clinical remission compared with the healthy population, and to establish a possible correlation between nutritional habits and these molecular assessments. UC patients (n 42) and healthy controls (n 37) participated in the study. All participants were histopathologically and medically diagnosed. Participants completed five separate 7d dietary records, food-frequency questionnaires and validated 24h recalls for nutritional assessment. The extent of chromosome 17 loss and the calculated chromosome index was determined in colon tissue biopsies by fluorescence in situ hybridisation. Correlations between the molecular and nutritional assessments were performed using Pearson's correlation coefficients. Significant differences in the nutritional intake of total fat (65 (SD 15) v. 89 (SD 25) g), cholesterol (330 (SD 168) v. 464 (SD 177) mg), dietary fibre (32 (SD 4·7) v. 9 (SD 4) g), vitamin A (1009 (SD 209) v. 506 (SD 204) μg), vitamin C (308 (SD 108) v. 72 (SD 53) mg) and folic acid (412 (SD 89 μg) v. 187 (SD 107)) were recorded for UC patients compared with controls. Significant correlations were found for the consumption of different food groups and the chromosome index for chromosome 17. The results of our study suggest that the nutritional habits adopted by UC patients during clinical remission may affect key cellular components of the colonic tissue, inducing a high degree of aneuploidy and genetic instability, and probably affecting the development of colon cancer.

Due to its low digestibility in the small intestine, a major fraction of the polyol isomalt reaches the colon. However, little is known about effects on the intestinal microflora. During two 4-week periods in a double-blind, placebo-controlled, cross-over design, nineteen healthy volunteers consumed a controlled basal diet enriched with either 30g isomalt or 30g sucrose daily. Stools were collected at the end of each test phase and various microbiological and luminal markers were analysed. Fermentation characteristics of isomalt were also investigated in vitro. Microbiological analyses of faecal samples indicated a shift of the gut flora towards an increase of bifidobacteria following consumption of the isomalt diet compared with the sucrose diet (P<0·05). During the isomalt phase, the activity of bacterial β-glucosidase decreased (P<0·05) whereas β-glucuronidase, sulfatase, nitroreductase and urease remained unchanged. Faecal polyamines were not different between test periods with the exception of cadaverine, which showed a trend towards a lower concentration following isomalt (P=0·055). Faecal SCFA, lactate, bile acids, neutral sterols, N, NH3, phenol and p-cresol were not affected by isomalt consumption. In vitro, isomalt was metabolized in several bifidobacteria strains and yielded high butyrate concentrations. Isomalt, which is used widely as a low-glycaemic and low-energy sweetener, has to be considered a prebiotic carbohydrate that might contribute to a healthy luminal environment of the colonic mucosa.

The non-long terminal repeat retrotransposons Rex1 and Rex3 were identified in 13 species of Antarctic fishes from five families of the suborder Notothenioidei. Partial reverse transcriptase gene sequences were characterized for Notothenia coriiceps, Trematomus newnesi and Dissostichus mawsoni (Nototheniidae), and Gymnodraco acuticeps (Bathydraconidae). Rex1 and Rex3 both formed a notothenioid-specific monophyletic group compared to the corresponding elements from other fishes. They globally evolved under purifying selection, showing their activity during notothenioid evolution. Fluorescence in situ hybridization analysis of the chromosomal distribution of Rex1 and Rex3 was performed for several notothenioid fish species. Rex1 was generally less abundant than Rex3, which was widely scattered on the chromosomes with more intense hybridization patterns in some specific zones. Particularly, Rex3 accumulated in Chionodraco hamatus in pericentromeric areas, short arms of some pairs as well as in an intercalary band in the long arm of the Y chromosome similarly to a previously described DNA transposon. Such pattern similarities suggest the presence of autosomal and gonosomal regions of preferential accumulation for different types of repeated elements in notothenioid genomes. To the best of our knowledge, this report is the first description and analysis of retrotransposable elements in Antarctic fish genomes.