Reversibility of hepatocyte nuclear modifications in mice fed on genetically modified soybean

In the literature, the reports on the effects of a genetically modified (GM) diet are scanty and heterogeneous; in particular, no direct evidence has so far been reported that GM food may affect human or animal health. Hepatocytes represent a suitable model for monitoring the effects of a GM diet, the liver potentially being a primary target. In a previous study, we demonstrated that some modifications occur in hepatocyte nuclei of mice fed on GM soybean. In order to elucidate whether such modifications can be reversed, in the present study, 3 months old mice fed on GM soybean since their weaning were submitted to a diet containing wild type soybean, for one month. In parallel, to investigate the influence of GM soybean on adult individuals, mice fed on wild type soybean were changed to a GM diet, for the same time. Using immunoelectron microscopy, we demonstrated that a one-month diet reversion can influence some nuclear features in adult mice, restoring typical characteristics of controls in GM-fed animals, and inducing in control mice modifications similar to those observed in animals fed on GM soybean from weaning. This suggests that the modifications related to GM soybean are potentially reversible, but also that some modifications are inducible in adult organisms in a short time.     

Strongyloides venezuelensis: longitudinal distribution of adult worms in the host intestine is influenced by mucosal sulfated carbohydrates

Mechanisms for the longitudinal distribution of parasitic females of Strongyloides venezuelensis in the host intestine were investigated in mice. Adult worms were mostly recovered from the anterior-most one-third of the small intestine throughout the infection after infective larvae inoculation. Surgically implanted adult worms established well in the small intestinal mucosa, either in the duodenum or in the ileum, whereas a few worms could establish in the large intestine. Implanted worms in the small intestine remained where they were implanted until expelled. Mucosal mast cells were induced in the whole small intestine after the worm implantation. In the large intestine, a considerable number of adult worms settled in the mucosa of mutant mice, whose goblet cell mucins were undersulfated because of a mutation in sulfate-activating enzymes. In these mice, the degree of sulfation of goblet cell mucins in the large intestine was significantly reduced to the level of normal small intestine goblet cell mucins. Our results suggest that sulfated glycoconjugates, either from mucosal mast cells or goblet cells, have important effects on the longitudinal distribution of parasitic females of S. venezuelensis.     

Dietary supplementation with ovine serum immunoglobulin is associated with an increased gut luminal mucin concentration in the growing rat

The mucus layer covering the gut epithelium is pivotal to host defence and is affected by various dietary components. Part of the reported beneficial effect of dietary immunoglobulins (Igs) on gut health may be due to effects on the gut mucus layer. The aim was to determine whether orally administered ovine serum Ig influence goblet cell count, mucin gene expression and digesta mucin protein content in the gut of the growing rat. Fourteen Sprague-Dawley male growing rats were used in a 21-day study and were fed either a casein-based control diet (CON; no Ig) or a similar diet but containing freeze-dried ovine Ig (FDOI). Daily food intake and growth rate were not affected by the dietary treatments. When compared to the rats consuming CON diet, those consuming the FDOI diet had significantly (P < 0.05) more intact and cavitated goblet cells in the intestinal villi. A similar result was found for crypt goblet cells in the small intestine and colon. Ileal Muc2, Muc3, Muc4 and stomach Muc5Ac mRNA expressions for the FDOI animals were higher (P < 0.05) compared to the the CON animals. Mucin protein content was higher (P < 0.05) in the stomach, ileum and colonic digesta of rats fed the FDOI diet. In conclusion, orally administered FDOI influenced gut mucins in the growing rat as evidenced by increased mucin gene expression and digesta mucin protein concentrations as well as an increased goblet cell count.     

Histochemical characteristics of mucins in the small intestine. A comparative study of normal mucosa, benign epithelial tumours and carcinoma

Synopsis The histochemical properties of the mucins in seven benign epithelial tumours and 15 carcinomas distributed along the duodenum, jejunum and ileum were investigated and compared with normal controls. This study reveals that (a) goblet cells in normal small intestine contain neutral and sialomucins but no sulphated material; (b) the proportion of the different types of mucins in the goblet cells vary along the crypts and villi with an increasing amount of sialomucins towards the villus top; (c) mucin composition also changes from duodenum to ileum particularly in the proportions of sialic acid types and in the presence of traces of sulphomucins in the ileal mucosa close to the ileo-caecal valve, suggesting a gradual transition through the small intestine to the colon; (d) benign tumours show the same mucin pattern as normal mucosa; (e) the mucosa adjacent to carcinoma shows increasing amounts of sialomucins and sulphomucins; (f) carcinomas present a variety of mucin patterns, and thus the study of mucins seems to be of no value in differentiating tumours of the small intestine from those elsewhere in the gastrointestinal tract. A working hypothesis based on the Unitary Theory of the origin of the intestinal epithelial cells is proposed to explain the variations in glycoprotein synthesis with cell differentiation and carcinogenesis.     

Ontogeny of the digestive tract during larval development of yellowtail flounder: a light microscopic and mucous histochemical study

The histological development and mucous histochemistry of the alimentary tract in larval yellowtail flounder were studied using light microscopy. Samples were taken when the larvae were first offered food at 3 days post-hatch, then at 7, 10, 29, 36, and 46 days post-hatch, at which time they were metamorphosing. Regional partitioning of the digestive tract into the buccal cavity, pharynx, oesophagus, post-oesophageal swelling (PES), intestine, and rectum was complete by day 10. Goblet cells were present only in the buccal cavity, pharynx and intestine by day 7, but increased in number and distribution as development continued. By day 29, the posterior zone of the oesophagus had a marked increase in goblet cell density and mucosal folding. At the transition from oesophagus to PES/stomach stratified epithelium with goblet cells changed abruptly to a columnar epithelium with no goblet cells. Multicellular glands in the PES of 36-day larvae allowed it to be defined as a stomach. The distinct brush border of columnar epithelium and the presence of goblet cells characterize the intestine and rectum. All goblet cells throughout the digestive tract were strongly positive for acid mucins as was the luminal layer of the stratified epithelia lining the buccal cavity, pharynx and oesophagus. The PES/stomach epithelium stained weakly for neutral mucins. No mucin staining was associated with the gastric glandular epithelium. The brush borders of the intestine and rectum were strongly positive for combinations of neutral and acid mucins.     

Elemental diet induces the proliferation of sialomucin goblet cells in the rat duodenum and jejunum

We histologically examined the effects of elemental diet (ED) on the goblet cell profile in the rat small intestine. The sulfomucin goblet cells were predominant throughout the small intestine in the control group, while sialomucin goblet cells were manifest in the duodenum and jejunum in the ED group. Next, we investigated the possible relevance of luminal osmolality to the goblet cell profile. Gastric osmolality in the ED group was within the physiological range. Meanwhile, ingestion of high glucose diet elevated gastric osmolality and increased the number of sialomucin goblet cells in the duodenum and jejunum. Further, it turned out that the lower sulfur contents in ED was not related to the unique goblet cell profile by ED ingestion. It is inductively suggested that the influx of high concentrations of low molecular nutrients into the small intestine could be associated with the goblet cell alteration, but the alteration was not necessarily due to the changes in the gastric osmolality by ED ingestion.     

Gastrointestinal mucins of Fut2-null mice lack terminal fucosylation without affecting colonization by Candida albicans

Posttranslational modification of apomucins by the sequential action of glycosyltransferases is required to produce mature mucins. The Secretor gene (FUT2) encodes an alpha(1,2)fucosyltransferase (EC 2.4.1.69) that catalyzes addition of terminal alpha(1,2)fucose residues on mucins and other molecules in mucosal epithelium. Mutant mice containing targeted replacement of Fut2 with the bacterial reporter gene lacZ were studied to determine the affect of the loss of Fut2 on glycosylation of mucins in the gastrointestinal tract. By whole organ X-gal staining, lacZ activity is prominently expressed in the foveolar pit and chief cells of the glandular stomach, Brunner's glands of the duodenum, and goblet cells in the large intestine of Fut2-LacZ-null mice. Staining with Aleuria aurantia agglutinin demonstrates loss of L-fucosylated epithelial glycans throughout the gastrointestinal tract of Fut2-LacZ-null mice, however, histologic appearance of the tissues appears normal. Analysis of oligosaccharides released from insoluble colonic mucins, largely Muc2, by mass spectrometry shows complete lack of terminal fucosylation of O-linked oligosaccharides in Fut2-LacZ-null mice. Precursor glycans accumulate with no evidence of compensation by other fucosyltransferases or sialyltransferases on mucin glycosylation. Because Candida albicans has been reported to adhere to intestinal mucins creating a potential reservoir associated with vaginitis, Fut2-LacZ-null and wild-type mice were inoculated by gastric lavage with C. albicans. We observe no difference in colonization between genotypes suggesting mucin terminal fucosylation does not significantly influence C. albicans-host interaction in the intestine, highlighting that infections caused by the same organism at different mucosal surfaces are not equal.     

Adequate oral threonine is critical for mucin production and gut function in neonatal piglets

In previous experiments, we found that the threonine requirement of neonatal piglets fed parenterally was 40% of that when fed intragastrically; we hypothesized that much of the oral supply of threonine is being used for mucin production. To investigate this hypothesis, intragastrically fed 2-day-old piglets were fed one of three treatments for 8 days: 1) a threonine-adequate diet (IG-A; 0.6 g threonine.kg(-1).day(-1) fed intragastrically); 2) a threonine-deficient diet (IG-D; 0.1 g threonine.kg(-1).day(-1) fed intragastrically); or 3) a threonine-deficient diet with adequate threonine delivered parenterally (IV-A; 0.5 g threonine.kg(-1).day(-1) fed parenterally plus 0.1 g threonine.kg(-1).day(-1) fed intragastrically). IG-D piglets experienced higher nitrogen excretion, higher plasma urea, and lower plasma threonine concentrations versus both of the other groups (P < 0.05), indicating profound threonine deficiency. Mucosal mass and total crude mucin content were lower in the colons of IG-D pigs (P < 0.05). Histopathological analysis showed lower numbers of acidic mucin-producing goblet cells in the duodenum and ileum of IG-D pigs. In IG-D pigs, acidic mucin subtypes were lower in the small intestine but higher in the colon, which corresponded with persistent diarrhea. The parenteral supply of threonine was adequate to maintain most outcome parameters, although IV-A pigs did have smaller colonic goblet cells with more acidic mucins compared with IG-A pigs. Overall, our results suggest that adequate dietary threonine was critical in the production of mucus and that a parenteral threonine supply can ameliorate most of the symptoms of oral threonine deficiency.     

Nutritional assessment and fate of DNA of soybean meal from roundup ready or conventional soybeans using rats

This study was conducted to compare the safety of soybean meal prepared from genetically modified (GM) glyphosate-tolerant (Roundup Ready; RR) soybeans and conventional soybeans. Eighty Sprague-Dawley rats (40 males and 40 females) were randomly allotted to one of four groups according to sex and body weight for a 13-week feeding experiment. The rats were fed corn-based diets containing 60% conventional soybean meal, a mixture of 30% conventional and 30% RR soybean meal, 60% or 90% RR soybean meal. All diets were adjusted to an identical nutrient level except the 90% RR diet. The two soybean meals were similar in chemical analysis and amino acid composition. During the 13-week growth trial, body weight (P < 0.05) and feed intake (P < 0.05) decreased only in rats fed with 90% RR soybean meal at the first week. No treatment-related deaths occurred during the experiment. Gross necropsy findings, haematological or urinalysis values and clinical serum parameters showed no meaningful differences between rats fed the control and RR soybean meals. A 145 bp of cp4 epsps gene specific for the GM constructs from RR soybean meal or a 407 bp of lec gene from endogenous soybean DNA could not be detected in investigated masseter muscle samples. No adverse effects of glyphosate-tolerant soybean meal on rats were seen even at levels as high as 90% of the diet.     

Nutritional assessment and fate of dna of soybean meal from roundup ready or conventional soybeans using rats

This study was conducted to compare the safety of soybean meal prepared from genetically modified (GM) glyphosate-tolerant (Roundup Ready; RR) soybeans and conventional soybeans. Eighty Sprague-Dawley rats (40 males and 40 females) were randomly allotted to one of four groups according to sex and body weight for a 13-week feeding experiment. The rats were fed corn-based diets containing 60% conventional soybean meal, a mixture of 30% conventional and 30% RR soybean meal, 60% or 90% RR soybean meal. All diets were adjusted to an identical nutrient level except the 90% RR diet. The two soybean meals were similar in chemical analysis and amino acid composition. During the 13-week growth trial, body weight (P?P?cp4 epsps gene specific for the GM constructs from RR soybean meal or a 407?bp of lec gene from endogenous soybean DNA could not be detected in investigated masseter muscle samples. No adverse effects of glyphosate-tolerant soybean meal on rats were seen even at levels as high as 90% of the diet.     

Morphological and histochemical characterisation of the mucosa of the digestive tract in matrinxã Brycon amazonicus (Teleostei: Characiformes)

This study describes anatomical, histological and histochemical features of the digestive tract mucosal layer of the matrinxã Brycon amazonicus, an omnivorous freshwater fish endemic from the Amazon basin. This species presents short thick oesophagus with longitudinal folds, that allow the passage of large food items. The mucosa is lined with a stratified secretory epithelium rich in goblet cells that secrete neutral and acid mucins. The two mucin types provide different viscosity in anterior and posterior oesophagus related to the protective and lubricant functions, respectively. The stomach is a highly distensible Y-shaped saccular organ. Here, it is proposed that this anatomical shape plays an essential role in food storage when food availability is abundant. The stomach mucosa is composed of epithelial cells with intense neutral mucin secretion to protects against gastric juice. The intestine is slightly coiled and presents internally a complex pattern of transversal folds that increases the absorption surface and the retention time of food. Goblet cells in the intestine secrete acid and neutral mucins that lubricate the epithelium and aid in the digestive processes. In the rectum, an increase in goblet cells population occurs that may be related to better lubrication.     

High-fat diet alters the oligosaccharide chains of colon mucins in mice

Mucins are high molecular weight epithelial proteins, strongly glycosylated, and are the main component of the mucus. Since mucus secretion can be altered in diseases, colon mucins can be regarded as a biomarker of chronic inflammatory bowel diseases or preneoplastic changes. Conventional histochemistry and lectin histochemistry combined with chemical treatment and enzymatic digestion were carried out to analyze the colon mucins in mice fed a high-fat diet for 25 weeks, a period sufficient to induce simple liver steatosis, to check whether the carbohydrate features of mucus can be altered by an inadequate diet. An increase in the sialo/sulfomucins ratio with respect to control mice, assessed by computerized image analysis, was observed in the colon, although differences in sialic acid acetylation between control and mice fed a high-fat diet were not found. High-fat diet was also associated with altered lectin-binding pattern of the mucus, with a probable shortening of oligosaccharide chains of glycoproteins. This pattern was leading to over-expression of Galβ1,3GalNAc terminal dimers (TF antigen) and GalNAc terminal residues (Tn antigen). This altered composition of mucins can be related to a defect in the process of glycosylation, or to incomplete maturation of goblet cells, and may be an early indication of preneoplastic and neoplastic changes. In conclusion, our findings confirm that a fatty-rich diet (Western-style diet) induces alteration of mucins and may be associated with colon diseases. Our investigation corroborates the usefulness of lectins histochemistry in the early diagnosis of prepathological states of the colon.     

Dietary-induced hypertrophic--hyperplastic obesity in mice

Metabolically intact NMRI mice and genetically obese NZO mice were fed ad lib. either a high-carbohydrate diet (standard) or a high-fat diet for a period of about 11 (NMRI mice) or 38 (NZO mice) wk. In both strains of mice, body weight increased more in the groups fed the high-fat diet. However, caloric intake by NMRI mice fed the high-fat diet was less than that of the controls. In NMRI mice fed the high-fat diet, epididymal and subcutaneous fat cell volumes increased; when these mice were fed the standard diet, only epididymal fat cell volume increased. Epididymal and subcutaneous fat cell numbers increased only in the group fed the high-fat diet. In NMRI mice fed either diet, the postprandial blood glucose was lower in older animals, but plasma insulin remained unchanged. The glucose tolerance deteriorated insignificantly. In NZO mice fed either diet, epididymal fat cell volumes and fat cell numbers increased. In this strain of mice the postprandial blood glucose and plasma insulin exhibited the strain-specific pattern, independent of the diet. In older animals fed either diet the glucose tolerance decreased.     

Ultrastructural morphometrical and immunocytochemical analyses of hepatocyte nuclei from mice fed on genetically modified soybean

No direct evidence that genetically modified (GM) food may represent a possible danger for health has been reported so far; however, the scientific literature in this field is still quite poor. Therefore, we carried out an ultrastructural morphometrical and immunocytochemical study on hepatocytes from mice fed on GM soybean, in order to investigate eventual modifications of nuclear components of these cells involved in multiple metabolic pathways related to food processing. Our observations demonstrate significant modifications of some nuclear features in GM-fed mice. In particular, GM fed-mice show irregularly shaped nuclei, which generally represents an index of high metabolic rate, and a higher number of nuclear pores, suggestive of intense molecular trafficking. Moreover, the roundish nucleoli of control animals change in more irregular nucleoli with numerous small fibrillar centres and abundant dense fibrillar component in GM-fed mice, modifications typical of increased metabolic rate. Accordingly, nucleoplasmic (snRNPs and SC-35) and nucleolar (fibrillarin) splicing factors are more abundant in hepatocyte nuclei of GM-fed than in control mice. In conclusion, our data suggest that GM soybean intake can influence hepatocyte nuclear features in young and adult mice; however, the mechanisms responsible for such alterations remain unknown.     

Prenatal intestinal histology and histochemistry in the goat

The mucosa of the small and large intestine of goat fetuses exhibited villi which had disappeared after the 32.5-cm curved crown rump (CVR) stage. At places, the stratified epithelial lining persisted among the normal columnar epithelium with goblet cells. The concentration of goblet cells increased with age, while the thickness of the epithelium decreased. The crypts of Lieberkühn were tortuous at the base. Brunner's glands appeared at the 14.2-cm CVR stage. Peyer's patches appeared at the 24.5-cm CVR stage in the ileum. The muscularis mucosae differentiated in the large intestine in group II (16.2- to 24.5-cm CVR length) and progressed caudocranially. The striated border of the intestinal epithelium presented with alkaline phosphatase activity; this border and the goblet cells also stained for mucin. Glycogen was demonstrable in the epithelium with greater concentrations in the duodenum and jejunum in group I (11.5- to 14.6-cm CVR length), and in the ileum and large intestine in group III (30.8- to 39.5-cm CVR length).     

Fermentation of soybean meal withAspergillus usamii improves zinc availability in rats

Soybean meal was fermented withAspergillus usamii to improve zinc availability through the degradation of phytic acid. Rats fed a diet containing fermented soybean meal showed greater femoral zinc than did animals fed a diet containing regular soybean meal. Zinc solubility in the small intestine was higher in the rats fed fermented soybean meal than in the rats fed regular soybean meal. These results suggested that fermentation withAspergillus usamii improved zinc availability in dietary soybean meal, which was induced by the increase of zinc solubility in the small intestine. Adding the same amount of phytate that was contained in the regular soybean mealbased diet did not affect the amount of zinc present in rats fed a fermented soybean meal-based diet with sodium phytate. Phytase activity was found in fermented soybean meal, and this activity may degrade added phytate in fermented soybean meal-based diet.