Mineralocorticoid receptor gene expression in the gastrointestinal tract: distribution and ontogeny

The gastrointestinal tract is a well characterized target tissue for aldosterone, where it regulates electrolyte transport, particularly in the descending colon. Previous studies have demonstrated the presence of aldosterone receptors in gastrointestinal tissues. We have used specific cRNA probes for the rat mineralocorticoid receptor to explore both the distribution and ontogeny of mineralocorticoid receptor gene expression in the gastrointestinal tract. Mineralocorticoid receptor gene expression is found throughout the small and large intestine, but is absent from the stomach. The highest levels are observed in the distal colon, and significant expression is found in the duodenum; in both tissues levels of expression are higher than those in kidney. In both the developing duodenum and colon, mineralocorticoid receptor gene expression precedes the development of the full physiological response to aldosterone. These findings emphasise the colon as an important target tissue for aldosterone, and raise the question of potential roles for aldosterone in the duodenum.     

Fungi inhabiting the healthy human gastrointestinal tract: a diverse and dynamic community

Fungal DNA was selectively amplified, and the ITS region sequenced, from fecal samples taken from 45 healthy human volunteers at one (21 volunteers) or two (24 volunteers) time points. Seventy-two operational taxonomic units, representing two phyla and ten classes of fungi, were recovered. Candida yeasts, notably Candida tropicalis (present in 51 samples), and yeasts in the Dipodascaceae (39 samples), dominated, while 38 OTUs were detected in a single sample each. Fungi included known human symbionts (Candida, Cryptococcus, Malassezia and Trichosporon spp.), common airborne fungi (Cladosporium sp.) and fungi known to be associated with food (Debaryomyces hansenii and high salt fermented foods; Penicillium roqueforti and blue cheese). In contrast with gut-associated bacteria, fungi occurred in much lower abundance and diversity, and fungal composition appeared unstable over time.     

Characterization of spore forming Bacilli isolated from the human gastrointestinal tract

Aims: To isolate and characterize spore‐former bacteria able to colonize the human gastrointestinal tract (GIT). Methods and Results: A total of 25 spore‐formers was isolated from faeces and ileal biopsies of healthy human volunteers and identified at the species level. Physiological analysis was performed to evaluate the ability of the various isolates to form biofilms, to swarm, to produce surfactants and molecules that have antimicrobial activity against selected pathogens. To assess the potential probiotic activity of the isolates, we tested the resistance of cells and spores to simulated gastric conditions, the ability to grow and sporulate in anaerobic conditions and the presence of toxin‐encoding genes in their genome. Conclusions: Spore‐formers belonging to various bacterial species have been isolated from the gut of healthy human volunteers. These strains appear to be well adapted to the intestinal environment and we propose them as potential probiotic strains for human use and as oral vaccine vehicles. Significance and Impact of the Study: To our knowledge this is the first detailed characterization of spore‐forming Bacilli from the human GIT. Our data suggest that the isolated species do not transit, but rather colonize this specific habitat and propose them as probiotic strains for human use.     

Kallikrein-gene expression in the rat gastrointestinal tract.

The serine proteinase glandular kallikrein has been demonstrated in the gastrointestinal tract, although there is some doubt as to whether it is synthesized there or derives from exocrine-gland secretions. Using a rat pancreatic kallikrein cRNA probe we have demonstrated kallikrein-like gene expression in the corpus, duodenum, jejunum, ileum, caecum and colon, and compared the pattern of expression with that of the gastrointestinal peptides somatostatin, gastrin and glucagon. In addition, using a panel of oligonucleotide probes specific for various members of the rat kallikrein-gene family, we have shown that the kallikrein-like gene expressed appears to be expressed as true kallikrein.     

Review: Chemosensing of nutrients and non-nutrients in the human and porcine gastrointestinal tract

The gastrointestinal tract (GIT) is an interface between the external and internal milieus that requires continuous monitoring for nutrients or pathogens and toxic chemicals. The study of the physiological/molecular mechanisms, mediating the responses to the monitoring of the GIT contents, has been referred to as chemosensory science. While most of the progress in this area of research has been obtained in laboratory rodents and humans, significant steps forward have also been reported in pigs. The objective of this review was to update the current knowledge on nutrient chemosensing in pigs in light of recent advances in humans and laboratory rodents. A second objective relates to informing the existence of nutrient sensors with their functionality, particularly linked to the gut peptides relevant to the onset/offset of appetite. Several cell types of the intestinal epithelium such as Paneth, goblet, tuft and enteroendocrine cells (EECs) contain subsets of chemosensory receptors also found on the tongue as part of the taste system. In particular, EECs show specific co-expression patterns between nutrient sensors and/or transceptors (transport proteins with sensing functions) and anorexigenic hormones such as cholecystokinin (CCK), peptide tyrosine tyrosine (PYY) or glucagon-like peptide-1 (GLP-1), amongst others. In addition, the administration of bitter compounds has an inhibitory effect on GIT motility and on appetite through GLP-1-, CCK-, ghrelin- and PYY-labelled EECs in the human small intestine and colon. Furthermore, the mammalian chemosensory system is the target of some bacterial metabolites. Recent studies on the human microbiome have discovered that commensal bacteria have developed strategies to stimulate chemosensory receptors and trigger host cellular functions. Finally, the study of gene polymorphisms related to nutrient sensors explains differences in food choices, food intake and appetite between individuals.     

Expression pattern of the homeotic gene Bapx1 during early chick gastrointestinal tract development

Regulation of the Bone Morphogenetic Protein (BMP) signaling pathway is essential for the normal development of vertebrate gastrointestinal (GI) tract, but also for the differentiation of the digestive mesenchymal layer into smooth muscles and submucosal layer. Different studies demonstrated that Bapx1 (for bagpipe homeobox homolog 1) negatively regulates the BMP pathway, but its precise expression pattern during the development and the differentiation of the GI tract mesenchyme actually remains to be examined. Here, we present the spatio-temporal expression profile of Bapx1 in the chick GI tract. We show that Bapx1 is first expressed in the undifferentiated mesenchyme of the gizzard and the colon. After the differentiation of the digestive mesenchyme, we found Bapx1 strongly expressed in the gizzard smooth muscle and in the submucosa layer of the colon. This expression pattern provides new insights into the roles of Bapx1 during the regionalization of the GI tract and the differentiation of the digestive mesenchyme of the colon and the stomach.     

Postnatal differential expression of chemoreceptors of free fatty acids along the gastrointestinal tract of supplemental feeding v. grazing kid goats

The gastrointestinal tract (GIT) of animals is capable of sensing various kinds of nutrients via G-protein coupled receptor-mediated signaling transduction pathways, and the process is known as ‘gut nutrient chemosensing’. GPR40, GPR41, GPR43 and GPR119 are chemoreceptors for free fatty acids (FFAs) and lipid derivatives, but they are not well studied in small ruminants. The objective of this study is to determine the expression of GPR40, GPR41, GPR43 and GPR119 along the GIT of kid goats under supplemental feeding (S) v. grazing (G) during early development. In total, 44 kid goats (initial weight 1.35±0.12 kg) were slaughtered for sampling (rumen, abomasum, duodenum, jejunum, ileum, cecum, colon and rectum) between days 0 and 70. The expression of GPR41 and GPR43 were measured at both mRNA and protein levels, whereas GPR40 and GPR119 were assayed at protein level only. The effects of age and feeding system on their expression were variable depending upon GIT segments, chemoreceptors and expression level (mRNA or protein), and sometimes feeding system × age interactions (P<0.05) were observed. Supplemental feeding enhanced expression of GPR40, GPR41 and GPR43 in most segments of the GIT of goats, whereas G enhanced expression of GPR119. GPR41 and GPR43 were mainly expressed in rumen, abomasum and cecum, with different responses to age and feeding system. GPR41 and GPR43 expression in abomasum at mRNA level was greatly (P<0.01) affected by both age and feeding system; whereas their expression in rumen and abomasum at protein level were different, feeding system greatly (P<0.05) affected GPR41 expression, but had no effect (P>0.05) on GPR43 expression; and there were no feeding system×age interactions (P>0.05) on GPR41 and GPR43 protein expression. The expression of GPR41 and GPR43 in rumen and abomasum linearly (P<0.01) increased with increasing age (from days 0 to 70). Meanwhile, age was the main factor affecting GPR40 expression throughout the GIT. These outcomes indicate that age and feeding system are the two factors affecting chemoreceptors for FFAs and lipid derivatives expression in the GIT of kids goats, and S enhanced the expression of chemoreceptors for FFAs, whereas G gave rise to greater expression of chemoreceptors for lipid derivatives. Our results suggest that enhanced expression of chemoreceptors for FFAs might be one of the benefits of early supplemental feeding offered to young ruminants during early development.     

Expression pattern of the homeotic gene Bapx1 during early chick gastrointestinal tract development

Regulation of the Bone Morphogenetic Protein (BMP) signaling pathway is essential for the normal development of vertebrate gastrointestinal (GI) tract, but also for the differentiation of the digestive mesenchymal layer into smooth muscles and submucosal layer. Different studies demonstrated that Bapx1 (for bagpipe homeobox homolog 1) negatively regulates the BMP pathway, but its precise expression pattern during the development and the differentiation of the GI tract mesenchyme actually remains to be examined. Here, we present the spatio-temporal expression profile of Bapx1 in the chick GI tract. We show that Bapx1 is first expressed in the undifferentiated mesenchyme of the gizzard and the colon. After the differentiation of the digestive mesenchyme, we found Bapx1 strongly expressed in the gizzard smooth muscle and in the submucosa layer of the colon. This expression pattern provides new insights into the roles of Bapx1 during the regionalization of the GI tract and the differentiation of the digestive mesenchyme of the colon and the stomach.     

Cold stress-induced changes in the aerobic heterotrophic gastrointestinal tract bacterial flora of red hybrid tilapia

Fifteen juvenile red hybrid tilapia Oreochromis mossambicus × O. macrochir averaging 50 g body weight were cold-stressed by immersion in 18° C sea water; control fish ( n = 15) were kept at the acclimation temperature of 26° C. Three fish from each group were killed 0, 24, 48 and 72 h after the start of the experiment. Gastrointestinal tracts were removed and dissected into the stomach, anterior gut and posterior gut regions. Aerobic heterotrophic bacteria were identified and enumerated relative to temperature, exposure time and gastrointestinal tract region. Gram negative genera included Alcaligenes, Flavobacterium, Photobacterium, Pseudomonas and Vibrio ; the latter three were predominant. Mean bacterial numbers and taxonomic composition of the microflora varied significantly ( P <0·05) in response to the three test variables. There were greater mean total bacterial numbers at 18 than at 26° C, due primarily to proliferation of Vibrio spp. Mean bacterial numbers after 24 h were greater than those at both the earlier and later sampling periods. Mean bacterial numbers in the stomach were less than those in the anterior and posterior gut, which were not significantly different. The relative abundance of Vibrio spp. was negatively correlated with that of Flavobacterium , which may have reflected competition between pathogenic and nonpathogenic species. Such stress-induced changes in the bacterial microflora may contribute to the onset of disease because several species of Vibrio are known primary or opportunistic fish pathogens.     

Trefoil Factor 1 as a marker of mucosal damage of the gastrointestinal tract in children with sepsis

Abstract

Intestinal ischemia and reperfusion is a common pathway for many diseases in children. The objective of our study was an analysis of Trefoil factor 1 levels dynamics in patients with SIRS or septic condition during a 5-day period. Analysis of TFF1 levels dynamics revealed that TFF1 levels kept steady state during the 5-day period. TFF1 levels were similar in patients with SIRS, sepsis and severe sepsis. Significantly higher levels of TFF1 were in patients with septic shock and MODS.     

Latent herpes simplex virus type 1 gene expression in ganglia innervating the human gastrointestinal tract.

Using in situ hybridization, we demonstrated that latent herpes simplex virus type 1 (HSV-1) gene expression is prevalent in human adult nodose ganglia. This suggests that infection of gastrointestinal sensory nerves, probably through swallowed virus-laden oral secretions, occurs commonly and that HSV-1 reactivating from this site may play a role in recurrent gastrointestinal disorders.     

Altered mucin expression in the gastrointestinal tract: a review

Early studies of changes in mucin expression in disorders of the gastrointestinal tract focused on alterations in the carbohydrate chain. This review briefly considers the various mechanisms by which such alterations may come about: (a) normal variation, (b) sialic acid alterations, (c) defective assembly of carbohydrate side-chains, (d) changed expression of core proteins and (e) epithelial metaplasia. The availability of monoclonal antibodies to mucin core proteins adds a new dimension to mucin histochemistry. It is now possible to offer explanations for traditional mucin histochemical findings on the basis of lineage-specific patterns of mucin core protein expression. Changes in core protein expression are described in inflammatory, metaplastic and neoplastic disorders of the gastrointestinal tract. The possibility that mucin change could be important in the aetiology of some diseases such as ulcerative colitis and H. pylori gastritis is considered. It is more probable, however, that changes in mucin expression are secondary to reprogramming of cellular differentiation and altered cell turnover. As such they may serve as markers to explain pathogenesis and provide novel diagnostic and prognositc information.     

Cubilin expression and posttranslational modification in the canine gastrointestinal tract

Cubilin is an endocytic receptor of the apical brush border membrane that is essential for intrinsic factor-mediated cobalamin absorption in small intestine. However, cubilin is more highly expressed in kidney and yolk sac, and recent molecular characterization of the receptor has focused on these tissues. The aim of this investigation was to examine tissue-specific cubilin expression and posttranslational modifications with an emphasis on the gastrointestinal tract. Intrinsic factor-cobalamin binding activity, cubilin immunoreactivity, and cubilin mRNA levels were determined in multiple segments of canine gastrointestinal mucosa and other tissues. These aspects of cubilin expression varied in parallel, suggesting that the major determinant of regional cubilin expression in the gastrointestinal tract is modulation of cubilin mRNA. Cell fractionation indicated that ileal cubilin is not strongly membrane associated. An approximately 185-kDa brush border specific and two >400-kDa precursor forms of cubilin were identified. Asparagine-linked oligosaccharide modifications characterized by differential glycosidase digestion of affinity-purified cubilin from ileal mucosa and renal cortex differed, but ileal and renal intracellular cubilin comigrated on SDS-PAGE at approximately 400 kDa after oligosaccharide removal, thus reconciling previous conflicting size estimates of the cubilin polypeptide.     

In vitro characterization of calcium transport along the gastrointestinal tract of freshwater rainbow trout Oncorhynchus mykiss

Using an in vitro gut-sac technique, this study examined the mechanisms of calcium (Ca) uptake along the gastrointestinal tract (GIT) of rainbow trout Oncorhynchus mykiss. Ca uptake into three different compartments (mucous-bound, mucosal epithelium and blood space) of four distinct GIT segments (stomach, anterior intestine, mid intestine and posterior intestine) was monitored after luminal exposure to 10 mM Ca saline (radiolabelled with (45) Ca). Ca transport was determined to be both time-dependent and concentration-dependent. The concentration-dependent kinetics of Ca uptake was investigated using varying luminal concentrations of Ca (1, 10, 30, 60 and 100 mM). In the blood-space compartment, Ca uptake was saturable at high Ca concentrations in the mid intestine (suggesting mediated transport), while linear uptake was found in the other gut segments. In the mucous-bound and mucosal epithelium compartments, however, saturation kinetics were found for most GIT segments, also suggesting mediated transport. Manipulation of serosal saline osmotic pressure with mannitol demonstrated that Ca uptake was not greatly affected by solvent drag. Elevated mucosal cadmium (Cd) did not appear to inhibit Ca uptake into the blood space in any of the GIT sections, and Ca uptake did not appear to be sodium dependent. Maximum transport capacities for Ca and Cd were found to be comparable between the gills and gut, but affinities were much higher at the gills (up to 3000 times).