The effect of diet on the structure of gut bacterial community of sympatric pair of whitefishes (Coregonus lavaretus): one story more

In the Coregonus lavaretus complex may be found lacustrine sympatric pairs, which serves as an intriguing model for studying different aspects of fish evolutionary biology. One such sympatric whitefish pair inhabits Teletskoye Lake (West Siberia, Russia) and includes a “large” form (Coregonus lavaretus pidschian (Gmelin, 1789)) and a “small” form (C. l. pravdinellus (Dulkeit, 1949)). C. l. pravdinellus has a narrow trophic specialization and feeds on zooplankton, whereas the diet of C. l. pidschian is based on benthic prey. In the present study we aimed to address the question of how the gut microbial community reflects the divergence in diet of a sympatric pair of whitefish. Studied samples included the mucosa and content were collected for cardiac and pyloric stomach, anterior, middle, and posterior intestine, but only mucosa was collected for the pyloric caeca. In addition, water, sediment, macrophyte (environmental microbiota) and invertebrate (microbiota of prey) samples were collected in the same location. The V3–V4 region of the 16S rRNA genes was chosen for microbiome analysis and the software PICRUSt used to estimate the difference functional roles of the microbiota. The number of OTUs and Chao1 index in mucosa and content of cardiac and pyloric stomach were significantly different between whitefish. Significant differences were observed between whitefish for content from different parts of the intestine in terms of OTU number and Chao1 indices, whereas for mucosa from the same parts of intestine these differences were absent. No significant differences were found for diversity estimates of mucosa and content of different parts of the gut (there were a few exceptions) between whitefish. The form of whitefish and the segment of the digestive system were factors with a significant determinative effect on the structure of the microbiota from gut mucosa and content. The most dominant phyla in mucosa and content of cardiac and pyloric stomach was Proteobacteria (57.0–84.0%) for both whitefish. Throughout the intestine of C. l. pidschian the dominant phyla in mucosa were Proteobacteria (38.8%) and Firmicutes (15.6%), whereas for C. l. pravdinellus–Tenericutes (49.6%) and Proteobacteria (28.1%). For both forms, the phylum Spirochaetes was found in a significant amount (20.0–25.0%) in the mucosa of the posterior intestine. While for the content obtained from anterior, middle and posterior intestines, the dominant bacterial phyla were the same as those described for mucosa from the same parts of the intestine for both whitefish. The bacterial community of the prey and environment was significantly different from bacterial communities found for all parts of the gut mucosa for both whitefish, with the exception of the mucosa of the cardiac stomach. According to PICRUSt the highest level of differences between whitefish at the L3 level were found for the intestinal mucosa (75.3%), whereas the lowest one was registered for stomach content (38.8%).

Gastroenterology

Nausea and vomiting can be defined, respectively, as the urge to or the actual act of expelling undigested food from the stomach. It is thought to be an evolutionary defence mechanism to protect against toxic insult (drugs or mi­crobes) and over- eating, while it can also be triggered during pregnancy, or by unpleasant sights or smells. In some instances, it may be the symptom of a more severe underlying pathology. Severity of nausea and vomiting varies considerably between individuals exposed to the same stimulus and symptoms can be highly detrimental to patient quality of life affecting not only their nutritional intake, but also mood and well- being. Although nausea itself is a subjective term, vomiting is a pathophysiological reflex triggered by the vomiting centre located in the medulla. The vomiting centre re­ceives signals from a number of afferent inputs, i.e. the chemoreceptor trigger zone (CTZ), vestibular nucleus, ab­dominal and cardiac vagal afferents, and cerebral cortex (Table 6.1). It may also be activated by hormonal triggers, which accounts for hyperemesis in pregnancy, and the increased incidence of nausea and vomiting associated with the female gender. As the vomiting centre is located close to centres responsible for salivation and breathing, vomiting is often associated with hypersalivation and hyperventilation. The CTZ is highly vascularized and lo­cated at the floor of the fourth ventricle, just outside the blood– brain barrier and, therefore, is itself directly sensi­tive to chemical stimuli. Afferent inputs activate the vomiting centre through several known neurotransmitter pathways; dopamine (D₂), serotonin (5- HT₃, 5- HT₄), acetylcholine (ACh), and substance P (neurokinin 1; NK₁). Each of which provides a potential pharmacological target in the management of nausea and vomiting, once the cause has been established. Efferent pathways from the vomiting centre induce autonomic changes, including vasoconstriction, pallor, tachycardia, salivation, sweating, and relaxation of the lower oesophagus and fundus of the stomach. In vomiting, oesophageal relaxation leads to contraction of the pyloric sphincter, thereby emptying the contents of the jejunum, duodenum, and pyloric stomach into the relaxed fundus. Coordination of muscle contraction occurs within the dia­phragm and abdomen, and retrograde contractions from the intestine then expel the contents of the fundus.

Reaction of stomach for feeding young pigs probiotics

The basis for the diets of pigs of different technologies of production and productivity in all areas and forage species are of plant origin, which is associated primarily with their availability. This group consists of feed grain cereals, grain legumes, green coarse, juicy, waste flour and other technical industries and others. Although omnivorous pig feed them digestion features displayed on the feasibility of forming foundations diet of concentrated feed. For industrial production of pork proportion of concentrated feed often 100%. However, partly in used feed feeding that are of poor quality, which in turn worsens their nutritional value and complicates digestion and nutrient absorption of food. Besides the low digestibility of grain mixtures in which a third of organic matter is not absorbed by the animals, lack of nutrients adversely affect the resistance and other reactions, reproductive function and performance. Studying the formative influence of the new feed factor on the structure of the digestive system of animals must pay attention to the morphological features of individual organs as the result of direct exposure to chemicals in the diet of the wall of the gastrointestinal tract. The effect of different doses of probiotic preparation Entero–active in growing young pigs on morphological indicators of cardiac, fundic and pyloric stomach areas and established its laws. The data indicate a probable thickening of the stomach wall for probiotic action by thickening muscle and mucous membranes in all investigated areas. The changes have no pathological character, and show an adaptive response to the action of gastric certain doses of the new feed factor.

Expression of claudins in the normal canine gastric mucosa

The aim of the present study was to investigate the expression pattern of claudin-1, -2, -3, -4, -5, -7, -8, -10 and -18 in the intact fundic and pyloric gastric mucosa of dogs. Intense, linear, membranous claudin-18 positivity was detected in the surface gastric cells and in the epithelial cells of the gastric glands both in the fundic and pyloric stomach regions. The mucous neck cells in the apical part of the glands, furthermore the parietal cells and chief cells of the basal part of the gland were all positive for claudin-18, in the same way as the enteroendocrine cells. Cells of the basal part of the pyloric glands showed intense, linear, membranous claudin-2 positivity, but cells of the superficial portion of these glands and the surface gastric cells in this region were claudin-2 negative. Fibroblasts, endothelial cells, lymphocytes of the propria layer, smooth muscle cells and vegetative neurons were all negative for claudin-2. All gastric epithelial cells were negative for claudin-1, -3, -4, -5, -6, -7, -8 and -10. The endothelial cells of the propria layer had intense claudin-5 positivity. We assume that claudin-18 forms a paracellular barrier against gastric acid in the healthy canine stomach, in the same way as in mice.

Functional morphology of the mouthparts and alimentary tract of the slipper lobster Thenus orientalis (Decapoda : Scyllaridae)

The mouthparts and proventriculus of Thenus orientalis Lund are adapted to ingest soft flesh, which is consistent with the diet of this and other scyllarids. The crista dentata are reduced, with food transfer into the oesophagus facilitated by large stout setae on the second and third maxillipeds. The mandibles exert little force and most food maceration is effected by the gastric mill. Ingestion is aided by mucus secreted by rosette glands in the paragnaths and membranous lobe, as well as expansion of four longitudinal folds in the oesophageal wall. The cardiac stomach has considerable food storage capacity by extension of its membranous walls, reduced ossicles and simplified ventral filtration channels. The filtering ability of the pyloric filter press is consistent with other macrophagous decapods. The dorsal caecum above the pyloric stomach has an absorptive columnar epithelium that contains acid mucin granules and protein. Muscular walls and longitudinal folds in the hindgut facilitate faecal pellet extrusion.