The comparative gastrointestinal morphology of five species of muroid rodents found in Saudi Arabia

Meriones rex (King jird), Meriones libycus (Libyan jird), Acomys dimidiatus (Eastern spiny mouse), Acomys cahirinus (Egyptian spiny mouse), and Dipodillus dasyurus (Wagner's dipodil) are five species of small rodents of the superfamily Muroidea with distributions in Eastern Africa, Egypt, and the desert regions of the Arabian Peninsula. Water is scarce in these regions and may result in relatively low‐digestible food. The aim of the present study is to describe and compare the gastrointestinal tract morphology and morphometry of these five species in order to elucidate whether morphology is influenced by phylogeny or dietary preference. Each segment of the gastrointestinal tract of each species was macroscopically examined and the length and basal surface area of each segment was measured. Standard histologic procedures were performed to determine a surface enlargement factor to determine the mucosal luminal surface area. A unilocular‐hemiglandular stomach was observed in all the species examined. The caeca of all the species were long and arranged into a loose spiral toward the caecal tip with the ileocaecal and caeco‐colic openings positioned close together. Two rows of oblique folds could be observed in the proximal colon of all species except in D. dasyurus which had longitudinal folds. Morphometric analysis showed the largest stomach in A. cahirinus and the largest caecum and colon in M. libycus. All the species can be grouped in the family Muridae in two subfamilies and similarities were observed including the hemiglandular stomach and relatively large caecum. It could be concluded that phylogeny plays an important role in determining gastrointestinal morphology while diet plays a subordinate role in the desert rodents in the present study. J. Morphol. 275:980–990, 2014. © 2014 Wiley Periodicals, Inc.     

The comparative gastrointestinal morphology of Jaculus jaculus (Rodentia) and Paraechinus aethiopicus (Erinaceomorpha)

Jaculus jaculus (Lesser Egyptian jerboa) and Paraechinus aethiopicus (Desert hedgehog) are small mammals which thrive in desert conditions and are found, among others, in the Arabian Peninsula. Jaculus jaculus is omnivorous while P. aethiopicus is described as being insectivorous. The study aims to describe the gastrointestinal tract (GIT) morphology of these animals which differ in diet and phylogeny. The GITs of J. jaculus (n = 8) and P. aethiopicus (n = 7) were weighed, photographed, and the length, basal surface areas, and luminal surface areas of each of the anatomically distinct gastrointestinal segments were determined. The internal aspects of each area were examined and photographed while representative histological sections of each area were processed to wax and stained using haematoxylin and eosin. Both species had a simple unilocular stomach which was confirmed as wholly glandular on histology sections. Paraechinus aethiopicus had a relatively simple GIT which lacked a caecum. The caecum of J. jaculus was elongated, terminating in a narrow cecal appendix which contained lymphoid tissue on histological examination. The internal aspect of the proximal colon of J. jaculus revealed distinct V‐shaped folds. Stomach content analysis of J. jaculus revealed mostly plant and seed material and some insects, whereas P. aethiopicus samples showed plant material in addition to insects, indicating omnivorous feeding tendencies in areas where insects may be scarce. J. Morphol. 277:671–679, 2016. © 2016 Wiley Periodicals, Inc.     

小鼠胃肠道嗜银细胞的分布及形态学观察

用Grimelius嗜银法对10只小鼠胃肠道嗜银细胞的分布及形态学作了观察研究,结果显示：（l）小鼠嗜银细胞的分布密度,在胃体部最高,从十二脂肠、空肠、回肠、盲肠直到结肠依次减少。（2）嗜银细胞的形态也是多种多样,有梭形、锥体形、椭圆形等。     

Kori bustard (Ardeotis kori struthiunculus) occurrence in the Serengeti grass plains,northern Tanzania

The kori bustard (Ardeotis kori struthiunculus) is indigenous to grasslands and lightly wooded savannahs of southern and eastern Africa. The species is categorized as near threatened in its entire range due to anthropogenic factors and low reproductive rates. The aim of this study was to analyse the impact of grass colour, grass height, season and location on the density/occurrence of this bird species in the Serengeti grass plains, Tanzania. Data were collected from January 2014 to June 2015 using transect counts in four seasons: (i) short dry, (ii) long rain, (iii) long dry and (iv) short rain seasons, respectively. The mean density of kori bustard in the grass plains was 0.25 ± 1.01 per 0.2 km² with near‐significant differences among the study sites. The occurrence of kori bustard was high in the medium height (11–30 cm) during the long rain and short dry seasons. The kori bustard density is relatively low, and the distribution varies with grass height and season. We suggest that conservation efforts should be directed at preventing its local extinction by protecting the habitat from excessive human activities, such as livestock grazing and illegal offtake.     

宏基因组学在人和动物胃肠道微生物研究中的应用进展

人和动物胃肠道存在大量微生物群落,这些微生物是与宿主长期共同进化的结果,并且同宿主的健康和疾病密切相关,因此胃肠道微生物研究已成为当今的热点研究领域。宏基因组学技术在这一领域的应用,使我们不仅能够对胃肠道微生物群落结构及多样性进行分析,还能进一步深入了解其代谢功能,开发和利用潜在的微生物及其基因资源。文中结合我们的研究工作,综述了宏基因组学在人和动物胃肠道微生物研究中的应用,同时着重介绍宏基因组研究的生物信息学技术。     

Anatomy and histology of the gastrointestinal tract of the neo-tropical opossum (Didelphis marsupialis insularis,Allen 1902)

The morphology of the gastrointestinal tract (GI) is a strong indicator of the dietary habits of a species. The goal of this study was to describe the gross and microanatomy of the digestive tract of the neo-tropical opossum (Didelphis marsupialis insularis) and relate them to the animals’ food habits. GI tracts from 12 adult animals were used for this study. Results found the small intestine made up 65.9% of the GI tract, and the stomach was simple with a prominent caecum. Histologically, the oesophageal mucosa was non-keratinized and glands were found throughout the oesophagus. The large intestine showed a great number of goblet cells, the jejunum possessed well-developed villi, and Peyer's patches were absent in the ileum. The absence of keratinization of the epithelial lining of the oesophagus and stomach and a high lymphocytic infiltration throughout the small and large intestine reflected a more carnivorous diet, whereas the presence of a well-developed caecum in the large intestine indicated the ability to digest plant matter. Overall, the morphology of GI tract of D. m. insularis displayed both carnivorous and herbivorous features, allowing us to conclude that it is an omnivorous animal.     

Direct and indirect evidence for polypeptide absorption by the teleost gastrointestinal tract

The ability of the gastrointestinal tract of chinook salmon, Oncorhynchus tshawytscha , to absorb polypeptides in vivo was investigated by reference to the appearance of orally administered adrenocorticotropic hormone (ACTH) within the blood of fish previously treated with dexamethasone (3μg g^−l body weight) in order to suppress endogenous ACTH secretion. Further, since cortisol presence within plasma is dependent upon the availability of ACTH, dexamethasone blockade of endogenous ACTH secretion, in conjunction with subsequent measurements of plasma cortisol levels, provides a means by which biological patency of absorbed exogenous ACTH may be demonstrated. Levels of ACTH and cortisol in plasma of dexamethasone-treated salmon were therefore measured for a period of 360 min immediately following oral intubation of ACTH (15μg g⁻¹ body weight). Peak plasma presence of ACTH-like immunoreactivity (676.6 ± 33.6 pg ml⁻¹ plasma) and cortisol (227.1 ± 29.0 ng ml⁻¹ plasma) were recorded 120 min after ACTH administration. Results from the experimental groups were compared to those of 15 control treatments. Since administration of ACTH to chinook salmon elicited a consistent and significant elevation in not only plasma ACTH but also cortisol presence, it is contended that the salmonid gut expresses an ability to absorb polypeptides of dietary origin. The significance of these findings with respect to the oral administration of biologically active peptides and proteins to fish of importance to aquaculture is discussed.     

Comparative gastrointestinal morphology of three small mammalian insectivores: Acomys spinosissimus (Rodentia), Crocidura cyanea (Eulipotyphla), and Amblysomus hottentotus (Afrosoricida)

The gastrointestinal morphology was investigated in three mammalian insectivorous species, namely Acomys spinosissimus, Crocidura cyanea, and Amblysomus hottentotus. The aim of the study was to provide a comprehensive morphological comparison between the different species and to explore whether anatomical gastrointestinal adaptations are associated with the insectivorous diet of these species. The shape, proportional length, and proportional surface areas of the different gastrointestinal regions were recorded and compared in the three insectivores. Hematoxylin and Eosin (H&E) and Alcian Blue/Periodic Acid Schiff (AB/PAS) were used for morphological assessment. In all three species, the stomach was simple and uncompartmentalized. The internal aspect of the stomach in A. spinosissimus was hemi‐glandular, containing stratified squamous epithelium in the fundus, with glandular epithelium in the body and pyloric region. However, C. cyanea and A. hottentotus had wholly glandular stomachs. Paneth cells were not observed in the intestinal tracts of C. cyanea and A. hottentotus. Acomys spinosissimus was the only species studied that had a cecum. The proximal colonic region of A. spinosissimus had V‐shaped mucosal folds. Histologically, C. cyanea had villi throughout the entire gastrointestinal tract (GIT), whereas for A. hottentotus villi were not present in the most distal gastrointestinal regions. In both C. cyanea and A. hottentotus, longitudinal mucosal folds were present in the distal part of the colon. The GITs of C. cyanea and A. hottentotus showed little morphological differentiation namely, a simple, glandular stomach and the lack of a cecum. J. Morphol., 2013. © 2013 Wiley Periodicals, Inc.     

On the distribution and metabolism of Fusarium-toxins along the gastrointestinal tract of endotoxaemic pigs

The aim of this study was to investigate the potential modulatory effect of E. coli lipopolysaccharides (LPS) on residues of deoxynivalenol (DON), de-epoxy-deoxynivalenol (DOM-1), zearalenone (ZEN) and its metabolites α-zearalenol (α-ZEL), β-zearalenol (β-ZEL), zearalanone (ZAN), α-zearalanol (α-ZAL) and β-zearalanol (β-ZAL) after pre- or post-hepatic administration along the gastrointestinal axis. Fifteen barrows were exposed to a naturally mycotoxin contaminated diet (4.59 mg DON/kg feed and 0.22 mg ZEN/kg feed) and equipped with jugular (ju) and portal (po) catheters. On sampling day (day 29), the barrows were infused with LPS or a control fluid (LPS, 7.5 µg/kg body weight; control, 0.9% NaCl) either pre- or post-hepatically, resulting in three infusion groups: CON_ju-CON_po, CON_ju-LPS_po and LPS_ju-CON_po. At 195 min relative to infusion start (210 min post-feeding), pigs were sacrificed and content of stomach and small intestine (proximal, medial and distal part) as well as faeces were collected. In all LPS-infused animals, higher amounts of dry matter were recovered irrespective of LPS entry site suggesting a reduced gastric emptying and a decreased gastrointestinal motility under endotoxaemic conditions. DON metabolism in the gastrointestinal tract (GIT) remained unaltered by treatments and included an increase in the proportion of DOM-1 along the GIT, particularly from distal small intestine to faeces. Variables describing ZEN metabolism suggest a stimulated biliary release of ZEN and its metabolites in LPS-infused groups, particularly in the LPS_ju-CON_po group. In conclusion, the GIT metabolism of ZEN was markedly influenced in endotoxaemic pigs whereby a jugular induction of an acute phase reaction was more effective than portal LPS infusion hinting at a strong hepatic first-pass effect.     

Ontogeny of immunoreactive glicentin in the human gastrointestinal tract and endocrine pancreas

The gestational time of appearance and distribution of immunoreactive glicentin was compared to that of immunoreactive glucagon in the gastrointestinal tract and endocrine pancreas of human fetuses, aged between 5 and 24 weeks, by an indirect immunoperoxidase method. With the glicentin antiserum No. R 64, the first immunoreactive cells were detected at the 10th week of gestation in the oxyntic mucosa and proximal small intestine, at the 8th week in the ileum and at the 12th week in the colon. In the endocrine pancreas, the first immunoreactive cells were observed as early as 8 weeks within the walls of the primitive pancreatic ductules. At a more advanced stage of development (12 weeks), they were found interspersed among the islet cell clusters and still later (16 weeks) inside the recognizable islets of Langerhans. With the glucagon antiserum No. GB 5667, no immunoreactive cells were demonstrated in the gastrointestinal tract whatever the age of the fetuses. In the endocrine pancreas, the first immunoreactive cells were observed at the 8th week of gestation in the pancreatic parenchyma. The distribution of glucagon-containing cells in the pancreas was similar to that of glicentin immunoreactivity throughout ontogenesis. In the pancreatic islets of one 18-week-old human fetus, the study of consecutive semithin sections treated by both antisera showed that the same cells were labelled. The significance of these findings concerning the role of glicentin as a glucagon precursor is discussed.     

Immunohistochemical localization of BAX and BAD in the normal and BCL-2 null gastrointestinal tract

BAX and BAD are members of the BCL-2 family of proteins. The over-expression of BAX protein has been shown to accelerate apoptosis and increasedbax mRNA levels have also been shown to be associated with the initiation of apoptosis. BAD has also been shown to accelerate apoptosis. In this paper we describe the localization of BAD and BAX expression throughout the gastrointestinal tract of the mouse and the effect that BCL-2 has on the expression of these two proteins. We have discussed the distribution of BAX and BAD in relation to the differences between the small and large bowel in (i) the susceptibility of stem cells to apoptosis and (ii) tumour incidence.This work was supported by the Cancer Research Campaign.     

Characterization of the ultrastructure of the gastrointestinal tract mucosa, stomach contents and liver enzyme activity of the pinfish during development

Carnivorous juveniles (<16 mm L_S) of pinfish Lagodon rhomboides apparently lacked gastric glands in the stomach while larger fish, intermediates (30-33 mm L_S) and herbivorous adults (>80 mm L_S) had numerous gastric glands. Two cell types were identified in the gastric glands of larger fish: mucous secreting cells and secretory cells which had ultrastructure features typical of digestive enzymes and acid secretion. Lipid absorption occurred throughout the caeca and intestine in all sizes of fish. Microvilli found on the rectal epithelial cells of the intermediate and adult pinfish occurred on stalks and were possibly associated with water reabsorption. Liver enzyme activities changed in small fish (26–39 mm L_S) compared to the adult fish. Alanine amino transferase (ALT) and fructose diphosphotase (FDP) activities declined while pyruvate kinase (PK) activities increased significantly. These changes were consistent with a change in diet from a carnivorous (high protein) diet in juveniles to an omnivorous (lower protein) diet determined by stomach content analyses.     

Impact of bioactive substances on the gastrointestinal tract and performance of weaned piglets: a review

The EU ban on in-feed antibiotics has stimulated research on weaning diets as a way of reducing post-weaning gut disorders and growth check in pigs. Many bioactive components have been investigated but only few have shown to be effective. Amongst these, organic acids (OA) have been shown to exert a bactericidal action mediated by non-dissociated OA, by lowering gastric pH, increasing gut and pancreas enzyme secretion and improving gut wall morphology. It has been postulated that they may also enhance non-specific immune responses and improve disease resistance. In contrast, relatively little attention has been paid to the impact of OA on the stomach but recent data show they can differently affect gastric histology, acid secretion and gastric emptying. Butyrate and precursors of butyric acid have received special attention and although promising results have been obtained, their effects are dependent upon the dose, treatment duration, initial age of piglets, gastrointestinal site and other factors. The amino acids (AA) like glutamine, tryptophan and arginine are supportive in improving digestion, absorption and retention of nutrients by affecting tissue anabolism, stress and (or) immunity. Glutamine, cysteine and threonine are important for maintaining mucin and permeability of intestinal barrier function. Spray-dried plasma (SDP) positively affects gut morphology, inflammation and reduces acquired specific immune responses via specific and a-specific influences of immunoglobulins and other bioactive components. Effects are more pronounced in early-weaned piglets and under poorer health conditions. Little interaction between plasma protein and antibiotics has been found, suggesting distinct modes of action and additive effects. Bovine colostrum may act more or less similarly to SDP. The composition of essential oils is highly variable, depending on environmental and climatic conditions and distillation methods. These oils differ widely in their antimicrobial activity in vitro and some components of weaning diets may decrease their activity. Results in young pigs are highly variable depending upon the product and doses used. These studies suggest that relatively high concentrations of essential oils are needed for beneficial effects to be observed and it has been assumed that these plant extracts mimic most of the effects of antibiotics active on gut physiology, microbiology and immunology. Often, bioactive substances protective to the gut also stimulate feed intake and growth performance. New insights on the effects of selected OA and AA, protein sources (especially SDP, bovine colostrum) and plant extracts with anti-bacterial activities on the gut are reported in this review.     

Genomic diversity of cultivable Lactobacillus populations residing in the neonatal and adult gastrointestinal tract

The objective of this study was to investigate the cultivable Lactobacillus population in adult and infant faecal material to identify strains shared across a number of individuals. A range of lactobacilli isolated on Lactobacillus-selective agar from faeces of 16 infants and 11 adults were genetically fingerprinted and further characterized by 16S rRNA gene sequencing. The relatedness of all the Lactobacillus strains isolated to known species was also determined both genetically and phenotypically. This study revealed that the human intestine is initially colonized by only a few (1-2) different cultivable strains whereas in adults the pattern becomes more complex with a higher diversity of strains. The adult samples contained three genetically distinct Lactobacillus strains in some cases, while infant samples generally harboured only one dominant Lactobacillus strain. Moreover, the species in general appeared to differ with Lactobacillus rhamnosus and Lactobacillus casei/paracasei found mainly in adults, whereas Lactobacillus gasseri and Lactobacillus salivarius were more commonly isolated in infant samples. The data reaffirm the differences in Lactobacillus populations both between individual subjects and between the infant and adult, with an overall change in the diversity and complexity from early stages of life to adulthood.     

Large size in an island-dwelling bird: intraspecific competition and the Dominance Hypothesis

Differences between island‐ and mainland‐dwelling forms provide several classic ecological puzzles. Why, for instance, are island‐dwelling passerine birds consistently larger than their mainland counterparts? We examine the ‘Dominance hypothesis’, based on intraspecific competition, which states that large size in island passerines evolves through selection for success in agonistic encounters. We use the Heron Island population of Capricorn silvereyes (Zosterops lateralis chlorocephalus), a large‐bodied island‐dwelling race of white‐eye (Zosteropidae), to test three assumptions of this hypothesis; that (i) large size is positively associated with high fitness, (ii) large size is associated with dominance, and (iii) the relationship between size and dominance is particularly pronounced under extreme intraspecific competition. Our results supported the first two of these assumptions, but provided mixed evidence on the third. On balance, we suggest that the Dominance Hypothesis is a plausible mechanism for the evolution of large size of island passerines, but urge further empirical tests on the role of intraspecific competition on oceanic islands versus that on mainlands.     

Immunohistochemical study of the gastrointestinal endocrine cells in the Korean aucha perch

The regional distribution and relative frequency of neurohormonal peptides‐producing cells were demonstrated in the gastrointestinal (GI) tract of the Korean aucha perch Coreoperca herzi , using 10 types of specific antisera raised against mammalian regulatory peptides. The GI tract was divided into four portions: stomach, gastro‐intestinal junction, and small and large intestine. Most of the immunoreactive (IR) cells were in the mucosal epithelium and they were generally spindle shaped with a long cytoplasmic process. In addition, ovoid cells were found in the gastric regions. Serotonin‐, somatostatin‐, glucagon‐, cholecystokinin‐8 (CCK‐8)‐ and pancreatic polypeptide (PP)‐IR cells were observed with various relative frequencies. No chromogranin A‐, secretin‐, vasoactive intestinal peptide‐, substance P‐ or bombesin‐IR cells, however, were found. Serotonin‐IR cells occurred throughout the GI tract and were the most numerous. Somatostatin‐IR cells were restricted to the stomach and gastro‐intestinal junction in numerous and moderate frequencies, respectively, but small numbers of glucagon‐IR cells were restricted to the small intestine. Numerous CCK‐8‐IR cells were found in the small intestine but variable numbers of PP‐IR cells occurred throughout the GI tract except for the large intestine. In general the distribution and relative frequency of these IR cells correspond well to previous reports in teleosts but there are some difference in this species.     

Microbial biofilms in the human gastrointestinal tract

The human gastrointestinal tract contains rich and diverse microbiotas along its length. However, while extensive studies have been made on lumenal bacterial communities in the gut, less work has been carried out on organisms growing in biofilms, where individual groups of bacteria exist in a multiplicity of different microhabitats and metabolic niches associated with the mucosa, the mucus layer and particulate surfaces in the gut lumen. Bacteria and yeasts also occur in biofilms attached to artificial surfaces and devices implanted in the host, such as in patients being fed via enteral tubes. Although we are just beginning to investigate the composition and metabolic activities of these structures, increasing evidence suggests that they are important to the host in both health and disease. There is mounting interest in mucosal biofilms in the colon, especially with respect to their role in inflammatory bowel disease. Because bacteria growing in biofilms are more resistant to antibiotics than unattached organisms, it is often difficult to modify the structure and composition of these communities, or to eradicate them from the body. However, recent work has shown that there is considerable potential to alter the species composition of mucosal biofilms in a beneficial way using synbiotics.     

Probiotic properties of human lactobacilli strains to be used in the gastrointestinal tract

AIMS: The study of two human strains of Lactobacillus to be used as probiotics in the gastrointestinal tract. METHODS AND RESULTS: The Lactobacillus acidophilus UO 001 and Lact. gasseri UO 002, were resistant to the gastrointestinal conditions (pH 2 and 3, presence of pepsin, pancreatin or bile salts), the resistance was enhanced in the presence of skimmed milk. Additionally, adhered to Caco-2 cells through glycoproteins in Lact. gasseri and carbohydrates in the case of Lact. acidophilus. These strains are able to inhibit the growth of certain enteropathogens: Salmonella, Listeria and Campylobacter without interfering with the normal microbiota of the gastrointestinal tract, as stated by using the mixed culture and the spot agar test. Finally, strongly adherent Lact. gasseri were found to inhibit the attachment of Escherichia coli O111 to intestinal Caco-2 cells under the condition of exclusion. CONCLUSIONS: These results indicate that the two strains of Lactobacillus from human origin present important properties for survival in, and colonization of, the gastrointestinal tract, that give them potential probiotic. SIGNIFICANCE AND IMPACT OF THE STUDY: Two strains of Lactobacillus isolated from human vagina of healthy premenopausal women could be promising candidates to be used in the preparation of probiotic products and for their use as health-promoting bacteria.     

Distribution and characterisation of immunoreactive somatostatin in human gastrointestinal tract

Immunoreactive somatostatin (IRS) was measured in acid extracts of human gastrointestinal tissue. The highest levels were found in the duodenum, pancreas, jejunum and stomach with lower levels in the ileum and colon. In the antrum, pylorus, duodenum and pancreas the main peak of IRS (1.6K IRS) coeluted with synthetic somatostatin-14 on both gel filtration chromatography and HPLC. In the body of stomach, jejunum, ileum and colon, a large peak coeluting with synthetic somatostatin-28 (3.5K IRS) on both chromatographic systems was also identified, while minor peaks of IRS assigned molecular weights of 6000 (6K) and greater than 15 000 (15K) were seen in some extracts. The total IRS content and pattern of molecular forms were similar in tissues obtained from adults at surgery or rapid post mortem, and in tissue taken from human fetuses after prostaglandin termination of pregnancy. When tissues were divided into mucosal and muscle layers, greater than 90% of the IRS was in the mucosa with less than 10% in the muscle layer. In the muscle layer the IRS was almost entirely the 1.6K form in all tissues. Immunohistochemical studies showed the IRS in the mucosa to be localised in endocrine-type cells, while in the muscle layer the IRS is present in nerve fibres and neurones of the myenteric plexus. It is suggested that (1) different mechanisms may control the biosynthesis of somatostatin-14 and somatostatin-28 in mucosal cells in different parts of the gut, (2) different biosynthetic controls may operate in endocrine-like and neuronal cells in the same region of the gut.