Lactobacillus succession in the piglet digestive tract demonstrated by plasmid profiling

Plasmid profiling was used to distinguish strains of lactobacilli inhabiting the digestive tract of piglets and the feces of sows. Fifteen plasmid profile types were detected among 328 isolates of lactobacilli. Plasmid profiling of lactobacilli permitted the following conclusions to be made: the maternal feces were a major source of lactobacilli colonizing the piglet digestive tract; the lactobacillus population of the gastric region of the piglet digestive tract was composed of lactobacillus strains different from those present in the rectal population; and a lactobacillus succession was observed in the digestive tract of piglets drawn from a single litter, and one plasmid profile type became dominant in the gastric region of these animals.     

Lactobacillus succession in the piglet digestive tract demonstrated by plasmid profiling.

Plasmid profiling was used to distinguish strains of lactobacilli inhabiting the digestive tract of piglets and the feces of sows. Fifteen plasmid profile types were detected among 328 isolates of lactobacilli. Plasmid profiling of lactobacilli permitted the following conclusions to be made: the maternal feces were a major source of lactobacilli colonizing the piglet digestive tract; the lactobacillus population of the gastric region of the piglet digestive tract was composed of lactobacillus strains different from those present in the rectal population; and a lactobacillus succession was observed in the digestive tract of piglets drawn from a single litter, and one plasmid profile type became dominant in the gastric region of these animals.     

Glucagon- and glicentin-immunoreactive cells in the human digestive tract

Summary The distribution and cellular location of substances reacting with anti-glucagon or anti-glicentin sera, i.e., glucagon-like and glicentin-like immunoreactivities, were studied in the human digestive tract using the immunofluorescence and immunoperoxidase methods. Both types of immunoreactivity were (1) absent in the antrum, (2) abundant in cells located at the periphery of pancreatic islets, (3) unevenly present in cells scattered in the epithelium of the small intestinal mucosa, the glicentin-immunoreactive cells being particularly abundant in the ileum. In the pancreas, and, when simultaneously present, in the intestine, both glucagon and glicentin immunoreactivities were located in the same cells.The precise ultrastructural location of each immunoreactivity was readily made using colloidal gold and ferritin tracers on ultrathin sections of glutaraldehyde-osmium fixed and epoxy resin-embedded tissues. In the pancreas, both glucagon and glicentin immunoreactivities were found in the granules of the A-type cells; the glucagon immunoreactivity was only present in the core of the granule, whereas the glicentin immunoreactivity was found either in the peripheral halo only, or throughout the entire granule. In the small intestine, both immunoreactivities were located inside the granules of the L-type cells.Quantitative specificity tests suggested that the glucagon- and the glicentin-like substances of the pancreas differ from those found in the intestine.Work supported by INSERM, A.T.P. number: 167539     

Molecular analysis of the bacterial community in digestive tract of rabbit

This work aimed to study the stability over time of the bacterial community in cæcum and fæces of the rabbit (diversity index and structure) without experimental disturbance and to evaluate its relationships with environmental parameters. Soft and hard fæces of 14 rabbits were sampled for 5 weeks while cæcal content was sampled on the 3rd week (by surgery) and the 5th week (at slaughter). Bacterial communities were assessed by studying CE-SSCP profiles of 16S rRNA genes fragments. Redox potential, pH, NH3-N concentration and volatile fatty acid concentrations were measured in the cæcum. Data showed that bacterial communities of soft and hard fæces barely differed from that of the cæcum (ANOSIM-R < 0.25; p < 0.05). Without disturbance, the bacterial communities of fæces were stable over time (ANOSIM-R < 0.25; p < 0.001). However, the bacterial communities of cæcum and fæces were affected by the surgery (ANOSIM-R = 0.22–0.33; p < 0.001). The cæcal content was an acidic (pH = 6.03 ± 0.33) and an anaerobic environment (redox potential = ?160 ± 43 mV). Only the redox potential was correlated with the diversity index of the bacterial community of the cæcum (R² = 0.35; p < 0.05) and no environmental parameters were correlated to its structure.     

消化道微生物与胰腺癌相关性研究

胰腺癌是世界上最致命的恶性肿瘤之一,目前胰腺癌的病因尚未完全明确,是肿瘤研究领域的一个热点。近年来大量研究表明,胰腺癌的发生发展可能与消化道微生物群密切相关。近期研究发现,某些口腔、胃肠道和胰腺内的细菌、真菌和肝细胞病毒可能在胰腺癌发病机制中发挥潜在的病因作用。具体机制主要包括维持炎症、调节免疫系统、影响新陈代谢和改变肿瘤的微环境。在这篇综述中,探讨了消化道微生物与胰腺癌之间的联系,探讨微生物群在胰腺癌诊断和治疗中的潜在应用,并深入了解消化道微生物群在胰腺癌中的作用。     

Fluorescent detection of APUD-type cells in the digestive tract of the rabbit fetus. Correlative study in electron microscopy

Previous studies performed on different species have shown that these cells could be recognized by their morphologic and immuno-histological features. In early stages, these cells are able to take up and decarboxylate amine precursors. Therefore the aim of the present work was to determine if this uptake could be correlated with ultrastructural modifications. A processing technique allowing amine detection and correlative ultrastructural examination was used. Rabbit foetuses 13, 14, 17 and 21 day old were studied. The gastro-intestinal tracts of L-DOPA treated or untreated foetuses were removed in a glutaraldehyde-formaldehyde mixture and embedded in epoxy-resin. Semi-thin sections allowed to locate fluorescent cells in U.V light microscopy; adjacent thin sections were observed in electron microscopy. The first green fluorescent cells appeared in the 13 day old foetuses treated with L-DOPA. By this stage, these cells were very scarce and appeared poorly differentiated in electron microscopy. Between the 15th and the 18th day, the green fluorescent cells contained only small round granules. By the day 19, orange-yellow cells can be observed in L-DOPA treated and untreated foetuses. These cells possessed characteristic enterochromaffin granules. The green fluorescent cells of 21 day old foetuses, treated with L-DOPA, exhibited various fluorescence intensities correlated with the heterogeneity of the secretory granules. Some foetuses of each stage were treated with Falck's technique. This method gave similar results concerning the chronology of fluorescent cell detection.     

扬子鳄消化道Ghrelin免疫活性细胞的分布及其在冬眠期的密度变化

目的 研究扬子鳄（Alligator sinensis）消化道中生长素释放肽ghrelin免疫活性（IR）细胞的分布、组织定位及其在冬眠期的变化.方法 应用链霉亲和素-生物素-过氧化物酶复合物（SABC）免疫组织化学方法结合生物统计学分析.结果 Ghrelin-IR细胞在扬子鳄的小胃密度最高,在胃贲门部、胃体和胃幽门部有少量分布,主要位于胃腺上皮细胞之间.在食管、十二指肠、空肠、回肠和直肠中均未检测出ghrelin-IR细胞.冬眠期小胃ghrelin-IR细胞显著性减少（P〈0.01）,其它部位无显著性变化（P〉0.05）.结论扬子鳄消化道ghrelin-IR细胞的分布同其它动物有相似之处,也有其一定的特异性.Ghrelin在扬子鳄冬眠期的代谢变化和能量稳态的调节中起重要作用.     

Genotypic adaptations associated with prolonged persistence of Lactobacillus plantarum in the murine digestive tract

Probiotic bacteria harbor effector molecules that confer health benefits, but also adaptation factors that enable them to persist in the gastrointestinal tract of the consumer. To study these adaptation factors, an antibiotic-resistant derivative of the probiotic model organism Lactobacillus plantarum WCFS1 was repeatedly exposed to the mouse digestive tract by three consecutive rounds of (re)feeding of the longest persisting colonies. This exposure to the murine intestine allowed the isolation of intestine-adapted derivatives of the original strain that displayed prolonged digestive tract residence time. Re-sequencing of the genomes of these adapted derivatives revealed single nucleotide polymorphisms as well as a single nucleotide insertion in comparison with the genome of the original WCFS1 strain. Detailed in silico analysis of the identified genomic modifications pinpointed that alterations in the coding regions of genes encoding cell envelope associated functions and energy metabolism appeared to be beneficial for the gastrointestinal tract survival of L. plantarum WCFS1. This work demonstrates the feasibility of experimental evolution for the enhancement of the gastrointestinal residence time of probiotic strains, while full-genome re-sequencing of the adapted isolates provided clues towards the bacterial functions involved. Enhanced gastrointestinal residence is industrially relevant because it enhances the efficacy of the delivery of viable probiotics in situ.     

Survival of Lactobacillus casei in the human digestive tract after consumption of fermented milk

A human trial was carried out to assess the ileal and fecal survival of Lactobacillus casei DN-114 001 ingested in fermented milk. Survival rates were up to 51.2% in the ileum and 28.4% in the feces. The probiotic bacterium has the capacity to survive during its transit through the human gut.     

Neuroendocrine cells along the digestive tract express neuropilin-2

Neuropilin-2 (np-2) is a receptor for semaphorin-3F (sema-3F) and semaphorin-3C (sema-3C). These semaphorins repel tips of growing axons that express np-2. In addition, np-2 functions as a receptor for heparin binding forms of the angiogenic factor vascular endothelial growth factor (VEGF) such as VEGF145 and VEGF165. We report that np-2 is strongly expressed in neuroendocrine cells located all along the human digestive tract. Confocal fluorescent microscopy revealed that np-2 is concentrated in vesicle-like structures located near the nucleus at the basolateral side of these cells. In the colon, the np-2-expressing subpopulation of neuroendocrine cell is almost identical with the serotonin-producing subpopulation of neuroendocrine cells. Gastrointestinal carcinoid tumors are digestive tract tumors that develop from neuroendocrine cells. Interestingly, most of the carcinoid tumors derived from the colon and the appendix did not contain np-2-producing cells. However, some carcinoid tumors derived from the small intestine and stomach did express low levels of np-2 in isolated foci of cells. By contrast, strong serotonin and chromogranin-A expression was observed in all of the carcinoid tumors that were examined. These results suggest that loss of np-2 expression may accompany tumor progression in carcinoid tumors.     

Identification of M cells and their distribution in rabbit intestinal Peyer's patches and appendix

The distribution of intestinal membranous (M) cells has been studied within the follicle-associated epithelium of rabbit Peyer's patches and appendix. Vimentin expression has been assessed as a primary criterion to identify rabbit M cells in tissue sections and in whole tissue preparations. This criterion has been compared to the use of the absence of alkaline phosphatase which, due to its heterogeneous distribution within the enterocyte population, is less reliable than vimentin expression as a marker for rabbit M cells. The pattern of vimentin immunostaining revealed that the majority of M cells are located in the periphery of the follicle-associated epithelium, the dome apex being largely free of M cells. This distribution was confirmed by scanning electron microscopy. Vimentin is also expressed by follicle-associated epithelial cells in the vicinity of crypts which lack the typical lymphocyte-containing pocket of M cells. Cytoplasmic peanut agglutinin binding coincides with vimentin-expression throughout the follicle-associated epithelium but is absent from vimentin-negative enterocytes. The co-localisation of these two phenotypic markers in both M cells and epithelial cells adjacent to crypts, which lack the typical morphology of fully developed rabbit M cells, suggests that they correspond to immature M cells which by their location appear to derive directly from undifferentiated crypt stem cells and not from mature columnar enterocytes.     

影响生物土壤结皮分布的环境因子

生物土壤结皮广泛分布于干旱荒漠地区,在干旱和荒漠生态系统中,有重要的生态功能。然而,并不是所有的干旱荒漠区都有生物土壤结皮的分布。在全球和区域尺度上,生物土壤结皮的分布与年降水、凝结水量和土壤含水量呈正相关趋势;温度对生物土壤结皮分布的影响因组成生物土壤结皮的物种而异。小尺度范围内,生物土壤结皮的分布受土壤类型、质地和养分的限制;维管植物对生物土壤结皮分布的影响,暂没有一致的结论。适度干扰对生物土壤结皮分布和生态功能无明显影响,但高强度干扰导致生物土壤结皮结构、功能和分布的退化与减少。全球变化背景下生物土壤结皮的分布变化、不同区域生物土壤结皮分布和演替的差异机理以及受损后恢复过程中的生态功能,将成为以后工作的重点。     

Concentration and size distribution of plant fiber in the digestive tract of muroid rodents

The weight parameters that characterize the size and the degree of fullness of fermentation chambers (forestomach and cecum), namely, the weight of the walls and the content of these organs, and the concentration and size distribution of fibers in the chyme have been investigated in five muroid rodent species (Arvicola terrestris, Microtus oeconomus, Microtus arvalis sp., Clethrionomys glareolus, and Sylvaemus flavicollis). No distinct regularities were observed in the above-mentioned parameters of the forestomach. These parameters of the cecum were generally found to be in good agreement with the conventional concept of dietary specialization of the rodent species under investigation, but the results have provided a more precise assessment of the role of dietary fiber in the diet of free-living rodents under specific environmental conditions.     

Aminopeptidase N- and human blood group A-antigenicity along the digestive tract and associated glands in the rabbit

Summary The cellular localization of an aminopeptidase N homologous to the brush-border intestinal enzyme and that of human blood group A-substances were investigated using the immunofluorescence technique on thin frozen sections (200 nm) of the digestive tract and associated glands of A⁺ and A^– rabbits. Aminopeptidase N was found to be a common specific marker of both the apical region of plasma membrane of acinar cells in submaxillary and parotid glands and pancreas and the brush border of jejunum and colon absorbing cells. In hepatocytes, the enzyme was localized in the sinusoidal domains. Soluble A-substances were present in mucus secretory granules of intestinal goblet cells and those of stomach and gall bladder mucous cells. In contrast, the mucous acini of sublingual and submaxillary glands were devoid of A-antigenicity. The columnar cells of striated ducts of these glands exhibited A-antigenicity. Soluble A-substances were also found in zymogen granules of parotid and pancreas acinar cells and those of stomach chief cells. Moreover, in all cells secreting A-substances, and in the non-secreting absorbing intestinal cells, the glycoproteins of the plasma membrane bore A-determinants. Aminopeptidase N was one of the membrane-bound glycoproteins that bore A-determinants in cells that expressed A-antigenicity.