Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “microbiota”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources
PubMed2006

Comparative effects of exopolysaccharides from lactic acid bacteria and fructo-oligosaccharides on infant gut microbiota tested in an in vitro colonic model with immobilized cells.

The aim of this study was to compare the effects of purified exopolysaccharides from Lactobacillus rhamnosus RW-9595M with those of a well-known prebiotic (short-chain fructo-oligosaccharides) on infant colonic microbiota using a new three-stage chemostat model with immobilized infant faecal microbiota. Two continuous cultures with different faecal inocula were tested with different compositions of carbohydrate media. During the first fermentation (F1), fructo-oligosaccharides tested at a concentration of 9.8 g L(-1) increased the number of lactobacilli and decreased coliforms both in gel beads and in effluent from all three reactors, in agreement with data from the literature. During the second fermentation (F2), the effect of fructo-oligosaccharides tested at a lower concentration (7.5 g L(-1)) was reduced compared with F1. Fructo-oligosaccharides also increased total organic acid concentration and decreased ammonia production. Results obtained for exopolysaccharide tested at 1.5 g L(-1) indicate that exopolysaccharides from L. rhamnosus RW-9595M was not metabolized by infant microbiota and lacked any prebiotic effect.

Ammonia↗
PubMed2006

PCR DGGE and RT-PCR DGGE show diversity and short-term temporal stability in the Clostridium coccoides-Eubacterium rectale group in the human intestinal microbiota.

As the Clostridium coccoides-Eubacterium rectale (Erec; clostridial phylogenetic cluster XIVa) group is one of the major groups of the human intestinal microbiota, DNA- and RNA-based population analysis techniques (denaturing gradient gel electrophoresis; DGGE) were developed and applied to assess the diversity and temporal stability (6 months-2 years) of this faecal clostridial microbiota in 12 healthy adults. The stability of the Erec group was compared with the stability of the predominant bacterial microbiota, which was also assessed with PCR-DGGE. In addition, the Erec group was quantified with a hybridization-based method. According to our results, the Erec group was diverse in each subject, but interindividual uniqueness was not as clear as that of the predominant bacteria. The Erec group was found to be temporally as stable as the predominant bacteria. Over 200 clones obtained from two samples proved the developed method to be specific. However, the amount of bacteria belonging to the Erec group was not related to the diversity of that same bacterial group. In conclusion, the newly developed DGGE method proved to be a valuable and specific tool for the direct assessment of the stability of the Erec group, demonstrating diversity in addition to short-term stability in most of the subjects studied.

Adult↗
PubMed2006

Presence of specific antibiotic (tet) resistance genes in infant faecal microbiota.

The widespread use of antibiotics for medical and veterinary purposes has led to an increase of microbial resistance. The antibiotic resistance of pathogenic bacteria has been studied extensively. However, antibiotics are not only selective for pathogens: they also affect all members of the gut microbiota. These microorganisms may constitute a reservoir of genes carrying resistance to specific antibiotics. This study was designed to characterize the gut microbiota with regard to the presence of genes encoding tetracycline resistance proteins (tet) in the gut of healthy exclusively breast-fed infants and their mothers. For this purpose we determined the prevalence of genes encoding ribosomal protection proteins (tet M, tet W, tet O, tet S, tet T and tet B) by PCR and characterized the gut microbiota by FISH in stools of infants and their mothers. The gene tet M was found in all the breast-fed infants and their mothers. tet O was found in all of the mothers' samples, whilst only 35% of the infants harboured this gene. tet W was less frequently found (85% of the mothers and 13% of the infants). None of the other genes analysed was found in any sample. Our results suggest that genes carrying antibiotic resistance are common in the environment, as even healthy breast-fed infants with no direct or indirect previous exposure to antibiotics harbour these genes.

Adult↗
PubMed2006

Diversity of the Clostridium coccoides group in human fecal microbiota as determined by 16S rRNA gene library.

Fecal microbiota were analyzed in seven healthy individuals by 16S rRNA gene libraries (universal library) using universal primers, and the Clostridium coccoides group libraries using the universal primer 27F and the C. coccoides group-specific primer Erec482. The universal libraries were used in our previous studies. The 972 clones obtained from two different primer set libraries belonged to the C. coccoides group and were classified into 139 operational taxonomic units (OTU) (at least 98% sequence similarity). Of these, 41 OTU were detected commonly from universal libraries and C. coccoides group libraries. One hundred and ten OTU were detected from the C. coccoides group libraries. Fifteen new OTU were isolated from the C. coccoides group libraries in human gut. Most of the OTU did not correspond to known species, thus representing as-yet-uncultured bacteria. We also detected OTU that related to the butyrate-producing bacteria. The C. coccoides group consisted of an average of 35 OTU, although there were differences in the number and the type of species in each individual. When fecal microbiota were analyzed using universal libraries, the OTU belonging to the C. coccoides group detected in elderly individuals were fewer than those detected in adult individuals. When C. coccoides group libraries were used, the numbers of OTU in elderly and adult individuals were not different. Interindividual differences in the composition of OTU belonging to the C. coccoides group were also observed in fecal microbiota.

Adult↗
PubMed1992

The effect of supragingival plaque control on the subgingival microbiota in subjects with periodontal disease.

The present investigation was performed to study the effect on the subgingival microbiota, of a plaque control program which included meticulous oral hygiene instruction, supragingival scaling and professional monitoring during a 2 year period. 300 subjects were examined for periodontal disease and monitored for 2 years without treatment. After the 2 year examination, 80 subjects were invited to participate in a treatment program intended to improve the standard of their self-performed plaque control. 40 of the invitees had a gingivitis and only minor attachment loss, while 40 subjects had moderate signs of periodontitis. 62 subjects volunteered for this treatment. 23 of the volunteers (Group AB) had several sites with deep pockets (> 4 mm). 39 of the volunteers had gingivitis but shallow pockets only (Group C). Group AB contributed 31 shallow pocket sites (A-sites) and 40 deep pocket sites (B-sites), while Group C contributed 63 shallow sites (C-sites). After the clinical examination, samples of the subgingival microbiota were harvested from the 134 A, B and C sites. The 62 subjects were enrolled in a supervised oral hygiene program. Supragingival scaling was carried out. Oral hygiene instruction was provided and repeated on an individual need basis so that all subjects reached and maintained a supragingival plaque score which was < 20%. 24 months after the year 2 examination, the 62 subjects were examined again using both clinical and microbiological examination procedures. The findings demonstrated that carefully performed supragingival plaque control changed the quantity and the composition of the supragingival microbiota.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2004

Subgingival microbiota of chronic periodontitis subjects from different geographic locations.

BACKGROUND: Most clinical studies assume that the subgingival microbiota is similar from one geographic location to another. The purpose of the present investigation was to examine the composition of the subgingival microbiota in chronic periodontitis subjects from four countries. METHOD: Subjects with chronic periodontitis (N, Sweden=101; USA=115; Brazil=58; Chile=26) were recruited. Subjects were measured at baseline for plaque, gingivitis, bleeding on probing (BOP), suppuration, pocket depth (PD) and attachment level (AL) at six sites per tooth. Subgingival plaque samples taken from the mesial aspect of each tooth at baseline were individually analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization (total samples=6036). % DNA probe counts comprised by each species was determined for each site and averaged across sites in each subject. Significance of differences in proportions of each species among countries was determined using ancova adjusting for age, mean pocket depth, gender and smoking status. p-Values were adjusted for multiple comparisons. RESULTS: On average, all species were detected in samples from subjects in the four countries. Thirteen species differed significantly in adjusted mean proportions among countries even after adjusting for multiple comparisons. Porphyromonas gingivalis, one species that differed in proportions among countries, comprised adjusted means of 7.5, 11.9, 1.6 and 6.6% of the microbiota in subjects from Brazil, Chile, Sweden and USA (p<0.001), while mean proportions of Treponema denticola were 6.7, 4.2, 0.8 and 2.3, respectively (p<0.001). In contrast, a key periodontal pathogen, Tannerella forsythensis, exhibited mean proportions ranging from 6.2-8.5% and did not differ significantly among countries. Besides these species, prominent species in Brazil were Actinomyces naeslundii genospecies 1 and 2 (8.4%, 7.2%) and Prevotella intermedia (6.5%); in Chile, Prevotella melaninogenica (6.4%) and Neisseria mucosa (5.3%); in Sweden A. naeslundii genospecies 2 (8.4%), Capnocytophaga gingivalis (7.1%) and Peptostreptococcus micros (5.0%); in USA A. naeslundii genospecies 2 (7.5%), P. intermedia (6.8%) and C. gingivalis (6.1%). CONCLUSIONS: The microbial profiles of subgingival plaque samples from chronic periodontitis subjects in four countries showed surprisingly marked differences. These differences persisted after adjusting for age, mean pocket depth, gender and smoking status.

Adult↗
PubMed2005

Molecular analysis of human oral microbiota.

OBJECTIVES: The application of molecular, mainly 16S ribosomal RNA (rRNA)-based approaches enables researchers to bypass the cultivation step and has proven its usefulness in studying the microbial composition in a variety of ecosystems, including the human oral cavity. In this mini-review, we describe the impact of these culture-independent approaches on our knowledge of the ecology of the human oral cavity and provide directions for future studies that should emphasize the role of specific strains, species and groups of microbes in periodontal disease. MATERIALS AND METHODS: Recent findings are summarized to elucidate the relationship between periodontal disease and human oral microbiota, including as-yet-to-be-cultured organisms. RESULTS: The real-time polymerase chain reaction (PCR) method was developed to detect and quantify periodontopathic bacteria, such as Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis (formerly Bacteroides forsythus) and Treponema denticola. The checkerboard DNA-DNA hybridization technique allowed enumeration of large numbers of species in very large numbers of samples. 16S rRNA gene clone library analysis revealed the diversity of human oral microbiota and the existence of as-yet-to-be-cultured organisms that are presumed periodontal pathogens. In addition, terminal restriction fragment length polymorphism (T-RFLP) analysis was applied for assessment of diversity of human oral microbiota. CONCLUSION: Culture-independent approaches are useful for studying the microbial ecology in the human oral cavity and should be useful in the future to elucidate the etiology of periodontal disease.

DNA Probes↗
PubMed2004

Orally administered targeted recombinant Beta-lactamase prevents ampicillin-induced selective pressure on the gut microbiota: a novel approach to reducing antimicrobial resistance.

Antibiotics that are excreted into the intestinal tract promote antibiotic resistance by exerting selective pressure on the gut microbiota. Using a beagle dog model, we show that an orally administered targeted recombinant beta-lactamase enzyme eliminates the portion of parenteral ampicillin that is excreted into the small intestine, preventing ampicillin-induced changes to the fecal microbiota without affecting ampicillin levels in serum. In dogs receiving ampicillin, significant disruption of the fecal microbiota and the emergence of ampicillin-resistant Escherichia coli and TEM genes were observed, whereas in dogs treated with ampicillin in combination with an oral beta-lactamase, these did not occur. These results suggest a new strategy for reducing antimicrobial resistance in humans.

Administration, Oral↗
PubMed2006

Tetracycline resistance in Escherichia coli and persistence in the infantile colonic microbiota.

The ecological impact of antibiotic resistance in the absence of selective pressure has been poorly studied. We assessed the carriage of tetracycline resistance genes, persistence in the microbiota, fecal population counts and virulence factor genes in 309 commensal, intestinal Escherichia coli strains obtained from 128 Swedish infants followed during the first year of life with regular quantitative fecal cultures. No infant was given tetracycline, but 25% received other antibiotics. Tetracycline resistance was identified in 12% of strains, all of which carried either tet(A) (49%) or tet(B) (51%) genes. Resistance to other antibiotics occurred in 50% of tet(A)-positive strains, 42% of tet(B)-positive strains and 13% of tetracycline-sensitive strains. However, colonization with tetracycline-resistant strains was unrelated to treatment with antibiotics. Strains that were tet(B)- or tet(A)-positive carried the genes for P fimbriae and aerobactin, respectively, more often than susceptible strains. Tetracycline-resistant and -susceptible strains were equally likely to persist among the intestinal microbiota for > or = 3 weeks and had similar population numbers. However, when a resistant strain and a susceptible strain colonized a child simultaneously, the resistant variety showed lower counts (P = 0.03). In cases of long-term colonization by initially tetracycline-resistant E. coli strains, loss of tet genes occurred in 3 of 13 cases with variable effects on population counts. The results indicate that there is limited pressure against the carriage of tet genes in the infantile gut microbiota even in the absence of antibiotics. Resistant strains may possess colonization factors that balance the cost of producing resistance elements.

Colon↗
PubMed2006

Molecular monitoring of the fecal microbiota of healthy human subjects during administration of lactulose and Saccharomyces boulardii.

Diet is a major factor in maintaining a healthy human gastrointestinal tract, and this has triggered the development of functional foods containing a probiotic and/or prebiotic component intended to improve the host's health via modulation of the intestinal microbiota. In this study, a long-term placebo-controlled crossover feeding study in which each subject received several treatments was performed to monitor the effect of a prebiotic substrate (i.e., lactulose), a probiotic organism (i.e., Saccharomyces boulardii), and their synbiotic combination on the fecal microbiota of three groups of 10 healthy human subjects differing in prebiotic dose and/or intake of placebo versus synbiotic. For this purpose, denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA gene amplicons was used to detect possible changes in the overall bacterial composition using the universal V(3) primer and to detect possible changes at the subpopulation level using group-specific primers targeting the Bacteroides fragilis subgroup, the genus Bifidobacterium, the Clostridium lituseburense group (cluster XI), and the Clostridium coccoides-Eubacterium rectale group (cluster XIVa). Although these populations remained fairly stable based on DGGE profiling, one pronounced change was observed in the universal fingerprint profiles after lactulose ingestion. Band position analysis and band sequencing revealed that a band appearing or intensifying following lactulose administration could be assigned to the species Bifidobacterium adolescentis. Subsequent analysis with real-time PCR (RT-PCR) indicated a statistically significant increase (P < 0.05) in total bifidobacteria in one of the three subject groups after lactulose administration, whereas a similar but nonsignificant trend was observed in the other two groups. Combined RT-PCR results from two subject groups indicated a borderline significant increase (P = 0.074) of B. adolescentis following lactulose intake. The probiotic yeast S. boulardii did not display any detectable universal changes in the DGGE profiles, nor did it influence the bifidobacterial levels. This study highlighted the capacity of an integrated approach consisting of DGGE analysis and RT-PCR to monitor and quantify pronounced changes in the fecal microbiota of healthy subjects upon functional food administration.

Adult↗
PubMed1977

In situ morphology of the gut microbiota of wood-eating termites [Reticulitermes flavipes (Kollar) and Coptotermes formosanus Shiraki].

Light microscopy and scanning and transmission electron microscopy were used to examine the in situ morphology of the gut microbiota of Reticulitermes flavipes and Caoptotermes formosanus. Laboratory-maintained termites were used and, for R. flavipes, specimens were also prepared immediately after collection from a natural infestation. The latter endeavor enabled a study of different castes and developmental stages of R. flavipes and revealed differences in the microbiota of field versus laboratory specimens. The termite paunch microbiota consisted of an abundance of morphologically diverse bacteria and protozoa. Thirteen bacterial morphotypes in the paunch were described in detail: seven were observed only in R. flavipes, three were observed only in C. formosanus, and three were common to both termite species. The paunch epithelium was densely colonized by bacteria, many of which possessed holdfast elements that secured them tightly to this tissue and to other bacterial cells. Besides bacteria, the protozoan Pyrsonympha vertens adhered to the paunch epithelium of R. flavipes by means of an attachment organelle. Cuplike indentations were present on the paunch epithelial surface and were sites of bacterial aggregation. Ultrastructural features of cups suggested their involvement in ion absorption. In addition to the paunch, the midgut was also colonized by bacteria that were situated between epithelial microvilli. Results suggest that bacteria are an integral part of the gut ecosystem.

Animals↗
PubMed1988

Carbon metabolism of the cryptoendolithic microbiota from the Antarctic desert.

The carbon metabolism of the cryptoendolithic microbiota of sandstones from the Ross Desert of Antarctica was studied in situ and in vitro. Organic and inorganic carbon compounds were metabolized by the microbiota, with bicarbonate incorporation into community lipids occurring primarily in the light. Light intensity affected the photometabolism of carbon with a photosynthesis-intensity response optimum at about 200 to 300 micromoles of photons per m2 per s. Photosynthesis was also affected by temperature, with a minimum activity at -5 degrees C, an optimum activity at 15 degrees C, and complete inhibition at 35 degrees C, indicating that the cryptoendolithic community was psychrophilic. The primary source of CO2 for photosynthesis in situ was the atmosphere. CO2 may also be photometabolized by using the carbon produced from respiration within the endolithic community. Photosynthesis occurred maximally when the microbiota was wet with liquid water and to a lesser extent in a humid atmosphere. This simple microbial community, therefore, exists under extremes of water, light, and temperature stress which affect and control its metabolism.

Acetates↗
PubMed1989

Mineralization of Surfactants by Microbiota of Aquatic Plants.

The biodegradation of linear alkylbenzene sulfonate (LAS) and linear alcohol ethoxylate (LAE) by the microbiota associated with duckweed (Lemna minor) and the roots of cattail (Typha latifolia) was investigated. Plants were obtained from a pristine pond and a pond receiving wastewater from a rural laundromat. Cattail roots and duckweed plants were incubated in vessels containing sterile water amended with [C]LAS, [C]LAE, or C-labeled mixed amino acids (MAA). Evolution of CO(2) was determined over time. The microbiota of cattail roots from both ponds mineralized LAS, LAE, and MAA without lag periods, and the rates and extents of mineralization were not significantly affected by the source of the plants. Mineralization of LAS and LAE was more rapid in the rhizosphere than in nearby root-free sediments, which exhibited differences as a function of pond. The microbiota of duckweed readily mineralized LAE and MAA but not LAS. The rate and extent of mineralization were not affected by the source of the duckweed.

Journal Article↗
PubMed2003

Degradation of cross-linked and non-cross-linked arabinoxylans by the intestinal microbiota in children.

In humans, nonstarch polysaccharides (NSP), such as arabinoxylans (AX), are not digested in the upper gut and provide fermentable carbon sources for bacteria growing in the large bowel. Despite the ubiquity of AX in nature, the microbiologic and physiologic consequences of AX digestion in the gut are poorly understood. In this study, we investigated the breakdown of ferulic acid-cross-linked AX (AXF) and non-cross-linked AX in children's intestinal microbiotas, using starch as a readily fermentable polysaccharide for comparative purposes. The experiments were performed using pH-controlled fermentation vessels under anaerobic conditions. The results demonstrated that there was variation in the metabolism of these polysaccharides by colonic microbiotas. AX was always degraded more slowly than starch, while ferulic acid cross-linking reduced the rate of AX fermentation, as shown by fermentation product measurements. Starch digestion was associated with significant acetate and butyrate production, whereas AX breakdown resulted in increased propionate formation. In general, the presence of fermentable carbohydrate significantly increased the total anaerobe counts and eubacterial rRNA concentrations (P < 0.01), while non-cross-linked AX digestion was principally associated with increased viable counts of Bacteroides fragilis group organisms, which was supported by increases in Bacteroides-Porphyromonas-Prevotella group rRNA (P < 0.01). Starch was considerably more bifidogenic than AX in these fermentations. In conclusion, in this study we found that the effects of AX and AXF on the microbial ecology and metabolism of intestinal microbiotas are similar in children and adults.

Anaerobiosis↗
PubMed2003

Secretory antibodies do not affect the composition of the bacterial microbiota in the terminal ileum of 10-week-old mice.

Terminal restriction fragment length polymorphism (T-RFLP) analysis was conducted on the 16S rRNA genes of the bacterial communities colonizing the epithelial surfaces of the terminal ilea of open conventionally housed mice in an institutional small-animal facility. Polymeric-immunoglobulin-receptor-deficient (pIgR(-/-)) mice that were unable to secrete antibodies across mucosal surfaces were cohoused with normal and otherwise genetically identical wild-type (C57BL/6) mice for 4 weeks. If secretory antibodies played a role in modeling the gastrointestinal microbiota, C57BL/6 mice would have had a more distinct and uniform microbiota than their pIgR(-/-) cage mates. The T-RFLP profiles of the bacterial communities were compared by using Sorensen's pairwise similarity coefficient, a newly developed weighted pairwise similarity coefficient, and on the basis of Shannon's and Simpson's diversity indices. No systematic differences were observed between the dominant components of the mucosa-associated bacterial communities of the terminal ileal walls of the two types of mice, indicating that secretory antibodies do not control the composition of this microbiota. Similar analyses of experiments conducted at two different times, between which the bacterial community composition of the mouse colony in the small-animal facility appeared to have changed, showed that differences could have been detected, had they existed.

Animals↗
PubMed2004

Impact of consumption of oligosaccharide-containing biscuits on the fecal microbiota of humans.

Human subjects consumed biscuits containing either galacto-oligosaccharides or fructo-oligosaccharides in a double-blinded, crossover study. The impact of supplementing the diet with three biscuits per day on the fecal microbiota was evaluated by selective culture of particular bacterial groups, measurement of beta-galactosidase activity, and nucleic acid-based analytical methods (PCR-denaturing gradient gel electrophoresis [PCR-DGGE] and fluorescent in situ hybridization). The composition of the bifidobacterial populations was monitored at the level of species (PCR-DGGE) and strains (pulsed-field gel electrophoresis of DNA digests), and representative cultures were tested quantitatively for their ability to use galacto-oligosaccharides. Technical improvements to DGGE analysis of the microbiota were made by the use of an internal standard that allowed valid comparisons of fragment staining intensities to be made between profiles, the use of S1 nuclease digestion to remove single-stranded DNA to facilitate cloning of DNA sequences cut from gels, and the extraction of RNA to be used as the template in reverse transcription-PCR-DGGE. RNA-DGGE profiles were markedly different (Dice's similarity coefficient, 58.5%) from those generated by DNA-DGGE. Neither the sizes of the bacterial populations nor the DNA-DGGE profiles of the microbiota were altered by the consumption of the biscuits, but the RNA-DGGE profiles were altered by the detection or increased staining intensity of 16S rRNA gene sequences originating from Bifidobacterium adolescentis and/or Colinsella aerofaciens in the feces of 11 of 15 subjects. beta-Galactosidase activity was elevated in the feces of some subjects as a result of biscuit consumption. Subjects differed in the ability of the bifidobacterial strains harbored in their feces to use galacto-oligosaccharides. Our observations suggest that a phylogenetic approach to analysis of the gut ecosystem may not always be optimal and that a more physiological (biochemical) method might be more informative.

Base Sequence↗
PubMed2005

1H nuclear magnetic resonance spectroscopy-based studies of the metabolism of food-borne carcinogen 2-amino-3-methylimidazo[4,5-f]quinoline by human intestinal microbiota.

2-Amino-3-methylimidazo[4,5-f]quinoline (IQ) is a mutagenic/carcinogenic compound formed from meat and fish during cooking. Following ingestion, IQ is metabolized mainly by liver xenobiotic-metabolizing enzymes, but intestinal bacteria may also contribute to its biotransformation. The aim of this study was to investigate the metabolism of IQ by the human intestinal microbiota. Following incubation of IQ (200 microM) under anoxic conditions with 100-fold dilutions of stools freshly collected from three healthy volunteers, we quantified residual IQ by high-pressure liquid chromatography (HPLC) analysis and characterized the production of IQ metabolites by in situ (1)H nuclear magnetic resonance ((1)H-NMR) spectroscopic analysis of crude incubation media. In addition, we looked for IQ-degrading bacteria by screening collection strains and by isolating new strains from the cecal contents of human-microbiota-associated rats gavaged with IQ on a regular basis. HPLC and (1)H-NMR analyses showed that the three human microbiota degraded IQ with different efficiencies (range, 50 to 91% after 72 h of incubation) and converted it into a unique derivative, namely, 7-hydroxy-IQ. We found 10 bacterial strains that were able to perform this reaction: Bacteroides thetaiotaomicron (n = 2), Clostridium clostridiiforme (n = 3), Clostridium perfringens (n = 1), and Escherichia coli (n = 4). On the whole, our results indicate that bacteria belonging to the predominant communities of the human intestine are able to produce 7-hydroxy-IQ from IQ. They also suggest interindividual differences in the ability to perform this reaction. Whether it is a metabolic activation is still a matter of debate, since 7-hydroxy-IQ has been shown to be a direct-acting mutagen in the Ames assay but not carcinogenic in laboratory rodents.

Adult↗
PubMed1996

No apparent influence of immunoglobulins on indigenous oral and intestinal microbiota of mice.

The role of secretory immunoglobulin A (sIgA) in the control of the indigenous microbiota is not well understood. In this study, we compared the oral and intestinal microbiota of transgenic B-cell-deficient (microMT) mice with their heterozygous (microMT/+) normal littermates. The levels of salivary IgA and serum IgA and IgG were normal in microMT/+ mice, while no immunoglobulins were detected in microMT/microMT mice. The acquisition and proportions of the different species of the oral and intestinal indigenous bacterial populations were not significantly different between the two groups of mice. Our results thus suggest that secretory IgA does not play a major role in the regulation of the indigenous microbiota of mice.

Animals↗