The rumen of sheep and cattle represents a mobile, self-sustaining fermentation system for plant material. Analysis of the rumen flora continues to provide fundamental knowledge of anaerobic ...microbiology and is now yielding microbial genes that have potential in biotechnology. Recent research has provided fascinating glimpses into the microbial enzyme systems that degrade plant material and into the complex interplay among members of the rumen community.
We describe an approach for determining the genetic composition of Bacteroides and Prevotella populations in gut contents based on selective amplification of 16S rRNA gene sequences (rDNA) followed ...by cleavage of the amplified material with restriction enzymes. The relative contributions of different ribotypes to total Bacteroides and Prevotella 16S rDNA are estimated after end labelling of one of the PCR primers, and the contribution of Bacteroides and Prevotella sequences to total eubacterial 16S rDNA is estimated by measuring the binding of oligonucleotide probes to amplified DNA. Bacteroides and Prevotella 16S rDNA accounted for between 12 and 62% of total eubacterial 16S rDNA in samples of ruminal contents from six sheep and a cow. Ribotypes 4, 5, 6, and 7, which include most cultivated rumen Prevotella strains, together accounted for between 20 and 86% of the total amplified Bacteroides and Prevotella rDNA in these samples. The most abundant Bacteroides or Prevotella ribotype in four animals, however, was ribotype 8, for which there is only one known cultured isolate, while ribotypes 1 and 2, which include many colonic Bacteroides spp., were the most abundant in two animals. This indicates that some abundant Bacteroides and Prevotella groups in the rumen are underrepresented among cultured rumen Prevotella isolates. The approach described here provides a rapid, convenient, and widely applicable method for comparing the genotypic composition of bacterial populations in gut samples
Goblet cells secrete mucin to create a protective mucus layer against invasive bacterial infection and are therefore essential for maintaining intestinal health. However, the molecular pathways that ...regulate goblet cell function remain largely unknown. Although GPR35 is highly expressed in colonic epithelial cells, its importance in promoting the epithelial barrier is unclear. In this study, we show that epithelial Gpr35 plays a critical role in goblet cell function. In mice, cell-type-specific deletion of Gpr35 in epithelial cells but not in macrophages results in goblet cell depletion and dysbiosis, rendering these animals more susceptible to Citrobacter rodentium infection. Mechanistically, scRNA-seq analysis indicates that signaling of epithelial Gpr35 is essential to maintain normal pyroptosis levels in goblet cells. Our work shows that the epithelial presence of Gpr35 is a critical element for the function of goblet cell-mediated symbiosis between host and microbiota.
A verocytotoxigenic bacteriophage isolated from a strain of enterohemorrhagic Escherichia coli O157, into which a kanamycin resistance gene (aph3) had been inserted to inactivate the verocytotoxin ...gene (vt2), was used to infect Enterobacteriaceae strains. A number of Shigella and E. coli strains were susceptible to lysogenic infection, and a smooth E. coli isolate (O107) was also susceptible to lytic infection. The lysogenized strains included different smooth E. coli serotypes of both human and animal origin, indicating that this bacteriophage has a substantial capacity to disseminate verocytotoxin genes. A novel indirect plaque assay utilizing an E. coli recA441 mutant in which phage-infected cells can enter only the lytic cycle, enabling detection of all infective phage, was developed.
The bacterial species diversity of three colonic tissue samples from elderly people was investigated by sequence analysis of randomly cloned eubacterial 16S rDNA. The majority of sequences (87%) ...clustered within three bacterial groups: (1) Bacteroides; (2) low G+C content Gram-positives related to Clostridium coccoides (cluster XIVa); (3) Gram-positives related to Clostridium leptum (cluster IV). These groups have been shown to dominate the human faecal flora. Only 25% of sequences were closely related (> 97%) to current species type strains, and 28% were less than 97% related to any database entry. 19% of sequences were most closely related to recently isolated butyrate-producing bacteria belonging to clusters XIVa and IV, with a further 18% of the sequences most closely related to Ruminococcus obeum and Ruminococcus torques (members of cluster XIVa). These results provide the first molecular information on the microbial diversity present in human colonic samples.
Mentoring in otolaryngology training programs Gurgel, Richard K; Schiff, Bradley A; Flint, John H ...
Otolaryngology-head and neck surgery,
April 2010, Letnik:
142, Številka:
4
Journal Article
Recenzirano
The Accreditation Council for Graduate Medical Education's focus on outcome-based training has made the mentoring process critical for resident education. It is unknown how otolaryngology training ...programs mentor residents. Our objective was to determine the current state of mentoring in otolaryngology training programs and describe resident perceptions of mentoring.
Cross-sectional survey.
Accredited U.S. otolaryngology training programs.
All U.S. otolaryngology residents and program directors were contacted via e-mail with a link to an online survey.
Of the 1411 residents contacted, 27.7 percent responded, representing 71 of the 103 accredited otolaryngology programs. Of the 103 program directors contacted, 37.9 percent responded. Of these programs, 26 had formal mentoring programs, 45 did not have formal mentoring programs, and 12 programs were listed in both categories. Fifty-one percent of male residents and 49 percent of female residents had mentors. The most important mentor characteristics were personality match, good clinical role model, and similar subspecialty interests. Least important characteristics were race, gender, and age. Twenty-six percent of residents felt that mentoring was critical to their training, while 63 percent of residents listed mentoring as important but not critical. Programs with fewer faculty and residents were less likely to offer formal mentoring (P = 0.007 and 0.054, respectively). Of residents who did not have mentors, 80 percent lacked a mentor because their residency had no formal mentoring program.
Residents perceive mentoring as important, and formal mentoring programs should be incorporated into otolaryngology training programs.
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