859,829 research outputs found
Kitab fi misahat al-mujassamat al-mukafiya
No full textpage, (left) folio 118 r, drawing of a dome profile; (right) fol. 119v, drawings of dome profile
An investigation of horizontal transfer of feed introduced DNA to the aerobic microbiota of the gastrointestinal tract of rats
No full textBACKGROUND:
Horizontal gene transfer through natural transformation of members of the microbiota of the lower gastrointestinal tract (GIT) of mammals has not yet been described. Insufficient DNA sequence similarity for homologous recombination to occur has been identified as the major barrier to interspecies transfer of chromosomal DNA in bacteria. In this study we determined if regions of high DNA similarity between the genomes of the indigenous bacteria in the GIT of rats and feed introduced DNA could lead to homologous recombination and acquisition of antibiotic resistance genes.
RESULTS:
Plasmid DNA with two resistance genes (nptI and aadA) and regions of high DNA similarity to 16S rRNA and 23S rRNA genes present in a broad range of bacterial species present in the GIT, were constructed and added to standard rat feed. Six rats, with a normal microbiota, were fed DNA containing pellets daily over four days before sampling of the microbiota from the different GI compartments (stomach, small intestine, cecum and colon). In addition, two rats were included as negative controls. Antibiotic resistant colonies growing on selective media were screened for recombination with feed introduced DNA by PCR targeting unique sites in the putatively recombined regions. No transformants were identified among 441 tested isolates.
CONCLUSIONS:
The analyses showed that extensive ingestion of DNA (100 μg plasmid) per day did not lead to increased proportions of kanamycin resistant bacteria, nor did it produce detectable transformants among the aerobic microbiota examined for 6 rats (detection limit < 1 transformant per 1,1 × 108 cultured bacteria). The key methodological challenges to HGT detection in animal feedings trials are identified and discussed. This study is consistent with other studies suggesting natural transformation is not detectable in the GIT of mammals
MUḤAMMAD IBN AḤMAD IBN ḤAMZA AL-RAMLĪ AL-ANṢĀRĪ. Nihāyat al-muḥtāǧ ilā ?arḥ al-Minhāǧ. Arabe 1018
No full textMinhāǧ (al-). CommentaireNihāyat al-muḥtāǧ ilā šarḥ al-minhāǧالمنهاج . شرحنهاية المحتاج الى شرح المنهاجNumérisation effectuée à partir d'un document de substitution : R 68044
MUḤAMMAD IBN AḤMAD IBN ḤAMZA AL-RAMLĪ AL-ANṢĀRĪ. Nihāyat al-muḥtāǧ ilā ?arḥ al-Minhāǧ. Arabe 1020
No full textMinhāǧ (al-). CommentaireNihāyat al-muḥtāǧ ilā šarḥ al-minhāǧالمنهاج . شرحنهاية المحتاج الى شرح المنهاجNumérisation effectuée à partir d'un document de substitution : R 68046
MUḤAMMAD IBN AḤMAD IBN ḤAMZA AL-RAMLĪ AL-ANṢĀRĪ. Nihāyat al-muḥtāǧ ilā ?arḥ al-Minhāǧ. Arabe 1017
No full textMinhāǧ (al-). CommentaireNihāyat al-muḥtāǧ ilā šarḥ al-minhāǧالمنهاج . شرحنهاية المحتاج الى شرح المنهاجNumérisation effectuée à partir d'un document de substitution : R 68043
ʿABD AL-KARĪM IBN MUḤAMMAD AL-QAZWĪNĪ AL-RĀFIʿĪ. al-Šarḥ al-ṣaġīr ʿalā l-waǧīz (4e volume). Arabe 987
No full textŠarḥ (aš-) al-ṣaġīr ʿalā l-waǧīzWaǧīz (al-). Commentaireالشرح الصغير على الوجيزالوجيز .شرحNumérisation effectuée à partir d'un document de substitution : R 67552.Copie achevée 7 šawwāl 738 h. / 28 avril 1338 (f. 230 v)
ʿABD AL-KARĪM IBN MUḤAMMAD AL-QAZWĪNĪ AL-RĀFIʿĪ. al-Šarḥ al-ṣaġīr ʿalā l-waǧīz (4e volume). Arabe 989
No full textŠarḥ (aš-) al-ṣaġīr ʿalā l-waǧīzWaǧīz (al-). Commentaireالشرح الصغير على الوجيزالوجيز .شرحNumérisation effectuée à partir d'un document de substitution : R 68102.Copie achevée le 1er ǧumādā II 739 h. / 15 décembre 1338 (f. 261)
ʿABD AL-KARĪM IBN MUḤAMMAD AL-QAZWĪNĪ AL-RĀFIʿĪ. al-Šarḥ al-ṣaġīr ʿalā l-waǧīz (4e volume). Arabe 988
No full textŠarḥ (aš-) al-ṣaġīr ʿalā l-waǧīzWaǧīz (al-). Commentaireالشرح الصغير على الوجيزالوجيز .شرحNumérisation effectuée à partir d'un document de substitution : R 67553.Copie achevée le 4 ramaḍān 738 h. / 26 mars 1338
Some Bacillus thuringiensis strains share rpoB nucleotide polymorphisms also present in Bacillus anthracis
No full textIdentification of Bacillus anthracis is considerably difficult because of its very high phenotypic and genotypic similarity to other members of the Bacillus cereus group. Differentiation methods based on morphological and phenotypic characteristics are time-consuming, and false results may be obtained for atypical strains. On the other hand molecular discrimination based on the presence of two B. anthracis virulence plasmids, pXO1 and pXO2, is not sufficient because plasmids can be lost or transferred to other bacilli. Therefore, several chromosomal markers have been investigated and applied (1, 8). In 2001 Qi et al. (7) described single nucleotide polymorphisms (SNPs) in the rpoB gene and their usefulness for B. anthracis identification. Since then, several articles describing various molecular methods for rpoB sequence-based detection of B. anthracis have been published (for example see references 2 and 9).
We conducted studies of single-strand conformation polymorphisms (SSCPs) of the rpoB gene in a large collection of B. cereus group strains. Surprisingly, we found that the nucleotide sequence of the rpoB gene fragment containing the marker SNPs of two reference strains of Bacillus thuringiensis was identical to that of the homologous region in B. anthracis. Therefore, rpoB gene-based tools could not distinguish these strains from B. anthracis, thus resulting in false-positive anthrax identification
- …
