Dnabased Identification Dna Probes

Several probes targeting genes such as those encoding the hemolysin (LLO), the invasion-associated protein, the DTH-18 gene, the PrfA regulator, the 16S rRNA gene, or the 16S/23S rRNA spacer have been described to differentiate Listeria genus and mainly the species L. monocytogenes.[12-18] Commercial DNA probe-based assays are now available for the rapid confirmation of L. monocytogenes from colonies (AccuProbeĀ®, GeneProbe, San Diego, CA; GENE-TRAKĀ® L. monocytogenes Assay, Gene-trak system, Framingham, MA). Both assays are nonradioactive hybridization methods (chem-iluminescently labeled probe or fluorescein-labeled probe for AccuProbe and Gene-trak, respectively) based on the detection of unique sequence in the 16S rRNA region. The sensitivity of both methods is achieved by the high copy number of 16S rRNA in the bacterium cell. The Gene-trak system is also usable for the rapid detection of Listeria spp. or L. monocytogenes from samples previously grown in selective enrichment broths.[19] The usefulness of these probes is restricted to the species containing nucleotide sequence that hybridize with the specific probe. In contrast, the analysis of the rRNA gene restriction patterns, after restriction hydrolysis of whole chromosomal DNA and hybridization with a 16S rRNA gene, allowed the identification of each Listeria spe-cies.[20] More recently, a fluorescence in situ hybridization (FISH) technique with 16S rRNA-targeted oligonucleotide has been developed for the identification of Listeria genus (but not L. grayi) by epifluorescence microscopy in a mixture with other bacteria. In addition, a technique for in situ detection of iap mRNA within intact cells of L. monocytogenes has also been devised.[21,22] These latter two methods will help in the analysis of the structure and dynamics of complex microbial communities and of the spatial distribution of probe-target populations in microbial biofilms and tissue samples.

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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