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Identification of 10 salmon species using DNA-based methodology was investigated. Amplification of DNA was carried out using a primer set which amplified a region of the mitochondrial cytochrome b gene. Sequences of PCR-amplified DNA from the salmon species were used to select six restriction enzymes allowing species to be uniquely classified. RFLP patterns generated following analysis with each enzyme were resolved using polyacrylamide gel electrophoresis and visualized by silver staining. Results indicate that it is possible to differentiate between all 10 salmon species and that the technique could be easily adopted by the food industry for analysis of processed salmon products.
This paper describes a method for isolation of DNA from blood samples involving a rapid chemical disintegration of proteins with 8 M urea and with a minimum of exposure to phenol. The DNA is further desalted and purified on Sephadex G-25 prepacked disposable columns. DNA isolated in this way was pure enough to be immediately cleaved by restriction enzymes.
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A polymerase chain reaction (PCR) was developed to differentiate the thickening agents locust bean gum (LBG) and the cheaper guar gum in finished food products. Universal primers for amplification of the intergenic spacer region between trnL 3' (UAA) exon and trnF (GAA) gene in the chloroplast (cp) genome and subsequent restriction analysis were applied to differentiate guar gum and LBG. The presence of <5% (w/w) guar gum powder added to LBG powder was detectable. Based on data obtained from sequencing this intergenic spacer region, a second PCR method for the specific detection of guar gum DNA was also developed. This assay detected guar gum powder in LBG in amounts as low as 1% (w/w). Both methods successfully detected guar gum and/or LBG in ice cream stabilizers and in foodstuffs, such as dairy products, ice cream, dry seasoning mixes, a finished roasting sauce, and a fruit jelly product, but not in products with highly degraded DNA, such as tomato ketchup and sterilized chocolate cream. Both methods detected guar gum and LBG in ice cream and fresh cheese at levels <0.1%.
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The phenotypic identification of the classical propionibacteria is essentially still problematic and alternative techniques for the identification of the various species are required. A rapid and sensitive technique for the routine identification of the classical propionibacteria, based on the amplification of 16S rRNA genes using the polymerase chain reaction and the subsequent restriction endonuclease digestion of the PCR products, was previously described. Although this technique enabled differentiation between the various classical species examined it was only evaluated on a limited number of type and reference strains. During this study, the taxonomic relationship between 135 Propionibacterium strains from diverse ecological niches, representing four classical species was investigated using this PCR/RFLP technique. Visual differentiation between the classical Propionibacterium was possible after restriction endonuclease digestion of the PCR products obtained using primers 16sP1-16sP4 and 16sP3-16sP4 with the restriction endonucleases HaeIII, AluI and HpaIII, respectively. With the exception of strains independently identified as "P. rubrum" and "P. sanguineum", the results of this study confirm the consolidation of the "old" species into the various classical species as they currently exist. It was therefore concluded that the PCR/RFLP protocol is suitable for the rapid and routine identification of the classical propionibacteria.
The 17 described genomic species (DNA groups) of the genus Acinetobacter, including the type strains of the seven named species, were studied by using a multiplex PCR. The multiplex PCR assay combined two primer sets (rA1 and rA2 for recA gene target; rib1 and rib2 for 16S rDNA sequence) in a single reaction. Restriction analysis with two enzymes (Mbol and Hinfl) of the enzymatically amplified products allowed identification of all genospecies. This technique proved to be a rapid and reliable method for the identification of the Acinetobacter genomic species including the closely related DNA groups (1, 2, 3, 13). The results of this study suggest that the proposed method can be used for the identification of Acinetobacter spp. and as such may help to elucidate the ecology and clinical significance of the different species of this genus.
The human homologue of the SEA oncogene has been mapped recently to chromosome band 11q13. While studying the possible involvement of this gene in the variant translocation t(9;22;11) (q34;q11;q13) in a case of chronic myelogenous leukemia, we identified novel polymorphisms for XbaI and SacI restriction enzyme sites in the SEA gene. Frequency of the polymorphic alleles was studied in 100 samples from healthy controls, 94 samples from patients with non-Hodgkin's lymphoma, 25 samples from patients with benign lymphadenopathy, and 38 samples from patients with chronic myelogenous leukemia. XbaI digestion showed a three-allele polymorphism with two frequent alleles A (8.0 kb) and B (9.2 kb) and a rare allele (5.8 kb). After SacI digestion the probe identified two primary genotypes. Genotype I showed two hybridizable DNA fragments, one each of 6.6 and 3.5 kb. In genotype II the 3.5 kb fragment was absent, instead two smaller fragments, one each of 1.9 kb and 1.6 kb were present. The 6.6 kb fragment (allele AA) had three polymorphic sites generating 6.2 kb fragment (allele BB), 7.4 kb fragment (allele CC), and 7.8 kb fragment (allele DD). Frequencies of the two genotypes and the four alleles followed Mendelian proportions in all the samples studied. Furthermore, this study shows the importance of restriction map analysis of DNA in the vicinity of the probe of an oncogene to distinguish natural polymorphisms from the disease-related rearrangements in the gene.
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The polymerase chain reaction was used to amplify a targeted region: an internal transcribed spacer region of the ribosomal DNA from 114 Candida isolates and 65 reference strains. Unique product sizes were obtained for Candida glabrata, C. guillermondii and C. inconspicua. Isolates of C. albicans, C. tropicalis, C. dubliniensis and C. krusei could be identified following restriction digestion of the PCR products. The methods proved to be both simple and reproducible and may offer potential advantages over phenotyping methods.