Assessment of lactobacillus bulgaricus strain in human intestinal samples by denaturation gradient gel electrophoresis

PURPOSE. The purpose of this work was to evaluate the content of Lactobacillus bulgaricus in faecal samples of volunteers after consumption of yoghurt produced with selected L. bulgaricus strain. METHODS. Using Denaturation Gradient Gel Electrophoresis (DGGE) the DNA band corresponding to L. bulgaricus was well separated from the DNA bands of other lactobacilli. RESULTS. Faecal samples of all four volunteers consumed yoghurt contained a major DNA band indicating the presence of L. bulgaricus, unlike the faecal samples from the three volunteers no consumed yoghurt where the specific for L. bulgaricus DNA band was absent. The differences in the intensity of the electrophoretic band of L. bulgaricus are influenced by the individuality of the volunteers and the duration of yoghurt consumption. By help of DGGE it was possible to assay the presence of L. bulgaricus in faecal samples and on the base of the intensity of the specific DNA fragment to evaluate the dynamics of L. bulgaricus content during 10 days consumption of yoghurt. CONCLUSIONS. DGGE proved to be an applicable tool to monitor the presence of L. bulgaricus strains in human intestinal samples.

D-genome suppression of gliadin electrophoretic band 45 in hexaploid wheat and the effect upon quality

The hexaploid wheat 'Prelude' (2n = 42 = AABBDD) contains the endosperm protein electrophoretic band 40, but not band 45, while the extracted tetraploid 'Tetraprelude' (2n = 28 = AABB) contains electrophoretic band 45 but not band 40. Moreover, F3 progeny from the cross between backcross lines of 'Prelude' and 'Marquis' segregated as if both of these proteins were controlled by alleles of one gene, or by two very closely linked genes. Examination of the F3 seed from the cross 'Prelude' × 'Canthatch' 7D nullisomic showed that band 45 was not expressed in any of the 334 F2 families, including nine nullisomics. Together, these results indicate that band 45 endosperm protein is not suppressed by a gene on chromosome 7D. Furthermore, removal of the D genome from 'Prelude' resulted in increased kernel hardness and increased gluten elastic strength but a decrease in sodium dodecyl sulfate sedimentation volume. However, the sodium dodecyl sulfate sedimentation volume of 'Tetraprelude', was the highest among the tetraploid cultivars evaluated.Key words: wheat, sodium dodecyl sulfate electrophoresis, endosperm protein, gene expression.

Variation in the electrophoretic band pattern of tuber proteins from somaclones of potato

The soluble tuber proteins of potato (Solatium tuberosum) may be separated by electrophoresis on the basis of charge or molecular weight (Stegemann & Schnick, 1982; Maier & Wagner, 1981: Park et al. 1983). Considerable cultivar specific variation exists in the band patterns of these proteins and separation of native proteins in 6% polyacrylamide gels at pH 7·9 has been used as the basis of characterizing cultivars for the Index of European Potato Varieties (Stegemann & Schnick, 1982).