PCR identification of Salmonella cells in food and stool samples after immunomagnetic separation

The purpose of the present study was to investigate the application of various sample preparation methods (cell washing before lysis, purification of DNA using phenol extraction method, immunomagnetic separation-IMS) for the final PCR identification of Salmonellacells. The presence of PCR inhibitors in processed food products (milk powder and dried eggs) can be the cause of false-negative results in PCR without IMS of target cells. It was also demonstrated that IMS-PCR was successfully used for identification and quick confirmation of untypical Salmonella strains isolated from human stool samples and rabbit meat. However, IMS cannot eliminate intracellular PCR inhibitors present in immunoseparated Salmonella cells. These inhibitors must be taken into consideration in evaluation of PCR procedure.     

Germinal Excision and Reinsertion Frequencies of the Mobile Element Ds Transposed from Two Unlinked T-DNA Loci in Tomato

Acceptor sites of unlinked transposed Ds element from two T-DNA loci in tomato were mapped. Experimental data obtained from TC₁ progeny testing were employed for estimation of germinal excision frequency (GEF) of Ds element and frequency of its reinsertion (FR). The donor T-DNAs 1481J and 1601D, containing a 35S:NPT transformation marker, a 35S:BAR or nos:BAR excision marker conferring phosphinothricine resistance and a Ds element in the 5 untranslated leader of the nos (or 35S): BAR gene, were located on chromosome 7 and 8, respectively. Ds transposition was induced by 105121 T-DNA carrying stabilized Ac (sAc) which provides a source of transposase and 2:GUS marker conferring -glucuronidase activity. Tomato plants harbouring the Ds in 1481J or 1601D locus and sAc were crossed and F₁D, were crossed individually as seed parents to wild-type plants to generate TC₁ progenies. TC₁ seed was germinated on phosphinothricine (Basta)-containing medium, and individual seedlings carrying a transposed Ds and lacking sAc were identified by PCR (to detect the Ds) on phosphinothricine resistant individuals that lacked -glucuronidase activity. From segregation ratio in TC₁ the germinal excision and reinsertion frequencies of the Ds element were estimated for individual F₁ plants. A total of 14560 TC₁ seedlings of 1481J and 16195 TC₁ seedlings of 1601D was analyzed. We observed high variation between individual plants as regards both GEF and FR despite of donor locus (1481J or 1601D), however, the average germinal excision frequencies as well as average frequencies of reinsertion were very similar for both donor loci: GEF_1481J = 24 %, GEF_1501D = 25 %, FR_1481J = 42 %, FR_1601D = 46 %.     

Comparative response ofPisum sativum nodulated with indigenous soilRhizobium populations and/or co-inoculated with aRhizobium leguminosarum strain

No significant differences in the acetylene-reducing activity and evolution of H₂ and CO₂ nodulated roots ofPisum sativum inoculated with soilRhizobium populations from two soils with different acidities (Ruzyně soil 7.6; Lukavec soil 4.9) were observed.Rhizobium population from Lukavec soil formed nodules, exhibiting a higher H₂ evolution. Co-inoculation with the Hup⁺ strain 128C30 (7×10⁷ cells per seedling) eliminated, to some extent, the effect of soil populations on physiological activity. Translated by Č. Novotny     

Ecotoxicological contamination processes: Interaction with vegetation (a review)

Up-to-date crop production concentrates on the maximisation of plant matter production, both by optimum utilization of solar energy by plants and by the application of additional energy. Therefore a natural strategy is being developed aimed at combining the physiological functions of the assimilation organs with their external shaping and strengthening their variety in space and area. As demonstrated by many deposition studies, this effect is contradictory to the factors conditioning the low deposition capacity of plant covers. A high level of particle, gas and solution deposition increases the danger of food chain contamination and has a negative impact on plant production. Data concentrated on transport values of pollutants and their long-term dynamics in stands could be used for the selection of ideal crop types; therefore every effort should be directed towards selection and breeding.     

Chromosome and nucleotide sequence differentiation in genomes of polyploid Triticum species

Summary The nature of genome change during polyploid evolution was studied by analysing selected species within the tribe Triticeae. The levels of genome changes examined included structural alterations (translocations, inversions), heterochromatinization, and nucleotide sequence change in the rDNA regions. These analyses provided data for evaluating models of genome evolution in polyploids in the genus Triticum, postulated on the basis of chromosome pairing at metaphase I in interspecies hybrids.The significance of structural chromosome alterations with respect to reduced MI chromosome pairing in interspecific hybrids was assayed by determining the incidence of heterozygosity for translocations and paracentric inversions in the A and B genomes of T. timopheevii ssp. araraticum (referred to as T. araraticum) represented by two lines, 1760 and 2541, and T. aestivum cv. Chinese Spring. Line 1760 differed from Chinese Spring by translocations in chromosomes 1A, 3A, 4A, 6A, 7A, 3B, 4B, 7B and possibly 2B. Line 2541 differed from Chinese Spring by translocations in chromosomes 3A, 6A, 6B and possibly 2B. Line 1760 also differed from Chinese Spring by paracentric inversions in arms 1AL and 4AL whereas line 2541 differed by inversions in 1BL and 4AL (not all chromosomes arms were assayed). The incidence of structural changes in the A and B genomes did not coincide with the more extensive differentiation of the B genomes relative to the A genomes as reflected by chromosome pairing studies.To assay changing degrees of heterochromatinization among species of the genus Triticum, all the diploid and polyploid species were C-banded. No general agreement was observed between the amount of heterochromatin and the ability of the respective chromosomes to pair with chromosomes of the ancestral species. Marked changes in the amount of heterochromatin were found to have occurred during the evolution of some of the polyploids.The analysis of the rDNA region provided evidence for rapid fixation of new repeated sequences at two levels, namely, among the 130 bp repeated sequences of the spacer and at the level of the repeated arrays of the 9 kb rDNA units. These occurred both within a given rDNA region and between rDNA regions on nonhomologous chromosomes. The levels of change in the rDNA regions provided good precedent for expecting extensive nucleotide sequence changes associated with differentiation of Triticum genomes and these processes are argued to be the principal cause of genome differentiation as revealed by chromosome pairing studies.     

Differential tolerance ofArabidopsis thaliana crown gall tumors and calli to 5-bromo-2′-deoxyuridine

The degree of tolerance of two crown gall tumors and leaf calli ofArabidopsis thaliana to BUdR was compared. The nopaline producing teratoma tumor tolerated BUdR in concentration as high as 2.10^?4 M. The tolerance of octopine producing unorganized crown gall tumor to BUdR was lower, but both exceeded significantly the degree of tolerance to BUdR of untransformedA. thaliana calli, where 10^?5 M BUdR already show some inhibitory effect on the growth rate.     

Racemization of the aqua-{N-salicylidene-(S)-alaninato}copper(II) by reaction with potassium cyanate

Copper(II) N-salicylidene-(S)-alaninate trihydrate reacting as the S-enantiomeric parent compound with KOCN in hot diluted methanol yielded by slow crystallisation from the cooled reaction mixture (in the course of 1 day) the racemic product K[Cu{sal-(RS)-ala}(NCO)]. The parameters of the axial type EPR spectrum in X-band region and the LF band position in the electronic spectrum are typical of an axially distorted square pyramidal coordination of the Cu(II) atom in this complex. The spectral properties of the complex cuprate prepared and its basal crystallographic data are consistent with those of the earlier studied¹⁵ K₂[Cu₂{sal-(RS)-ala}₂(μ-NCO)₂] synthetized by using [Cu{sal-(RS)-ala}(H₂O)].H₂O as the racemic parent complex in the reaction mixture with KOCN.     

Application of enzyme flow microcalorimetry to the study of microkinetic properties of immobilized biocatalyst

Summary Flow microcalorimeter was used for the study of microkinetic properties of Escherichia coli cells enriched with the penicillin G acylase activity immobilized in calcium pectate gel. The experimental kinetic data were obtained by measurement of the thermometric signal in the microcalorimetric column with immobilized enzyme and described by the introduced mathematical model involving the mass transfer and reaction kinetic phenomena.