A certified plasmid reference material for the standardisation of BCR-ABL1 mRNA quantification by real-time quantitative PCR.

Serial quantification of BCR-ABL1 mRNA is an important therapeutic indicator in chronic myeloid leukaemia, but there is a substantial variation in results reported by different laboratories. To improve comparability, an internationally accepted plasmid certified reference material (CRM) was developed according to ISO Guide 34:2009. Fragments of BCR-ABL1 (e14a2 mRNA fusion), BCR and GUSB transcripts were amplified and cloned into pUC18 to yield plasmid pIRMM0099. Six different linearised plasmid solutions were produced with the following copy number concentrations, assigned by digital PCR, and expanded uncertainties: 1.08±0.13 × 10(6), 1.08±0.11 × 10(5), 1.03±0.10 × 10(4), 1.02±0.09 × 10(3), 1.04±0.10 × 10(2) and 10.0±1.5 copies/µl. The certification of the material for the number of specific DNA fragments per plasmid, copy number concentration of the plasmid solutions and the assessment of inter-unit heterogeneity and stability were performed according to ISO Guide 35:2006. Two suitability studies performed by 63 BCR-ABL1 testing laboratories demonstrated that this set of 6 plasmid CRMs can help to standardise a number of measured transcripts of e14a2 BCR-ABL1 and three control genes (ABL1, BCR and GUSB). The set of six plasmid CRMs is distributed worldwide by the Institute for Reference Materials and Measurements (Belgium) and its authorised distributors (https://ec.europa.eu/jrc/en/reference-materials/catalogue/; CRM code ERM-AD623a-f).

A microbial biosensor to predict bioavailable nickel in soil and its transfer to plants.

Ralstonia eutropha strain AE2515 was constructed and optimised to serve as a whole-cell biosensor for the detection of bioavailable concentrations of Ni2+ and Co2+ in soil samples. Strain AE2515 is a Ralstonia eutropha CH34 derivative containing pMOL1550, in which the cnrYXH regulatory genes are transcriptionally fused to the bioluminescent luxCDABE reporter system. Strain AE2515 was standardised for its specific responses to Co2+ and Ni2+. The detection limits for AE2515 were 0.1 microM Ni2+ and 9 microM Co2+, respectively. The signal to noise (S/N) bioluminescence response and the metal cation concentration could be linearly correlated: for Ni2+ this was applicable within the range 0.1-60 microM, and between 9 and 400 microM for Co2+. The AE2515 biosensor strain was found to be highly selective for nickel and cobalt: no induction was observed with Zn(II), Cd(II), Mn(II), Cu(III) and Cr(VI). In mixed metal solutions, the bioluminescent response always corresponded to the nickel concentrations. Only in the presence of high concentrations of Co2+ (2 mM), the sensitivity to nickel was reduced due to metal toxicity. AE2515 was used to quantify the metal bioavailability in various nickel-enriched soils, which had been treated with additives for in situ metal immobilisation. The data obtained with strain AE2515 confirmed that the bioavailability of nickel was greatly reduced following the treatment of the soils with the additives beringite and steel shots. Furthermore, the data were found to correlate linearly with those on the biological accumulation of Ni2+ in specific parts of important agricultural crops, such as maize and potato. Therefore, the test can be used to assess the potential transfer of nickel to organisms of higher trophic levels, in this case maize and potato plants grown on nickel-enriched soils, and the potential risk of transfer of these elements to the food chain.

Influence of the energetic pattern of mitochondria in cell ageing.

Injections of mitochondria isolated from liver of young or old rats have been performed in young or old WI-38 human fibroblasts and the survival of the injected cells was followed with time. Cells having received young mitochondria behave as the control non-injected cells while cells having received old mitochondria showed signs of degeneration after a few days. Such a behaviour could however be obtained with young mitochondria when partially uncoupled. The negative effect of the presence of uncoupled mitochondria could be overcome by addition of a ketone body: D(-) beta-hydroxybutyrate. When comparisons were performed between injected young and old fibroblasts, old cells were found less efficient in counteracting the presence of uncoupled mitochondria. These results clearly indicate that old cells contain partly altered mitochondria which are less able to fulfil their energy requirement so that a general lowering of homeostasis but also an increased susceptibility, toward unfavorable situations is obtained.

luxAB gene fusions with the arsenic and cadmium resistance operons of Staphylococcus aureus plasmid pI258.

pC101, a novel shuttle vector between Escherichia coli and Staphylococcus aureus carrying the lux genes encoding luciferase from Vibrio harveyi, selectable ampicillin and chloramphenicol markers and origins of replication for Gram-negative and Gram-positive bacteria has been constructed. The inducibility of the arsenic and cadmium operon from S. aureus plasmid pI258 to different ions has been tested in E. coli and in S. aureus with two fusions in pC101: an arsB-luxAB and a cadA-luxAB transcriptional gene fusion. Patterns of induction are influenced by the host strain and are slightly different from previous reports using the blaZ gene as reporter gene.