Response patterns in adult forest trees to chronic ozone stress: identification of variations and consistencies

The responsiveness of adult beech and spruce trees to chronic O(3) stress was studied at a free-air O(3) exposure experiment in Freising/Germany. Over three growing seasons, gas exchange characteristics, biochemical parameters, macroscopic O(3) injury and the phenology of leaf organs were investigated, along with assessments of branch and stem growth as indications of tree performance. To assess response pattern to chronic O(3) stress in adult forest trees, we introduce a new evaluation approach, which provides a comprehensive, readily accomplishable overview across several tree-internal scaling levels, different canopy regions and growing seasons. This new approach, based on a three-grade colour coding, combines statistical analysis and the proficient ability of the "human eye" in pattern recognition.     

Prenatal diagnosis for Epidermolysis bullosa: a study of 144 consecutive pregnancies at risk

Epidermolysis bullosa (EB) is a group of inherited disorders characterized by increased skin fragility, resulting in blisters and erosions after minor trauma. Mutations in 10 structural genes expressed in the cutaneous basement membrane zone have been reported. The DebRA Molecular Diagnostics Laboratory at Jefferson Medical College has performed 144 DNA-based prenatal diagnoses since 1993 in families at risk for recurrence of the most severe forms of EB, including the recessive dystrophic EB (RDEB), junctional EB (JEB), EB with pyloric atresia (EB-PA), and EB simplex (EBS). A mutation-detection strategy using either conformation-sensitive gel electrophoresis (CSGE) or denaturing high-performance liquid chromatography (dHPLC) scanning analysis, followed by nucleotide sequencing, was applied to most cases with DEB and to all JEB, EB-PA, and EBS families. For some RDEB families, linkage analysis was performed, either alone when the inheritance pattern was clear or in combination with one mutation. Among the 144 prenatal diagnoses, 63 were for RDEB, 69 for JEB, 6 for EB-PA, and 6 for EBS. Twenty-eight normal, 73 heterozygous carrier, and 28 affected RDEB, JEB, and EB-PA pregnancies were reported in these recessively inherited diseases. Two affected and four normal pregnancies were predicted in dominantly inherited EBS. Among the 144 pregnancies, 9 were terminated without confirmation, 13 cases were lost to follow-up, and 6 pregnancies are ongoing. There were 6 families with inconclusive results due either to recombination events between flanking markers, absence of informative markers for one allele, or lack of sample from the previously affected child. There were three discordant results, one that was explained by maternal contamination of the chorionic villus sample and two that were unresolved. Overall, the availability, relative ease, and over 98% success rate make molecular DNA-based prenatal diagnosis a viable option for EB families at risk. Copyright © 2003 John Wiley & Sons, Ltd.     

First trimester diagnosis of β-thalassaemia in a twin pregnancy

This paper reports the results of first trimester prenatal diagnosis in a twin pregnancy at risk for homozygous β°−thalassaemia (β°−39 mutant). Trophoblast samples from both twins were obtained at 10 weeks gestation with a forceps guided by ultrasound. Trophoblast DNA analysis, carried out with the oligonucleotide technique, revealed that one fetus was homozygous and the other heterozygous for the β−39 mutant. This diagnosis was confirmed at 17 weeks gestation by amniocyte DNA analysis. DNA polymorphism analysis within the α-globin gene provided useful genetic markers for twin differentiation.     

Recombinant luminescent bacterial sensors for the measurement of bioavailability of cadmium and lead in soils polluted by metal smelters

Environmental hazard of heavy metals in soils depends to a large extent on their bioavailability. The approach used in this study enables the determination of bioavailable metals in solid-phase samples. Two recombinant bacterial sensors, one responding specifically to cadmium and the other to lead and cadmium by increase of luminescence (firefly luciferase was used as a reporter) were used to determine the bioavailability of these metals in soil-water suspensions (a contact assay) and respective particle-free extracts. Fifty agricultural soils sampled near zinc and lead smelters in the Northern France containing up to (mg/kg) 20.1 of Cd, 1050 of Pb and 1390 of Zn were analysed. As the soil matrix interferes with the assay, recombinant luminescent control bacteria lacking the metal recognizing protein and corresponding promoter (thus, being not metal-inducible) but otherwise comparable to the sensor bacteria (the same host bacterium and plasmid encoding luciferase) were used in parallel to take into account the possible quenching and/or stimulating effects of the sample on the luminescence of the sensor bacteria. Both, chemical and sensor analysis showed that only microg/l levels of metals were extracted from the soil into the water phase (0.1% of the total Cd, 0.07% of Pb and 0.5% of Zn). However, 115-fold more Cd and 40-fold more Pb proved bioavailable if the sensor bacteria were incubated in soil suspensions (i.e., in the contact assay). The bioavailability of metals in different soils varied (depending probably on soil type) ranging from 0.5% to 56% for cadmium and from 0.2% to 8.6% for lead.