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.     

A chemical and toxicological profile of Dutch North Sea surface sediments

Chemical and toxicological profiles were assessed in surface sediments (fraction <63 μm) from the southern North Sea. In extracts of freeze-dried samples, polybrominated biphenyl (PBB), Irgarol 1051 and phthalate concentrations were below the respective detection limits (except di(2-ethylhexyl)phthalate, which was between 170 and 3300 μg kg⁻¹ dry weight (dw)). Hexabromocyclododecane (HBCD) concentrations were between 0.8 and 6.9 μg kg⁻¹ dw, with highest concentrations at river mouths. Polybrominated diphenylethers (PBDE) concentrations were 0.4–0.6 μg kg⁻¹ dw, decabromodiphenylether (BDE209) 1–32 μg kg⁻¹ dw. The ratio BDE209/PCB153 was used as a tracer for recent emissions, and pointed towards a BDE209 source in the Western Scheldt’s upper estuary. PCBs and PAHs were between 0.19–4.7 and 2.6–200 μg kg⁻¹ dw respectively and generally had highest concentrations at near-shore locations and river mouths.

Responses in the Microtox broad-spectrum and the Mutatox genotoxicity assays were generally low, with near-shore locations giving higher responses. The umu-C genotoxicity and the ER-CALUX assay for estrogenicity showed no response, with the exception of one near-shore location (IJmuiden outer harbour, ER-CALUX).

Highest dioxin-like toxicity (DR-CALUX) was found at near-shore locations, in the outflow of the Rhine/Meuse estuary including a dumping site of harbour sludge. At the Oyster Grounds, DR-CALUX responses appeared to be linked to the occurrence of larger PAHs (4–6 rings). A new, non-destructive clean up procedure resulted in significantly higher DR-CALUX responses than the current protocol. The Dutch legislation on disposal of harbour sludge at sea, dictates the use of the conventional clean up procedure. Our results therefore indicate that probably more dioxin-like toxicity associated with harbour sludge is disposed off at sea than assumed.     

A case of mosaicism involving an unstable 13/14 Robertsonian translocation

Prenatal diagnosis of mosaicism involving an apparently unstable 13/14 Robertsonian trans-location is reported. This illustrates the difficulties encountered in counselling when mosaicism is ascertained prenatally. Other reported examples of apparently unstable Robertsonian translocations are discussed.     

Contribution of a New PCR assay to the prenatal diagnosis of congenital toxoplasmosis

A polymerase chain reaction (PCR) assay has been developed for the detection of Toxoplasma gondii. The target sequence (88 bp) is part of a rDNA repetitive gene. A signal can be observed with only one parasite. It is directly and rapidly detected by electrophoresis and ethidium bromide staining. We report a prospective study of 80 documented cases of toxoplasmic seroconversions during pregnancy. The PCR assay of the amniotic fluids was compared with the current standard methods for diagnosis of fetal infection. Seventy specimens gave no PCR signal, and were negative according to prenatal tests and postnatal examinations. The presence of T. gondii was detected in ten specimens by PCR analysis. Four were confirmed by isolation of the parasite from the amniotic fluid; four by biological study of the fetal blood. For the remaining two, infection was diagnosed after birth. Together with ultrasonographic and biological data, this technique permits prenatal diagnosis within 1 day.     

US energy policy in historical perspective

Energy ‘policy’ is not a recent invention. What is new is that instead of a variety of policies rooted for the most part in notions other than adequacy of reasonably priced and readily available energy supplies, the past fifteen years or so have witnessed the emergence of a set of policies that are more pointedly directed at energy targets as such. These include, above all, such cross cutting issues as efficiency in use, security against supply disruptions, incentives to oil and gas producers, opportunities for the development of alternative energy sources and concern for the equitable sharing of costs associated with any of these policies. If there is one overriding issue that permeates the policy fabric it is the delineation of the governmental role versus market forces. Debate and controversy on that topic is bound to continue.     

The predictive value of cytogenetic diagnosis after CVS based on 4860 cases with both direct and culture methods

Cytogenetic analysis was performed in 4860 chorionic villus samples by means of both direct preparation and long-term culture. The results of the analysis were compared with a classification including all theoretical types of combinations between the chromosomal constitution of the cytotrophoblast, extraembryonal mesoderm, and fetus, with the aim of evaluating the cytogenetic variability along the trophoblast—embryo axis. Eighteen of 29 possible combinations were found demonstrating a considerable heterogeneity. A mosaic conceptus was found in 1·5 per cent of cases, with generalized mosaicisms and confined mosaicisms in 0·2 and 1·3 per cent, respectively. Cytogenetic variability along the trophoblast—embryo axis was found in 1·42 per cent of cases. Results possibly leading to diagnostic errors (false-positive and false-negative results) were found in only 1·38 per cent. False-positive results of direct preparation were the most commonly observed discrepancy (0·8 per cent), while the incidence of false-positive results of the culture method and of both methods was 0·31 and 0·16 per cent respectively. The incidence of false-negative results was 0·1 per cent, with false-negative results of direct preparation 0·08 per cent and false-negative results of both methods 0·02 per cent. False-negative results of the culture method were not found. Our data confirm the high diagnostic accuracy of chorionic villus sampling and the utility of the combined use of the two methods in minimizing diagnostic errors and in reducing the need for follow-up amniocentesis.     

Maternal age and amniocentesis: Should this be lowered to 30 years?

We have reviewed the results of 10000 2nd trimester amniocenteses performed at our centre. Over 80 per cent of these were done only because of maternal age (MA); there were three times as many < 35 year-old women in 1984 compared to 1975. Of women aged 30–34 years at delivery 0·69 per cent were found to have a MA-related chromosome abnormality compared to 0·94 per cent in those aged 35–40 years. Because only about 7 per cent of births occurred to women ⩾ 35 years and 18·6 per cent between 30–34 years, and a practical utilization rate of 50 per cent, we recommend that amniocentesis be made available to women aged ⩾ 30 years. We believe that 27 per cent of Down syndrome (DS) pregnancies could be identified if 50 per cent of pregnant women in this age category availed themselves of the test. With the same utilization rate, about three times as many amniocenteses would be required in California as performed here in 1983.