Phytoremediation organischer Schadstoffe

Ohne Zusammenfassung     

Low level inhalation experiments with four different cadmium compounds in rats†

This long‐term inhalation study was designed to describe the toxicity and the carcinogenic risk from Cd compounds because it had been shown from former long‐term inhalation studies that cadmium choloride induced primary lung tumors in Wistar rats. It was therefore logical to examine whether other cadmium compounds to which human beings are more frequently exposed have also carcinogenic potency. In a long‐term inhalation study cadmium aerosols consisting of cadmium chloride (CdCl₂), cadmium oxide (CdO) as dusts and fumes, cadmium sulfate (CdSO₄), cadmium sulfide (CdS) and a combination of cadmium oxide/zinc oxide were used. Wistar rats were continuously exposed in inhalation chambers for 18 months 22 hrs a day or for 40 hrs a week. The studies will be terminated at the mean survival life time of the species. The aerosols were generated by several different systems. The particles of the cadmium aerosols have the average mass medium diameters in the range from 0.2 to 0.5 μm.     

Trophic role of small cyclopoid copepod nauplii in the microbial food web: a case study in the coastal upwelling system off central Chile

Copepod grazing impact on planktonic communities has commonly been underestimated due to the lack of information on naupliar feeding behaviour and ingestion rates. That is particularly true for small cyclopoid copepods, whose nauplii are mainly in the microzooplankton size range (<200 μm). The trophic role of Oithona spp. nauplii was investigated off Concepción (central Chile, ~36°S) during the highly productive upwelling season, when maximum abundances of these nauplii were expected. Diet composition, ingestion rates, and food-type preferences were assessed through grazing experiments with different size fractions of natural planktonic assemblages (<3, <20, <100, and <125 μm) and cultures of the nanoflagellate Isochrysis galbana. When the Oithona spp. nauplii were offered a wide range of size fractions as food (pico- to microplankton), they mostly ingested small (2–5 μm) nanoflagellates (5–63 × 10³ cells nauplius⁻¹ day⁻¹). No ingestion on microplankton was detected, and picoplankton was mainly ingested when it was the only food available. Daily carbon (C) uptake by the nauplii ranged between 28 and 775 ng C nauplius⁻¹, representing an overall mean of 378% of their body C. Our relatively high ingestion rate estimates can be explained by methodological constraints in previous studies on naupliar feeding, including those dealing with “over-crowding” and “edge” effects. Overall, the grazing impact of the Oithona spp. nauplii on the prey C standing stocks amounts up to 21% (average = 13%) for picoplankton and 54% (average = 28%) for nanoplankton. These estimates imply that the nauplii of the most dominant cyclopoid copepods exert a significant control on the abundances of nanoplankton assemblages and, thereby, represent an important trophic link between the classical and microbial food webs in this coastal upwelling system.     

How maize root volatiles affect the efficacy of entomopathogenic nematodes in controlling the western corn rootworm?

Because the ferocious maize pest Diabrotica virgifera virgifera LeConte can adapt to all currently used control strategies, focus has turned to the development of novel, more sustainable control methods, such as biological control using entomopathogenic nematodes (EPN). A good understanding of the biology and behaviour of these potential control agents is essential for their successful deployment. Root systems of many maize varieties emit (E)-β-caryophyllene (EβC) in response to feeding by larvae of the beetle D. v. virgifera. This sesquiterpene has been shown to attract certain species of EPN, thereby enhancing their control potential. In this study, we tested the effect of this root-produced volatile on the field efficacy of the three EPN Heterorhabditis bacteriophora, Heterorhabditis megidis and Steinernema feltiae against D. v. virgifera larvae in southern Hungary. By comparing beetle emergence and root damage for two maize varieties, one that emits EβC and one that does not, it was found that root protection by H. megidis and S. feltiae was higher on the emitting variety, but this was not the case for H. bacteriophora. Overall, all three nematode species showed good control potential. We conclude that, if properly applied and in combination with the right maize variety, the release of these nematodes can be as effective as other control methods.     

First-trimester sonographic diagnosis of distal urethral atresia with megalourethra in VACTERL association

Congenital megalourethra is a rare disorder. We present an early case diagnosed in the first trimester. Prenatal ultrasound showed a megalourethra with a normal fetal bladder, hyperechogenic cystic right kidney and single umbilical artery. After termination of pregnancy, necropsy confirmed all sonographic findings and revealed other malformations (spina bifida occulta, anal atresia, tracheo-oesophageal fistula, brachydactylia) resulting in the diagnosis of VACTERL association. The prenatal diagnostician should seek histological examination firstly to confirm his findings and secondly to avoid missing associations and inherited malformations. Copyright © 2002 John Wiley & Sons, Ltd.     

Biochemical screening for chromosomal disorders and neural tube defects (NTD): is adjustment of maternal alpha-fetoprotein (AFP) still appropriate in insulin-dependent diabetes mellitus (IDDM)?

Maternal serum alpha-fetoprotein (AFP) has been reported to be decreased in insulin-dependent diabetes mellitus (IDDM). The objective of the present study was to reinvestigate this finding in detail. Maternal serum levels of AFP, human chorionic gonadotropin (hCG), and unconjugated estriol (uE3) in 114 diabetic women, of whom 84 had IDDM, were compared to those of 19,251 control pregnancies in the second trimester (15th to 20th gestational weeks). The mean body weight at the date of sampling was 73.7 kg in all diabetic women, 72.7 kg in women with IDDM and 68.3 kg in non-diabetic women, respectively. Body weights were significantly (p<0.001) elevated in all diabetic pregnancies. Using weight-adjusted MoM (multiple of the median) values no statistical difference of serum levels in diabetic and non-diabetic pregnant women was found. Median MoM levels were 1.01 (hCG), 1.01 (uE3), 1.06 (AFP) in all diabetic women, and 0.95 (hCG), 0.96 (uE3), 0.96 (AFP) in women with IDDM, respectively. Ignoring adjustment for maternal weight leads to a reduction of all serum parameters in diabetic pregnancies. However, median MoM values of all three analytes are not statistically different when compared to non-diabetic pregnancies. This finding is contrary to the results of former studies from the 1970s and 1980s. It is concluded that progress in insulin adjustment and blood glucose surveillance of diabetic patients on the whole has balanced out serum levels. Therefore adjustment of serum AFP values for diabetic status no longer seems reasonable. Copyright © 2001 John Wiley & Sons, Ltd.