Elevated alpha-fetoprotein and human chorionic gonadotropin as a marker for placental trisomy 16 in the second trimester?

In a series of 2961 consecutive cases with second-trimester biochemical triple screening for Down's syndrome and neural tube defect (NTD), ten (0.3 per cent) showed an apparent increased risk for both conditions. Three cases had chromosomal abnormalities, namely trisomy 16 confined to the placenta. Since placental trisomy 16 as well as cases with increased alpha-fetoprotein (AFP) and human chorionic gonadotropin (hCG) are associated with (intrauterine growth retardation (IUGR), oligohydramnios, and fetal demise, at least some cases with this atypical biochemical profile could be explained by this chromosomal abnormality. From our results we recommend that in cases with increased risk for both Down's syndrome and NTD, fetal karyotyping should preferably be done on a placental biopsy, especially when ultrasound in the absence of anomalies demonstrates early IUGR.     

Untersuchungskonzept zur Charakterisierung toxischer Stoffe in belastetem Wasser

Zusammenfassung  Zur ?kotoxikologischen Beurteilung von belastetem Wasser werden h?ufig einfache Biotests eingesetzt. Nicht selten werden dabei toxische Effekte festgestellt. Es stellt sich dann die Frage nach den verantwortlichen Wasserinhalts-stoffen. Durch Festphasenextraktion (SPE) werden diese angereichert, gewonnen und dünnschichtchromatographisch unter Verwendung der automatisierten Mehrfachentwicklung aufgetrennt. Von der DC-Platte wird ein Streifen abgetrennt und darauf direkt die biologische Detektion mit Mikroorganismen (Bacillus subtilis, Leuchtbakterien) durchgeführt. Dadurch k?nnen toxische Banden erkannt werden, Auf dem DC-Plattenrest wird von der toxischen Bande mit einem DC-scanner ein UV-Spektrum aufgenommen, die entsprechende Bande herausgekratzt, der toxische Stoff eluiert und infrarotspektroskopisch untersucht. Durch Spektrenvergleich gelingt es meistens, den Stoff zu charakterisieren. In der vorliegenden Arbeit wird am Beispiel eines Zitzengummieluates das Analysenkonzept vorgestelit. Es zeigte sich, dass dieser Gummiartikel einen Vulkanisationsbeschleuniger (2-Mercaptobenzothiazol) freisetzt. Online-Publikation am: 21.12.1999     

Chemical composition of Eurasian lynx urine conveys information on reproductive state,individual identity,and urine age

In mammals, the chemical profiles of individuals are complex and variable mixtures, and animals perceive information based on variation in the overall quality of these mixtures. A variety of compounds potentially involved in chemical communication have been characterized in the urine of different felid species, but little is known about the information content of felid scent marks. In this study, we investigated whether chemical composition of Eurasian lynx Lynx lynx urine was related to sex, reproductive state, and individual identity. We further analysed if elemental sulphur in lynx urine could serve as a dietary cue or as an indicator for the freshness of a scent mark. We collected urine from captive and wild Eurasian lynx, and analysed volatile constituents of urine by means of solid phase microextraction and gas chromatography-mass spectrometry. Our results show that lynx scent profiles contain sex-specific information on reproductive state, as well as individual identity cues. Urine marks are, therefore, well-suited to fulfil a role in reproductive behaviour and social organisation of wild lynx populations. Relative sulphur content was unrelated to time since last feeding, but decreased with age of the urine sample. The influence of diet and body condition on scent profiles should be further investigated by means of experimental studies, and may shed more light on the messages encoded in carnivore scent-marks.     

Some Perspectives on the Risks and Benefits of Biological Control of Invasive Alien Plants in the Management of Natural Ecosystems

Globally, invasions by alien plants are rapidly increasing in extent and severity, leading to large-scale ecosystem degradation. Weed biological control offers opportunities to arrest or even reverse these trends and, although it is not always effective or appropriate as a management strategy, this practice has an excellent record of safety and many notable successes over two centuries. In recent years, growing concerns about the potential for unintended, non-target damage by biological control agents, and fears about other unpredictable effects on ecosystems, have created an increasingly demanding risk-averse regulatory environment. This development may be counter-productive because it tends to overemphasize potential problems and ignores or underestimates the benefits of weed biological control; it offers no viable alternatives; and it overlooks the inherent risks of a decision not to use biological control. The restoration of badly degraded ecosystems to a former pristine condition is not a realistic objective, but the protection of un-invaded or partial restoration of invaded ecosystems can be achieved safely, at low cost and sustainably through the informed and responsible application of biological control. This practice should therefore be given due consideration when management of invasive alien plants is being planned. This discussion paper provides a perspective on the risks and benefits of classical weed biological control, and it is aimed at assisting environmental managers in their deliberations on whether or not to use this strategy in preference, or as a supplement to other alien invasive plant control practices.     

Pesticide concentrations in agricultural storm drainage inlets of a small Swiss catchment

Agricultural pesticides transported to surface waters pose a major risk for aquatic ecosystems. Modelling studies indicate that the inlets of agricultural storm drainage systems can considerably increase the connectivity of surface runoff and pesticides to surface waters. These model results have however not yet been validated with field measurements. In this study, we measured discharge and concentrations of 51 pesticides in four out of 158 storm drainage inlets of a small Swiss agricultural catchment (2.8 km²) and in the receiving stream. For this, we performed an event-triggered sampling during 19 rain events and collected plot-specific pesticide application data. Our results show that agricultural storm drainage inlets strongly influence surface runoff and pesticide transport in the study catchment. The concentrations of single pesticides in inlets amounted up to 62 µg/L. During some rain events, transport through single inlets caused more than 10% of the stream load of certain pesticides. An extrapolation to the entire catchment suggests that during selected events on average 30 to 70% of the load in the stream was transported through inlets. Pesticide applications on fields with surface runoff or spray drift potential to inlets led to increased concentrations in the corresponding inlets. Overall, this study corroborates the relevance of such inlets for pesticide transport by establishing a connectivity between fields and surface waters, and by their potential to deliver substantial pesticide loads to surface waters.

     

The Economic Consequences of Alien Plant Invasions: Examples of Impacts and Approaches to Sustainable Management in South Africa

The invasion of natural ecosystems by alien plants is a serious environmental problem that threatens the sustainable use of benefits derived from such ecosytems. Most past studies in this field have focussed on the history, ecology and management of invasive alien species, and little work has been done on the economic aspects and consequences of invasions. This paper reviews what is known of the economic consequences of alien plant invasions in South Africa. These economic arguments have been used to successfully launch the largest environmental management programme in Africa.Ten million hectares of South Africa has been invaded by 180 alien species, but their impacts are not fully understood, although they are undoubtedly significant. The indications are that the total costs of these impacts are substantial. Selected studies show that invasions have reduced the value of fynbos ecosystems by over US$ 11.75 billion; that the total cost of invasion would be about US$ 3.2 billion on the Agulhas Plain alone; that the net present cost of invasion by black wattles amounts to US$ 1.4 billion; that invasions by red water fern have cost US$ 58 million; and that the cost to clear the alien plant invasions in South Africa is around US$ 1.2 billion. These few examples indicate that the economic consequences of invasions are huge.One of the unique aspects of invasive plant control programmes in South Africa has been the ability to leverage further benefits (mainly through employment) for the expensive control programmes from the government's poverty relief budget. This has made it possible to allocate substantial funding to a programme that would otherwise have struggled to obtain significant support. Biological control of invasive species also offers considerable benefits, but is often the subject of debate. We believe that, at least in the case of many invasive alien plant species in South Africa, biological control offers one of the best, and most cost-effective, interventions for addressing the problem.     

Computerized offices in Canada and the United States: Investigating dispositional similarities and differences

A scale measuring computer dispositions was used in order to examine whether computerization of work affects employees similarly or differently in Canada and the United States. The study explores the possibility that employees may differ intraculturally, that is, according to gender, hierarchical level in the firm, and whether they work with intelligent work-stations or main-frame terminals. The data indicates that intracultural differences are apparent according to type of computer used, gender, and hierarchical level of the respondents. What concerned U.S. female respondents about computer-mediated work did not necessarily apply to their Canadian counterparts.     

Aphid alarm pheromone (E)-β-farnesene: A host finding kairomone for the aphid primary parasitoidAphidius uzbekistanicus (Hymenoptera: Aphidiinae)

Summary The present study aimed to test the possible function of the aphid alarm pheromone (E)--farnesene (EBF) as a host finding kairomone for aphid primary parasitoids. Extracts of volatile emissions of undisturbed aphids and of aphids under parasitoid attack were obtained by air entrainment. Extracts of cornicle secretions were gained by disturbing aphids and taking their secretions into solution. Extracts were compared by gas chromatography. Only air entrainments of aphids under attack and solvent extracts of cornicle secretions contained the alarm pheromone. In Y-tube olfactometer bioassays, femaleA. uzbekistanicus were attracted to aphid groups under attack of parasitoids, presumably by released EBF. High concentrations of synthetic EBF (1.4 µg to 5.7 µg) also attractedA. uzbekistanicus females. Females with oviposition experience reacted more readily to lower concentrations of EBF than females without experience. In experiments designed as Petri-dish bioassays, the test animals could contact filter paper discs that were treated with solutions containing EBF. Behavioural effects like antennation or stinging attack were not observed. With computer video analysis of parasitoid movements, some effects onA. uzbekistanicus behaviour were detected, again indicating attraction to EBF.As the volatile aphid alarm pheromone attractedA. uzbekistanicus females, it can be concluded that this chemical stimulus acts as a host finding kairomone for this parasitoid species. However, its effect over long distances seems to be limited due to the relatively high concentrations required for reactions. Of two other parasitoid species examined (P. volucre andL. testaceipes) onlyP. volucre was also significantly attracted to the volatile EBF in the Y-tube olfactometer.     

Interaction of soil pH and phosphorus efficacy: Long-term effects of P fertilizer and lime applications on wheat,barley, and sugar beet

Phosphorus (P), a plant macronutrient, must be adequately supplied for crop growth. In Germany, many soils are high in plant-available P; specifically in arable farming, P fertilizer application has been reduced or even omitted in the last decade. Therefore, it is important to understand how long these soils can support sustainable crop production, and what concentrations of soil P are required for it. We analyzed a 36-year long-term field experiment regarding the effects of different P application and liming rates on plant growth and soil P concentrations with a crop rotation of sugar beet, wheat, and barley. Sugar beet reacted to low soil P and low soil pH levels more sensitively than wheat, which was not significantly affected by the long-term omitted P application. All three crop species showed adequate growth at soil P levels lower than the currently recommended levels, if low soil pH was optimized by liming. The increase in efficacy of soil and fertilizer P by reduced P application rates therefore requires the adaptation of the soil pH to a soil type-specific optimal level.