Fetal akinesia/hypokinesia sequence: Prenatal diagnosis and intra-familial variability

Intrauterine fetal movement plays a key role in normal embryonic and fetal development (Moessinger, 1983). When movement is absent or decreased, abnormal development takes place which can be appreciated in newborns and/or fetuses with the fetal akinesia/ hypokinesia sequence. This sequence is caused by a number of heterogeneous entities which result in decreased fetal movements by the action of intrinsic or extrinsic factors. Prenatal diagnosis of the akinesia/hypokinesia sequence may be possible during the second trimester through the use of real-time ultrasonographic evaluation of fetal movement. We report a family with three consecutive affected pregnancies in which the prenatal presentation of this sequence varied. Based on the phenotypic findings of the three affected fetuses, we believe that although they superficially resemble those features found in the New–Laxova syndrome, they are probably affected with a distinctly different lethal form of akinesia/ hypokinesia transmitted in an autosomal recessive fashion.     

Memory dynamics and foraging strategies of honeybees

Summary The foraging behavior of a single bee in a patch of four electronic flower dummies (feeders) was studied with the aim of analyzing the informational components in the choice process. In different experimental combinations of reward rates, color marks, odors and distances of the feeders, the behavior of the test bee was monitored by a computer in real time by several devices installed in each feeder. The test bee optimizes by partially matching its choice behavior to the reward rates of the feeders. The matching behavior differs strongly between stay flights (the bee chooses the feeder just visited) and shift flights (the bee chooses one of the three alternative feeders). The probability of stay and shift flights depends on the reward sequence and on the time interval between successive visits. Since functions describing the rising probability of stay flights with rising amounts of sucrose solution just experienced differ for the four feeders, it is concluded that bees develop feeder-specific memories. The choice profiles of shift flights between the three alternative feeders depend on the mean reward rate of the feeder last visited. Good matching is found after visits to the low-reward feeders and poor matching following departure from the high-reward feeders. These results indicate that bees use two different kinds of memories to guide their choice behavior: a transient short-term working memory that is not feeder-specific, and a feeder-specific long-term reference memory. Model calculations were carried out to test this hypothesis. The model was based on a learning rule (the difference rule) developed by Rescorla and Wagner (1972), which was extended to the two forms of memories to predict this operant behavior. The experiments show that a foraging honeybee learns the properties of a food source (its signals and rewards) so effectively that specific expectations guide the choice behavior. Correspondence to: R. Menzel     

Factors affecting heavy-duty diesel vehicle emissions

Societal and governmental pressures to reduce diesel exhaust emissions are reflected in the existing and projected future heavy-duty certification standards of these emissions. Various factors affect the amount of emissions produced by a heterogeneous charge diesel engine in any given situation, but these are poorly quantified in the existing literature. The parameters that most heavily affect the emissions from compression ignition engine-powered vehicles include vehicle class and weight, driving cycle, vehicle vocation, fuel type, engine exhaust aftertreatment, vehicle age, and the terrain traveled. In addition, engine control effects (such as injection timing strategies) on measured emissions can be significant. Knowing the effect of each aspect of engine and vehicle operation on the emissions from diesel engines is useful in determining methods for reducing these emissions and in assessing the need for improvement in inventory models. The effects of each of these aspects have been quantified in this paper to provide an estimate of the impact each one has on the emissions of diesel engines.     

An air quality data analysis system for interrelating effects, standards, and needed source reductions: Part 13--Applying the EPA Proposed Guidelines for Carcinogen Risk Assessment to a set of asbestos lung cancer mortality data

The Clean Air Act Amendments of 1990 (CAAA-90) list 189 hazardous air pollutants (HAPs) for which "safe" ambient concentrations are to be determined. The primary purpose of this paper is to develop two mathematical models, lognormal and logarithmic, that effectively express excess lung cancer mortality as a function of asbestos concentration for an example set of data and also to suggest using these two models for additional HAPs. The secondary purpose of this paper is to calculate a "safe" asbestos concentration by first assuming a default linear extrapolation (to one excess death per million people, as specified for carcinogenic HAPs). The resulting "safe" concentration is an impossible-to-achieve 1/1000 of present background asbestos concentrations. A letter to the editor and a response in this Journal issue use additional asbestos data that suggest that the "safe" concentration should be about 730 times higher than first calculated here and that a default nonlinear extrapolation should be used instead, with the "safe" concentration proportional to the desired mortality level raised to the 0.39 power. These results suggest that the most important problem in setting a "safe" concentration for each carcinogenic HAP is to determine the correct nonlinear extrapolation to use for each HAP.     

Expression profiling of five different xenobiotics using a Caenorhabditis elegans whole genome microarray

The soil nematode Caenorhabditis elegans is frequently used in ecotoxicological studies due to its wide distribution in terrestrial habitats, its easy handling in the laboratory, and its sensitivity against different kinds of stress. Since its genome has been completely sequenced, more and more studies are investigating the functional relation of gene expression and phenotypic response. For these reasons C. elegans seems to be an attractive animal for the development of a new, genome based, ecotoxicological test system. In recent years, the DNA array technique has been established as a powerful tool to obtain distinct gene expression patterns in response to different experimental conditions. Using a C. elegans whole genome DNA microarray in this study, the effects of five different xenobiotics on the gene expression of the nematode were investigated. The exposure time for the following five applied compounds beta-NF (5 mg/l), Fla (0.5 mg/l), atrazine (25 mg/l), clofibrate (10 mg/l) and DES (0.5 mg/l) was 48+/-5 h. The analysis of the data showed a clear induction of 203 genes belonging to different families like the cytochromes P450, UDP-glucoronosyltransferases (UDPGT), glutathione S-transferases (GST), carboxylesterases, collagenes, C-type lectins and others. Under the applied conditions, fluoranthene was able to induce most of the induceable genes, followed by clofibrate, atrazine, beta-naphthoflavone and diethylstilbestrol. A decreased expression could be shown for 153 genes with atrazine having the strongest effect followed by fluoranthene, diethylstilbestrol, beta-naphthoflavone and clofibrate. For upregulated genes a change ranging from approximately 2.1- till 42.3-fold and for downregulated genes from approximately 2.1 till 6.6-fold of gene expression could be affected through the applied xenobiotics. The results confirm the applicability of the gene expression for the development of an ecotoxicological test system. Compared to classical tests the main advantages of this new approach will be the increased sensitivity and it's potential for a substance class specific effect determination as well as the large numbers of genes that can be screened rapidly at the same time and the selection of well regulated marker genes to study more in detail.     

Synthesis of branched para-nonylphenol isomers: occurrence and quantification in two commercial mixtures

Eight tertiary nonanols were synthesized via Grignard reaction and coupled by Friedel–Crafts alkylation with phenol to the corresponding nonylphenols. Six branched para-nonylphenols (NP) were obtained: 4-(3′-methyl-3′-octyl)phenol (33NP), 4-(2′-methyl-2′-octyl)phenol (22NP), 4-(2′,5′-dimethyl-2′-heptyl)phenol (252NP), 4-(2′,5′,5′-trimethyl-2′-hexyl)phenol (2552NP), 4-(2′,4′-dimethyl-2′-heptyl)phenol (242NP) and 4-(4′-ethyl-2′-methyl-2′-hexyl)phenol (4E22NP). Their structures were confirmed by GC–MS and NMR spectroscopy. These six isomers as well as the earlier synthesized 4-(3′,5′-dimethyl-3′-heptyl)phenol (353NP), 4-(3′,6′-dimethyl-3′-heptyl)phenol (363NP) and 4-(2′,6′-dimethyl-2′-heptyl)phenol (262NP) were compared with commercial NP mixtures purchased from Acros and Fluka by GC–MS (equipped with a 100 m polysiloxane column). The analyses revealed that all obtained isomers are occurring in different quantities in both commercial NP mixtures.     

Nutzung der induzierbaren Genexpression des NematodenCaenorhabditis elegans als Biomonitor

The soil nematodeCaenorhabditis elegans is one of the simplest animals having the status of a laboratory model. Its already completely sequenced genome contains the remarkable number of 80 cytochrome P450 genes (CYP) and many further genes coding for enzymes involved in biotransformation. In order to study xenobiotically induced gene expression inC. elegans, liquid cultures were exposed to different, well-known xenobiotic inducers. The mRNA expression was detected by two different types of DNA arrays and semi-quantitative RT-PCR. β-naphthoflavone, PCB52 and lansoprazol were the most active and, in particular, induced almost all CYP35 isoforms strongly. In conclusion, the xenobiotic dependent gene expression ofC. elegans is a useful tool to reveal defense mechanisms against potential damaging substances as well as for developing a biomonitoring system.     

Comparative accumulation of (109)Cd and (75)Se from water and food by an estuarine fish (Tetractenos glaber)

Few data are available on the comparative accumulation of metal(loid)s from water and food in estuarine/marine fish. Smooth toadfish (Tetractenos glaber), commonly found in estuaries in south-eastern Australia, were separately exposed to radio-labelled seawater (14kBqL(-1) of (109)Cd and 24kBqL(-1) of (75)Se) and food (ghost shrimps; Trypaea australiensis: 875Bqg(-1)(109)Cd and 1130Bqg(-1)(75)Se) for 25 days (uptake phase), followed by exposure to radionuclide-free water or food for 30 days (loss phase). Toadfish accumulated (109)Cd predominantly from water (85%) and (75)Se predominantly from food (62%), although the latter was lower than expected. For both the water and food exposures, (109)Cd was predominantly located in the gut lining (60-75%) at the end of the uptake phase, suggesting that the gut may be the primary pathway of (109)Cd uptake. This may be attributed to toadfish drinking large volumes of water to maintain osmoregulation. By the end of the loss phase, (109)Cd had predominantly shifted to the excretory organs - the liver (81%) in toadfish exposed to radio-labelled food, and in the liver, gills and kidney (82%) of toadfish exposed to radio-labelled water. In contrast, (75)Se was predominantly located in the excretory organs (gills, kidneys and liver; 66-76%) at the end of the uptake phase, irrespective of the exposure pathway, with minimal change in percentage distribution (76-83%) after the loss phase. This study emphasises the importance of differentiating accumulation pathways to better understand metal(loid) transfer dynamics and subsequent toxicity, in aquatic biota.     

Isolation by distance in the scleractinian coral <Emphasis Type="Italic">Seriatopora hystrix</Emphasis> from the Red Sea

Pelagic dispersal of larvae in sessile marine invertebrates could in principle lead to a homogeneous gene pool over vast distances, yet there is increasing evidence of surprisingly high levels of genetic differentiation on small spatial scale. To evaluate whether larval dispersal is spatially limited and correlated with distance, we conducted a study on the widely distributed, viviparous reef coral Seriatopora hystrix from the Red Sea where we investigated ten populations separated between ~0.150 km and ~610 km. We addressed these questions with newly developed, highly variable microsatellite markers. We detected moderate genetic differentiation among populations based on both F _ST and R _ST (0.089 vs. 0.136, respectively) as well as considerable heterozygote deficits. Mantel tests revealed isolation by distance effects on a small geographic scale (≤20 km), indicating limited dispersal of larvae. Our data did not reveal any evidence against strictly sexual reproduction among the studied populations.     

Preliminary evaluation of the Community Multiscale Air Quality model for 2002 over the Southeastern United States

The Visibility Improvement State and Tribal Association of the Southeast (VISTAS) is one of five Regional Planning Organizations that is charged with the management of haze, visibility, and other regional air quality issues in the United States. The VISTAS Phase I work effort modeled three episodes (January 2002, July 1999, and July 2001) to identify the optimal model configuration(s) to be used for the 2002 annual modeling in Phase II. Using model configurations recommended in the Phase I analysis, 2002 annual meteorological (Mesoscale Meterological Model [MM5]), emissions (Sparse Matrix Operator Kernal Emissions [SMOKE]), and air quality (Community Multiscale Air Quality [CMAQ]) simulations were performed on a 36-km grid covering the continental United States and a 12-km grid covering the Eastern United States. Model estimates were then compared against observations. This paper presents the results of the preliminary CMAQ model performance evaluation for the initial 2002 annual base case simulation. Model performance is presented for the Eastern United States using speciated fine particle concentration and wet deposition measurements from several monitoring networks. Initial results indicate fairly good performance for sulfate with fractional bias values generally within +/-20%. Nitrate is overestimated in the winter by approximately +50% and underestimated in the summer by more than -100%. Organic carbon exhibits a large summer underestimation bias of approximately -100% with much improved performance seen in the winter with a bias near zero. Performance for elemental carbon is reasonable with fractional bias values within +/- 40%. Other fine particulate (soil) and coarse particular matter exhibit large (80-150%) overestimation in the winter but improved performance in the summer. The preliminary 2002 CMAQ runs identified several areas of enhancements to improve model performance, including revised temporal allocation factors for ammonia emissions to improve nitrate performance and addressing missing processes in the secondary organic aerosol module to improve OC performance.