Musterbildung bei Drosophila

Drosophila proved an excellent system to study molecular processes in establishing the body pattern of an embryo. Genes which are active during oogenesis provide localized cues which regulate a cascade of zygotic genes that determines the developmental fate of the blastoderm cells along the longitudinal axis of the embryo.     

Amniotic fluid digestive enzymes: Diagnostic value in fetal gastrointestinal obstructions

The diagnostic value of amniotic fluid gamma-glutamyl-transpeptidase (GGTP) and intestinal alkaline phos-phatase (iALP) was evaluated in 55 patients who underwent amniocentesis for karyotyping because fetal gastric or small bowel dilatation had been detected by ultrasound. Gastrointestinal malformation was confirmed in 46 cases and there was no gastrointestinal anomaly in nine cases. Prenatal ultrasound was suggestive of gastroduodenal dilatation in 34 cases (group I) and small bowel dilatation in 21 cases (group II). In group I, amniotic fluid GGTP above the 99th percentile was 71 per cent sensitive and 100 per cent specific for a true anatomical defect of the digestive tract (mainly duodenal atresia). In group II, high levels of GGTP and/or iALP were 69 per cent sensitive and 83 per cent specific for a fetal digestive tract anomaly. In other words, when digestive tract dilatations were diagnosed by prenatal sonography, abnormal amniotic fluid enzyme activities were strongly suggestive of such an anomaly, the possibility of which was not precluded by normal amniotic fluid iALP and GGTP activities. But amniotic fluid digestive enzyme activities do not help in defining the prognosis.     

Characteristics of feeding on dinoflagellates by newly hatched larval crabs

The zoeal larvae of brachyuran crabs must feed soon after hatching on a diet that includes large micro- and mesozooplankton in order to satisfy nutritional requirements. However, newly hatched larvae have been shown to ingest a variety of dinoflagellates, perhaps using microbial carbon sources to sustain them until they encounter more favored prey. Ingestion of dinoflagellates by larval crabs has been documented previously under conditions in which the larvae were exposed to algae provided in monoculture or in defined mixtures of cells. We report here on experiments conducted on the hatching stage of five crab species to determine if ingestion of dinoflagellates occurred when they were provided in combination with Artemia sp. nauplii or after a period of feeding on mesozooplankton. Quantitative measurements of chl a in the larval guts provided evidence of ingestion of algal cells. Active ingestion of the dinoflagellate Prorocentrum micans at specified intervals during an extended feeding period was determined on larvae of two crab species using fluorescently labeled cells provided for brief periods at prescribed time intervals. Stage 1 larvae of four of the five crab species ingested dinoflagellates when they were provided in combination with nauplii and larvae of all five species ingested cells after feeding solely on nauplii for 24 h. Ingestion of algal cells was first evident in the larval guts after 6 h of feeding at both low (200 cell ml⁻¹) and high (1,000 cells ml⁻¹) prey densities. Higher prey densities resulted in higher gut chl a. Larvae continuously exposed to dinoflagellates actively ingested cells at every 3 h interval tested over a 36 h period. Results confirm previous studies that larvae will ingest dinoflagellates even when they are encountered in a mixed prey field or when having previously fed. Ingestion of cells may occur on a continual basis over time.     

Biologische Detektionsverfahren in der Dünnschichtchromatographie

The goal of this work is to make ecotoxicologically-relevant substance bands visible on thin-layer chromatographic plates. Bacteria (Bacillus subtilis, Vibrio fischeri, Salmonella typhimurium), fungi (Aspergillus niger), algi (Pseudokirchneriella subcapitata) and pollen (Impatiens walleriana) were used as test organisms. With the aid of these organisms, it has been possible to identify bactericide, fungicide, algicide, phytotoxic and genotoxic bands.     

Not Only Single Mating in Stingless Bees

Queens of the large, pantropical and fully eusocial taxon Meliponinae (stingless bees) are generally considered to be singly mated. We indirectly estimated queen mating frequency in two meliponids, Melipona beecheii and Scaptotrigona postica, by examining genotypes of workers at microsatellite DNA loci. Microsatellites were highly variable, providing suitable markers with which to assign patrilinial origin of workers within colonies headed by single queens. Queen mating frequency varied between 1 and 3 (M. beecheii) and 1 and 6 (S. postica), representing the first clear documentation of polyandry in the Meliponinae. Effective paternity frequency, m _e , was lower, although above 2 for S. postica. Stingless bees may provide suitable subjects for the testing of recent inclusive fitness arguments describing intracolony kin conflict in social Hymenoptera. Received: 26 August 1998 / Accepted in revised form: 18 November 1998     

Ozone and grosswetterlagen

Meteorological conditions have a decisive impact on surface ozone concentrations. In this study, an empirical model is used to explain the interdependence of ozone and grosswetterlagen. Different meteorological parameters such as air temperature, global solar radiation, relative humidity, wind direction and wind speed are used. Additional nitric oxide (NO) was taken as a representative for the emission situation and ozone maximum of the preceding day in order to evaluate the development of the photochemical situation. The dataset includes data collected over a period of three years (1992–1994) from three stations outside of Munich and one in the center of Munich. All values become variables by calculating means, sums or maxima of the basic dataset consisting of half-hour means. Seasonal periodicity of data is detected with Fourier analysis and eliminated by a division method after computing a seasonal index. The dataset is divided into three different grosswetterlagen groups, depending on main wind direction. One mostly cyclonic (westerly winds), one mixed (alternating winds) and one only anticyclonic (easterly winds). The last is completed with one summertime group including values from April to August. Factor analysis is performed for each group to obtain independent linear variable combinations. Overall, relative humidity is the dominant parameter, a typical value indicating meteorological conditions during a grosswetterlage. Linear multiple regression analysis is performed using the factors obtained to reveal how the ozone concentrations are explained in terms of meteorological parameters and NO. The results improve from cyclonic to anticyclonic grosswetterlagen in conformance with the increasing significance of photochemistry, indicated by the high solar radiation and high temperature, and the low relative humidity and low wind speed. The explained variance r² reaches its maximum with more than 50 % of the time in Munich center. This empirical model is applicable to the forecasting of local ozone maximum concentrations with a total standard error deviation of 8.5 to 12.8 % and, if ozone concentrations exceed 80 ppb, with a standard error deviation of 5.4 to 9.5 %.     

Isolation, characterization and diuron transformation capacities of a bacterial strain Arthrobacter sp. N2

A bacterial strain able to transform diuron was isolated from a soil by enrichment procedures. Strain isolation was realized by plating on minimal-agarose medium spread with this herbicide and selecting the colonies surrounded by a clear thin halo. One strain was characterized and identified as an Arthrobacter sp. It metabolized diuron and the final transformation product, 3,4-dichloroaniline, was produced in stoichiometric amounts. The transformation of diuron at different concentrations was more efficient in the presence of alternative sources of carbon and nitrogen. The bacterial activity was also evaluated in soil microcosms with a consequent disappearance of diuron and concomitant appearance of 3,4-dichloroaniline, of which the concentration decreased thereafter. Bacterial cells inoculated in the microcosms survived as viable but eventually nonculturable cells.     

Ozone and grosswetterlagen

Meteorological conditions have a decisive impact on surface ozone concentrations. In this study, an empirical model is used to explain the interdependence of ozone and grosswetterlagen. Different meteorological parameters such as air temperature, global solar radiation, relative humidity, wind direction and wind speed are used. Additional nitric oxide (NO) was taken as a representative for the emission situation and ozone maximum of the preceding day in order to evaluate the development of the photochemical situation. The dataset includes data collected over a period of three years (1992–1994) from three stations outside of Munich and one in the center of Munich. All values become variables by calculating means, sums or maxima of the basic dataset consisting of half-hour means. Seasonal periodicity of data is detected with Fourier analysis and eliminated by a division method after computing a seasonal index. The dataset is divided into three different grosswetterlagen groups, depending on main wind direction. One mostly cyclonic (westerly winds), onemixed (alternating winds) and one onlyanticyclonic (easterly winds). The last is completed with one summertime group including values from April to August. Factor analysis is performed for each group to obtain independent linear variable combinations. Overall, relative humidity is the dominant parameter, a typical value indicating meteorological conditions during a grosswetterlage. Linear multiple regression analysis is performed using the factors obtained to reveal how the ozone concentrations are explained in terms of meteorological parameters and NO. The results improve from cyclonic to anticyclonic grosswetterlagen in conformance with the increasing significance of photochemistry, indicated by the high solar radiation and high temperature, and the low relative humidity and low wind speed. The explained variance r² reaches its maximum with more than 50 % of the time in Munich center. This empirical model is applicable to the forecasting of local ozone maximum concentrations with a total standard error deviation of 8.5 to 12.8 % and, if ozone concentrations exceed 80 ppb, with a standard error deviation of 5.4 to 9.5 %.     

Prenatal overgrowth and mosaic trisomy 15q25-qter including the IGF1 receptor gene

Overgrowth is rarely associated with chromosomal imbalances. Here, we report on a male foetus presenting with overgrowth and additional material on the short arm of one of the chromosome 15 in 12% of lymphocytes and 50% of amniotic cells. Parents' karyotypes were normal, indicating a de novo origin for this unbalanced rearrangement. Complementary studies using cytogenetic and FISH studies showed that this additional material resulted in a 15q25-qter trisomy and confirmed the presence of three copies of the insulin-like growth factor 1 receptor (IGF1R) gene, included in the trisomic region. Autopsy performed after termination of pregnancy revealed isolated overgrowth and absence of visceral malformations. The possible mechanisms and origins for the formation of this mosaic pure trisomy are complex. The present observation emphasises the hypothesis that the overgrowth phenotype, frequently reported in patients with trisomy including the 15q26 region, might be causally related to a dosage effect of the IGF1R gene, as well as the importance of chromosome analysis in patients with overgrowth. It also confirms that the overgrowth is of prenatal onset in those observations. Copyright © 2004 John Wiley & Sons, Ltd.