Characterization of Glutathione S-Transferase Isoforms in Three Maize Inbred Lines Exhibiting Differential Sensitivity to Alachlor

Glutathione S-transferases (GSTs) are a family of isozymes that catalyze the conjugation of glutathione to several xenobiotics, including a number of important herbicides. Several GST isoforms have been identified in maize (Zea mays L.). In this study we focused on three isoforms, GST I, II, and IV, derived from homo-or heterodimerization of two subunits GST-29 and GST-27, which have been shown to be responsible for reactivity to alachlor. The expression of these isoforms was examined in three inbred lines of maize that showed tolerance, susceptibility, and intermediate resistance to alachlor (2-Cl-N-[2,6-diethylphenyl]-N-[methoxymethyl]acetamide) treatment. The different isoforms were separated by anion-exchange chromatography and subunits were quantified by western blot analysis. GST assays were performed against both 1-Cl-2,4-dinitrobenzene and alachlor. This analysis showed that the susceptible and intermediate lines exhibit impaired function in the GST-27 and GST-29 subunits, respectively. In addition, this study suggests that GST IV is the principal, detoxifying enzyme for alachlor, although GST I and II are required to achieve tolerance to high rates of the herbicide.     

Co-expression of vimentin and cytokeratins in M cells of rabbit intestinal lymphoid follicle-associated epithelium

Summary Membranous epithelial (M) cells within the follicle-associated epithelium which overlies gut-associated lymphoid tissue in Peyer's patches and of appendix have been shown by immunocytochemical staining, in rabbit, to contain both vimentin- and cytokeratin-type intermediate filaments. The specificity of vimentin immunostaining has been confirmed by blocking with purified vimentin and by immunoblotting. No evidence was obtained for the expression of vimentin in rat, mouse or human M cells. The possible significance of vimentin-expression in these specialized epithelial cells and the potential use of vimentin as a positive marker for M cells are discussed.     

Giant cells fromSaccharomyces uvarum grown after X-irradiation

Yeast cells, Saccharomyces uvarum, were irradiated with X-rays and grown in liquid suspension. Glucose as the only carbon source was limited to 12.5 mM. Under these conditions giant cells are formed. Cell number, glucose utilization, ethanol production and oxygen consumption are measured during the time of growth. The mean weight of single cells in the stationary phase increases up to 75 krad and is not due to an uptake of water. In irradiated cultures oxygen consumption and glucose utilization per cell are higher than in control cells. The data demonstrate that synthesis- and energy-metabolism during the formation of non-dividing, radiation-induced giant cells is increased.     

A mass stranding of white-sided dolphins (Lagenorhynchus acutus) in Ireland: biological and pathological studies

We give details of the biological and pathological findings in a mass stranding of 19 white-sided dolphins on the west coast of Ireland. The pod consisted of adults and calves; no juveniles were present. The calf of a recently parturient female was not found. The presence of small foetuses suggested that mating took place in late August or early September. The largest and oldest male was severely diseased but the remainder of the pod were in good health although some minor lesions were found. The site where the animals came ashore was compatible with the geomagnetic theory of mass strandings.     

Temporal and spatial changes in aphid and parasitoid populations following applications of deltamethrin in winter wheat

The spatial and temporal effects of the pyrethroid insecticide, deltamethrin, on populations of cereal aphids and their primary parasitoids and hyperparasitoids were investigated in a large scale field experiment in winter wheat. Four hectare plots were treated at the recommended field concentration or a reduced concentration representing one twentieth of field rate. A control plot was left unsprayed. Invertebrate populations were sampled at sites within a grid layout covering the whole plots, enabling the use of geostatistical analysis. Hymenopteran populations were monitored using transparent sticky traps and suction sampling. Aphid populations were recorded by visual counts. Monitoring continued for 36 days after treatment. The full rate deltamethrin treatment resulted in initial reductions of aphid populations by 78%. Primary parasitoid and hyperparasitoid populations were reduced in suction samples by 90% and 47% respectively, when corrected for control fluctuations. The reduced deltamethrin concentration caused reductions of aphid, primary parasitoid and hyperparasitoid populations of 40, 60 and 54% respectively. Aphid population recovery over the full rate plot occurred slowly and in a patchy manner following treatment. No significant reinvasion gradients were detected. Aphid population density recovered more rapidly in the reduced rate treatment; with initial evidence for increased densities at the plot centre. Significant patterns of reinvasion were initially detected for both groups of Hymenoptera in the full rate treatment, suggesting that reinvasion of the sprayed area was taking place from untreated surrounding reservoirs. It was concluded that experiments that examine pesticide impacts within small plots will lead to underestimates of effects on dispersive groups including parasitic Hymenoptera.     

Automatic morphometric analysis of retrograde changes in the nucleus n. facialis at different ontogenetic stages in the rat

Summary The grey level index (= GLI) and the fresh volume were determined with the image analyser Micro-Videomat for the nucl. n. facialis after axotomy of the left n. facialis. The experiments were performed on 10 rats in different stages of ontogenesis. The GLI is a quantitative parameter which could be quickly obtained and which demonstrated quantitative changes during retrograde reaction in the respective centres. A decrease in the fresh volumes of the affected nucl. n. facialis could also be demonstrated. The meaning of GLI is discussed.Supported by Deutsche Forschungsgemeinschaft grants Kr 289/10 and Zi 192/1Dedicated to Prof. Dr. H. Leonhardt on the occasion of his 60th birthday     

Targeting of an enteropathogenic Escherichia coli (EPEC) effector protein to host mitochondria

Many Gram-negative pathogens use a type III secretion apparatus to deliver effector molecules into host cells to subvert cellular processes in favour of the pathogen. Enteropathogenic Escherichia coli (EPEC) uses such a system to deliver the Tir effector molecule into host cells. In this paper, we show that the gene upstream of tir , orf 19, encodes an additional type III secreted effector protein. Orf19 is delivered into host cells by a mechanism independent of endocytosis, but dependent on EspB. Orf19 is targeted to host mitochondria, where it appears to interfere with the ability to maintain membrane potential. Although the precise role of Orf19 remains to be elucidated, its interaction with mitochondria suggests a possible role in the subversion of key functions of these organelles, such as energy production or control of cell death. This is the first example of a type III secreted protein targeted to mitochondria; it is probable that homologues (present in EPEC and Shigella species) and other bacterial effectors will also target this organelle.     

Hoverfly oviposition response to aphids in broccoli fields

The oviposition response of predacious hoverflies (Diptera: Syrphidae) to Brevicoryne brassicae L. and Myzus persicae (Sulzer) (Homoptera: Aphididae) in commercial broccoli, Brassica oleracea var. italica L., Plenck (Brassicaceae), fields was investigated at two sites over the course of a growing season. The hoverfly oviposition responses to these aphid species on different parts of the broccoli plant canopy were also examined. There were no hoverfly eggs on broccoli plants without aphids, egg numbers were very low on plants with fewer than 50 aphids, and no peak in oviposition relative to aphid numbers was observed. Within individual plants that were colonized by aphids, there was some oviposition on individual leaves without aphids, and no hoverfly eggs were seen on leaves that had more than 400 aphids. Leaves in the broccoli plant canopy, and the datasets associated with them, were divided into three sections vertically, ‘upper’, ‘middle’, and ‘lower’. Brevicoryne brassicae was more abundant in the upper and middle canopy sections, while M. persicae was found mostly in the lower section. The rate of hoverfly oviposition per aphid was higher in the upper section than in the two other sections. Modeling of the oviposition response using logistic regression showed that the presence of hoverfly eggs was positively correlated with numbers of each aphid species and sampling date.