Herbicide effects on planktonic systems of different complexity

Bioassays of different complexity were compared with respect to their capability to predict the environmental impact of the herbicide atrazine in aquatic systems. Acute toxicity tests with Daphnia did not yield meaningful results. Sublethal tests with Daphnia (feeding inhibition, reduction of growth and reproduction) were more sensitive, but effective concentrations of atrazine were still rather high (2 mg/L). A relatively complicated artificial food chain system that incorporated direct and indirect effects on Daphnia yielded significant reduction of daphnid population growth at 0.1 mg/L. Enclosure experiments with natural communities were by far the most sensitive tools. Community responses could be measured at concentrations as low as 1 µg/L and 0.1 µg atrazine/L. At the lowest concentration, however, communities recovered after three weeks. We conclude that in complex systems indirect effects can be more important than direct effects, so that, contrary to the conditions in simple tests, non-target organisms may be the better indicators of herbicide stress to natural communities.     

Afferent and efferent connections of lateral geniculate body pars ventralis in albino rats

The afferent and efferent connections of the Corpus geniculatum laterale, pars ventralis (Cglv) of the albino rat were investigated lightmicroscopically by using either silver degeneration methods and the HRP-method as well. In contrast to the dorsal Cgl the results show remarkably different afferent connections in the ventral Cgl. The afferent fibres originate from the following areas: a) Retina: the terminal degeneration area of optic fibres includes the lateral part of the Cglv only. b) Regio praetectalis: degenerating fibres from these region can also be observed in the medial part of the Cglv. c) Colliculus superior: degenerating fibres terminate mainly in the lateral part of the Cglv. In the superior colliculus these fibres originate particularly from the cells of lamina III. d) Visual cortex: neurons of layer V of area 17 project mainly to the lateral half of the Cglv. There was no evidence for a projecting of the parastriate cortex (area 18 a) to the Cglv. The efferent fibres reach the following target areas: a) Nucleus lateralis posterior, Regio praetectalis and Colliculus superior. Evidence for a projection to the dorsal Cgl requires further investigation. b) Zona incerta, Formatio reticularis mesencephali and Nucleus medialis et lateralis pontis. Neurons in the medial half ot eh Cglv project to the pons region. c) Crossing the Commissura posterior and the Commissura suprachiasmatica, efferent fibres reach the contralateral Cglv, the Regio praetectalis and the Colliculus superior. The results obtained from the rat are compared with findings from other mammalian species. The functional importance of the Cglv in the visual processes is discussed taking into consideration the specific connections.     

Comparison of (R)-[3H] Tomoxetine and (R/S)-[3H] Nisoxetine Binding in Rat Brain

Abstract: ( R )-[³H]Tomoxetine is a radioligand that binds to the norepinephrine (NE) uptake site with high affinity but also binds to a second, lower-affinity site. The goal of the present study was to identify the nature of this low-affinity site by comparing the binding properties of ( R )-[³H]tomoxetine with those of ( R/S )-[³H]nisoxetine, a highly selective ligand for the NE uptake site. In homogenate binding studies, both radioligands bound to the NE uptake site with high affinity, whereas ( R )-[³H]tomoxetine also bound to a second, lower-affinity site. The autoradiographic distribution of binding sites for both radioligands is consistent with the known distribution of NE-containing neurons. However, low levels of ( R )-[³H]-tomoxetine binding were seen in the caudate-putamen, globus pallidus, olfactory tubercle, and zona reticulata of the substantia nigra, where ( R/S )-[³H]nisoxetine binding was almost absent. In homogenates of the caudate-putamen, the NE uptake inhibitors desipramine and ( R )-nisoxetine and the serotonin (5-HT) uptake inhibitor citalopram produced biphasic displacement curves. Autoradiographic studies using 10 n M ( R )-nisoxetine to mask the binding of ( R )-[³H]tomoxetine to the NE uptake site produced autoradiograms that were similar to those produced by [³H]citalopram. Therefore, ( R )-[³H]tomoxetine binds to the NE uptake site with high affinity and the 5-HT uptake site with somewhat lower affinity.     

Metabolomics standards initiative: ontology working group work in progress

In this article we present the activities of the Ontology Working Group (OWG) under the Metabolomics Standards Initiative (MSI) umbrella. Our endeavour aims to synergise the work of several communities, where independent activities are underway to develop terminologies and databases for metabolomics investigations. We have joined forces to rise to the challenges associated with interpreting and integrating experimental process and data across disparate sources (software and databases, private and public). Our focus is to support the activities of the other MSI working groups by developing a common semantic framework to enable metabolomics-user communities to consistently annotate the experimental process and to enable meaningful exchange of datasets. Our work is accessible via a public webpage and a draft ontology has been posted under the Open Biological Ontology umbrella. At the very outset, we have agreed to minimize duplications across omics domains through extensive liaisons with other communities under the OBO Foundry. This is work in progress and we welcome new participants willing to volunteer their time and expertise to this open effort. See the MSI Ontology Working Group website for a complete list of members and contributors. Web URL:     

Identification of a novel integrin alphaMbeta2 binding site in CCN1 (CYR61), a matricellular protein expressed in healing wounds and atherosclerotic lesions

CCN1 (cysteine-rich 61) and CCN2 (connective tissue growth factor) are growth factor-inducible immediate-early gene products found in atherosclerotic lesions, restenosed blood vessels, and healing cutaneous wounds. Both CCN proteins have been shown to support cell adhesion and induce cell migration through interaction with integrin receptors. Recently, we have identified integrin alphaMbeta2 as the major adhesion receptor mediating monocyte adhesion to CCN1 and CCN2 and have shown that the alphaMI domain binds specifically to both proteins. In the present study, we demonstrated that activated monocytes adhered to a synthetic peptide (CCN1-H2, SSVKKYRPKYCGS) derived from a conserved region within the CCN1 C-terminal domain, and this process was blocked by the anti-alphaM monoclonal antibody 2LPM19c. Consistently, a glutathione S-transferase (GST) fusion protein containing the alphaMI domain (GST-alphaMI) bound to immobilized CCN1-H2 as well as to the corresponding H2 sequence in CCN2 (CCN2-H2, TSVKTYRAKFCGV). By contrast, a scrambled CCN1-H2 peptide and an 18-residue peptide derived from an adjacent sequence of CCN1-H2 failed to support monocyte adhesion or alphaMI domain binding. To confirm that the CCN1-H2 sequence within the CCN1 protein mediates alphaMbeta2 interaction, we developed an anti-peptide antibody against CCN1-H2 and showed that it specifically blocked GST-alphaMI binding to intact CCN1. Collectively, these results identify the H2 sequence in CCN1 and CCN2 as a novel integrin alphaMbeta2 binding motif that bears no apparent homology to any alphaMbeta2 binding sequence reported to date.     

Characterization of neuropeptide Y Y1-like and Y2-like receptor subtypes in the mouse brain

To characterize receptor subtypes in the mouse, we performed autoradiographic localization and pharmacological characterization studies using the selective radiolabeled agonists, [(125)I]-Leu(31), Pro(34)-PYY and [(125)I]-PYY 3-36. The pharmacology of [(125)I]-Leu(31), Pro(34)-PYY and [(125)I]-PYY 3-36 binding to mouse brain homogenates were consistent with Y1-like and Y2-like receptors, respectively. Using receptor autoradiography, high Y1-like binding was observed in the islands of Calleja and dentate gyrus. [(125)I]-PYY 3-36 binding was highest in the hippocampus, lateral septum, stria terminalis of the thalamus, and compacta and lateralis of the substantia nigra. In addition, there are differences in receptor distribution in mouse brain compared to other species that may translate into different functional roles for the NPY receptors within each species.     

PET-compatible endothelin receptor radioligands: Synthesis and first in vitro and in vivo studies

The expression and function of endothelin (ET) receptors is abnormal in cardiovascular diseases, tumor progression, and tumor metastasis. In this study, we prepared two [¹⁸F]-fluorinated derivatives of the non-peptide ET_A receptor antagonist PD 156707 and evaluated their ET receptor binding potencies. Ex vivo as well as in vivo biodistribution studies in mice were performed, as well as the metabolism of the radiotracer, which was examined by metabolite analysis in mice and rats. All tested derivatives of PD 156707 exhibited potent in vitro pharmacological characteristics with K_i values comparable to that of the lead compound. The biodistribution studies showed a high accumulation of the tracer in bile and intestine. In vivo we were able to show that the visualization of the heart as a major target organ with high ET_AR expression is possible.     

MALDI-TOF MS of phosphatidylethanolamines: different adducts cause different post source decay (PSD) fragment ion spectra

Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) is increasingly applied to lipids. However, positional acyl chain analysis of lipids by MALDI was so far scarcely described. In this paper, the fragmentation behavior of phosphatidylethanolamine (PE) is investigated by using post-source decay (PSD) MS. In dependence on the investigated adduct, significant differences could be obtained. It will be shown that in particular the negative ion spectra enable the determination of the individual acyl chains as well as their positions (sn-1 or sn-2). Therefore, MALDI-TOF PSD spectra are a real alternative to more sophisticated MS/MS methods.