Lack of angiotensin II conversion to angiotensin III increases water but not alcohol consumption in aminopeptidase A-deficient mice

Elevated central concentrations of the vasopressor octapeptide angiotensin (Ang) II increase the water intake in mammals. Recently, we showed that central AngII is also crucial in alcohol-consuming behavior. Since the heptapeptide AngIII, an AngII metabolite, is discussed to mediate AngII-related effects, we investigated water and alcohol consumption in mice, genetically deficient in aminopeptidase A (APA), a peptidase responsible for AngII conversion to AngIII. Sixteen male APA-deficient mice and their age matched wild-type controls were monitored on their water intake under basal conditions and total fluid and alcohol intake before and after social stress in a two-bottle free-choice paradigm. Alterations were connected to the regulation in activity of Ang-related peptidases (APA, ACE; ACE2) in brain regions involved in alcohol intake and peripheral organs. In comparison to their wild-type controls, APA-deficient mice drank significantly more water but not more alcohol at all investigated time points. A reduction in water intake, as observed in wild-type animals after social stress, did not occur in knockout mice. However, the reduction in alcohol consumption after social stress was significantly reduced in both strains. Alcohol consumption upregulated all three peptidases in the kidney, but not in lung. Notable, renal ACE2 activity was significantly higher in APA-deficient mice under basal condition. While the inhibition of AngII metabolism to AngIII does not influence the alcohol intake, water consumption in mice deficient for APA was significantly elevated. These differences induced by an altered AngII/AngIII ratio oppose the hypothesis that central AngII and AngIII act in a congruent pattern.     

Multiple Environmental Factor Analysis in Habitats of the Harvest Mite Neotrombicula autumnalis (Acari: Trombiculidae) Suggests Extraordinarily High Euryoecious Biology

The harvest mite Neotrombicula autumnalis (Trombiculidae) has become a great nuisance in various vegetated areas in Germany over the last 15 years. According to reports of dermatologists, this species appears to have propagated and spread significantly. Moreover, cases of severe trombidiosis or trombidiosis-like skin reactions have been noticed at unusually early times of the year. Due to the lack of scientific studies, little is known about the ecology of N. autumnalis and its distribution, and preferred habitats cannot be predicted. A four-year study was conducted to identify trombiculid foci in different areas of Bonn in order (1) to determine the timing of larvae appearance in different years, (2) to identify the factors that lead to high larvae abundances at the mite foci (‘multiple factor analysis’), and (3) to develop an ecological control strategy. By means of the ‘tile catch method’ (TCM) which turned out to be most appropriate to collect data on the distribution and abundances of trombiculid mites, larvae of N. autumnalis were caught from mid July until the end of October/beginning of November. The distribution of the mites was patchy, supporting the hypothesis that certain factors cause a concentration in foci. Most of the mite foci had a fixed location for at least three years. Efforts to isolate nymphs and adults in larger quantities to gain knowledge about their preferred soil areas and soil depths failed. Only some nymphs of N. autumnalis could be found living 10–40 cm deep in the soil. Due to the restriction that the nymphs and adults can only rarely be isolated in the ground, the analysis of environmental factors was executed based on abundances of questing larvae on the soil surface. The detailed analysis of soil-physical, soil-chemical and meso-faunistic factors could not finally explain the unequal distribution of the mites, although the porosity of the soil had a statistically significant slight influence on the abundance of larvae, and soil pH bordered significance, also suggesting a slight influence. Furthermore, soil temperatures during the winter seasons in three subsequent years appeared too high to affect the harvest mite. The field experiments suggest that N. autumnalis and particularly its larval stages are extremely euryoecious (meaning tolerating very different environmental conditions). Further studies are necessary: additional investigations on the influence of certain abiotic environmental factors on N. autumnalis, the search for factors underlying the rhythmicity of its life cycle (‘zeitgeber’), and the reasons and mechanisms for heterogeneous distribution of soil fauna in general. Ecological control of the mite is, in principle, possible but only after identifying the foci and ascertaining their approximate dimensions with the TCM. This control strategy is the most promising one, albeit very laborious, emphasising the need of further research on the ecology of the harvest mite.     

Cellular adhesion molecules as targets for bacterial infection

A large number of bacterial pathogens targets cell adhesion molecules to establish an intimate contact with host cells and tissues. Members of the integrin, cadherin and immunoglobulin-related cell adhesion molecule (IgCAM) families are frequently recognized by specific bacterial surface proteins. Binding can trigger bacterial internalization following cytoskeletal rearrangements that are initiated upon receptor clustering. Moreover, signals emanating from the occupied receptors can result in cellular responses such as gene expression events that influence the phenotype of the infected cell. This review will address recent advances in our understanding of bacterial engagement of cellular adhesion molecules by discussing the binding of integrins by Staphylococcus aureus as well as the exploitation of IgCAMs by pathogenic Neisseria species.     

Integration of bimodal looming signals through neuronal coherence in the temporal lobe

The ability to integrate information across multiple sensory systems offers several behavioral advantages, from quicker reaction times and more accurate responses to better detection and more robust learning. At the neural level, multisensory integration requires large-scale interactions between different brain regions--the convergence of information from separate sensory modalities, represented by distinct neuronal populations. The interactions between these neuronal populations must be fast and flexible, so that behaviorally relevant signals belonging to the same object or event can be immediately integrated and integration of unrelated signals can be prevented. Looming signals are a particular class of signals that are behaviorally relevant for animals and that occur in both the auditory and visual domain. These signals indicate the rapid approach of objects and provide highly salient warning cues about impending impact. We show here that multisensory integration of auditory and visual looming signals may be mediated by functional interactions between auditory cortex and the superior temporal sulcus, two areas involved in integrating behaviorally relevant auditory-visual signals. Audiovisual looming signals elicited increased gamma-band coherence between these areas, relative to unimodal or receding-motion signals. This suggests that the neocortex uses fast, flexible intercortical interactions to mediate multisensory integration.     

Crystal structures of human saposins C andD: implications for lipid recognition and membrane interactions

Human saposins are essential proteins required for degradation of sphingolipids and lipid antigen presentation. Despite the conserved structural organization of saposins, their distinct modes of interaction with biological membranes are not fully understood. We describe two crystal structures of human saposin C in an "open" configuration with unusual domain swapped homodimers. This form of SapC dimer supports the "clip-on" model for SapC-induced vesicle fusion. In addition, we present the crystal structure of SapD in two crystal forms. They reveal the monomer-monomer interface for the SapD dimer, which was confirmed in solution by analytical ultracentrifugation. The crystal structure of SapD suggests that side chains of Lys10 and Arg17 are involved in initial association with the preferred anionic biological membranes by forming salt bridges with sulfate or phosphate lipid headgroups.     

Phytoremediation of organic xenobiotics - Glutathione dependent detoxification in Phragmites plants from European treatment sites

Studies on the uptake of several organic xenobiotics and on their subsequent conjugation to biomolecules have been performed to elucidate the use of reed plants in phytoremediation of polluted water. Phragmites australis plants were able to accumulate organic xenobiotics in their rhizomes. The uptake was correlated to the logKOW and pKa of the xenobiotics and highest with compounds exhibiting logKOWs between 1 and 3. Detoxification of xenobiotics was demonstrated when the activity of glutathione S-transferase was determined in plants from various treatment sites. Enzyme activities were strongly dependent on the provenience of the plant and the history of the stand. Detoxification enzymes were also inducible. Naphthylic acetic acid (NAA), 2,4-dichlorophenol and BION were tested as potential inducers. BION was able to induce the GST activity 5-fold, albeit only for a short period of hours. The mechanism of induction and the flexibility of the detoxification system of certain ecotypes of reed toward stress or the pollution level will require further investigation.     

The CIMT-monitoring panel: a two-step approach to harmonize the enumeration of antigen-specific CD8+ T lymphocytes by structural and functional assays

The interpretation of the results obtained from immunomonitoring of clinical trials is a difficult task due to the variety of methods and protocols available to detect vaccine-specific T-cell responses. This heterogeneity as well as the lack of standards has led to significant scepticism towards published results. In February 2005, a working group was therefore founded under the aegis of the Association for Immunotherapy of Cancer ("CIMT") in order to compare techniques and protocols applied for the enumeration of antigen-specific T-cell responses. Here we present the results from two consecutive phases of an international inter-laboratory testing project referred to as the "CIMT monitoring panel". A total of 13 centers from six European countries participated in the study in which pre-tested PBMC samples, synthetic peptides and PE-conjugated HLA-tetramers were prepared centrally and distributed to participants. All were asked to determine the number of antigen-specific T-cells in each sample using tetramer staining and one functional assay. The results of the first testing round revealed that the total number of cells analyzed was the most important determinant for the sensitive detection of antigen-specific CD8(+) T-cells by tetramer staining. Analysis by ELISPOT was influenced by a combination of cell number and a resting phase after thawing of peripheral blood mononuclear cells. Therefore, the experiments were repeated in a second phase but now the participants were asked to change their protocols according to the new guidelines distilled from the results of the first phase. The recommendations improved the number of antigen-specific T-cell responses that were detected and decreased the variability between the laboratories. We conclude that a two-step approach in inter-laboratory testing allows the identification of distinct variables that influence the sensitivity of different T-cell assays and to formally show that a defined correction to the protocols successfully increases the sensitivity and reduces the inter-center variability. Such "two-step" inter-laboratory projects could define rational bases for accepted international guidelines and thereby lead to the harmonization of the techniques used for immune monitoring.