Electron microscopic observations on isolated mitochondrial membranes,prepared by various histological methods

Summary The pictures of isolated mitochondrial membranes, as seen on the electron-microscope, depend very much on the method of specimen preparation. Subunits of linear dimensions of about 25 m, (electron transport particles) are observed in carbon-replicas of the membranes and in specimens treated with trypsin or pepsin (0.02% for 30 mins) and shadowed with platinum. A three-layered structure of the unit membrane is seen in sections of specimens fixed with osmium tetroxide or formalin followed by post-fixation with osmium tetroxide. But fixation with potassium permanganate or with formalin, followed by post-fixation with potassium permanganate reveals an electron-dense globular structural element in the unit membrane. An electron-transparent ultrastructural element of the unit membrane is observed after treatment with trypsin (0.2% for 5 mins) and fixation with osmium tetroxide. Unsectioned specimens treated with 0.02% trypsin for 30 mins show a honeycomb-like structure of the membrane. Thus, part of the results appear to support the concept of a mosaic-like structure of the unit membrane, whereas other results are in agreement with the classical concept of a three-layered structure.The authors wish to express their gratitude to Dr. Sina Rosenthal, Department of Physiological Chemistry, Humboldt University, Berlin, who prepared the isolated membranes, to Mr. E. Fischer, Head Technician of the Department of Electron Microscopy, Greifswald University, who took most of the electron micrographs, to Mr. G. Bartsch, Department of Electron Microscopy, Greifswald University, and especially to Prof. W. Bargmann and to Doz. E. Lindner, Department of Anatomy, Kiel University, for many valuable suggestions.     

A high-throughput chemically induced inflammation assay in zebrafish

Background  

Studies on innate immunity have benefited from the introduction of zebrafish as a model system. Transgenic fish expressing fluorescent proteins in leukocyte populations allow direct, quantitative visualization of an inflammatory response in vivo. It has been proposed that this animal model can be used for high-throughput screens aimed at the identification of novel immunomodulatory lead compounds. However, current assays require invasive manipulation of fish individually, thus preventing high-content screening.     

Residential Selection across the Life Course: Adolescent Contextual and Individual Determinants of Neighborhood Disadvantage in Mid-Adulthood

Background

Numerous cross-sectional studies have examined neighborhood effects on health. Residential selection in adulthood has been stressed as an important cause of selection bias but has received little empirical attention, particularly its determinants from the earlier life course. The present study aims to examine whether neighborhood, family, school, health behaviors and health in adolescence are related to socioeconomic disadvantage of one''s neighborhood of residence in adulthood.

Methods

Based on the prospective Northern Swedish Cohort (analytical N = 971, 90.6% retention rate), information was collected at age 16 years concerning family circumstances, school adjustment, health behaviors and mental and physical health. Neighborhood register data was linked to the cohort and used to operationalize aggregated measures of neighborhood disadvantage (ND) at age 16 and 42. Data was analyzed with linear mixed models, with ND in adulthood regressed on adolescent predictors and neighborhood of residence in adolescence as the level-2 unit.

Results

Neighborhood disadvantage in adulthood was clustered by neighborhood of residence in adolescence (ICC = 8.6%). The clustering was completely explained by ND in adolescence. Of the adolescent predictors, ND (b = .14 (95% credible interval = .07–.22)), final school marks (b = −.18 (−.26–−.10)), socioeconomic disadvantage (b = .07 (.01–.14)), and, with borderline significance, school peer problems (b = .07 (−.00–.13)), were independently related to adulthood ND in the final adjusted model. In sex-stratified analyses, the most important predictors were school marks (b = −.21 (−.32–−.09)) in women, and neighborhood of residence (ICC = 15.5%) and ND (b = .20 (.09–.31)) in men.

Conclusions

These findings show that factors from adolescence – which also may impact on adult health – could influence the neighborhood context in which one will live in adulthood. This indicates that residential selection bias in neighborhood effects on health research may have its sources in early life.     

Immune regulation of protease-activated receptor-1 expression in murine small intestine during Nippostrongylus brasiliensis infection

Infection with gastrointestinal nematodes exerts profound effects on both immune and physiological responses of the host. Helminth infection induces a hypercontractility of intestinal smooth muscle that is dependent on the Th2 cytokines, IL-4 and IL-13, and may contribute to worm expulsion. Protease-activated receptors (PARs) are expressed throughout the gut, and activation of PAR-1 was observed in asthma, a Th2-driven pathology. In the current study we investigated the physiologic and immunologic regulation of PAR-1 in the murine small intestine, specifically 1) the effect of PAR-1 agonists on small intestinal smooth muscle contractility, 2) the effects of Nippostrongylus brasiliensis infection on PAR-1 responses, 3) the roles of IL-13 and IL-4 in N. brasiliensis infection-induced alterations in PAR-1 responses, and 4) the STAT6 dependence of these responses. We demonstrate that PAR-1 activation induces contraction of murine intestinal smooth muscle that is enhanced during helminth infection. This hypercontractility is associated with an elevated expression of PAR-1 mRNA and protein. N. brasiliensis-induced changes in PAR-1 function and expression were seen in IL-4-deficient mice, but not in IL-13- or STAT6-deficient mice, indicating the dependence of IL-13 on the STAT6 signaling pathway independent of IL-4.     

Association between CSN3 and BCO2 gene polymorphisms and milk performance traits in the Czech Fleckvieh cattle breed

Daily milk, fat and protein yield and amount of somatic cells in cow milk are very important factors that influence milk performance traits. An association between polymorphisms in the kappa casein (CSN3) gene and milk production, composition and technical properties has been previously reported; however, this type of information is not available for the bovine β-carotene oxygenase 2 (BCO2) gene--the BCO2 gene has relationship with milk color and meat fat color, which is dependent on content of β-carotene. We analyzed these two genes and their relationship with milk performance traits (daily milk, fat and protein yield, somatic cell count, SCC) in one cattle population, Czech Fleckvieh (N = 152). All animals were milked twice a day and kept in the same environmental conditions. The Fleckvieh is a typical Czech cattle breed farming for milk and meat production. It is the most common breed in the Czech Republic. DNA was isolated from milk or from hairs. Genes were analyzed using PCR-RFLP, frequencies of alleles and genotypes were calculated and association analysis was performed using a GLM Procedure in SAS. Statistical analysis established that the CSN3 gene has no statistically significant influence on daily milk, fat and protein yield and SCC. Compared to other references this result can be explained by, e.g., small group of animals and different cattle breed. The BCO2 gene (genotypes AA and AG) shows a statistically significant relationship (P = 0.05) with daily milk, protein yield and SCC.     

Increased openness around retained oaks increases species richness of saproxylic beetles

The decrease of old deciduous trees in northern Europe is a threat to the saproxylic fauna. In northern Europe, oak sustains the highest richness of saproxylic invertebrates, among which beetles is a large group. In order to preserve species associated with old trees, it has become common practice in commercial forestry to retain such trees at final felling. However, to create beneficial conditions for species associated with retained trees, the surrounding plantation has to be managed with regard to their specific demands. In the case of oak-associated species, including many red-listed species, several studies have shown that light is an important factor. The aim of this study was to analyze the effects of increased openness around oaks (Quercus robur) in spruce plantations (Picea abies) on species richness and abundance of oak-associated saproxylic beetles. The study was performed in nine spruce plantations located in southern Sweden, with mature oaks standing in a gradient of canopy openness. Beetles were collected from 54 oaks from May to September during two seasons, using window traps. The analyses revealed that increased openness around oaks increases species richness and abundance of oak-associated beetles. By including insolation angle in the analysis, we found that it is mainly the degree of openness directed south from the oak that has positive effects on beetle richness. These findings imply that it is desirable to maintain an open area around retained oaks, and that this area should be placed on the southern side of the oak to maximize the biodiversity benefit in relation to costs for the forest owner.     

Dynamic connectivity in the mitral cell-granule cell microcircuit

The interactions between excitatory mitral cells and inhibitory granule cells are critical for the regulation of olfactory bulb activity. Here we review anatomical and physiological data on the mitral cell-granule cell circuit and provide a quantitative estimate of how this connectivity varies as a function of distance between mitral cells. We also discuss the ways in which the functional connectivity can be altered rapidly during olfactory bulb activity.     

Evidence for dimerization of dimers in K+ channel assembly

Voltage-gated K+ channels are tetrameric, but how the four subunits assemble is not known. We analyzed inactivation kinetics and peak current levels elicited for a variety of wild-type and mutant Kv1.3 subunits, expressed singly, in combination, and as tandem constructs, to show that 1) the dominant pathway involves a dimerization of dimers, and 2) dimer-dimer interaction may involve interaction sites that differ from those involved in monomer-monomer association. Moreover, using nondenaturing gel electrophoresis, we detected dimers and tetramers, but not trimers, in the translation reaction of Kv1.3 monomers.