Survey of <Emphasis Type="Italic">Alternaria</Emphasis> toxin contamination in food from the German market,using a rapid HPLC-MS/MS approach

A HPLC-MS/MS-based method for the quantification of nine mycotoxins produced by fungi of the genus Alternaria in various food matrices was developed. The method relies on a single-step extraction, followed by dilution of the raw extract and direct analysis. In combination with an analysis time per sample of 12 min, the sample preparation is cost-effective and easy to handle. The method covers alternariol (AOH), alternariol monomethyl ether (AME), tenuazonic acid (TeA), altenuene (ALT), iso-altenuene (isoALT), tentoxin (TEN), altertoxin-I (ATX-I), and the AAL toxins TA₁ and TA₂. Some Alternaria toxins which are either not commercially available or very expensive, namely AOH, AME, ALT, isoALT, and ATX-I, were isolated as reference compounds from fungal cultures. The method was extensively validated for tomato products, bakery products, sunflower seeds, fruit juices, and vegetable oils. AOH, AME, TeA, and TEN were found in quantifiable amounts and 92.1 % of all analyzed samples (n?=?96) showed low level contamination with one or more Alternaria toxins. Based on the obtained results, the average daily exposure to Alternaria toxins in Germany was calculated.     

Influence of hydrocortisone on the mechanical properties of the cerebral endothelium in vitro

Cerebral endothelial cells accomplish the barrier functions between blood and brain interstitium. Structural features are the tight junctions between adjacent endothelial cells and the formation of marginal folds at the cell-cell contacts. The glucocorticoid hydrocortisone (HC) has been reported to enforce the blood-brain-barrier in vitro measurable by an increase of the transendothelial electrical resistance. This study shows the impact of HC on the mechanical and morphological properties of confluent cell layers of brain microvascular endothelial cells. HC induces an increase in height of these marginal folds and a reduction of the intercellular contact surface. These morphological changes are accompanied by changes in cell elasticity. Staining of fibrous actin indicates that HC induces a reorganization of the actin cortex. The quantitative determination of the local elastic properties of cells reveals for the first time an HC-induced increase of the representative Young's modulus according to cytoskeletal rearrangements. For this study, cells of two different species, porcine brain capillary endothelial cells and murine brain capillary endothelial cells, were used yielding similar results, which clearly demonstrates that the HC effect on the cell elasticity is species independent.     

PHOTOSYNTHESIS AND PRODUCTION OF HYDROGEN PEROXIDE BY SYMBIODINIUM (PYRRHOPHYTA) PHYLOTYPES WITH DIFFERENT THERMAL TOLERANCES1

Occurrences whereby cnidaria lose their symbiotic dinoflagellate microalgae (Symbiodinium spp.) are increasing in frequency and intensity. These so‐called bleaching events are most often related to an increase in water temperature, which is thought to limit certain Symbiodinium phylotypes from effectively dissipating absorbed excitation energy that is otherwise used for photochemistry. Here, we examined photosynthetic characteristics and hydrogen peroxide (H₂O₂) production, a possible signal involved in bleaching, from two Symbiodinium types (a thermally “tolerant” A1 and “sensitive” B1) representative of cnidaria–Symbiodinium symbioses of reef‐building Caribbean corals. Under steady‐state growth at 26°C, a higher efficiency of PSII photochemistry, rate of electron turnover, and rate of O₂ production were observed for type A1 than for B1. The two types responded very differently to a period of elevated temperature (32°C): type A1 increased light‐driven O₂ consumption but not the amount of H₂O₂ produced; in contrast, type B1 increased the amount of H₂O₂ produced without an increase in light‐driven O₂ consumption. Therefore, our results are consistent with previous suggestions that the thermal tolerance of Symbiodinium is related to adaptive constraints associated with photosynthesis and that sensitive phylotypes are more prone to H₂O₂ production. Understanding these adaptive differences in the genus Symbiodinium will be crucial if we are to interpret the response of symbiotic associations, including reef‐building corals, to environmental change.     

Improved tolerance to bile salts of aggregated Bifidobacterium longum produced during continuous culture with immobilized cells

The effect of cell immobilization and continuous culture was studied on selected physiological and technological characteristics of Bifidobacterium longum NCC2705 cultivated for 20 days in a two stage continuous fermentation system. Continuous immobilized cell (IC) cultures with and without glucose limitation exhibited formation of macroscopic cell aggregates after 12 and 9 days, respectively. Auto-aggregation resulted in underestimation of viable cell counts by plate counts by more than 2 log units CFU/ml compared with qPCR method. Modifications of cell membrane composition might partially explain aggregate formation in IC cultures. Decreases in the ratio of unsaturated to saturated fatty acid content from 1.74 to 0.58 might also contribute to the enhanced tolerance of IC cells to porcine bile salts and aminoglycosidic antibiotics compared with free cells from batch cultures.The enhanced resistance against bile salts in combination with auto-aggregation may confer an advantage to probiotic bacteria produced by IC technology.     

Using Affordable LED Arrays for Photo-Stimulation of Neurons

Standard slice electrophysiology has allowed researchers to probe individual components of neural circuitry by recording electrical responses of single cells in response to electrical or pharmacological manipulations^1,2. With the invention of methods to optically control genetically targeted neurons (optogenetics), researchers now have an unprecedented level of control over specific groups of neurons in the standard slice preparation. In particular, photosensitive channelrhodopsin-2 (ChR2) allows researchers to activate neurons with light^3,4. By combining careful calibration of LED-based photostimulation of ChR2 with standard slice electrophysiology, we are able to probe with greater detail the role of adult-born interneurons in the olfactory bulb, the first central relay of the olfactory system. Using viral expression of ChR2-YFP specifically in adult-born neurons, we can selectively control young adult-born neurons in a milieu of older and mature neurons. Our optical control uses a simple and inexpensive LED system, and we show how this system can be calibrated to understand how much light is needed to evoke spiking activity in single neurons. Hence, brief flashes of blue light can remotely control the firing pattern of ChR2-transduced newborn cells.Download video file.^{(48M, mov)}     

Hell Is Other People? Gender and Interactions with Strangers in the Workplace Influence a Person’s Risk of Depression

We suggest that interactions with strangers at work influence the likelihood of depressive disorders, as they serve as an environmental stressor, which are a necessary condition for the onset of depression according to diathesis-stress models of depression. We examined a large dataset (N = 76,563 in K = 196 occupations) from the German pension insurance program and the Occupational Information Network dataset on occupational characteristics. We used a multilevel framework with individuals and occupations as levels of analysis. We found that occupational environments influence employees’ risks of depression. In line with the quotation that ‘hell is other people’ frequent conflictual contacts were related to greater likelihoods of depression in both males and females (OR = 1.14, p<.05). However, interactions with the public were related to greater likelihoods of depression for males but lower likelihoods of depression for females (OR_intercation = 1.21, p<.01). We theorize that some occupations may involve interpersonal experiences with negative emotional tones that make functional coping difficult and increase the risk of depression. In other occupations, these experiences have neutral tones and allow for functional coping strategies. Functional strategies are more often found in women than in men.     

The signals of selective constraints on the mitochondrial non-coding control region: insights from comparative mitogenomics of Clupeoid fishes

Genetica - The vertebrate mitochondrial genome is characterized by an exceptional organization evolving towards a reduced size. However, the persistence of a non-coding and highly variable control...