Additive genetic variation of transcriptional regulation: metallothionein expression in the soil insect Orchesella cincta

Field-selected metal tolerance in Orchesella cincta is correlated with overexpression of the single copy cadmium (Cd) inducible metallothionein (mt). Previously, we have demonstrated large phenotypic variation in mt gene expression, and a higher frequency of high-expression phenotypes in a tolerant population. Here, we describe midparent-offspring regression analysis of mt gene expression in a laboratory culture originating from a noncontaminated natural population. Families were either not exposed (n=47) or exposed to 0.5 micromol Cd per gram dry food (n=46). Mean mt gene expressions normalized to 28S rRNA and beta-actin RNA were generated using real-time RT-PCR applied to parents and offspring RNA and subjected to regression analysis. A significant heritability (h2) for mt gene expression was estimated between 0.36 (beta-actin normalized) and 0.46 (28S normalized) in Cd exposed families. Nontreated families did not yield a significant h2 value. Restriction Fragment Length Polymorphism analysis of the metallothionein promoter sequence revealed eight promoter alleles that show structural variation. Three alleles show increased frequencies in families with high mt expression. Another gene, croquemort (isolated from a differential screening for 1 micromole Cd treatment) showed no h2 of gene expression in response to 0.5 micromol Cd. This gene codes for a receptor-protein involved in recognition of apoptotic cells and may participate in the general stress response. The present data suggest that evolution of metal tolerance in O. cincta can occur in the field by selection for high mt expression due to structural changes in mt cis-regulation.     

Automated Recording of Vertical Negative Phototactic Behaviour in Daphnia magna Straus (Crustacea)

Diurnal vertical migration is a well-known phenomenon in the circadian activity rhythms of zooplankton. Our goal was to test whether negative phototaxis in Daphnia magna clone BEAK (provoked by artificially induced light stress, alternating light and dark phases in 2 h intervals), and its interference with the endogenous rhythm of diurnal vertical migration, can be automatically registered with a biomonitor. For the first time the vertical swimming behaviour of D. magna was recorded quantitatively based on non-optical data recording in a fully automated biotest system, the Multispecies Freshwater Biomonitor in a new experimental setup consisting of a column of three recording units (3-level chambers). Circadian vertical migration was clearly recorded in the 3-level chambers and the rhythm was more clear with 5 than with 1 organism per chamber. The organisms clearly responded to induced light stress with negative phototaxis, however best in larger chambers. The artificially induced rhythm was influenced by the endogenous rhythm. This approach may facilitate long-term observations of vertical swimming activity of zooplankton in the future.     

Increase in short-chain ceramides correlates with an altered lipid organization and decreased barrier function in atopic eczema patients

A hallmark of atopic eczema (AE) is skin barrier dysfunction. Lipids in the stratum corneum (SC), primarily ceramides, fatty acids, and cholesterol, are crucial for the barrier function, but their role in relation to AE is indistinct. Filaggrin is an epithelial barrier protein with a central role in the pathogenesis of AE. Nevertheless, the precise causes of AE-associated barrier dysfunction are largely unknown. In this study, a comprehensive analysis of ceramide composition and lipid organization in nonlesional SC of AE patients and control subjects was performed by means of mass spectrometry, infrared spectroscopy, and X-ray diffraction. In addition, the skin barrier and clinical state of the disease were examined. The level of ceramides with an extreme short chain length is drastically increased in SC of AE patients, which leads to an aberrant lipid organization and a decreased skin barrier function. Changes in SC lipid properties correlate with disease severity but are independent of filaggrin mutations. We demonstrate for the first time that changes in ceramide chain length and lipid organization are directly correlated with the skin barrier defects in nonlesional skin of AE patients. We envisage that these insights will provide a new therapeutic entry in therapy and prevention of AE.     

Glycine and its N-methylated analogues cause pH-dependent membrane damage to enterotoxigenic Escherichia coli

The current study first investigates the emulsifying potential of glycine and its N-methylated derivatives N-methylglycine (sarcosine), N,N-dimethylglycine (DMG) and N,N,N-trimethylglycine (betaine) under varying pH conditions. Subsequently, the effect of these test compounds on the membrane integrity of enterotoxigenic Escherichia coli (ETEC) was evaluated. Oil in water emulsions containing each compound show that DMG is a more potent enhancer of emulsification than glycine, sarcosine and betaine under the conditions tested. Flow cytometry was used to investigate whether the emulsifying potential is associated with an effect on ETEC membrane integrity. The bacteria were exposed to each of the test compounds under varying pH conditions and membrane integrity was assessed using the LIVE/DEAD BacLight kit. Results show a membrane deteriorating effect caused by glycine, sarcosine and DMG, but not by betaine. This effect is pH- and time-dependent and has an apparent threshold at pH 9.0. Conventional plate counts confirmed concomitant changes in culturability of the membrane comprised bacteria.     

Corridor network design in hinterland transportation systems

In this paper the design of the service network in intermodal barge transport is studied. The network of inland barge terminals is modelled to demonstrate potential cooperations in a corridor network. Cooperation between inland terminals leads to bundling of freight flows in the hinterland of major ports. A service network design model for intermodal barge transport is developed and applied to the hinterland network of the port of Antwerp in Belgium. Selected cooperation schemes are simulated by means of a discrete event simulation model for intermodal barge transport and compared with simulation results of bundling in the port area. Cooperation between inland terminals offers an opportunity to attain economies of scale, but may not be perceived as a sole solution for reducing waiting times of inland barges at sea terminals. A combination of bundling measures in the port area and in the hinterland may be necessary to improve the intermodal transport chain.     

The human‐induced imbalance between C,N and P in Earth's life system

Human‐induced carbon and nitrogen fertilization are generating a strong imbalance with P. This imbalance confers an increasingly important role to P availability and N : P ratio in the Earth's life system, affecting carbon sequestration potential and the structure, function and evolution of the Earth's ecosystems.