Basic electrophysiological parameters and frequency sensitivity of the ventricular myocardium of human embryos

The basic electrophysiological manifestations of the ventricular myocardium of twelve 7- to 12-week human embryos were measured with a glass electrode and a programmed stimulation technique. The resting membrane potential value was 79.37 +/- 0.34 mV and the overshoot 32.7 +/- 0.57 mV; the action potential (AP) duration at 1 Hz stimulation frequency was 120.0 +/- 5.7 ms at AP plateau phase levels and 258 +/- 17 ms at the level corresponding to 95% repolarization. The duration of the AP was a function of the stimulation frequency. i.e. it altered in correlation to the stimulation programme fully developed frequency sensitivity). In stimulation with different frequencies the duration of the steady state AP was in an inverse relation to the stimulation frequency, the maximum changes being found in the terminal repolarization zone. An interpolated extrasystole mainly affected the duration of the plateau phase.     

Food availability affects the strength of mutualistic host–microbiota interactions in Daphnia magna

The symbiotic gut microbial community is generally known to have a strong impact on the fitness of its host. Nevertheless, it is less clear how the impact of symbiotic interactions on the hosts'' fitness varies according to environmental circumstances such as changes in the diet. This study aims to get a better understanding of host–microbiota interactions under different levels of food availability. We conducted experiments with the invertebrate, experimental model organism Daphnia magna and compared growth, survival and reproduction of conventionalized symbiotic Daphnia with germ-free individuals given varying quantities of food. Our experiments revealed that the relative importance of the microbiota for the hosts'' fitness varied according to dietary conditions. The presence of the microbiota had strong positive effects on Daphnia when food was sufficient or abundant, but had weaker effects under food limitation. Our results indicate that the microbiota can be a potentially important factor in determining host responses to changes in dietary conditions. Characterization of the host-associated microbiota further showed that Aeromonas sp. was the most prevalent taxon in the digestive tract of Daphnia.     

Different effects of carbohydrate binding modules on the viscoelasticity of nanocellulose gels

Many cellulose degrading and modifying enzymes have distinct parts called carbohydrate binding modules (CBMs). The CBMs have been shown to increase the concentration of enzymes on the insoluble substrate and thereby enhance catalytic activity. It has been suggested that CBMs also have a role in disrupting or dispersing the insoluble cellulose substrate, but dispute remains and explicit evidence of such a mechanism is lacking. We produced the isolated CBMs from two major cellulases (Cel6A and Cel7A) from Trichoderma reesei as recombinant proteins in Escherichia coli. We then studied the viscoelastic properties of native unmodified cellulose nanofibrils (CNF) in combination with the highly purified CBMs to detect possible functional effects of the CBMs on the CNF. The two CBMs showed clearly different effects on the viscoelastic properties of CNF. The difference in effects is noteworthy, yet it was not possible to conclude for example disruptive effects. We discuss here the alternative explanations for viscoelastic effects on CNF caused by CBMs, including the effect of ionic cosolutes.     

Richness and abundance of stream fish communities in a fragmented neotropical landscape

Environmental Biology of Fishes - Environmental conditions influence ecological processes that shape stream community diversity and abundance. Deforestation has the potential to limit available...     

mTORC1 activity is supported by spatial association with focal adhesions

The mammalian target of rapamycin complex 1 (mTORC1) integrates mitogenic and stress signals to control growth and metabolism. Activation of mTORC1 by amino acids and growth factors involves recruitment of the complex to the lysosomal membrane and is further supported by lysosome distribution to the cell periphery. Here, we show that translocation of lysosomes toward the cell periphery brings mTORC1 into proximity with focal adhesions (FAs). We demonstrate that FAs constitute discrete plasma membrane hubs mediating growth factor signaling and amino acid input into the cell. FAs, as well as the translocation of lysosome-bound mTORC1 to their vicinity, contribute to both peripheral and intracellular mTORC1 activity. Conversely, lysosomal distribution to the cell periphery is dispensable for the activation of mTORC1 constitutively targeted to FAs. This study advances our understanding of spatial mTORC1 regulation by demonstrating that the localization of mTORC1 to FAs is both necessary and sufficient for its activation by growth-promoting stimuli.     

Modeling the circular economy in environmentally extended input–output: A web application

Global environmental and resource problems ask for new ways of managing the production and consumption of resources. The implementation of new paradigms, such as the circular economy, requires decision‐makers at multiple levels to make complex decisions. For this, clear analyses and modeling of scenarios are of utmost importance. Meanwhile, as the sophistication of databases and models increases so does the need for user‐friendly tools to use them. The RaMa‐Scene web platform reduces these barriers by allowing users to visualize easily diverse impacts of implementing circular‐economy interventions. This online web platform makes use of the multi‐regional environmentally extended input–output database EXIOBASE version 3 in monetary units, which has been modified to show explicit transactions of raw materials from recycling activities.     

Seed Architecture Shapes Embryo Metabolism in Oilseed Rape

Constrained to develop within the seed, the plant embryo must adapt its shape and size to fit the space available. Here, we demonstrate how this adjustment shapes metabolism of photosynthetic embryo. Noninvasive NMR-based imaging of the developing oilseed rape (Brassica napus) seed illustrates that, following embryo bending, gradients in lipid concentration became established. These were correlated with the local photosynthetic electron transport rate and the accumulation of storage products. Experimentally induced changes in embryo morphology and/or light supply altered these gradients and were accompanied by alterations in both proteome and metabolome. Tissue-specific metabolic models predicted that the outer cotyledon and hypocotyl/radicle generate the bulk of plastidic reductant/ATP via photosynthesis, while the inner cotyledon, being enclosed by the outer cotyledon, is forced to grow essentially heterotrophically. Under field-relevant high-light conditions, major contribution of the ribulose-1,5-bisphosphate carboxylase/oxygenase–bypass to seed storage metabolism is predicted for the outer cotyledon and the hypocotyl/radicle only. Differences between in vitro– versus in planta–grown embryos suggest that metabolic heterogeneity of embryo is not observable by in vitro approaches. We conclude that in vivo metabolic fluxes are locally regulated and connected to seed architecture, driving the embryo toward an efficient use of available light and space.     

Ve1‐mediated resistance against Verticillium does not involve a hypersensitive response in Arabidopsis

The recognition of pathogen effectors by plant immune receptors leads to the activation of immune responses that often include a hypersensitive response (HR): rapid and localized host cell death surrounding the site of attempted pathogen ingress. We have demonstrated previously that the recognition of the Verticillium dahliae effector protein Ave1 by the tomato immune receptor Ve1 triggers an HR in tomato and tobacco. Furthermore, we have demonstrated that tomato Ve1 provides Verticillium resistance in Arabidopsis upon Ave1 recognition. In this study, we investigated whether the co‐expression of Ve1 and Ave1 in Arabidopsis results in an HR, which could facilitate a forward genetics screen. Surprisingly, we found that the co‐expression of Ve1 and Ave1 does not induce an HR in Arabidopsis. These results suggest that an HR may occur as a consequence of Ve1/Ave1‐induced immune signalling in tomato and tobacco, but is not absolutely required for Verticillium resistance.