Stress related epigenetic changes may explain opportunistic success in biological invasions in Antipode mussels

Different environmental factors could induce epigenetic changes, which are likely involved in the biological invasion process. Some of these factors are driven by humans as, for example, the pollution and deliberate or accidental introductions and others are due to natural conditions such as salinity. In this study, we have analysed the relationship between different stress factors: time in the new location, pollution and salinity with the methylation changes that could be involved in the invasive species tolerance to new environments. For this purpose, we have analysed two different mussels’ species, reciprocally introduced in antipode areas: the Mediterranean blue mussel Mytilus galloprovincialis and the New Zealand pygmy mussel Xenostrobus securis, widely recognized invaders outside their native distribution ranges. The demetylathion was higher in more stressed population, supporting the idea of epigenetic is involved in plasticity process. These results can open a new management protocols, using the epigenetic signals as potential pollution monitoring tool. We could use these epigenetic marks to recognise the invasive status in a population and determine potential biopollutants

Continued Neurogenesis in Adult Drosophila as a Mechanism for Recruiting Environmental Cue-Dependent Variants

Background The skills used by winged insects to explore their environment are strongly dependent upon the integration of neurosensory information comprising visual, acoustic and olfactory signals. The neuronal architecture of the wing contains a vast array of different sensors which might convey information to the brain in order to guide the trajectories during flight. In Drosophila, the wing sensory cells are either chemoreceptors or mechanoreceptors and some of these sensors have as yet unknown functions. The axons of these two functionally distinct types of neurons are entangled, generating a single nerve. This simple and accessible coincidental signaling circuitry in Drosophila constitutes an excellent model system to investigate the developmental variability in relation to natural behavioral polymorphisms. Methodology/Principal Findings A fluorescent marker was generated in neurons at all stages of the Drosophila life cycle using a highly efficient and controlled genetic recombination system that can be induced in dividing precursor cells (MARCM system, flybase web site). It allows fluorescent signals in axons only when the neuroblasts and/or neuronal cell precursors like SOP (sensory organ precursors) undergo division during the precedent steps. We first show that a robust neurogenesis continues in the wing after the adults emerge from the pupae followed by an extensive axonal growth. Arguments are presented to suggest that this wing neurogenesis in the newborn adult flies was influenced by genetic determinants such as the frequency dependent for gene and by environmental cues such as population density. Conclusions We demonstrate that the neuronal architecture in the adult Drosophila wing is unfinished when the flies emerge from their pupae. This unexpected developmental step might be crucial for generating non-heritable variants and phenotypic plasticity. This might therefore constitute an advantage in an unstable ecological system and explain much regarding the ability of Drosophila to robustly adapt to their environment

Corporate Cash Holdings in the Oil and Gas Industry:The Role of Energy Directives

With the implementation of energy directives and increasing competition among the market players, energy firms face more uncertainty than past. As being one of the most prominent factors for energy firms, industry-specific regulations and directives related to the energy security and climate change have a considerable impact not only on their performances but also on their corporate strategies. In this chapter, we investigate the impact of the energy directives on the corporate cash holding decisions of the energy firms in Europe. Using a large number of firms and a variety of econometric approaches, our findings suggest that there are significant differences among countries in terms of cash holding decisions and the impact of energy directives. We find that the energy firms in the Northern and Western Europe increase their cash holdings as a buffer against the unexpected cash shortages with the implementation of the Second and Third Energy Directives. However, directives do not have any impact on the cash accumulation of the energy companies in the UK and Eastern Europe. Our results also suggest that speed of adjustment toward the target cash position for the energy firms in Eastern Europe (Northern Europe) decreases (increases) with the implementation of the Second and the Third Energy Directives. Overall, the results suggest that energy directives have a strong influence on the energy firms in Northern, Western, and Eastern Europe, but firms in the UK are less sensitive to the changes in the industry dynamics in terms of cash accumulation and the speed of adjustment toward the target cash position. The findings of this study shed important lights on how industry-specific regulations affect the cash holding decision of energy firms, which is often a neglected issue in the energy economics