Helper component proteinase of the genus Potyvirus is an interaction partner of translation initiation factors eIF(iso)4E and eIF4E and contains a 4E binding motif

The multifunctional helper component proteinase (HCpro) of potyviruses (genus Potyvirus; Potyviridae) shows self-interaction and interacts with other potyviral and host plant proteins. Host proteins that are pivotal to potyvirus infection include the eukaryotic translation initiation factor eIF4E and the isoform eIF(iso)4E, which interact with viral genome-linked protein (VPg). Here we show that HCpro of Potato virus A (PVA) interacts with both eIF4E and eIF(iso)4E, with interactions with eIF(iso)4E being stronger, as judged by the data of a yeast two-hybrid system assay. A bimolecular fluorescence complementation assay on leaves of Nicotiana benthamiana showed that HCpro from three potyviruses (PVA, Potato virus Y, and Tobacco etch virus) interacted with the eIF(iso)4E and eIF4E of tobacco (Nicotiana tabacum); interactions with eIF(iso)4E and eIF4E of potato (Solanum tuberosum) were weaker. In PVA-infected cells, interactions between HCpro and tobacco eIF(iso)4E were confined to round structures that colocalized with 6K2-induced vesicles. Point mutations introduced to a 4E binding motif identified in the C-terminal region of HCpro debilitated interactions of HCpro with translation initiation factors and were detrimental to the virulence of PVA in plants. The 4E binding motif conserved in HCpro of potyviruses and HCpro-initiation factor interactions suggest new roles for HCpro and/or translation factors in the potyvirus infection cycle.     

Epistatic selection between coding and regulatory variation in human evolution and disease

Interaction (nonadditive effects) between genetic variants has been highlighted as an important mechanism underlying phenotypic variation, but the discovery of genetic interactions in humans has proved difficult. In this study, we show that the spectrum of variation in the human genome has been shaped by modifier effects of cis-regulatory variation on the functional impact of putatively deleterious protein-coding variants. We analyzed 1000 Genomes population-scale resequencing data from Europe (CEU [Utah residents with Northern and Western European ancestry from the CEPH collection]) and Africa (YRI [Yoruba in Ibadan, Nigeria]) together with gene expression data from arrays and RNA sequencing for the same samples. We observed an underrepresentation of derived putatively functional coding variation on the more highly expressed regulatory haplotype, which suggests stronger purifying selection against deleterious coding variants that have increased penetrance because of their regulatory background. Furthermore, the frequency spectrum and impact size distribution of common regulatory polymorphisms (eQTLs) appear to be shaped in order to minimize the selective disadvantage of having deleterious coding mutations on the more highly expressed haplotype. Interestingly, eQTLs explaining common disease GWAS signals showed an enrichment of putative epistatic effects, suggesting that some disease associations might arise from interactions increasing the penetrance of rare coding variants. In conclusion, our results indicate that regulatory and coding variants often modify the functional impact of each other. This specific type of genetic interaction is detectable from sequencing data in a genome-wide manner, and characterizing these joint effects might help us understand functional mechanisms behind genetic associations to human phenotypes-including both Mendelian and common disease.     

Global change synergies and trade‐offs between renewable energy and biodiversity

Reliance on fossil fuels is causing unprecedented climate change and is accelerating environmental degradation and global biodiversity loss. Together, climate change and biodiversity loss, if not averted urgently, may inflict severe damage on ecosystem processes, functions and services that support the welfare of modern societies. Increasing renewable energy deployment and expanding the current protected area network represent key solutions to these challenges, but conflicts may arise over the use of limited land for energy production as opposed to biodiversity conservation. Here, we compare recently identified core areas for the expansion of the global protected area network with the renewable energy potential available from land‐based solar photovoltaic, wind energy and bioenergy (in the form of Miscanthus × giganteus). We show that these energy sources have very different biodiversity impacts and net energy contributions. The extent of risks and opportunities deriving from renewable energy development is highly dependent on the type of renewable source harvested, the restrictions imposed on energy harvest and the region considered, with Central America appearing at particularly high potential risk from renewable energy expansion. Without restrictions on power generation due to factors such as production and transport costs, we show that bioenergy production is a major potential threat to biodiversity, while the potential impact of wind and solar appears smaller than that of bioenergy. However, these differences become reduced when energy potential is restricted by external factors including local energy demand. Overall, we found that areas of opportunity for developing solar and wind energy with little harm to biodiversity could exist in several regions of the world, with the magnitude of potential impact being particularly dependent on restrictions imposed by local energy demand. The evidence provided here helps guide sustainable development of renewable energy and contributes to the targeting of global efforts in climate mitigation and biodiversity conservation.     

Glutamate Uptake Triggers Transporter-Mediated GABA Release from Astrocytes

Background

Glutamate (Glu) and γ-aminobutyric acid (GABA) transporters play important roles in regulating neuronal activity. Glu is removed from the extracellular space dominantly by glial transporters. In contrast, GABA is mainly taken up by neurons. However, the glial GABA transporter subtypes share their localization with the Glu transporters and their expression is confined to the same subpopulation of astrocytes, raising the possibility of cooperation between Glu and GABA transport processes.

Methodology/Principal Findings

Here we used diverse biological models both in vitro and in vivo to explore the interplay between these processes. We found that removal of Glu by astrocytic transporters triggers an elevation in the extracellular level of GABA. This coupling between excitatory and inhibitory signaling was found to be independent of Glu receptor-mediated depolarization, external presence of Ca²⁺ and glutamate decarboxylase activity. It was abolished in the presence of non-transportable blockers of glial Glu or GABA transporters, suggesting that the concerted action of these transporters underlies the process.

Conclusions/Significance

Our results suggest that activation of Glu transporters results in GABA release through reversal of glial GABA transporters. This transporter-mediated interplay represents a direct link between inhibitory and excitatory neurotransmission and may function as a negative feedback combating intense excitation in pathological conditions such as epilepsy or ischemia.     

Metabolic control analysis of integrated energy metabolism in permeabilized cardiomyocytes - experimental study

The main focus of this research was to apply Metabolic Control Analysis to quantitative investigation of the regulation of respiration by components of the Mitochondrial Interactosome (MI, a supercomplex consisting of ATP Synthasome, mitochondrial creatine kinase (MtCK), voltage dependent anion channel (VDAC), and tubulin) in permeabilized cardiomyocytes. Flux control coefficients (FCC) were measured using two protocols: 1) with direct ADP activation, and 2) with MtCK activation by creatine (Cr) in the presence of ATP and pyruvate kinase-phosphoenolpyruvate system. The results show that the metabolic control is much stronger in the latter case: the sum of the measured FCC is 2.7 versus 0.74 (ADP activation). This is consistent with previous data showing recycling of ADP and ATP inside the MI due to the functional coupling between MtCK and ANT and limited permeability of VDAC for these compounds, PCr being the major energy carrier between the mitochondria and ATPases. In physiological conditions, when the MI is activated, the key sites of regulation of respiration in mitochondria are MtCK (FCC = 0.93), adenine nucleotide translocase ANT (FCC = 0.95) and CoQ cytochrome c oxidoreductase (FCC = 0.4). These results show clearly that under the physiological conditions the energy transfer from mitochondria to the cytoplasm is regulated by the MI supercomplex and is very sensitive to metabolic signals.     

A new model estimating stonefly species production in the West Carpathian torrents

Samples of stoneflies were collected from 15 streams of Slovakia during 1976–2000. The model of growth rate is based on 219 data of 50 stonefly species. The non-linear relationship among growth rate (G) of stoneflies and monthly mean water temperature (T) and body mass (W) is described by equation: G = 0.014W ^−0.19 T ^0.25. The model estimates the species production of the families Taeniopterygidae, Nemouridae, Capniidae, Leuctridae and Perlodidae. This model is combined with Morin’s & Dumont’s (1994) model for Perlidae and Chloroperlidae. There is positive evidence that the total stonefly production of mountain and submountain streams increases with discharge. On the other hand, increasing altitude has a negative influence on production.     

Extreme Female Promiscuity in a Non-Social Invertebrate Species

Background

While males usually benefit from as many matings as possible, females often evolve various methods of resistance to matings. The prevalent explanation for this is that the cost of additional matings exceeds the benefits of receiving sperm from a large number of males. Here we demonstrate, however, a strongly deviating pattern of polyandry.

Methodology/Principal Findings

We analysed paternity in the marine snail Littorina saxatilis by genotyping large clutches (53–79) of offspring from four females sampled in their natural habitats. We found evidence of extreme promiscuity with 15–23 males having sired the offspring of each female within the same mating period.

Conclusions/Significance

Such a high level of promiscuity has previously only been observed in a few species of social insects. We argue that genetic bet-hedging (as has been suggested earlier) is unlikely to explain such extreme polyandry. Instead we propose that these high levels are examples of convenience polyandry: females accept high numbers of matings if costs of refusing males are higher than costs of accepting superfluous matings.     

Suppression of neuronal network excitability and seizure-like events by 2-methyl-4-oxo-3H-quinazoline-3-acetyl piperidine in juvenile rat hippocampus: involvement of a metabotropic glutamate receptor

We present data on the antiepileptic potency of 2-methyl-4-oxo-3H-quinazoline-3-acetyl piperidine (Q5) in juvenile (P9-13) rat hippocampal slices and in particular Q5's action mechanism and target. Q5 (200-500 microM), but not alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/Kainate receptor antagonists blocked low-[Mg2+]-induced seizure-like events (SLE) in the CA3 region. Q5 (100 microM) decreased Glu-induced [35S]guanosine 5'-O-(3-thiotriphosphate) binding enhancement in brain homogenates, without interaction with ionotropic Glu receptor sites and Glu transport. In voltage-clamped CA3 pyramidal cells, Q5 (500 microM) depressed activities of spontaneous excitatory and inhibitory postsynaptic currents without affecting miniature inhibitory currents. Metabotropic Glu receptor (mGluR) subtype antagonists affected network excitability dissimilarly. Intracellular Ca2+ ion transients induced by the mGluR agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD) were suppressed by Q5. Agreeing predictions obtained by modelling Q5 binding to different experimental conformations of mGlu1, Q5 was bound partially to an mGluR binding site in the presence of 1mM ACPD. Findings suggest the apparent involvement of a novel phenotype of action or a new mGluR subtype in the specific suppression of epileptiform activity by Q5 through the depression of network excitability.