The membrane-binding domain of the Rous sarcoma virus Gag protein.

The Gag protein of Rous sarcoma virus (RSV) can direct particle assembly and budding at the plasma membrane independently of the other virus-encoded products. A previous deletion analysis has suggested that the first 86 amino acids of RSV Gag constitute a large membrane-binding domain that is absolutely required for these processes. To test this hypothesis, we inserted these residues in place of the N-terminal membrane-binding domain of the pp60v-src, a transforming protein whose biological activity requires plasma membrane localization. The ability of the Src chimera to induce cellular transformation suggests that the RSV sequence indeed contains an independent, functional domain.     

Pyramidal Neurons Derived from Human Pluripotent Stem Cells Integrate Efficiently into Mouse Brain Circuits In Vivo

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Formal Models of the Network Co-occurrence Underlying Mental Operations

Systems neuroscience has identified a set of canonical large-scale networks in humans. These have predominantly been characterized by resting-state analyses of the task-unconstrained, mind-wandering brain. Their explicit relationship to defined task performance is largely unknown and remains challenging. The present work contributes a multivariate statistical learning approach that can extract the major brain networks and quantify their configuration during various psychological tasks. The method is validated in two extensive datasets (n = 500 and n = 81) by model-based generation of synthetic activity maps from recombination of shared network topographies. To study a use case, we formally revisited the poorly understood difference between neural activity underlying idling versus goal-directed behavior. We demonstrate that task-specific neural activity patterns can be explained by plausible combinations of resting-state networks. The possibility of decomposing a mental task into the relative contributions of major brain networks, the "network co-occurrence architecture" of a given task, opens an alternative access to the neural substrates of human cognition.     

The auxin-signaling pathway is required for the lateral root response of Arabidopsis to the rhizobacterium Phyllobacterium brassicacearum

Plant root development is highly responsive both to changes in nitrate availability and beneficial microorganisms in the rhizosphere. We previously showed that Phyllobacterium brassicacearum STM196, a plant growth-promoting rhizobacteria strain isolated from rapeseed roots, alleviates the inhibition exerted by high nitrate supply on lateral root growth. Since soil-borne bacteria can produce IAA and since this plant hormone may be implicated in the high nitrate-dependent control of lateral root development, we investigated its role in the root development response of Arabidopsis thaliana to STM196. Inoculation with STM196 resulted in a 50% increase of lateral root growth in Arabidopsis wild-type seedlings. This effect was completely abolished in aux1 and axr1 mutants, altered in IAA transport and signaling, respectively, indicating that these pathways are required. The STM196 strain, however, appeared to be a very low IAA producer when compared with the high-IAA-producing Azospirillum brasilense sp245 strain and its low-IAA-producing ipdc mutant. Consistent with the hypothesis that STM196 does not release significant amounts of IAA to the host roots, inoculation with this strain failed to increase root IAA content. Inoculation with STM196 led to increased expression levels of several IAA biosynthesis genes in shoots, increased Trp concentration in shoots, and increased auxin-dependent GUS staining in the root apices of DR5::GUS transgenic plants. All together, our results suggest that STM196 inoculation triggers changes in IAA distribution and homeostasis independently from IAA release by the bacteria.     

Association of ebola virus matrix protein VP40 with microtubules

Viruses exploit a variety of cellular components to complete their life cycles, and it has become increasingly clear that use of host cell microtubules is a vital part of the infection process for many viruses. A variety of viral proteins have been identified that interact with microtubules, either directly or via a microtubule-associated motor protein. Here, we report that Ebola virus associates with microtubules via the matrix protein VP40. When transfected into mammalian cells, a fraction of VP40 colocalized with microtubule bundles and VP40 coimmunoprecipitated with tubulin. The degree of colocalization and microtubule bundling in cells was markedly intensified by truncation of the C terminus to a length of 317 amino acids. Further truncation to 308 or fewer amino acids abolished the association with microtubules. Both the full-length and the 317-amino-acid truncation mutant stabilized microtubules against depolymerization with nocodazole. Direct physical interaction between purified VP40 and tubulin proteins was demonstrated in vitro. A region of moderate homology to the tubulin binding motif of the microtubule-associated protein MAP2 was identified in VP40. Deleting this region resulted in loss of microtubule stabilization against drug-induced depolymerization. The presence of VP40-associated microtubules in cells continuously treated with nocodazole suggested that VP40 promotes tubulin polymerization. Using an in vitro polymerization assay, we demonstrated that VP40 directly enhances tubulin polymerization without any cellular mediators. These results suggest that microtubules may play an important role in the Ebola virus life cycle and potentially provide a novel target for therapeutic intervention against this highly pathogenic virus.     

High‐Throughput DNA sequencing of ancient wood

Reconstructing the colonization and demographic dynamics that gave rise to extant forests is essential to forecasts of forest responses to environmental changes. Classical approaches to map how population of trees changed through space and time largely rely on pollen distribution patterns, with only a limited number of studies exploiting DNA molecules preserved in wooden tree archaeological and subfossil remains. Here, we advance such analyses by applying high‐throughput (HTS) DNA sequencing to wood archaeological and subfossil material for the first time, using a comprehensive sample of 167 European white oak waterlogged remains spanning a large temporal (from 550 to 9,800 years) and geographical range across Europe. The successful characterization of the endogenous DNA and exogenous microbial DNA of 140 (~83%) samples helped the identification of environmental conditions favouring long‐term DNA preservation in wood remains, and started to unveil the first trends in the DNA decay process in wood material. Additionally, the maternally inherited chloroplast haplotypes of 21 samples from three periods of forest human‐induced use (Neolithic, Bronze Age and Middle Ages) were found to be consistent with those of modern populations growing in the same geographic areas. Our work paves the way for further studies aiming at using ancient DNA preserved in wood to reconstruct the micro‐evolutionary response of trees to climate change and human forest management.     

Chronic administration of clomipramine inhibits morphine hot plate analgesia

Clomipramine, chronically administered in mice, for 3 days, inhibits partially but significantly morphine analgesia in the hot plate test, when used at dose of 10 mg/kg/day, i.p.; 2.5 and 5 mg/kg/day were ineffective. Neither higher doses (20 and 40 mg/kg/day) nor longer duration of pretreatment (8 and 16 days) modified the intensity of this inhibition. Reduction in morphine analgesia was obtained after a 24h delay between the last injection of clomipramine and that of morphine (30 min before testing), while clomipramine did not induce any antinociceptive effect and clomipramine and desmethylclomipramine plasma and brain levels were low or undetectable. These results provide new evidence for the interaction between clomipramine and the endogenous opiate system. A pharmacokinetic interaction between clomipramine and morphine was excluded; involvement of change in opiate and 5 HT2 receptors by chronic administration of clomipramine is discussed.     

The human genome puzzle - the role of copy number variation in somatic mosaicism

The discovery of copy number variations (CNV) in the human genome opened new perspectives in the study of the genetic causes of inherited disorders and the etiology of common diseases. Differently patterned instances of somatic mosaicism in CNV regions have been shown to be present in monozygotic twins and throughout different tissues within an individual. A single-cell-level investigation of CNV in different human cell types led us to uncover mitotically derived genomic mosaicism, which is stable in different cell types of one individual. A unique study of immortalized B-lymphoblastoid cell lines obtained with 20 year interval from the same two subjects shows that mitotic changes in CNV regions may happen early during embryonic development and seem to occur only once, as levels of mosaicism remained stable. This finding has the potential to change our concept of dynamic human genome variation. We propose that further genomic studies should focus on the single-cell level, to understand better the etiology and physiology of aging and diseases mediated by somatic variations.