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The majority of our genome is composed of repeated DNA sequences that assemble into heterochromatin, a highly compacted structure that constrains their mutational potential. How heterochromatin forms during development and how its structure is maintained are not fully understood. Here, we show that mouse heterochromatin phase-separates after fertilization, during the earliest stages of mammalian embryogenesis. Using high-resolution quantitative imaging and molecular biology approaches, we show that pericentromeric heterochromatin displays properties consistent with a liquid-like state at the two-cell stage, which change at the four-cell stage, when chromocenters mature and heterochromatin becomes silent. Disrupting the condensates results in altered transcript levels of pericentromeric heterochromatin, suggesting a functional role for phase separation in heterochromatin function. Thus, our work shows that mouse heterochromatin forms membrane-less compartments with biophysical properties that change during development and provides new insights into the self-organization of chromatin domains during mammalian embryogenesis.

SummaryShort tracts of trinucleotide repeats with less than 10 repeats are found frequently throughout the genome without any apparent negative impact on DNA replication fork progression or transcription elongation. CGG binding protein 1 (CGGBP1) binds to CGG triplet repeats and has been implicated in multiple cellular processes such as transcription, replication and DNA damage. Here, we show that CGGBP1 binds to human gene promoter sites prone to G-quadruplex and R-loop secondary structure formation. Altering CGGBP1 levels results in the accumulation of R-loops and causes a defect in transcriptional elongation by RNA polymerase II, which subsequently leads to replication fork stalling and transcription-replication conflicts. Together, our work shows that short trinucleotide repeats are a source of genome-destabilizing secondary structures and cells rely on specific DNA-binding factors to maintain proper transcription and replication progression at short trinucleotide repeats.

Guaranteed ”Safety-Reaction-Times” (SRT) according to mandatory safety standards is a highly decisive issue before realising the commissioning of industrial robot working systems. The SRT as part of technical standard procedures still remains to be highly sensitive to errors and it is effort taking because of utilizing vast numbers of values from many different tabular sources. The current paper presents the design of an SRT calculation process with goal to perform it more time-saving, reliable and user-friendly. As a proof of concept a hardware-in-the-loop demonstrator will be used, in order to accomplish a maximum of certainty before starting the certification process.

Epstein-Barr virus (EBV), a herpes virus also termed HHV 4 and the first identified human tumor virus, establishes a stable, long-term latent infection in human B cells, its preferred host. Upon induction of EBV’s lytic phase, the latently infected cells turn into a virus factory, a process that is governed by EBV. In the lytic, productive phase, all herpes viruses ensure the efficient induction of all lytic viral genes to produce progeny, but certain of these genes also repress the ensuing antiviral responses of the virally infected host cells, regulate their apoptotic death or control the cellular transcriptome. We now find that EBV causes previously unknown massive and global alterations in the chromatin of its host cell upon induction of the viral lytic phase and prior to the onset of viral DNA replication. The viral initiator protein of the lytic cycle, BZLF1, binds to >105 binding sites with different sequence motifs in cellular chromatin in a concentration dependent manner implementing a binary molar switch probably to prevent noise-induced erroneous induction of EBV’s lytic phase. Concomitant with DNA binding of BZLF1, silent chromatin opens locally as shown by ATAC-seq experiments, while previously wide-open cellular chromatin becomes inaccessible on a global scale within hours. While viral transcripts increase drastically, the induction of the lytic phase results in a massive reduction of cellular transcripts and a loss of chromatin-chromatin interactions of cellular promoters with their distal regulatory elements as shown in Capture-C experiments. Our data document that EBV’s lytic cycle induces discrete early processes that disrupt the architecture of host cellular chromatin and repress the cellular epigenome and transcriptome likely supporting the efficient de novo synthesis of this herpes virus.

Adoptive T cell therapy (ACT) is highly effective in the treatment of hematologic malignancies, but shows limited success in solid tumors. Inactivation of T cells in the tumor milieu is a major hurdle to a wider application of ACT. Cytotoxicity is the most relevant activity for tumor eradication. Here, we document that cytotoxic T cells (CTL) in lactic acidosis exhibited strongly reduced tumor cell killing, which could be compensated partly by increasing the CTL to tumor cell ratio. Lactic acid intervened at multiple steps of the killing process. Lactic acid repressed the number of CTL that performed lytic granule exocytosis (degranulation) in tumor cell co-culture, and, additionally impaired the quality of the response, as judged by the reduced intensity of degranulation and lower secretion of cytotoxins (perforin, granzyme B, granzyme A). CTL in lactic acid switched to a low bioenergetic profile with an inability to metabolize glucose efficiently. They responded to anti-CD3 stimulation poorly with less extracellular acidification rate (ECAR). This might explain their repressed granule exocytosis activity. Using live cell imaging, we show that CTL in lactic acid have reduced motility, resulting in lower field coverage. Many CTL in lactic acidosis did not make contact with tumor cells; however, those which made contact, adhered to the tumor cell much longer than a CTL in normal medium. Reduced motility together with prolonged contact duration hinders serial killing, a defining feature of killing potency, but also locally confines cytotoxic activity, which helps to reduce the risk of collateral organ damage. These activities define lactic acid as a major signaling molecule able to orchestrate the spatial distribution of CTL inside inflamed tissue, such as cancer, as well as moderating their functional response. Lactic acid intervention and strategies to improve T cell metabolic fitness hold promise to improve the clinical efficacy of T cell–based cancer immunotherapy.

End-binding proteins (EBs) are adaptors that recruit functionally diverse microtubule plus-end-tracking proteins (+TIPs) to growing microtubule plus ends. To test with high spatial and temporal accuracy how, when and where + TIP complexes contribute to dynamic cell biology, we developed a photo-inactivated EB1 variant (pi-EB1) by inserting a blue-light-sensitive protein-protein interaction module between the microtubule-binding and + TIP-binding domains of EB1 pi-EB1 replaces endogenous EB1 function in the absence of blue light. By contrast, blue-light-mediated pi-EB1 photodissociation results in rapid + TIP complex disassembly, and acutely and reversibly attenuates microtubule growth independent of microtubule end association of the microtubule polymerase CKAP5 (also known as ch-TOG and XMAP215). Local pi-EB1 photodissociation allows subcellular control of microtubule dynamics at the second and micrometre scale, and elicits aversive turning of migrating cancer cells. Importantly, light-mediated domain splitting can serve as a template to optically control other intracellular protein activities.

Purpose Demand for service convenience, defined as a consumer’s perception of minimized time and effort spent to obtain a service, has increased in conjunction with certain sociocultural and demographic changes. Previous research notes the significance of service convenience, but the importance of different dimensions of service convenience and the role of key moderators affecting the link between convenience and satisfaction (like customer psychographic and sociodemographic characteristics) remain unaddressed. Thus, the purpose of this research is to identify those customer groups for which offering convenience will have the highest leverage to increase satisfaction. Design/methodology/approach Two models are developed and tested: a multidimensional model of service convenience with a formative measure of five service convenience dimensions, namely, decision, access, search, transaction and after-sales convenience, and a moderator model hypothesizing different customer psychographic and sociodemographic characteristics (time pressure, shopping enjoyment, age, household size and income) that affect the link between service convenience and satisfaction. Findings This study reveals that search convenience, followed by transaction and decision convenience, exerts the greatest influence on the perception of overall service convenience. In addition, those who value service convenience most are high-income, time-pressed consumers in smaller households who experience low shopping enjoyment. Originality/value Providers have limited budgets for enhancing their services. Thus, it is important to identify which dimension has the greatest influence on the perception of service convenience and the customer segments for which service convenience is most critical.

Summary Many microtubule (MT) functions are mediated by a diverse class of proteins (+TIPs) at growing MT plus ends that control intracellular MT interactions and dynamics and depend on end-binding proteins (EBs) [1]. Cryoelectron microscopy has recently identified the EB binding site as the interface of four tubulin dimers that undergoes a conformational change in response to β-tubulin GTP hydrolysis [2, 3]. Doublecortin (DCX), a MT-associated protein (MAP) required for neuronal migration during cortical development [4, 5], binds to the same site as EBs [6], and recent in vitro studies proposed DCX localization to growing MT ends independent of EBs [7]. Because this conflicts with observations in neurons [8, 9] and the molecular function of DCX is not well understood, we revisited intracellular DCX dynamics at low expression levels. Here, we report that DCX is not a +TIP in cells but, on the contrary, is excluded from the EB1 domain. In addition, we find that DCX-MT interactions are highly sensitive to MT geometry. In cells, DCX binding was greatly reduced at MT segments with high local curvature. Remarkably, this geometry-dependent binding to MTs was completely reversed in the presence of taxanes, which reconciles incompatible observations in cells [9] and in vitro [10]. We propose a model explaining DCX specificity for different MT geometries based on structural changes induced by GTP hydrolysis that decreases the spacing between adjacent tubulin dimers [11]. Our data are consistent with a unique mode of MT interaction in which DCX specifically recognizes this compacted GDP-like MT lattice.

Regulated intramembrane proteolysis (RIP) is a key mechanism for activating transmembrane proteins such as epithelial cell adhesion molecule (EpCAM) for cellular signaling and degradation. EpCAM is highly expressed in carcinomas and progenitor and embryonic stem cells and is involved in the regulation of cell adhesion, proliferation, and differentiation. Strictly sequential cleavage of EpCAM through RIP involves initial shedding of the extracellular domain by α-secretase (ADAM) and β-secretase (BACE) sheddases, generating a membrane-tethered C-terminal fragment EpCTF. Subsequently, the rate-limiting γ-secretase complex catalyzes intramembrane cleavage of EpCTF, generating an extracellular EpCAM-Aβ–like fragment and an intracellular EpICD fragment involved in nuclear signaling. Here, we have combined biochemical approaches with live-cell imaging of fluorescent protein tags to investigate the kinetics of γ-secretase–mediated intramembrane cleavage of EpCTF. We demonstrate that γ-secretase–mediated proteolysis of exogenously and endogenously expressed EpCTF is a slow process with a 50% protein turnover in cells ranging from 45 min to 5.5 h. The slow cleavage was dictated by γ-secretase activity and not by EpCTF species, as indicated by cross-species swapping experiments. Furthermore, both human and murine EpICDs generated from EpCTF by γ-secretase were degraded efficiently (94–99%) by the proteasome. Hence, proteolytic cleavage of EpCTF is a comparably slow process, and EpICD generation does not appear to be suited for rapidly transducing extracellular cues into nuclear signaling, but appears to provide steady signals that can be further controlled through efficient proteasomal degradation. Our approach provides an unbiased bioassay to investigate proteolytic processing of EpCTF in single living cells.

© 2015 Elsevier Inc. CRISPR-based technologies have emerged as powerful tools to alter genomes and mark chromosomal loci, but an inexpensive method for generating large numbers of RNA guides for whole genome screening and labeling is lacking. Using a method that permits library construction from any source of DNA, we generated guide libraries that label repetitive loci or a single chromosomal locus in Xenopus egg extracts and show that a complex library can target the E.coli genome at high frequency. Lane etal. utilize an enzymatic approach capable of generating complex libraries from any source of DNA termed CRISPR-EATING (Everything Available Turned Into New Guides) to image single loci in egg extract and generate a complex library densely targeting the E.coli genome.

Neural stem and progenitor cells in the developing cerebral cortex, but also when grown in culture, display a range of distinct phenomena during cytokinesis. Cleavage furrow ingression in neural progenitor cells can bisect their basal processes and, later on, result in midbody formation at the apical surface. After abscission, these midbodies are released as membrane-bound particles into the extracellular space, in contrast to uptake and degradation of postabscission midbodies in other cell types. Whether these cellular dynamics are unique to neural stem cells, or more ubiquitously found, and what biological significance these processes have for cell differentiation or cell-cell communication, are open questions that require a combination of approaches. Here, we discuss techniques to study the specific membrane dynamics underlying the basal process splitting and postabscission midbody release in neural stem cells. We provide some basic concepts and protocols to isolate, enrich and stain released midbodies, and follow midbody dynamics over time. Moreover, we discuss techniques to prepare cortical sections for high-voltage electron microscopy to visualize the fine basal processes of progenitor cells.

Turnover of integrin-based focal adhesions (FAs) with the extracellular matrix (ECM) is essential for coordinated cell movement. In collectively migrating human keratinocytes, FAs assemble near the leading edge, grow and mature as a result of contractile forces and disassemble underneath the advancing cell body. We report that clustering of microtubule-associated CLASP1 and CLASP2 proteins around FAs temporally correlates with FA turnover. CLASPs and LL5β (also known as PHLDB2), which recruits CLASPs to FAs, facilitate FA disassembly. CLASPs are further required for FA-associated ECM degradation, and matrix metalloprotease inhibition slows FA disassembly similarly to CLASP or PHLDB2 (LL5β) depletion. Finally, CLASP-mediated microtubule tethering at FAs establishes an FA-directed transport pathway for delivery, docking and localized fusion of exocytic vesicles near FAs. We propose that CLASPs couple microtubule organization, vesicle transport and cell interactions with the ECM, establishing a local secretion pathway that facilitates FA turnover by severing cell-matrix connections.

Skin wound healing in mammals is a complex, multicellular process that depends on the precise supply of oxygen. Hypoxia-inducible factor (HIF) prolyl hydroxylase 2 (PHD2) serves as a crucial oxygen sensor and may therefore play an important role during reepithelialization. Hence, this study was aimed at understanding the role of PHD2 in cutaneous wound healing using different lines of conditionally deficient mice specifically lacking PHD2 in inflammatory, vascular, or epidermal cells. Interestingly, PHD2 deficiency only in keratinocytes and not in myeloid or endothelial cells was found to lead to faster wound closure, which involved enhanced migration of the hyperproliferating epithelium. We demonstrate that this effect relies on the unique expression of β3-integrin in the keratinocytes around the tip of the migrating tongue in an HIF1α-dependent manner. Furthermore, we show enhanced proliferation of these cells in the stratum basale, which is directly related to their attenuated transforming growth factor β signaling. Thus, loss of the central oxygen sensor PHD2 in keratinocytes stimulates wound closure by prompting skin epithelial cells to migrate and proliferate. Inhibition of PHD2 could therefore offer novel therapeutic opportunities for the local treatment of cutaneous wounds.

Around a century ago, the midbody (MB) was described as a structural assembly within the intercellular bridge during cytokinesis that served to connect the two future daughter cells. The MB has become the focus of intense investigation through the identification of a growing number of diverse cellular and molecular pathways that localize to the MB and contribute to its cytokinetic functions, ranging from selective vesicle trafficking and regulated microtubule (MT), actin, and endosomal sorting complex required for transport (ESCRT) filament assembly and disassembly to post-translational modification, such as ubiquitination. More recent studies have revealed new and unexpected functions of MBs in post-mitotic cells. In this review, we provide a historical perspective, discuss exciting new roles for MBs beyond their cytokinetic function, and speculate on their potential contributions to pluripotency.

Our empirical research investigates the impact of dimensions of shopping convenience (decision, access, search, transaction, and after-sales convenience) on customer retention, including customer behavioral loyalty (shares of wallet and visits) and attitudinal loyalty (exit intention). Our findings show that for utilitarian shopping, behavioral and attitudinal loyalty are partly affected by different dimensions. Decision and access convenience, dimensions that come into play prior to the purchase, are most important for share of visits and share of wallet. Apart from decision convenience, exit intention is very much affected by transaction convenience, which is an in-store dimension. Furthermore, comparing our results with results of hedonic shopping purposes shows that major differences exist.

SummaryA fundamental question in development is how cells assemble to form a tubular network during organ formation. In glandular organs, tubulogenesis is a multistep process requiring coordinated proliferation, polarization and reorganization of epithelial cells to form a lumen, and lumen expansion. Although it is clear that epithelial cells possess an intrinsic ability to organize into polarized structures, the mechanisms coordinating morphogenetic processes during tubulogenesis are poorly understood. Here, we demonstrate that parasympathetic nerves regulate tubulogenesis in the developing salivary gland. We show that vasoactive intestinal peptide (VIP) secreted by the innervating ganglia promotes ductal growth, leads to the formation of a contiguous lumen, and facilitates lumen expansion through a cyclic AMP/protein kinase A (cAMP/PKA)-dependent pathway. Furthermore, we provide evidence that lumen expansion is independent of apoptosis and involves the cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-regulated Cl(−) channel. Thus, parasympathetic innervation coordinates multiple steps in tubulogenesis during organogenesis.

Today's regulatory demands are providing incentives for cost reductions to network operators in Germany and several other countries. If no corrective measures are taken by national regulation authorities (NRA), this could result in a reduction of costs at the expense of quality of supply. Thus, in 2011 the German NRA has implemented a quality regulation scheme which incentivizes network operators to integrate aspects of quality of supply in their considerations of cost reductions. This paper presents an approach which calculates the impact of changes of network asset and of operational service staff on the reliability of distribution systems. The approach uses a detailed reliability model to display the network structure, network equipment and customers' loads in order to determine failure events, the respective remedial strategy and the impact on quality of supply. Furthermore, a detailed model of the network operators' organizational structure and operational service staff is used. The effects of changes in operational expenditures (OPEX) and capital expenditures (CAPEX) on the quality of supply can be analyzed individually per customer as well as system-wide. Thus, it is possible to discover weaknesses in the network structure and the organization of service staff. This approach allows network operators to determine the effects of foreseen measures on quality of supply before implementing time-consuming and expensive projects in network and organization.

Today's regulatory demands are providing strong incentives for cost reduction to network operators. If no corrective measures are taken by national regulation authorities (NRA) a substantial negative effect can occur: A reduction of costs at the expense of the customers' quality of supply. To prevent this, in 2012 the German NRA has implemented a quality regulation scheme, so that network operators are forced to integrate aspects of quality of supply in their considerations of cost reductions. This paper presents an approach which allows the simultaneous simulation of network asset and operational service staff to quantify their impacts on quality of supply. A detailed model of the network structure is used to determine failure events and the respective remedial strategy and the impact on customers' demands. A detailed organization model displays the distribution system operators' organizational structure and its employees. Thus, it is possible to discover strengths and weaknesses in the network structure and the organization of service staff simultaneously in one model. The focus of this paper is to present the additional value the reliability calculation gains by the extensive simulation of network operators' organization and the corresponding operational service staff.

Engro Fertilizer and Siemens PTI jointly completed a study on the supply reliability situation and on the asset management process in Engro Fertilizer's Daharki (Pakistan) plant. This project complemented earlier projects on, e.g., the overall design and the dynamic performance of the captive generation units in this industrial power supply system. Probabilistic reliability calculations validated that the reliability level throughout the plant is adequate and rather constant. A few individual exceptions are well-known to the operators and covered by explicit processes and measures. Also the asset management process was reviewed from the perspective of the plant's overall reliability performance, and the development plans existing with Engro Fertilizer were confirmed. For certain individual assets or groups of assets, the investigations indicated the need for faster implementation in order to maintain the required risk levels for the plant's operation. (4 pages)

Coordination of multiple kinesin and myosin motors is required for intracellular transport, cell motility and mitosis. However, comprehensive resources that allow systems analysis of the localization and interplay between motors in living cells do not exist. Here, we generated a library of 243 amino- and carboxy-terminally tagged mouse and human bacterial artificial chromosome transgenes to establish 227 stably transfected HeLa cell lines, 15 mouse embryonic stem cell lines and 1 transgenic mouse line. The cells were characterized by expression and localization analyses and further investigated by affinity-purification mass spectrometry, identifying 191 candidate protein-protein interactions. We illustrate the power of this resource in two ways. First, by characterizing a network of interactions that targets CEP170 to centrosomes, and second, by showing that kinesin light-chain heterodimers bind conventional kinesin in cells. Our work provides a set of validated resources and candidate molecular pathways to investigate motor protein function across cell lineages.

In scope of this paper, the question of how to optimally utilize, dimension and allocate a battery storage unit (BSU) has been briefly addressed. Based on a novel generic BSU model, three main application fields of BSU are explored: market arbitrage, renewable firming, and network support. Main obstacles of modelling and simulation are identified in the process, and practical solution and applicable examples are analyzed to address these topics. (4 pages)

With an increasing number of electric vehicles in operation new requirements on the electrical power networks will occur. Currently these networks are designed to supply on average a typical household load of around 2 kW. If electric vehicles will be connected then this household load might, depending on simultaneity of charging process and charging power, increase to more than 10 kW causing overloading of elements such as lines. On the other hand the storage capacity of the car battery allows providing new services to the networks, like balancing power for increasing shares of stochastically variable generation by renewable energy sources.

This paper describes the application of a probabilistic reliability calculation method to a countrywide transmission network in an actual case study. The calculation method and certain general aspects of reliability analyses in the transmission level are presented at first. The case study is introduced, and special considerations on defining suitable parameters for the Markov-based calculation algorithm are discussed. The main results of the reliability analysis are summarized, and an updated scenario of the system verifies selected improvements derived from these results.