131 research outputs found

    Achieving Efficient and Realistic Full-Radar Simulations and Automatic Data Annotation by Exploiting Ray Meta Data from a Radar Ray Tracing Simulator

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    In this work, a novel radar simulation concept for efficiently simulating realistic radar data for range, Doppler, and arbitrary antenna positions is introduced. With the concept, the simulated radar signal can also be automatically annotated by splitting it into multiple parts. Annotations that are almost perfect - including the annotation of exotic effects, such as multi-path - can be produced with this approach. Signal parts originating from different parts of an object can be labelled with it as well. To this end, the computation process used in a Monte Carlo shooting and bouncing rays (SBR) simulator is adapted. By considering the hits of each simulated ray, various meta data can be stored, such as hit position, mesh pointer, object IDs, and many more. This collected meta data can then be utilized to predict path-length changes caused by object motion to obtain Doppler information or to apply specific ray filter rules to obtain radar signals that only fulfil specific conditions, such as multiple bounces, or signals that contain specific object IDs. Using this approach, perfect, and otherwise almost impossible, annotation schemes can be realized

    A virally encoded de-sumoylase activity is required for cytomegalovirus reactivation from latency

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    A subset of viral genes is required for the long term latent infection of haematopoietic cells by human cytomegalovirus (HCMV). Here we show that a latency-associated gene product (LUNA) promotes the disruption of cellular PML bodies during latency. Mutation and inhibitor studies reveal that LUNA encodes a novel de-sumoylase activity responsible for this disruption. Specifically, LUNA activity expressed a conserved Asp-Cys-Gly motif common to all de-sumoylases. Importantly, mutation of the putative catalytic cysteine was sufficient to reverse LUNA mediated PML dispersal and markedly reduced the efficiency of viral reactivation. The depletion of PML from cells was sufficient to rescue the reactivation of the LUNA-deficient viruses arguing that targeting PML was an important biological role of LUNA. Finally, we demonstrate that reactivation of naturally latent HCMV is blocked by de-sumoylase inhibitors. Thus latent HCMV primes the cellular environment for efficient reactivation via the activity of a virally encoded de-sumoylas

    Highly conserved interaction profiles between clinically relevant mutants of the cytomegalovirus CDK-like kinase pUL97 and human cyclins: functional significance of cyclin H

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    The complex host interaction network of human cytomegalovirus (HCMV) involves the regulatory protein kinase pUL97, which represents a viral cyclin-dependent kinase (CDK) ortholog. pUL97 interacts with the three human cyclin types T1, H, and B1, whereby the binding region of cyclin T1 and the pUL97 oligomerization region were both assigned to amino acids 231-280. We further addressed the question of whether HCMVs harboring mutations in ORF-UL97, i.e., short deletions or resistance-conferring point mutations, are affected in the interaction with human cyclins and viral replication. To this end, clinically relevant UL97 drug-resistance-conferring mutants were analyzed by whole-genome sequencing and used for genetic marker transfer experiments. The recombinant HCMVs indicated conservation of pUL97-cyclin interaction, since all viral UL97 point mutants continued to interact with the analyzed cyclin types and exerted wild-type-like replication fitness. In comparison, recombinant HCMVs UL97 Δ231-280 and also the smaller deletion Δ236-275, but not Δ241-270, lost interaction with cyclins T1 and H, showed impaired replication efficiency, and also exhibited reduced kinase activity. Moreover, a cellular knock-out of cyclins B1 or T1 did not alter HCMV replication phenotypes or pUL97 kinase activity, possibly indicating alternative, compensatory pUL97-cyclin interactions. In contrast, however, cyclin H knock-out, similar to virus deletion mutants in the pUL97-cyclin H binding region, exhibited strong defective phenotypes of HCMV replication, as supported by reduced pUL97 kinase activity in a cyclin H-dependent coexpression setting. Thus, cyclin H proved to be a very relevant determinant of pUL97 kinase activity and viral replication efficiency. As a conclusion, the results provide evidence for the functional importance of pUL97-cyclin interaction. High selective pressure on the formation of pUL97-cyclin complexes was identified by the use of clinically relevant mutants

    Cyclin-Dependent Kinase Activity Controls the Onset of the HCMV Lytic Cycle

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    The onset of human cytomegalovirus (HCMV) lytic infection is strictly synchronized with the host cell cycle. Infected G0/G1 cells support viral immediate early (IE) gene expression and proceed to the G1/S boundary where they finally arrest. In contrast, S/G2 cells can be infected but effectively block IE gene expression and this inhibition is not relieved until host cells have divided and reentered G1. During latent infection IE gene expression is also inhibited, and for reactivation to occur this block to IE gene expression must be overcome. It is only poorly understood which viral and/or cellular activities maintain the block to cell cycle or latency-associated viral IE gene repression and whether the two mechanisms may be linked. Here, we show that the block to IE gene expression during S and G2 phase can be overcome by both genotoxic stress and chemical inhibitors of cellular DNA replication, pointing to the involvement of checkpoint-dependent signaling pathways in controlling IE gene repression. Checkpoint-dependent rescue of IE expression strictly requires p53 and in the absence of checkpoint activation is mimicked by proteasomal inhibition in a p53 dependent manner. Requirement for the cyclin dependent kinase (CDK) inhibitor p21 downstream of p53 suggests a pivotal role for CDKs in controlling IE gene repression in S/G2 and treatment of S/G2 cells with the CDK inhibitor roscovitine alleviates IE repression independently of p53. Importantly, CDK inhibiton also overcomes the block to IE expression during quiescent infection of NTera2 (NT2) cells. Thus, a timely block to CDK activity not only secures phase specificity of the cell cycle dependent HCMV IE gene expression program, but in addition plays a hitherto unrecognized role in preventing the establishment of a latent-like state

    Scenario Analysis as a Tool for Informing the Design of Behaviour Change Interventions

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    This article presents the design process behind the specification of a behaviour change intervention method to promote energy saving. The amount of energy used for food preparation is highly influenced by people’s behaviours. A user-centred design approach based on scenario analysis was applied to provide understanding of context of use and specification of user requirements. This knowledge was applied to the design of behaviour change interventions to motivate sustainable behaviours

    Minor groove contacts are essential for an interaction of the human cytomegalovirus IE2 protein with its DNA target.

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    The 86 kDa immediate early-2 protein (IE2, IE86) of human cytomegalovirus (HCMV) is a multifunctional polypeptide that can regulate gene expression both positively and negatively. In particular, it represses its own mRNA synthesis by binding directly to a sequence element, termed cis repression signal (CRS), that is located between the TATA box and the transcriptional start site of the major IE enhancer/promoter of HCMV. Here, we provide evidence that IE86, unlike most sequence-specific DNA-binding proteins, interacts primarily within the minor groove of the DNA helix. This was shown by hydroxyl radical and methylation interference assays. In addition, binding studies with inosine-substituted oligonucleotides which have an altered major groove morphology without changing the surface of the minor groove, confirmed the results obtained in interference analyses. This establishes IE86 as a member of a small group of DNA binding proteins that interact with A - T rich sequences within the minor groove and which also includes the TATA-box binding protein TBP. Remarkably, IE86 and TBP are able to bind simultaneously in an immediate vicinity at the major IE enhancer/promoter of HCMV. As minor groove binding proteins are known to bend DNA heavily this could contribute to the observed negative regulation of transcription by IE86
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