Abstract 2524: Critical interactions and tumor-specific mutations of Bcl-2 transmembrane domains revealed by a novel split luciferase assay

In intrinsic apoptosis, the interaction network of the Bcl-2 protein family controls the decision over life and death. Cells are sentenced to death when pro-apoptotic multidomain effector proteins BAX, BAK or BOK oligomerize and form pores in the mitochondrial outer membrane. This releases cytochrome c, which induces the activation of cell-wrecking proteases, the caspases. Interactions of Bcl-2 proteins with other family members essentially regulate cell death. The interaction via the BH3 region was intensively studied in the last decades. As a result, small-molecule drugs, BH3-mimetics, were developed which bind and inhibit anti-apoptotic Bcl-2 proteins. Since anti-apoptotic Bcl-2 proteins are often overexpressed in hematopoietic malignancies, BH3-mimetics e.g. Venetoclax are approved for anti-cancer therapy. Unlike the BH3 interaction site, the c-terminal α9-helix referred to as the transmembrane domain (TMD) is mostly neglected in Bcl-2 interaction studies. However, TMDs not only dictate subcellular localization, but also substantially influence protein-protein interactions. Interestingly, Bcl-2 TMDs can harbor several tumor-specific mutations. The functional basis for TMD interaction as well as the resulting functional relevance for apoptosis signaling, however, remains poorly understood. To unravel the Bcl-2 TMD interaction network, we developed a split luciferase assay system enabling us to detect Bcl-2 TMD interactions in living cells. Simultaneously encoding for the expression of a fluorophore and TMD fusion peptides this system was used to generate fluorescence-normalized luminescence-based interaction data. Here, we identified a homotypic interaction pattern among effector TMDs of BAX, BAK and BOK. Molecular modelling of effector TMD interaction in mimics of cellular membranes also supports these findings. TMD swap experiments show significant influence of TMD sequence on subcellular localization and cell death signaling as assessed via confocal laser scanning microscopy and flow cytometry-based cell death assays. Moreover, we tested previously described mutations of the BAX-TMD (S184A, S184D) as well as a tumor-specific mutation (V180G) in the novel interaction assay. S184 (de-)phosphorylation as mimicked with S184A/S184D affects subcellular localization. In accordance, we find that S184A enhanced and S184D abolished interaction with wildtype BAX-TMD. Intriguingly, V180G not only modulates BAX subcellular localization but also prevents interaction with wildtype BAX-TMD. These findings verify a crucial role of Bcl-2 TMDs in subcellular localization and furthermore strongly support a function in interaction and cell death regulation. Further efforts to explore the Bcl-2 TMD interaction network as well as functional analysis of tumor-specific TMD mutations could pave the way to establish TMDs as a target of cancer therapy.

Citation Format: Tobias B. Beigl, Alexander Paul, Sandra Weller, Benjamin Schäfer, Walter E. Aulitzky, Hans-Georg Kopp, Thomas Fellmeth, Kristyna Pluhackova, Markus Rehm, Frank Essmann. Critical interactions and tumor-specific mutations of Bcl-2 transmembrane domains revealed by a novel split luciferase assay [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2524.

Lockdown Effects on Air Quality in Megacities During the First and Second Waves of COVID-19 Pandemic

Air pollution is among the highest contributors to mortality worldwide, especially in urban areas. During spring 2020, many countries enacted social distancing measures in order to slow down the ongoing COVID-19 pandemic. A particularly drastic measure, the “lockdown”, urged people to stay at home and thereby prevent new COVID-19 infections during the first (2020) and second wave (2021) of the pandemic. In turn, it also reduced traffic and industrial activities. But how much did these lockdown measures improve air quality in large cities, and are there differences in how air quality was affected? Here, we analyse data from two megacities: London as an example for Europe and Delhi as an example for Asia. We consider data during first and second-wave lockdowns and compare them to 2019 values. Overall, we find a reduction in almost all air pollutants with intriguing differences between the two cities except Delhi in 2021. In London, despite smaller average concentrations, we still observe high-pollutant states and an increased tendency towards extreme events (a higher kurtosis of the probability density during lockdown) during 2020 and low pollution levels during 2021. For Delhi, we observe a much stronger decrease in pollution concentrations, including high pollution states during 2020 and higher pollution levels in 2021. These results could help to design policies to improve long-term air quality in megacities.

Understanding Braess’ Paradox in power grids

The ongoing energy transition requires power grid extensions to connect renewable generators to consumers and to transfer power among distant areas. The process of grid extension requires a large investment of resources and is supposed to make grid operation more robust. Yet, counter-intuitively, increasing the capacity of existing lines or adding new lines may also reduce the overall system performance and even promote blackouts due to Braess’ paradox. Braess’ paradox was theoretically modeled but not yet proven in realistically scaled power grids. Here, we present an experimental setup demonstrating Braess’ paradox in an AC power grid and show how it constrains ongoing large-scale grid extension projects. We present a topological theory that reveals the key mechanism and predicts Braessian grid extensions from the network structure. These results offer a theoretical method to understand and practical guidelines in support of preventing unsuitable infrastructures and the systemic planning of grid extensions.

Spatial heterogeneity of air pollution statistics in Europe

Air pollution is one of the leading causes of death globally, and continues to have a detrimental effect on our health. In light of these impacts, an extensive range of statistical modelling approaches has been devised in order to better understand air pollution statistics. However, the time-varying statistics of different types of air pollutants are far from being fully understood. The observed probability density functions (PDFs) of concentrations depend very much on the spatial location and on the pollutant substance. In this paper, we analyse a large variety of data from 3544 different European monitoring sites and show that the PDFs of nitric oxide (NO), nitrogen dioxide ([Formula: see text]) and particulate matter ([Formula: see text] and [Formula: see text]) concentrations generically exhibit heavy tails and are asymptotically well approximated by q-exponential distributions with a given width parameter [Formula: see text]. We observe that the power-law parameter q and the width parameter [Formula: see text] vary widely for the different spatial locations. For each substance, we find different patterns of parameter clouds in the [Formula: see text] plane. These depend on the type of pollutants and on the environmental characteristics (urban/suburban/rural/traffic/industrial/background). This means the effective statistical physics description of air pollution exhibits a strong degree of spatial heterogeneity.

Abstract 3704: The C-terminal transmembrane domain of BAX is essential for BAX auto-inhibition

Apoptosis is a complex and highly regulated cellular suicide program culminating in a caspase-dependent self-destruction. As a critical step of intrinsic apoptosis, pro-apoptotic effector Bcl-2 proteins BAX, BAK and BOK form pores in the mitochondrial outer membrane (MOM) which causes Cytochrome C release, followed by caspase-activation and ultimately cell death. In contrast to BAK and BOK, BAX mainly resides in the cytosol and translocates to mitochondria when activated by pro-apoptotic signals. During activation and translocation, BAX undergoes conformational changes including dislodging of the c-terminal α-9 helix from the hydrophobic groove and insertion in the MOM. Most studies concerning BAX activation focus on the interaction of the BH3 domain and the hydrophobic groove, which is essential for BAX inhibition by members of the Bcl-2 family. In contrast, how modifications of the α-9 transmembrane domain (TMD) can impair BAX inhibition and membrane insertion remains understudied so far, so that functional roles of the TMD in BAX activation and translocation are yet to be defined. To determine the role of the BAX-TMD in activation and translocation, we generated several plasmids encoding for BAX chimeras in which the original BAX-TMD sequence was swapped for TMDs of other Bcl-2 proteins. The chimeric BAX proteins were expressed in human cell lines and cell death as well as protein localisation was investigated. Surprisingly, we found that swapping the BAX-TMD for another effector TMD increases BAX pro-apoptotic activity assessed via Annexin-V staining and flow cytometry. In addition, confocal microscopy revealed that BAX shows an increased tendency to mitochondrial localisation and oligomerisation when bearing TMDs of BAK or BOK. Interestingly, co-expressed anti-apoptotic BCL-2 an antagonistic binding-partner of BAX co-localises with BAX chimeras but poorly prevents cell death induced by the BAX chimera with the BAK-TMD. These findings strongly support a crucial regulatory role of the BAX-TMD in activation and translocation. In fact, the increased apoptotic potential of the BAX-TMD chimeras as well as augmented mitochondrial localisation suggest an auto-inhibitory function of the BAX-TMD ensured by its affinity to the BAX hydrophobic groove. Moreover, the decreased inhibitory capacity of Bcl-2 for the BAK-TMD-containing BAX chimera could point to an involvement of the BAX-TMD in interaction with BCL-2. In contrast to the archetypical understanding of the TMD as a mere membrane anchor, these results also indicate that the TMD can regulate the activity of BAX and other Bcl-2 family proteins.

Citation Format: Tobias Benjamin Beigl, Sandra Weller, Benjamin Schäfer, Walter Erich Aulitzky, Hans-Georg Kopp, Markus Rehm, Frank Essmann. The C-terminal transmembrane domain of BAX is essential for BAX auto-inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3704.

Revealing drivers and risks for power grid frequency stability with explainable AI

Stable operation of an electric power system requires strict operational limits for the grid frequency. Fluctuations and external impacts can cause large frequency deviations and increased control efforts. Although these complex interdependencies can be modeled using machine learning algorithms, the black box character of many models limits insights and applicability. In this article, we introduce an explainable machine learning model that accurately predicts frequency stability indicators for three European synchronous areas. Using Shapley additive explanations, we identify key features and risk factors for frequency stability. We show how load and generation ramps determine frequency gradients, and we identify three classes of generation technologies with converse impacts. Control efforts vary strongly depending on the grid and time of day and are driven by ramps as well as electricity prices. Notably, renewable power generation is central only in the British grid, while forecasting errors play a major role in the Nordic grid.

Fluctuations of water quality time series in rivers follow superstatistics

Superstatistics is a general method from nonequilibrium statistical physics which has been applied to a variety of complex systems, ranging from hydrodynamic turbulence to traffic delays and air pollution dynamics. Here, we investigate water quality time series (such as dissolved oxygen concentrations and electrical conductivity) as measured in rivers and provide evidence that they exhibit superstatistical behavior. Our main example is time series as recorded in the River Chess in South East England. Specifically, we use seasonal detrending and empirical mode decomposition to separate trends from fluctuations for the measured data. With either detrending method, we observe heavy-tailed fluctuation distributions, which are well described by log-normal superstatistics for dissolved oxygen. Contrarily, we find a double peaked non-standard superstatistics for the electrical conductivity data, which we model using two combinedχ 2 -distributions.

Statistical characterization of airplane delays

The aviation industry is of great importance for a globally connected economy. Customer satisfaction with airlines and airport performance is considerably influenced by how much flights are delayed. But how should the delay be quantified with thousands of flights for each airport and airline? Here, we present a statistical analysis of arrival delays at several UK airports between 2018 and 2020. We establish a procedure to compare both mean delay and extreme events among airlines and airports, identifying a power-law decay of large delays. Furthermore, we note drastic changes in plane delay statistics during the COVID-19 pandemic. Finally, we find that delays are described by a superposition of simple distributions, leading to a superstatistics.

Open database analysis of scaling and spatio-temporal properties of power grid frequencies

The electrical energy system has attracted much attention from an increasingly diverse research community. Many theoretical predictions have been made, from scaling laws of fluctuations to propagation velocities of disturbances. However, to validate any theory, empirical data from large-scale power systems are necessary but are rarely shared openly. Here, we analyse an open database of measurements of electric power grid frequencies across 17 locations in 12 synchronous areas on three continents. The power grid frequency is of particular interest, as it indicates the balance of supply and demand and carries information on deterministic, stochastic, and control influences. We perform a broad analysis of the recorded data, compare different synchronous areas and validate a previously conjectured scaling law. Furthermore, we show how fluctuations change from local independent oscillations to a homogeneous bulk behaviour. Overall, the presented open database and analyses constitute a step towards more shared, collaborative energy research.

Power grid frequencies mirror the state of the grid. Here, Rydin Gorjão et al. analyse measurements of power grid frequencies across areas and continents and uncover scaling laws of their fluctuations and spatio-temporal dynamics, which could aid the design, operation and control of power systems.

Multilayer modeling of adoption dynamics in energy demand management

Due to the emergence of new technologies, the whole electricity system is undergoing transformations on a scale and pace never observed before. The decentralization of energy resources and the smart grid have forced utility services to rethink their relationships with customers. Demand response (DR) seeks to adjust the demand for power instead of adjusting the supply. However, DR business models rely on customer participation and can only be effective when large numbers of customers in close geographic vicinity, e.g., connected to the same transformer, opt in. Here, we introduce a model for the dynamics of service adoption on a two-layer multiplex network: the layer of social interactions among customers and the power-grid layer connecting the households. While the adoption process-based on peer-to-peer communication-runs on the social layer, the time-dependent recovery rate of the nodes depends on the states of their neighbors on the power-grid layer, making an infected node surrounded by infectious ones less keen to recover. Numerical simulations of the model on synthetic and real-world networks show that a strong local influence of the customers' actions leads to a discontinuous transition where either none or all the nodes in the network are infected, depending on the infection rate and social pressure to adopt. We find that clusters of early adopters act as points of high local pressure, helping maintaining adopters, and facilitating the eventual adoption of all nodes. This suggests direct marketing strategies on how to efficiently establish and maintain new technologies such as DR schemes.

Wind Power Persistence Characterized by Superstatistics

Mitigating climate change demands a transition towards renewable electricity generation, with wind power being a particularly promising technology. Long periods either of high or of low wind therefore essentially define the necessary amount of storage to balance the power system. While the general statistics of wind velocities have been studied extensively, persistence (waiting) time statistics of wind is far from well understood. Here, we investigate the statistics of both high- and low-wind persistence. We find heavy tails and explain them as a superposition of different wind conditions, requiring q-exponential distributions instead of exponential distributions. Persistent wind conditions are not necessarily caused by stationary atmospheric circulation patterns nor by recurring individual weather types but may emerge as a combination of multiple weather types and circulation patterns. This also leads to Fréchet instead of Gumbel extreme value statistics. Understanding wind persistence statistically and synoptically may help to ensure a reliable and economically feasible future energy system, which uses a high share of wind generation.

[Acute perioperative right heart insufficiency : Diagnostics and treatment]

Acute right heart failure is often overlooked as a cause of cardiopulmonary insufficiency. The various pathologies underlying right heart failure at the level of afterload, preload and contractility, make rapid, targeted diagnostics necessary. In addition to clinical symptoms and laboratory chemical parameters, echocardiography in particular is relevant for making a diagnosis. Symptomatic treatment of the endangered patient is essential. The focus is on a reduction of right ventricular pressure and afterload, a correction of systemic hypotension and positive inotropic support of the right ventricle. Mechanical organ replacement and support procedures are increasingly being used in the case of persistent right heart failure and expand the possibilities for treatment. Decisive for the prognosis is a causal treatment adapted to the underlying triggering disease.

Dynamical modeling of cascading failures in the Turkish power grid

A reliable supply of electricity is critical for our modern society, and any large-scale disturbance of the electrical system causes substantial costs. In 2015, one overloaded transmission line caused a cascading failure in the Turkish power grid, affecting about 75×10⁶ people. Here, we analyze the Turkish power grid and its dynamical and statistical properties. Specifically, we propose, for the first time, a model that incorporates the dynamical properties and the complex network topology of the Turkish power grid to investigate cascading failures. We find that the network damage depends on the load and generation distribution in the network with centralized generation being more susceptible to failures than a decentralized one. Furthermore, economic considerations on transmission line capacity are shown to conflict with stability.

Dynamically induced cascading failures in power grids

Reliable functioning of infrastructure networks is essential for our modern society. Cascading failures are the cause of most large-scale network outages. Although cascading failures often exhibit dynamical transients, the modeling of cascades has so far mainly focused on the analysis of sequences of steady states. In this article, we focus on electrical transmission networks and introduce a framework that takes into account both the event-based nature of cascades and the essentials of the network dynamics. We find that transients of the order of seconds in the flows of a power grid play a crucial role in the emergence of collective behaviors. We finally propose a forecasting method to identify critical lines and components in advance or during operation. Overall, our work highlights the relevance of dynamically induced failures on the synchronization dynamics of national power grids of different European countries and provides methods to predict and model cascading failures.

Escape routes, weak links, and desynchronization in fluctuation-driven networks

Shifting our electricity generation from fossil fuel to renewable energy sources introduces large fluctuations to the power system. Here, we demonstrate how increased fluctuations, reduced damping, and reduced intertia may undermine the dynamical robustness of power grid networks. Focusing on fundamental noise models, we derive analytic insights into which factors limit the dynamic robustness and how fluctuations may induce a system escape from an operating state. Moreover, we identify weak links in the grid that make it particularly vulnerable to fluctuations. These results thereby not only contribute to a theoretical understanding of how fluctuations act on distributed network dynamics, they may also help designing future renewable energy systems to be more robust.

Daily changes of individual gait patterns identified by means of support vector machines

Despite the common knowledge about the individual character of human gait patterns and about their non-repeatability, little is known about their stability, their interactions and their changes over time. Variations of gait patterns are typically described as random deviations around a stable mean curve derived from groups, which appear due to noise or experimental insufficiencies. The purpose of this study is to examine the nature of intrinsic inter-session variability in more detail by proving separable characteristics of gait patterns between individuals as well as within individuals in repeated measurement sessions. Eight healthy subjects performed 15 gait trials at a self-selected speed on eight days within two weeks. For each trial, the time-continuous ground reaction forces and lower body kinematics were quantified. A total of 960 gait patterns were analysed by means of support vector machines and the coefficient of multiple correlation. The results emphasise the remarkable amount of individual characteristics in human gait. Support vector machines results showed an error-free assignment of gait patterns to the corresponding individual. Thus, differences in gait patterns between individuals seem to be persistent over two weeks. Within the range of individual gait patterns, day specific characteristics could be distinguished by classification rates of 97.3% and 59.5% for the eight-day classification of lower body joint angles and ground reaction forces, respectively. Hence, gait patterns can be assumed not to be constant over time and rather exhibit discernible daily changes within previously stated good repeatability. Advantages for more individual and situational diagnoses or therapy are identified.

Translation, modification and cellular distribution of two AC4 variants of African cassava mosaic virus in yeast and their pathogenic potential in plants

Plant infecting geminiviruses encode a small (A)C4 protein within the open reading frame of the replication-initiator protein. In African cassava mosaic virus, two in-frame start codons may be used for the translation of a longer and a shorter AC4 variant. Both were fused to green fluorescent protein or glutathione-S-transferase genes and expressed in fission yeast. The longer variant accumulated in discrete spots in the cytoplasm, whereas the shorter variant localized to the plasma membrane. A similar expression pattern was found in plants. A myristoylation motif may promote a targeting of the shorter variant to the plasma membrane. Mass spectrometry analysis of the yeast-expressed shorter variant detected the corresponding myristoylation. The biological relevance of the second start codon was confirmed using mutated infectious clones. Whereas mutating the first start codon had no effect on the infectivity in Nicotiana benthamiana plants, the second start codon proved to be essential.

Integrated multidisciplinary care of headache disorders: A narrative review

Background

Recent evidence shows that multidisciplinary treatment is effective in chronic pain syndromes, especially in headache disorders.

Aim

The aim of this review is to summarize current knowledge on integrative care concepts in headache patients regarding the optimal and necessary treatment parts, optimal duration and setting.

Methods

We present a narrative review reporting current literature and personal experience.

Results and conclusion

Based on current knowledge, multidisciplinary treatment programs appear to be reasonable and efficient in headache disorders. Sufficient controlled studies regarding the need for individual parts of the integrative care approach are missing as yet. Recommendations are therefore at least partly based on personal experiences. It seems to be unambiguous that patients should be referred to a specialized headache center offering such a program instead of being sent sequentially to various medical specialists. The extent and kind of required therapy (e.g. personal consultation versus group sessions) is not known yet. All patients should learn relaxation training, although it is unclear yet which training is the best for which patient. Physiotherapy with guidance on more activity and individual exercises should be used in all patients. Some patients might benefit from cognitive behavioral therapy. However, therapies often depend more on country-specific health care systems than on clinical needs or scientific data.

Properties of African Cassava Mosaic Virus Capsid Protein Expressed in Fission Yeast

The capsid proteins (CPs) of geminiviruses combine multiple functions for packaging the single-stranded viral genome, insect transmission and shuttling between the nucleus and the cytoplasm. African cassava mosaic virus (ACMV) CP was expressed in fission yeast, and purified by SDS gel electrophoresis. After tryptic digestion of this protein, mass spectrometry covered 85% of the amino acid sequence and detected three N-terminal phosphorylation sites (threonine 12, serines 25 and 62). Differential centrifugation of cell extracts separated the CP into two fractions, the supernatant and pellet. Upon isopycnic centrifugation of the supernatant, most of the CP accumulated at densities typical for free proteins, whereas the CP in the pellet fraction showed a partial binding to nucleic acids. Size-exclusion chromatography of the supernatant CP indicated high order complexes. In DNA binding assays, supernatant CP accelerated the migration of ssDNA in agarose gels, which is a first hint for particle formation. Correspondingly, CP shifted ssDNA to the expected densities of virus particles upon isopycnic centrifugation. Nevertheless, electron microscopy did not reveal any twin particles, which are characteristic for geminiviruses.

Photothermal method for absorption measurements in anisotropic crystals

A measurement system for quantitative determination of both surface and bulk contributions to the photo-thermal absorption has been extended to anisotropic optical media. It bases upon a highly sensitive Hartmann-Shack wavefront sensor, accomplishing precise on-line monitoring of wavefront deformations of a collimated test beam transmitted perpendicularly through the laser-irradiated side of a cuboid sample. Caused by the temperature dependence of the refractive index as well as thermal expansion, the initially plane wavefront of the test beam is distorted. Sign and magnitude depend on index change and expansion. By comparison with thermal theory, a calibration of the measurement is possible, yielding a quantitative absolute measure of bulk and surface absorption losses from the transient wavefront distortion. Results for KTP and BBO single crystals are presented.

Light-dependent segregation of begomoviruses in Asystasia gangetica leaves

Asystasia gangetica (Acanthaceae) from tropical Africa and Asia is used as source of food and for medical applications. Plants collected in West Africa in the 1980s with typical geminivirus symptoms showed an unusual symptom segregation that included vein yellowing, curling and mosaic, which were present simultaneously or separately on different leaves of the same plant or on different plants propagated as cuttings from a single plant. Rolling-circle amplification in combination with restriction fragment length polymorphism analysis followed by deep sequencing of the RCA products identified two geminiviruses in these plants. One with a bipartite genome, Asystasia begomovirus 1, and the other with a monopartite genome together with its defective DNA, Asystasia begomovirus 2. The relationship between leaf symptoms and virus distribution under different light regimes was investigated, and showed for the first time an unusual segregation of symptoms and viruses, either within a single plant, or even within a leaf.

The RXL motif of the African cassava mosaic virus Rep protein is necessary for rereplication of yeast DNA and viral infection in plants

Geminiviruses, single-stranded DNA plant viruses, encode a replication-initiator protein (Rep) that is indispensable for virus replication. A potential cyclin interaction motif (RXL) in the sequence of African cassava mosaic virus Rep may be an alternative link to cell cycle controls to the known interaction with plant homologs of retinoblastoma protein (pRBR). Mutation of this motif abrogated rereplication in fission yeast induced by expression of wildtype Rep suggesting that Rep interacts via its RXL motif with one or several yeast proteins. The RXL motif is essential for viral infection of Nicotiana benthamiana plants, since mutation of this motif in infectious clones prevented any symptomatic infection. The cell-cycle link (Clink) protein of a nanovirus (faba bean necrotic yellows virus) was investigated that activates the cell cycle by binding via its LXCXE motif to pRBR. Expression of wildtype Clink and a Clink mutant deficient in pRBR-binding did not trigger rereplication in fission yeast.

Analysis of the oligomeric state and transactivation potential of TAp73α

The proteins p73 and p63 are members of the p53 protein family and are involved in important developmental processes. Their high sequence identity with the tumor suppressor p53 has suggested that they act as tumor suppressors as well. While p63 has a crucial role in the maintenance of epithelial stem cells and in the quality control of oocytes without a clear role as a tumor suppressor, p73's tumor suppressor activity is well documented. In a recent study we have shown that the transcriptional activity of TAp63α, the isoform responsible for the quality control in oocytes, is regulated by its oligomeric state. The protein forms an inactive, dimeric and compact conformation in resting oocytes, while the detection of DNA damage leads to the formation of an active, tetrameric and open conformation. p73 shows a high sequence identity to p63, including those domains that are crucial in stabilizing its inactive state, thus suggesting that p73's activity might be regulated by its oligomeric state as well. Here, we have investigated the oligomeric state of TAp73α by size exclusion chromatography and detailed domain interaction mapping, and show that in contrast to p63, TAp73α is a constitutive open tetramer. However, its transactivation potential depends on the cellular background and the promoter context. These results imply that the regulation of p73's transcriptional activity might be more closely related to p53 than to p63.

Circular DNA genomics (circomics) exemplified for geminiviruses in bean crops and weeds of northeastern Brazil

Circomics was coined to describe the combination of rolling circle amplification (RCA), restriction fragment length polymorphism (RFLP) and pyro-sequencing to investigate the genome structures of small circular DNAs. A batch procedure is described using 61 plant samples from Asia, South America and Central America which revealed 83 contig sequences of geminiviral DNA components and 4 contig sequences of DNA satellites. The usefulness of this approach is validated for the Brazilian begomoviruses, and the sequence fidelity is determined by comparing the results with those of conventional cloning and sequencing of Bolivian begomoviruses reported recently. Therefore, circomics has been proven to be a major step forward to economize costs and labor and to characterize reliably geminiviral genomes in their population structure of the quasispecies.

Time-resolved investigation of nanometer scale deformations induced by a high flux x-ray beam

We present results of a time-resolved pump-probe experiment where a Si sample was exposed to an intense 15 keV beam and its surface monitored by measuring the wavefront deformation of a reflected optical laser probe beam. By reconstructing and back propagating the wavefront, the deformed surface can be retrieved for each time step. The dynamics of the heat bump, build-up and relaxation, is followed with a spatial resolution in the nanometer range. The results are interpreted taking into account results of finite element method simulations. Due to its robustness and simplicity this method should find further developments at new x-ray light sources (FEL) or be used to gain understanding on thermo-dynamical behavior of highly excited materials.

The genomes of four novel begomoviruses and a new Sida micrantha mosaic virus strain from Bolivian weeds

Begomovirus is the largest genus within the family Geminiviridae and includes economically important plant DNA viruses infecting a broad range of plant species and causing devastating crop diseases, mainly in subtropical and tropical countries. Besides cultivated plants, many weeds act as virus reservoirs. Eight begomovirus isolates from Bolivian weeds were examined using rolling-circle amplification (RCA) and restriction fragment length polymorphism (RFLP). An efficient, novel cloning strategy using limited Sau3A digestion to obtain tandem-repeat inserts allowed the sequencing of the complete genomes. The viruses were classified by phylogenetic analysis as typical bipartite New World begomoviruses. Four of them represented distinct new virus species, for which the names Solanum mosaic Bolivia virus, Sida mosaic Bolivia virus 1, Sida mosaic Bolivia virus 2, and Abutilon mosaic Bolivia virus are proposed. Three were variants of a new strain of Sida micrantha mosaic virus (SimMV), SimMV-rho[BoVi07], SimMV-rho[Bo:CF1:07] and SimMV-rho[Bo:CF2:07], and one was a new variant of a previously described SimMV, SimMV-MGS2:07-Bo.

Wave microcarrier cultivation of MDCK cells for influenza virus production in serum containing and serum-free media

A process for equine influenza virus vaccine production using a microcarrier system (Cytodex 1) in a 2 L Wave bioreactor is described. Growth of Madin Darby canine kidney (MDCK) cells in serum containing GMEM medium (SC) is compared to growth in serum-free Ex-Cell MDCK medium (SF) without washing steps and medium exchange before infection. Cultivations with microcarrier concentrations of 2 and 4 g/L for both media are shown. Metabolic data from carbon and amino acid metabolism are discussed. Additionally, in roller bottle experiments the influence of multiplicity of infection (moi) and trypsin concentration on the HA value was investigated. Analysis of HA and TCID(50) at 37 degrees C showed a stable HA of maximum 2.6 log HA/100 microL for 2 weeks. Peak TCID(50) titers of 10(7.7) viruses/mL were achieved 20h post infection, but infectivity was below detection limit after 150 h. Cell attachment onto microcarriers under serum-free conditions was improved by Ca(2+) addition and by cell harvesting without trypsin using only an EDTA/PBS solution. For the wave cultivation maximum virus titers of 2.3-2.6 log HA units/100 microL were reached from infection with a moi of 0.05. However, in SF medium pH dropped to less than pH 6.8 which resulted in lower HA titers of 1.7 log HA units/100 microL. For the higher microcarrier concentration (4 g/L) medium exchange steps (500 mL) were needed for both media. Omission of the washing step and medium exchange before infection in SF medium clearly simplified the influenza production process; however, for higher virus yields a better pH control of the wave bioreactor would be required. Higher cell densities (2.8 x 10(6) cells/mL for 2 g/L microcarrier) and better attachment compared to stirred tank bioreactors showed, that the wave bioreactor is a good alternative to stirred tank processes for expanding production capacities in case of a pandemic.

The in vivo form of the murine class VI POU protein Emb is larger than that encoded by previously described transcripts

The class VI POU domain family member known as Emb in the mouse (rat Brn5 or human mPOU/TCFbeta1) is present in vivo as a protein migrating at about 80 kDa on western blots, considerably larger than that predicted (about 42 kDa) from previously cloned coding sequences. By RT-PCR and 5' RACE strategies a full-length Emb sequence, Emb FL, is now identified. Shorter sequences encoding the -COOH terminal, and an -NH(2) terminal isoform, EmbN, were also isolated. Comparisons of Emb coding sequences between species, including the full-length zebra fish, POU(c), are presented, together with a compilation of the multiple transcripts produced by alternative splicing and the presence of different transcriptional start and stop sites, from the Emb gene.