Epstein-Barr virus nuclear antigen 1 interacts with regulator of chromosome condensation 1 dynamically throughout the cell cycle

The Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) is a sequence-specific DNA binding protein which plays an essential role in viral episome replication and segregation, by recruiting the cellular complex of DNA replication onto the origin (oriP) and by tethering the viral DNA onto the mitotic chromosomes. Whereas the mechanisms of viral DNA replication are well documented, those involved in tethering EBNA1 to the cellular chromatin are far from being understood. Here, we have identified Regulator of Chromosome Condensation 1 (RCC1) as a novel cellular partner for EBNA1. RCC1 is the major nuclear guanine nucleotide exchange factor (RanGEF) for the small GTPase Ran enzyme. RCC1, associated with chromatin, is involved in the formation of RanGTP gradients critical for nucleo-cytoplasmic transport, mitotic spindle formation, and nuclear envelope reassembly following mitosis. Using several approaches, we have demonstrated a direct interaction between these two proteins and found that the EBNA1 domains responsible for EBNA1 tethering to the mitotic chromosomes are also involved in the interaction with RCC1. The use of an EBNA1 peptide array confirmed the interaction of RCC1 with these regions and also the importance of the N-terminal region of RCC1 in this interaction. Finally, using confocal microscopy and FRET analysis to follow the dynamics of interaction between the two proteins throughout the cell cycle, we have demonstrated that EBNA1 and RCC1 closely associate on the chromosomes during metaphase, suggesting an essential role for the interaction during this phase, perhaps in tethering EBNA1 to mitotic chromosomes

Locating-dominating sets: From graphs to oriented graphs

A locating-dominating set of an undirected graph is a subset of vertices S such that S is dominating and for every u, v is not an element of S, the neighbourhood of u and v on S are distinct (i.e. N(u) & cap; S &NOTEQUexpressionL; N(v) & cap; S). Locating-dominating sets have received a considerable attention in the last decades. In this paper, we consider the oriented version of the problem. A locating-dominating set in an oriented graph is a set S such that for each w is an element of V \ S, N-(w) & cap; S &NOTEQUexpressionL; Phi and for each pair of distinct vertices u, v is an element of V \ S, N-(u) & cap; S &NOTEQUexpressionL; N-(v) & cap; S. We consider the following two parameters. Given an undirected graph G, we look for (gamma)over the arrow(LD) (G) ((gamma)over the arrow(LD) (G)) which is the size of the smallest (largest) optimal locating-dominating set over all orientations of G. In particular, if D is an orientation of G, then (gamma)over the arrow(LD)(G) = gamma(LD)(G) and some for which (gamma)over the arrow(LD)(G) = alpha(G). Finally, we show that for many graph classes (gamma)over the arrow(LD)(G) is polynomial on n but we leave open the question whether there exist graphs with (gamma)over the arrow(LD)(G) is an element of O (log n). (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).</p

Incidence, a Scoring Positional Game on Graphs

Positional games have been introduced by Hales and Jewett in 1963 and have been extensively investigated in the literature since then. These games are played on a hypergraph where two players alternately select an unclaimed vertex of it. In the Maker-Breaker convention, if Maker manages to fully take a hyperedge, she wins, otherwise, Breaker is the winner. In the Maker-Maker convention, the first player to take a hyperedge wins. In both cases, the game stops as soon as Maker has taken a hyperedge. By definition, this family of games does not handle scores and cannot represent games in which players want to maximize a quantity. In this work, we introduce scoring positional games, that consist in playing on a hypergraph until all the vertices are claimed, and by defining the score as the number of hyperedges a player has fully taken. We focus here on Incidence, a scoring positional game played on a 2-uniform hypergraph, i.e. an undirected graph. In this game, two players alternately claim the vertices of a graph and score the number of edges for which they own both end vertices. In the Maker-Breaker version, Maker aims at maximizing the number of edges she owns, while Breaker aims at minimizing it. In the Maker-Maker version, both players try to take more edges than their opponent. We first give some general results on scoring positional games such that their membership in Milnor's universe and some general bounds on the score. We prove that, surprisingly, computing the score in the Maker-Breaker version of Incidence is PSPACE-complete whereas in the Maker-Maker convention, the relative score can be obtained in polynomial time. In addition, for the Maker-Breaker convention, we give a formula for the score on paths by using some equivalences due to Milnor's universe. This result implies that the score on cycles can also be computed in polynomial time

Multidifferential study of identified charged hadron distributions in ZZ-tagged jets in proton-proton collisions at s=\sqrt{s}=13 TeV

Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a $Z$ boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum 20 $< p_{\textrm{T}} < 100$ GeV and in the pseudorapidity range $2.5 < \eta < 4$. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.64 fb$^{-1}$. Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb public pages

Study of the B−→Λc+Λˉc−K−B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-} decay

The decay $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ is studied in proton-proton collisions at a center-of-mass energy of $\sqrt{s}=13$ TeV using data corresponding to an integrated luminosity of 5 $\mathrm{fb}^{-1}$ collected by the LHCb experiment. In the $\Lambda_{c}^+ K^{-}$ system, the $\Xi_{c}(2930)^{0}$ state observed at the BaBar and Belle experiments is resolved into two narrower states, $\Xi_{c}(2923)^{0}$ and $\Xi_{c}(2939)^{0}$, whose masses and widths are measured to be $$m(\Xi_{c}(2923)^{0}) = 2924.5 \pm 0.4 \pm 1.1 \,\mathrm{MeV}, \\ m(\Xi_{c}(2939)^{0}) = 2938.5 \pm 0.9 \pm 2.3 \,\mathrm{MeV}, \\ \Gamma(\Xi_{c}(2923)^{0}) = \phantom{000}4.8 \pm 0.9 \pm 1.5 \,\mathrm{MeV},\\ \Gamma(\Xi_{c}(2939)^{0}) = \phantom{00}11.0 \pm 1.9 \pm 7.5 \,\mathrm{MeV},$$ where the first uncertainties are statistical and the second systematic. The results are consistent with a previous LHCb measurement using a prompt $\Lambda_{c}^{+} K^{-}$ sample. Evidence of a new $\Xi_{c}(2880)^{0}$ state is found with a local significance of $3.8\,\sigma$, whose mass and width are measured to be $2881.8 \pm 3.1 \pm 8.5\,\mathrm{MeV}$ and $12.4 \pm 5.3 \pm 5.8 \,\mathrm{MeV}$, respectively. In addition, evidence of a new decay mode $\Xi_{c}(2790)^{0} \to \Lambda_{c}^{+} K^{-}$ is found with a significance of $3.7\,\sigma$. The relative branching fraction of $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ with respect to the $B^{-} \to D^{+} D^{-} K^{-}$ decay is measured to be $2.36 \pm 0.11 \pm 0.22 \pm 0.25$, where the first uncertainty is statistical, the second systematic and the third originates from the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb public pages

Measurement of the ratios of branching fractions R(D∗)\mathcal{R}(D^{*}) and R(D0)\mathcal{R}(D^{0})

The ratios of branching fractions $\mathcal{R}(D^{*})\equiv\mathcal{B}(\bar{B}\to D^{*}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(\bar{B}\to D^{*}\mu^{-}\bar{\nu}_{\mu})$ and $\mathcal{R}(D^{0})\equiv\mathcal{B}(B^{-}\to D^{0}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(B^{-}\to D^{0}\mu^{-}\bar{\nu}_{\mu})$ are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb${ }^{-1}$ of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode $\tau^{-}\to\mu^{-}\nu_{\tau}\bar{\nu}_{\mu}$. The measured values are $\mathcal{R}(D^{*})=0.281\pm0.018\pm0.024$ and $\mathcal{R}(D^{0})=0.441\pm0.060\pm0.066$, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is $\rho=-0.43$. Results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the Standard Model.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-039.html (LHCb public pages

Metric dimension parameterized by treewidth in chordal graphs

The metric dimension has been introduced independently by Harary, Melter [HM75] and Slater [Sla75] in 1975 to identify vertices of a graph G using its distances to a subset of vertices of G. A resolving set X of a graph G is a subset of vertices such that, for every pair (u, v) of vertices of G, there is a vertex x in X such that the distance between x and u and the distance between x and v are distinct. The metric dimension of the graph is the minimum size of a resolving set. Computing the metric dimension of a graph is NP-hard even on split graphs and interval graphs. Bonnet and Purohit [BP21] proved that the metric dimension problem is W[1]-hard parameterized by treewidth. Li and Pilipczuk strenghtened this result by showing that it is NP-hard for graphs of treewidth 24 in [LP22]. In this article, we prove that metric dimension is FPT parameterized by treewidth in chordal graphs

Locating-dominating sets: from graphs to oriented graphs

International audienceA locating-dominating set of an undirected graph is a subset of vertices $S$ such that $S$ is dominating and for every $u,v \notin S$, the neighbourhood of $u$ and $v$ on $S$ are distinct (i.e. $N(u) \cap S \ne N(v) \cap S$). In this paper, we consider the oriented version of the problem. A locating-dominating set of an oriented graph is a set $S$ such that for every $u,v \in V \setminus S$, $N^-(u) \cap S \ne N^-(v) \cap S$. We consider the following two parameters. Given an undirected graph $G$, we look for $\overset{\rightarrow}{\gamma}_{LD}(G)$ ($\overset{\rightarrow}{\Gamma}_{LD}(G))$ which is the size of the smallest (largest) optimal locating-dominating set over all orientations of $G$. In particular, if $D$ is an orientation of $G$, then $\overset{\rightarrow}{\gamma}_{LD}(G)\leq{\gamma}_{LD}(D)\leq\overset{\rightarrow}{\Gamma}_{LD}(G)$. For the best orientation, we prove that, for every twin-free graph $G$ on $n$ vertices, $\overset{\rightarrow}{\gamma}_{LD}(G) \le n/2$ proving a ``directed version'' of a conjecture on $\gamma_{LD}(G)$. Moreover, we give some bounds for $\overset{\rightarrow}{\gamma}_{LD}(G)$ on many graph classes and drastically improve value $n/2$ for (almost) $d$-regular graphs by showing that $\overset{\rightarrow}{\gamma}_{LD}(G) \in O(\log d / d \cdot n)$ using a probabilistic argument. While $\overset{\rightarrow}{\gamma}_{LD}(G)\leq\gamma_{LD}(G)$ holds for every graph $G$, we give some graph classes graphs for which $\overset{\rightarrow}{\Gamma}_{LD}(G)\geq{\gamma}_{LD}(G)$ and some for which $\overset{\rightarrow}{\Gamma}_{LD}(G)\leq {\gamma}_{LD}(G)$. We also give general bounds for $\overset{\rightarrow}{\Gamma}_{LD}(G)$. Finally, we show that for many graph classes $\overset{\rightarrow}{\Gamma}_{LD}(G)$ is polynomial on $n$ but we leave open the question whether there exist graphs with $\overset{\rightarrow}{\Gamma}_{LD}(G)\in O(\log n)$

Locating-dominating sets: from graphs to oriented graphs

International audienceA locating-dominating set of an undirected graph is a subset of vertices $S$ such that $S$ is dominating and for every $u,v \notin S$, the neighbourhood of $u$ and $v$ on $S$ are distinct (i.e. $N(u) \cap S \ne N(v) \cap S$). In this paper, we consider the oriented version of the problem. A locating-dominating set of an oriented graph is a set $S$ such that for every $u,v \in V \setminus S$, $N^-(u) \cap S \ne N^-(v) \cap S$. We consider the following two parameters. Given an undirected graph $G$, we look for $\overset{\rightarrow}{\gamma}_{LD}(G)$ ($\overset{\rightarrow}{\Gamma}_{LD}(G))$ which is the size of the smallest (largest) optimal locating-dominating set over all orientations of $G$. In particular, if $D$ is an orientation of $G$, then $\overset{\rightarrow}{\gamma}_{LD}(G)\leq{\gamma}_{LD}(D)\leq\overset{\rightarrow}{\Gamma}_{LD}(G)$. For the best orientation, we prove that, for every twin-free graph $G$ on $n$ vertices, $\overset{\rightarrow}{\gamma}_{LD}(G) \le n/2$ proving a ``directed version'' of a conjecture on $\gamma_{LD}(G)$. Moreover, we give some bounds for $\overset{\rightarrow}{\gamma}_{LD}(G)$ on many graph classes and drastically improve value $n/2$ for (almost) $d$-regular graphs by showing that $\overset{\rightarrow}{\gamma}_{LD}(G) \in O(\log d / d \cdot n)$ using a probabilistic argument. While $\overset{\rightarrow}{\gamma}_{LD}(G)\leq\gamma_{LD}(G)$ holds for every graph $G$, we give some graph classes graphs for which $\overset{\rightarrow}{\Gamma}_{LD}(G)\geq{\gamma}_{LD}(G)$ and some for which $\overset{\rightarrow}{\Gamma}_{LD}(G)\leq {\gamma}_{LD}(G)$. We also give general bounds for $\overset{\rightarrow}{\Gamma}_{LD}(G)$. Finally, we show that for many graph classes $\overset{\rightarrow}{\Gamma}_{LD}(G)$ is polynomial on $n$ but we leave open the question whether there exist graphs with $\overset{\rightarrow}{\Gamma}_{LD}(G)\in O(\log n)$

On the Cycle Rank Conjecture About Metric Dimension and Zero Forcing Number in Graphs

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