The rockefeller university

RNAs are remarkably versatile molecules that can fold into intricate three-dimensional (3D) structures to perform diverse cellular and viral functions. Despite their biological importance, relatively few RNA 3D structures have been solved, and our understanding of RNA structure-function relationships remains in its infancy. This limitation partly arises from challenges posed by RNA's complex conformational landscape, characterized by structural flexibility, formation of multiple states, and a propensity to misfold. Recently, cryoelectron microscopy (cryo-EM) has emerged as a powerful tool for the visualization of conformationally dynamic RNA- only 3D structures. However, RNA's characteristics continue to pose challenges. We discuss experimental methods developed to overcome these hurdles, including the engineering of modular modifications that facilitate the visualization of small RNAs, improve particle alignment, and validate structural models.

Diboson production in association with jets is studied in the fully leptonic final states, pp -> (Z/gamma(*))(Z/gamma(*)) + jets -> 2l2l'+ jets, (l, l ' = e or mu) in proton-proton collisions at a center-of-mass energy of 13 TeV. The data sample corresponds to an integrated luminosity of 138 fb(-1) collected with the CMS detector at the LHC. Differential distributions and normalized differential cross sections are measured as a function of jet multiplicity, transverse momentum p(T), pseudorapidity eta, invariant mass and eta of the highest-p(T) and second-highest-p(T) jets, and as a function of invariant mass of the four-lepton system for events with various jet multiplicities. These differential cross sections are compared with theoretical predictions that mostly agree with the experimental data. However, in a few regions we observe discrepancies between the predicted and measured values. Further improvement of the predictions is required to describe the ZZ+jets production in the whole phase space.

Chromothripsis describes the catastrophic shattering of mis-segregated chromosomes trapped within micronuclei. Although micronuclei accumulate DNA double-strand breaks and replication defects throughout interphase, how chromosomes undergo shattering remains unresolved. Using CRISPRCas9 screens, we identify a non-canonical role of the Fanconi anemia (FA) pathway as a driver of chromothripsis. Inactivation of the FA pathway suppresses chromosome shattering during mitosis without impacting interphase-associated defects within micronuclei. Mono-ubiquitination of FANCIFANCD2 by the FA core complex promotes its mitotic engagement with under-replicated micronuclear chromosomes. The structure-selective SLX4-XPF-ERCC1 endonuclease subsequently induces largescale nucleolytic cleavage of persistent DNA replication intermediates, which stimulates POLD3-dependent mitotic DNA synthesis to prime shattered fragments for reassembly in the ensuing cell cycle. Notably, FA-pathway-induced chromothripsis generates complex genomic rearrangements and extra- chromosomal DNA that confer acquired resistance to anti-cancer therapies. Our findings demonstrate how pathological activation of a central DNA repair mechanism paradoxically triggers cancer genome evolution through chromothripsis.

Pain management in amphibians is an emerging field of veterinary medicine with only a limited number of analgesics studied for their efficacy. The African-clawed frog, Xenopus laevis, is a popular animal model in research due to its oocyte morphology and embryonic development. We investigated analgesic effects of 2 formulations of meloxicam (standard and extended release [ER]) along with their pharmacokinetics and potential toxicity in this species. Adult female African-clawed frogs (n = 6/group) received either standard (0.2, 0.4, 1, or 5 mg/kg) or ER meloxicam (0.6, 1.2, 3, or 15 mg/kg) injected into the dorsal lymph sac. The acetic acid test (AAT) was performed at -1, 1, 6, 12, 24, 48, and 72 h postadministration to evaluate pain response. In addition, a subset of frogs (n = 2/group) were euthanized 72 h postinjection and submitted for necropsy. There were no significant differences in AAT with both formulations compared with saline control. No signs of meloxicam-induced toxicity with either formulation was present in histology. A pharmacokinetic study was conducted for both the standard and ER formulation of meloxicam at 5 and 15 mg/kg, respectively. Results were consistent with the fact that both formulations of meloxicam were readily absorbed with the standard plasma concentrations peaking at 20.40 mu g/mL at 2 h and ER plasma concentration at 30.4 mu g/mL at 12 h. The elimination half-life was only determinable for standard formulation (7.74 h). According to the AAT, both formulations of meloxicam did not provide effective analgesia in adult female Xenopus laevis despite reaching high plasma concentrations.

Two-particle correlations are presented for K-S(0), Lambda, and (Lambda) over bar strange hadrons as a function of relative momentum in lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The dataset corresponds to an integrated luminosity of 0.607 nb(-1) and was collected using the CMS detector at the CERN LHC. These correlations are sensitive to quantum statistics and to final-state interactions between the particles. The source size extracted from the (KSKS0)-K-0 correlations is found to decrease from 4.6 to 1.6 fm in going from central to peripheral collisions. Strong interaction scattering parameters (i.e., scattering length and effective range) are determined from the Lambda K-S(0) and Lambda Lambda (including their charge conjugates) correlations using the Lednicky-Lyuboshitz model and are compared to theoretical and other experimental results.

How do neural circuits coordinate multiple behavioral responses to a single sensory cue? Here, we investigate how sweet taste drives appetitive behaviors in Drosophila, , including feeding, locomotor suppression, spatial preference, and associative learning. We find that neural circuits mediating different innate responses to sugar are partially overlapping and diverge at the second and third layers. Connectomic analyses reveal distinct subcircuits that mediate different behaviors. Connectome-based simulations of neuronal activity predict that second-order sugar neurons act synergistically to promote downstream activity and that bitter input overrides the sugar circuit through multiple pathways acting at third- and fourth-order neurons. Consistent with the latter prediction, optogenetic experiments suggest that bitter input inhibits third- and fourth-order sugar neurons to override the sugar pathway, whereas hunger and diet act earlier in the circuit to modulate behavior. Together, these studies provide insight into how circuits are organized to drive diverse behavioral responses to a single stimulus.

A search for electroweak production of a single vectorlike T quark in association with a bottom (b) quark in the all-hadronic decay channel is presented. This search uses proton-proton collision data at root s = 13 TeV collected by the CMS experiment at the CERN LHC during 2016-2018, corresponding to an integrated luminosity of 138 fb(-1). The T quark is assumed to have charge 2/3 and decay to a top (t) quark and a Higgs (H) or Z boson. Hadronic decays of the t quark and the H or Z boson are reconstructed from the kinematic properties of jets, including those containing b hadrons. No deviation from the standard model prediction is observed in the reconstructed tH and tZ invariant mass distributions. The 95% confidence level upper limits on the product of the production cross section and branching fraction of a T quark produced in association with a b quark and decaying via tH or tZ range from 1260 to 68 fb for T quark masses of 600-1200 GeV.

A search for Higgs boson pair (HH) production in association with a vector boson V (W or Z boson) is presented. The search is based on proton-proton collision data at a center-of-mass energy of 13 TeV, collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb(-1). Both hadronic and leptonic decays of V bosons are used. The leptons considered are electrons, muons, and neutrinos. The HH production is searched for in the b (b) over barb (b) over bar decay channel. An observed (expected) upper limit at 95% confidence level of VHH production cross section is set at 294 (124) times the standard model prediction. Constraints are also set on the modifiers of the Higgs boson trilinear self-coupling, k(lambda), assuming k(2V) = 1, and vice versa on the coupling of two Higgs bosons with two vector bosons, k(2V). The observed (expected) 95% confidence intervals of these coupling modifiers are -37.7 < k(lambda) < 37.2 (-30.1 < k(lambda) < 28.9) and -12.2 < k(2V) < 13.5 (-7.2 < k(2V) < 8.9), respectively.

Infants with biallelic IL7R loss-of-function variants have severe combined immune deficiency (SCID) characterized by the absence of autologous T lymphocytes, but normal counts of circulating B and NK cells (T-B+NK+ SCID). We report 6 adults (aged 22 to 59 years) from 4 kindreds and 3 ancestries (Colombian, Israeli Arab, Japanese) carrying homozygous IL7 loss-of-function variants resulting in combined immunodeficiency (CID). Deep immunophenotyping revealed relatively normal counts and/or proportions of myeloid, B, NK, and innate lymphoid cells. By contrast, the patients had profound T cell lymphopenia, with low proportions of innate-like adaptive mucosal-associated invariant T and invariant NK T cells. They also had low blood counts of T cell receptor (TCR) excision circles, recent thymic emigrant T cells and naive CD4(+) T cells, and low overall TCR repertoire diversity, collectively indicating impaired thymic output. The proportions of effector memory CD4(+) and CD8(+) T cells were high, indicating IL-7-independent homeostatic T cell proliferation in the periphery. Intriguingly, the proportions of other T cell subsets, including TCR gamma delta(+) T cells and some TCR alpha beta(+) T cell subsets (including Th1, Tfh, and Treg) were little affected. Peripheral CD4(+) T cells displayed poor proliferation, but normal cytokine production upon stimulation with mitogens in vitro. Thus, inherited IL-7 deficiency impairs T cell development less severely and in a more subset-specific manner than IL-7R deficiency. These findings suggest that another IL-7R-binding cytokine, possibly thymic stromal lymphopoietin, governs an IL-7-independent pathway of human T cell development.

DNA damage that obstructs the replication machinery poses a significant threat to genome stability. Replication-coupled repair mechanisms safeguard stalled replication forks by coordinating proteins involved in the DNA damage response (DDR) and replication. SLF1 (SMC5-SMC6 complex localization factor 1) is crucial for facilitating the recruitment of the SMC5/6 complex to damage sites through interactions with SLF2, RAD18, and nucleosomes. However, the structural mechanisms of SLF1's interactions are unclear. In this study, we determined the crystal structure of SLF1's ankyrin repeat domain bound to an unmethylated histone H4 tail, illustrating how SLF1 reads nascent nucleosomes. Using structure-based mutagenesis, we confirmed a phosphorylation-dependent interaction necessary for a stable complex between SLF1's tandem BRCA1 C-Terminal domain (tBRCT) and the phosphorylated C-terminal region (S442 and S444) of RAD18. We validated a functional role of conserved phosphate-binding residues in SLF1, and hydrophobic residues in RAD18 that are adjacent to phosphorylation sites, both of which contribute to the strong interaction. Interestingly, we discovered a DNA-binding property of this RAD18-binding interface, providing an additional domain of SLF1 to enhance binding to nucleosomes. Our results provide critical structural insights into SLF1's interactions with post-replicative chromatin and phosphorylation-dependent DDR signalling, enhancing our understanding of SMC5/6 recruitment and/or activity during replication-coupled DNA repair. Graphical Abstract