Observation of Gravitational Waves from a Binary Black Hole Merger

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral

On August 17, 2017 at 12∶41:04 UTC the Advanced LIGO and Advanced Virgo gravitational-wave detectors made their first observation of a binary neutron star inspiral. The signal, GW170817, was detected with a combined signal-to-noise ratio of 32.4 and a false-alarm-rate estimate of less than one per 8.0×10^{4}  years. We infer the component masses of the binary to be between 0.86 and 2.26  M_{⊙}, in agreement with masses of known neutron stars. Restricting the component spins to the range inferred in binary neutron stars, we find the component masses to be in the range 1.17-1.60  M_{⊙}, with the total mass of the system 2.74_{-0.01}^{+0.04}M_{⊙}. The source was localized within a sky region of 28  deg^{2} (90% probability) and had a luminosity distance of 40_{-14}^{+8}  Mpc, the closest and most precisely localized gravitational-wave signal yet. The association with the γ-ray burst GRB 170817A, detected by Fermi-GBM 1.7 s after the coalescence, corroborates the hypothesis of a neutron star merger and provides the first direct evidence of a link between these mergers and short γ-ray bursts. Subsequent identification of transient counterparts across the electromagnetic spectrum in the same location further supports the interpretation of this event as a neutron star merger. This unprecedented joint gravitational and electromagnetic observation provides insight into astrophysics, dense matter, gravitation, and cosmology.

Factors affecting the efficiency of introducing foreign DNA into mice by microinjecting eggs

Microinjection of foreign DNA into fertilized mammalian eggs is a convenient means of introducing genes into the germ line. Some of the more important parameters that influence successful integration of foreign DNA into mouse chromosomes are described. The effects of DNA concentration, size, and form (supercoiled vs. linear with a variety of different ends) are considered as well as the site of injection (male pronucleus, female pronucleus, or cytoplasm) and buffer composition. The optimal conditions for integration entail injection of a few hundred linear molecules into the male pronucleus of fertilized one-cell eggs. Under these conditions about 25% of the mice that develop inherit one or more copies of the microinjected DNA. The overall efficiency also depends on the choice of mouse strains; for example, generating transgenic mice that express foreign growth hormone genes is about eight times easier with C57/BL6 X SJL hybrid mice than with inbred C57/BL6 mice.

Inactivation of the mouse melanocortin-3 receptor results in increased fat mass and reduced lean body mass

Genetic and pharmacological studies have defined a role for the melanocortin-4 receptor (Mc4r) in the regulation of energy homeostasis. The physiological function of Mc3r, a melanocortin receptor expressed at high levels in the hypothalamus, has remained unknown. We evaluated the potential role of Mc3r in energy homeostasis by studying Mc3r-deficient (Mc3r(-/-)) mice and compared the functions of Mc3r and Mc4r in mice deficient for both genes. The 4-6-month Mc3r-/- mice have increased fat mass, reduced lean mass and higher feed efficiency than wild-type littermates, despite being hypophagic and maintaining normal metabolic rates. (Feed efficiency is the ratio of weight gain to food intake.) Consistent with increased fat mass, Mc3r(-/-) mice are hyperleptinaemic and male Mc3r(-/-) mice develop mild hyperinsulinaemia. Mc3r(-/-) mice did not have significantly altered corticosterone or total thyroxine (T4) levels. Mice lacking both Mc3r and Mc4r become significantly heavier than Mc4r(-/-) mice. We conclude that Mc3r and Mc4r serve non-redundant roles in the regulation of energy homeostasis.

Presenilin 1 is required for Notch1 and DII1 expression in the paraxial mesoderm

Approximately 10% of cases of Alzheimer's disease are familial and associated with autosomal dominant inheritance of mutations in genes encoding the amyloid precursor protein, presenilin 1 (PS1) and presenilin 2 (PS2). Mutations in PS1 are linked to about 25% of cases of early-onset familial Alzheimer's disease. PS1, which is endoproteolytically processed in vivo, is a multipass transmembrane protein and is a functional homologue of SEL-12, a Caenorhabditis elegans protein that facilitates signalling mediated by the Notch/LIN-12 family of receptors. To examine potential roles for PS1 in facilitating Notch-mediated signalling during mammalian embryogenesis, we generated mice with targeted disruptions of PS1 alleles (PS1-/- mice). PS1-/- embryos exhibited abnormal patterning of the axial skeleton and spinal ganglia, phenotypes traced to defects in somite segmentation and differentiation. Moreover, expression of mRNA encoding Notch1 and Dll1 (delta-like gene 1), a vertebrate Notch ligand, is markedly reduced in the presomitic mesoderm of PS1-/- embryos compared to controls. Hence, PS1 is required for the spatiotemporal expression of Notch1 and Dll1, which are essential for somite segmentation and maintenance of somite borders.

beta-Amyloid precursor protein-deficient mice show reactive gliosis and decreased locomotor activity

In several pedigrees of early onset familial Alzheimer's disease (FAD), point mutations in the beta-amyloid precursor protein (APP) gene are genetically linked to the disease. This finding implicates APP in the pathogenesis of Alzheimer's disease in these individuals. To understand the in vivo function of APP and its processing, we have generated an APP-null mutation in mice. Homozygous APP-deficient mice were viable and fertile. However, the mutant animals weighed 15%-20% less than age-matched wild-type controls. Neurological evaluation showed that the APP-deficient mice exhibited a decreased locomotor activity and forelimb grip strength, indicating a compromised neuronal or muscular function. In addition, four out of six homozygous mice showed reactive gliosis at 14 weeks of age, suggesting an impaired neuronal function as a result of the APP-null mutation.

Orexigenic action of peripheral ghrelin is mediated by neuropeptide Y and agouti-related protein

Ghrelin, a stomach-derived orexigenic hormone, has stimulated great interest as a potential target for obesity control. Pharmacological evidence indicates that ghrelin's effects on food intake are mediated by neuropeptide Y (NPY) and agouti-related protein (AgRP) in the central nervous system. These include intracerebroventricular application of antibodies to neutralize NPY and AgRP, and the application of an NPY Y1 receptor antagonist, which blocks some of the orexigenic effects of ghrelin. Here we describe treatment of Agrp(-/-);Npy(-/-) and Mc3r(-/-);Mc4r(-/-) double knockout mice as well as Npy(-/-) and Agrp(-/-) single knockout mice with either ghrelin or an orally active nonpeptide ghrelin agonist. The data demonstrate that NPY and AgRP are required for the orexigenic effects of ghrelin, as well as the involvement of the melanocortin pathway in ghrelin signaling. Our results outline a functional interaction between the NPY and AgRP pathways. Although deletion of either NPY or AgRP caused only a modest or nondetectable effect, ablation of both ligands completely abolished the orexigenic action of ghrelin. Our results establish an in vivo orexigenic function for NPY and AgRP, mediating the effect of ghrelin.

Somatic expression of herpes thymidine kinase in mice following injection of a fusion gene into eggs

A plasmid, designated pMK, containing the structural gene for thymidine kinase from herpes simplex virus (HSV) fused to the promoter/regulatory region of the mouse metallothionein-I gene, was injected into the pronucleus of fertilized one-cell mouse eggs; the eggs were subsequently reimplanted into the oviducts of pseudopregnant mice. The first experiment produced 19 offspring, one of which expressed high levels of HSV thymidine kinase activity in the liver and kidney. pMK DNA sequences were detected in equal amounts in several tissues of the expressing mouse as well as in three mice that did not express HSV thymidine kinase activity. In all cases, several copies of the pMK plasmid were tandemly duplicated and integrated into mouse DNA. It appears as though multiple copies of the intact plasmid were fused by homologous recombination either before or after integration at a single site in the mouse genome. The overall efficiency of obtaining somatic expression of thymidine kinase in experiments performed to date is about 10% (4/41), and twice this number have integrated pMK DNA. This procedure not only provides a means of introducing new genes into mice, but it will also be a valuable system for studying tissue-specific regulation of gene expression.

Transgenic mice harboring SV40 T-antigen genes develop characteristic brain tumors

A high percentage of transgenic mice developing from eggs microinjected with plasmids containing the SV40 early region genes and a metallothionein fusion gene develop tumors within the choroid plexus. A line of mice has been established in which nearly every affected animal succumbs to this brain tumor. Thymic hypertrophy and kidney pathology are also observed in some mice. SV40 T-antigen mRNA and protein are readily detected in affected tissues; however, SV40 T-antigen gene expression is barely detectable in unaffected tissues or in susceptible tissues prior to overt pathology, suggesting that tumorigenesis depends upon activation of the SV40 genes. Comparison of DNA from tumor tissue (or cell lines derived from tumors) with DNA from unaffected tissues reveals structural rearrangements as well as changes in DNA methylation of the foreign DNA. The SV40 genes are frequently amplified in tumor tissue, which further indicates that their expression is intimately involved in tumorigenesis in transgenic mice.

Fatal familial insomnia, a prion disease with a mutation at codon 178 of the prion protein gene

BACKGROUND

We previously described two members of a family affected by an apparently genetically determined fatal disease characterized clinically by progressive insomnia, dysautonomia, and motor signs and characterized pathologically by severe atrophy of the anterior ventral and mediodorsal thalamic nuclei. Five other family members who died of this disease, which we termed "fatal familial insomnia," had broader neuropathologic changes suggesting that fatal familial insomnia could be a prion disease.

METHODS

We used antibodies to prion protein (PrP) to perform dot and Western blot analyses, with and without proteinase K, on brain tissue obtained at autopsy from two patients with fatal familial insomnia, three patients with sporadic Creutzfeldt-Jakob disease, and six control subjects. The coding region of the PrP gene was amplified and sequenced in the samples from the two patients with fatal familial insomnia. Restriction-enzyme analysis was carried out with amplified PrP DNA from 33 members of the kindred.

RESULTS

Protease-resistant PrP was found in both patients with fatal familial insomnia, but the size and number of protease-resistant fragments differed from those in Creutzfeldt-Jakob disease. In the family with fatal familial insomnia, all 4 affected members and 11 of the 29 unaffected members had a point mutation in PrP codon 178 that results in the substitution of asparagine for aspartic acid and elimination of the Tth111 I restriction site. Linkage analysis showed a close relation between the point mutation and the disease (maximal lod score, 3.4 when theta was zero).

CONCLUSIONS

Fatal familial insomnia is a prion disease with a mutation in codon 178 of the PrP gene, but the disease phenotype seems to differ from that of previously described kindreds with the same point mutation.

Differential regulation of metallothionein-thymidine kinase fusion genes in transgenic mice and their offspring

A fusion plasmid, pMK, containing the mouse metallothionein-I promoter/regulatory region joined to the structural gene of herpesvirus thymidine kinase, was introduced into mice by microinjection into fertilized eggs followed by reinsertion of the eggs into foster mothers. Fifteen percent (10 of 69) of the mice developing from this procedure carried pMK sequences. Seven of these mice expressed high levels of viral thymidine kinase in the liver. This enzyme is inducible by heavy metals, as indicated by assay of thymidine kinase activity following sequential partial hepatectomies with or without cadmium treatment. However, glucocorticoid treatment has been ineffective in all transgenic mice tested. The pMK sequences are extensively methylated at a variety of restriction sites, indicating the existence of a de novo methylation enzyme. We have analyzed the inheritance of pMK sequences and their expression in several pedigrees. These fusion genes are inherited as though they were integrated into a single chromosome; however, their expression may be extinguished, diminished or enhanced in the offspring relative to that of the parent. In some animals there is a correlation between changes in DNA methylation and expression of these fusion genes.

A 12-base-pair DNA motif that is repeated several times in metallothionein gene promoters confers metal regulation to a heterologous gene

To define DNA sequences involved in mouse metallothionein-I (MT-I) gene promoter function and metal regulation, we fused the 5' flanking sequences of the MT-I gene to the coding sequences of a viral thymidine kinase (TK) gene. A series of 5' deletion, 3' deletion, linker-scanning, and internal deletion mutants of the MT-I promoter was constructed and assayed by microinjection into mouse eggs. The results indicate that at least two related promoter elements can confer some metal regulation independently. Those mutations that had the most severe effect on regulation impinge on a 12-base-pair conserved sequence that is repeated several times within the mouse MT-I and other MT promoters. To test the regulatory function of this sequence, it was synthesized as a pair of complementary oligonucleotides and inserted into the promoter of the TK gene. A single insertion of this sequence conferred limited metal regulation onto the TK promoter, whereas a construct with two separate inserts was regulated as efficiently as the MT-I promoter.

GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence

We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a significance greater than 5σ. The signal persisted in the LIGO frequency band for approximately 1 s, increasing in frequency and amplitude over about 55 cycles from 35 to 450 Hz, and reached a peak gravitational strain of 3.4_{-0.9}^{+0.7}×10^{-22}. The inferred source-frame initial black hole masses are 14.2_{-3.7}^{+8.3}M_{⊙} and 7.5_{-2.3}^{+2.3}M_{⊙}, and the final black hole mass is 20.8_{-1.7}^{+6.1}M_{⊙}. We find that at least one of the component black holes has spin greater than 0.2. This source is located at a luminosity distance of 440_{-190}^{+180}  Mpc corresponding to a redshift of 0.09_{-0.04}^{+0.03}. All uncertainties define a 90% credible interval. This second gravitational-wave observation provides improved constraints on stellar populations and on deviations from general relativity.

miR-21 is a key therapeutic target for renal injury in a mouse model of type 2 diabetes

AIMS/HYPOTHESIS

As microRNA-21 (miR-21) plays a pathological role in fibrosis, we hypothesised that it may be a therapeutic target for diabetic nephropathy.

METHODS

Abundance of miR-21 was examined in diabetic kidneys from db/db mice. The therapeutic potential of miR-21 in diabetic kidney injury was examined in db/db mice by an ultrasound-microbubble-mediated miR-21 small hairpin RNA transfer. In addition, the role and mechanisms of miR-21 in diabetic renal injury were examined in vitro under diabetic conditions in rat mesangial and tubular epithelial cell lines by overexpressing or downregulating miR-21.

RESULTS

In db/db mice, a mouse model of type 2 diabetes, renal miR-21 at age 20 weeks was increased twofold compared with db/m (+) mice at the same age, and this increase was associated with the development of microalbuminuria and renal fibrosis and inflammation. More importantly, gene transfer of miR-21 knockdown plasmids into the diabetic kidneys of db/db mice at age 10 weeks significantly ameliorated microalbuminuria and renal fibrosis and inflammation at age 20 weeks, revealing a therapeutic potential for diabetic nephropathy by targeting miR-21. Overexpression of miR-21 in kidney cells enhanced, but knockdown of miR-21 suppressed, high-glucose-induced production of fibrotic and inflammatory markers. Targeting Smad7 may be a mechanism by which miR-21 regulates renal injury because knockdown of renal miR-21 restored Smad7 levels and suppressed activation of the TGF-β and NF-κB signalling pathways.

CONCLUSIONS/INTERPRETATION

Inhibition of miR-21 might be an effective therapy for diabetic nephropathy.

Age-related cognitive deficits, impaired long-term potentiation and reduction in synaptic marker density in mice lacking the beta-amyloid precursor protein

Mutations in the beta-amyloid precursor protein are strongly associated with some cases of familial Alzheimer's disease. The normal physiological role of beta-amyloid precursor protein in the brain was evaluated in a cross-sectional analysis of mice deficient in beta-amyloid precursor protein. Compared with wild-type control mice the beta-amyloid precursor protein-null mice developed age-dependent deficits in cognitive function and also had impairments in long-term potentiation. In addition, the brains of the beta-amyloid precursor protein-null mice had marked reactive gliosis in many areas, especially in the cortex and hippocampus. A subpopulation of mice (n = 15) died prematurely (between three and 18 months of age). Analysis of another six mice from the same population that were showing weight loss and hypolocomotor activity exhibited a marked reactive gliosis as detected by immunoreactivity for glial fibrillary acidic protein and a profound loss of immunoreactivities for the presynaptic terminal vesicle marker proteins synaptophysin and synapsin and the dendritic marker microtubule-associated protein-2 in many brain areas, but most predominantly in the cortex and hippocampus. These results suggest that normal beta-amyloid precursor protein may serve an essential role in the maintenance of synaptic function during ageing. A compromise of this function of the beta-amyloid precursor protein may contribute to the progression of the memory decline and the neurodegenerative changes seen in Alzheimer's disease.

Regulation of metallothionein--thymidine kinase fusion plasmids injected into mouse eggs

A plasmid was constructed with the promoter/regulatory region of the mouse metallothionein-I gene fused to the structural gene of herpesvirus thymidine kinase. When mouse eggs were microinjected with this plasmid and incubated with cadmium (a natural inducer of metallothionein gene transcription) thymidine kinase activity increased approximately 10-fold compared with control eggs not exposed to cadmium. Analysis of a set of deletion mutants revealed that the minimum sequence required for cadmium regulation lies within 90 nucleotides of the transcription start site.

GW170104: Observation of a 50-Solar-Mass Binary Black Hole Coalescence at Redshift 0.2

We describe the observation of GW170104, a gravitational-wave signal produced by the coalescence of a pair of stellar-mass black holes. The signal was measured on January 4, 2017 at 10∶11:58.6 UTC by the twin advanced detectors of the Laser Interferometer Gravitational-Wave Observatory during their second observing run, with a network signal-to-noise ratio of 13 and a false alarm rate less than 1 in 70 000 years. The inferred component black hole masses are 31.2_{-6.0}^{+8.4}M_{⊙} and 19.4_{-5.9}^{+5.3}M_{⊙} (at the 90% credible level). The black hole spins are best constrained through measurement of the effective inspiral spin parameter, a mass-weighted combination of the spin components perpendicular to the orbital plane, χ_{eff}=-0.12_{-0.30}^{+0.21}. This result implies that spin configurations with both component spins positively aligned with the orbital angular momentum are disfavored. The source luminosity distance is 880_{-390}^{+450}  Mpc corresponding to a redshift of z=0.18_{-0.07}^{+0.08}. We constrain the magnitude of modifications to the gravitational-wave dispersion relation and perform null tests of general relativity. Assuming that gravitons are dispersed in vacuum like massive particles, we bound the graviton mass to m_{g}≤7.7×10^{-23}  eV/c^{2}. In all cases, we find that GW170104 is consistent with general relativity.

Role of the melanocortin-4 receptor in metabolic rate and food intake in mice

We evaluated the role of the melanocortin-4 receptor (MC-4R) in the control of metabolic rate and food intake in mice. Intraperitoneal administration of the non-selective MC-R agonist melanotan II (MT-II; a cyclic heptapeptide) increases metabolic rate in wildtype mice, while MC-4R knockout mice are insensitive to the effects of MT-II on metabolic rate. MC-4R knockout mice are also insensitive to the effects of MT-II on reducing food intake. We conclude that MC-4R can mediate control of both metabolic rate and food intake in mice. We infer that a role for MC-3R in mediating the acute effects of MT-II on basal metabolic rate and food intake in wildtype mice seems limited.

GW170817: Measurements of Neutron Star Radii and Equation of State

On 17 August 2017, the LIGO and Virgo observatories made the first direct detection of gravitational waves from the coalescence of a neutron star binary system. The detection of this gravitational-wave signal, GW170817, offers a novel opportunity to directly probe the properties of matter at the extreme conditions found in the interior of these stars. The initial, minimal-assumption analysis of the LIGO and Virgo data placed constraints on the tidal effects of the coalescing bodies, which were then translated to constraints on neutron star radii. Here, we expand upon previous analyses by working under the hypothesis that both bodies were neutron stars that are described by the same equation of state and have spins within the range observed in Galactic binary neutron stars. Our analysis employs two methods: the use of equation-of-state-insensitive relations between various macroscopic properties of the neutron stars and the use of an efficient parametrization of the defining function p(ρ) of the equation of state itself. From the LIGO and Virgo data alone and the first method, we measure the two neutron star radii as R_{1}=10.8_{-1.7}^{+2.0}  km for the heavier star and R_{2}=10.7_{-1.5}^{+2.1}  km for the lighter star at the 90% credible level. If we additionally require that the equation of state supports neutron stars with masses larger than 1.97  M_{⊙} as required from electromagnetic observations and employ the equation-of-state parametrization, we further constrain R_{1}=11.9_{-1.4}^{+1.4}  km and R_{2}=11.9_{-1.4}^{+1.4}  km at the 90% credible level. Finally, we obtain constraints on p(ρ) at supranuclear densities, with pressure at twice nuclear saturation density measured at 3.5_{-1.7}^{+2.7}×10^{34}  dyn cm^{-2} at the 90% level.

Mechanical properties and wear behavior of light-cured packable composite resins

OBJECTIVES

Determination of flexural strength, flexural modulus, fracture toughness and wear resistance of three packable composites (Solitaire, Surefil, ALERT) and a packable ormocer (Definite) in comparison with an advanced hybrid composite (Tetric Ceram) and an ion-releasing composite (Ariston pHc).

METHODS

Flexural strength, flexural modulus and fracture toughness of each material were determined in three-point bending (each test n = 10). Single-edge notched-bend specimens were used to evaluate the fracture toughness (K1C). Wear of the materials (n = 8) was determined in a pin-on-block-design with a spherical Degusit antagonist at 50 N vertical load and quantified by a replica technique using a 3D-laser scanner. Replicas were made after 6000, 10,000, 30,000 and 50,000 load cycles. The mean wear rate (MWR (micron 3 cycle-1)) was obtained by a linear regression analysis in the steady-state of the time-wear-curve. All results were statistically analyzed with ANOVA and post hoc Tukey HSD tests (p < 0.05).

RESULTS

ALERT exhibited the highest flexural modulus (12.5 +/- 2.1 GPa) and K1C (2.3 +/- 0.2 MN m-3/2), but the lowest wear resistance (8275 micron 3 cycle-1). Solitaire presented the highest wear resistance (1591 micron 3 cycle-1), but significantly lower flexural strength (81.6 +/- 10.0 MPa), flexural modulus (4.4 +/- 0.3 GPa), and K1C (1.4 +/- 0.2 MN m-3/2) than all other materials. Surefil revealed a significantly higher flexural modulus (9.3 +/- 0.9 GPa) and wear resistance (3028 micron 3 cycle-1) than Tetric Ceram (6.8 +/- 0.5 GPa; 5417 micron 3 cycle-1) and Ariston pHc (7.3 +/- 0.8 GPa; 7194 micron 3 cycle-1).

SIGNIFICANCE

The tested packable composite resins differed significantly in their mechanical properties. This study suggested that fracture and wear behavior of the composite resins are highly influenced by the filler system. Overall, Surefil demonstrated good fracture mechanics parameters and a low wear rate.

Tests of General Relativity with GW150914

The LIGO detection of GW150914 provides an unprecedented opportunity to study the two-body motion of a compact-object binary in the large-velocity, highly nonlinear regime, and to witness the final merger of the binary and the excitation of uniquely relativistic modes of the gravitational field. We carry out several investigations to determine whether GW150914 is consistent with a binary black-hole merger in general relativity. We find that the final remnant's mass and spin, as determined from the low-frequency (inspiral) and high-frequency (postinspiral) phases of the signal, are mutually consistent with the binary black-hole solution in general relativity. Furthermore, the data following the peak of GW150914 are consistent with the least-damped quasinormal mode inferred from the mass and spin of the remnant black hole. By using waveform models that allow for parametrized general-relativity violations during the inspiral and merger phases, we perform quantitative tests on the gravitational-wave phase in the dynamical regime and we determine the first empirical bounds on several high-order post-Newtonian coefficients. We constrain the graviton Compton wavelength, assuming that gravitons are dispersed in vacuum in the same way as particles with mass, obtaining a 90%-confidence lower bound of 10^{13}  km. In conclusion, within our statistical uncertainties, we find no evidence for violations of general relativity in the genuinely strong-field regime of gravity.

Observation of electron-antineutrino disappearance at Daya Bay

The Daya Bay Reactor Neutrino Experiment has measured a nonzero value for the neutrino mixing angle θ(13) with a significance of 5.2 standard deviations. Antineutrinos from six 2.9 GWth reactors were detected in six antineutrino detectors deployed in two near (flux-weighted baseline 470 m and 576 m) and one far (1648 m) underground experimental halls. With a 43,000 ton-GWth-day live-time exposure in 55 days, 10,416 (80,376) electron-antineutrino candidates were detected at the far hall (near halls). The ratio of the observed to expected number of antineutrinos at the far hall is R=0.940±0.011(stat.)±0.004(syst.). A rate-only analysis finds sin(2)2θ(13)=0.092±0.016(stat.)±0.005(syst.) in a three-neutrino framework.

Collagenase-2 (MMP-8) and collagenase-3 (MMP-13) in adult periodontitis: molecular forms and levels in gingival crevicular fluid and immunolocalisation in gingival tissue

AIM

To determine the cellular and molecular forms of MMP-8 (collagenase-2) and MMP-13 (collagenase-3) associated with chronic adult periodontitis by examining the species present in gingival crevicular fluid (GCF) and enzyme distribution in gingival tissue.

METHODS

30-s GCF samples were collected directly from the periodontal pockets of 12 untreated patients using filter paper strips. After elution into buffer, the samples were examined by Western immunoblotting with polyclonal antibodies for MMP-8 and MMP-13 and quantification by scanning image analysis. Individual band intensities were expressed as a percentage of total sample absorbance and mean patient values were calculated. Gingival tissue from 6 patients was fixed in formalin and embedded in paraffin wax. MMP-8 and MMP-13 were localised using the same antibodies and an avidin-biotin-peroxidase detecting system. Double staining was performed with a contrasting substrate reaction.

RESULTS

The majority of MMP-8 staining in pre-treatment GCF was present in 80, 75 and 60 kD bands corresponding to prepro-, pro- and active forms of PMN-type enzyme. 43 and 38 kD bands evidently represented active, fibroblast-type MMP-8. Immunoreactivities at >100 kD and < or =30 kD were probably enzyme-inhibitor complex and degraded fragments, respectively. MMP-13 was seen mainly as 60 kD proenzyme with some 40 kD active enzyme and a small proportion of >100 kD complex. The percentages of MMP-8 PMN-type enzyme and MMP-13 proenzyme bands correlated significantly with gingival and bleeding indices (p<0.05). Immunohistochemistry demonstrated MMP-8 in PMNs, sulcular epithelial and also plasma cells in inflamed gingival connective tissue. MMP-13 immunoreactivity was detected in the sulcular epithelium and in macrophage-like cells.

CONCLUSION

Multiple species and elevated levels of both MMP-8 and MMP-13 from many rather than single cellular sources in the diseased periodontium are identified in untreated periodontitis GCF and active forms contribute to GCF collagenase activity.

GW170814: A Three-Detector Observation of Gravitational Waves from a Binary Black Hole Coalescence

On August 14, 2017 at 10∶30:43 UTC, the Advanced Virgo detector and the two Advanced LIGO detectors coherently observed a transient gravitational-wave signal produced by the coalescence of two stellar mass black holes, with a false-alarm rate of ≲1 in 27 000 years. The signal was observed with a three-detector network matched-filter signal-to-noise ratio of 18. The inferred masses of the initial black holes are 30.5_{-3.0}^{+5.7}M_{⊙} and 25.3_{-4.2}^{+2.8}M_{⊙} (at the 90% credible level). The luminosity distance of the source is 540_{-210}^{+130}  Mpc, corresponding to a redshift of z=0.11_{-0.04}^{+0.03}. A network of three detectors improves the sky localization of the source, reducing the area of the 90% credible region from 1160   deg^{2} using only the two LIGO detectors to 60  deg^{2} using all three detectors. For the first time, we can test the nature of gravitational-wave polarizations from the antenna response of the LIGO-Virgo network, thus enabling a new class of phenomenological tests of gravity.

Rapid deubiquitination of nucleosomal histones in human tumor cells caused by proteasome inhibitors and stress response inducers: effects on replication, transcription, translation, and the cellular stress response

The proteasome inhibitors, lactacystin and N-acetyl-leucyl-leucyl-norlucinal, caused a rapid and near-complete loss of approximately 22-23-kDa ubiquitinated nucleoproteins, which we have identified as monoubiquitinated nucleosomal histones H2A and H2B by immunological and two-dimensional electrophoretic techniques. In human SKBr3 breast tumor cells, depletion of monoubiquitinated histones by the proteasome inhibitors coincided with the accumulation of high molecular weight ubiquitinated proteins in both nucleoprotein and cytosolic fractions and decreased unconjugated ubiquitin in the cytosol, without changes in the nonubiquitinated core histones. Unconjugated ubiquitin was not detected in isolated tumor cell nuclei. A similar loss in monoubiquitinated histones occurred in cells harboring a defective, temperature-sensitive mutation of the ubiquitin-activating E1 enzyme, after these cells were elevated from 33 degrees C to the non-permissive temperature of 39 degrees C. DNA replication and RNA transcription were decreased by the proteasome inhibitors most strongly after 90% of the ubiquitin had been removed from ubiquitinated histones H2A and H2B, suggesting a relationship between the nucleosomal histone ubiquitin status and the processing of genetic information. Interestingly, although both proteasome inhibitors caused a generalized decrease in methionine incorporation into proteins, they strongly induced the synthesis of the hsp72 and hsp90 stress proteins. Finally, treating cells with heat-shock at 43 degrees C, with stress response-provoking chemicals or with several other proteasome inhibitors caused ubiquitinated proteins to accumulate, depleted free ubiquitin, and concomitantly decreased nucleosomal monoubiquitinated histones. These results suggest that deubiquitination of nucleosomal histones H2A and H2B may play a previously unrecognized role in the cellular stress response, as well as in the processing of chromatin, and emphasize the important role of the proteasome in cellular homeostasis.