Negative feedback at kinetochores underlies a responsive spindle checkpoint signal

Kinetochores are specialized multi-protein complexes that play a crucial role in maintaining genome stability. They bridge attachments between chromosomes and microtubules during mitosis and they activate the spindle assembly checkpoint (SAC) to arrest division until all chromosomes are attached. Kinetochores are able to efficiently integrate these two processes because they can rapidly respond to changes in microtubule occupancy by switching localized SAC signalling ON or OFF. We show that this responsiveness arises because the SAC primes kinetochore phosphatases to induce negative feedback and silence its own signal. Active SAC signalling recruits PP2A-B56 to kinetochores where it antagonizes Aurora B to promote PP1 recruitment. PP1 in turn silences the SAC and delocalizes PP2A-B56. Preventing or bypassing key regulatory steps demonstrates that this spatiotemporal control of phosphatase feedback underlies rapid signal switching at the kinetochore by: allowing the SAC to quickly transition to the ON state in the absence of antagonizing phosphatase activity; and ensuring phosphatases are then primed to rapidly switch the SAC signal OFF when kinetochore kinase activities are diminished by force-producing microtubule attachments.</p

A meta-analysis of long-term effects of conservation agriculture on maize grain yield under rain-fed conditions

Conservation agriculture involves reduced tillage, permanent soil cover and crop rotations to enhance soil fertility and to supply food from a dwindling land resource. Recently, conservation agriculture has been promoted in Southern Africa, mainly for maize-based farming systems. However, maize yields under rain-fed conditions are often variable. There is therefore a need to identify factors that influence crop yield under conservation agriculture and rain-fed conditions. Here, we studied maize grain yield data from experiments lasting 5 years and more under rain-fed conditions. We assessed the effect of long-term tillage and residue retention on maize grain yield under contrasting soil textures, nitrogen input and climate. Yield variability was measured by stability analysis. Our results show an increase in maize yield over time with conservation agriculture practices that include rotation and high input use in low rainfall areas. But we observed no difference in system stability under those conditions. We observed a strong relationship between maize grain yield and annual rainfall. Our meta-analysis gave the following findings: (1) 92% of the data show that mulch cover in high rainfall areas leads to lower yields due to waterlogging; (2) 85% of data show that soil texture is important in the temporal development of conservation agriculture effects, improved yields are likely on well-drained soils; (3) 73% of the data show that conservation agriculture practices require high inputs especially N for improved yield; (4) 63% of data show that increased yields are obtained with rotation but calculations often do not include the variations in rainfall within and between seasons; (5) 56% of the data show that reduced tillage with no mulch cover leads to lower yields in semi-arid areas; and (6) when adequate fertiliser is available, rainfall is the most important determinant of yield in southern Africa. It is clear from our results that conservation agriculture needs to be targeted and adapted to specific biophysical conditions for improved impact

Mitochondrial calcium uniporter Mcu controls excitotoxicity and is transcriptionally repressed by neuroprotective nuclear calcium signals

The recent identification of the mitochondrial Ca(2+) uniporter gene (Mcu/Ccdc109a) has enabled us to address its role, and that of mitochondrial Ca(2+) uptake, in neuronal excitotoxicity. Here we show that exogenously expressed Mcu is mitochondrially localized and increases mitochondrial Ca(2+) levels following NMDA receptor activation, leading to increased mitochondrial membrane depolarization and excitotoxic cell death. Knockdown of endogenous Mcu expression reduces NMDA-induced increases in mitochondrial Ca(2+), resulting in lower levels of mitochondrial depolarization and resistance to excitotoxicity. Mcu is subject to dynamic regulation as part of an activity-dependent adaptive mechanism that limits mitochondrial Ca(2+) overload when cytoplasmic Ca(2+) levels are high. Specifically, synaptic activity transcriptionally represses Mcu, via a mechanism involving the nuclear Ca(2+) and CaM kinase-mediated induction of Npas4, resulting in the inhibition of NMDA receptor-induced mitochondrial Ca(2+) uptake and preventing excitotoxic death. This establishes Mcu and the pathways regulating its expression as important determinants of excitotoxicity, which may represent therapeutic targets for excitotoxic disorders

Anemie du Premature et Pratiques Transfusionnelles au Centre Hospitalo-Universitaire de Yopougon à Abidjan, Cote d’Ivoire

En C&ocirc;te d&rsquo;Ivoire la transfusion sanguine reste importante. Notre objectif &eacute;tait de proposer une ligne directrice de pratique de transfusion sanguine chez le nouveau n&eacute; pr&eacute;matur&eacute;. Notre &eacute;tude a port&eacute; sur 2 ans de janvier 1997 &agrave; 1999. Tous nouveau-n&eacute;s de moins de 37 semaines hospitalis&eacute;s au Centre Hospitalier Universitaire de Yopougon et dont le taux d&rsquo;h&eacute;moglobine &eacute;tait inf&eacute;rieure &agrave; 13 g/mL ont &eacute;t&eacute; inclus. De cette &eacute;tude il ressort que la pr&eacute;valence de l&rsquo;an&eacute;mie &eacute;tait de 25%, et celle de la transfusion sanguine de 56%. Le taux d&rsquo;h&eacute;moglobine inf&eacute;rieure &agrave; 10 g/mL (p = 0, 000081), la p&acirc;leur (p = 0, 000003) &eacute;taient nos crit&egrave;res de transfusion. Nous concluons que tout pr&eacute;matur&eacute; de moins de 32 semaines dont le taux d&rsquo;h&eacute;moglobine &eacute;tait inf&eacute;rieure ou &eacute;gale &agrave; 10 g/mL admis avant le 15&egrave;me jours de vie doit b&eacute;n&eacute;ficier d&rsquo;une transfusion sanguine et le tauxMots Cl&eacute;s pr&eacute;matur&eacute; ; an&eacute;mie ; transfusion ; Abidja

Experimental and computational study of trace element distribution between orthopyroxene and anhydrous silicate melts: substitution mechanisms and the effect of iron

Although orthopyroxene (Opx) is present during a wide range of magmatic differentiation processes in the terrestrial and lunar mantle, its effect on melt trace element contents is not well quantified. We present results of a combined experimental and computational study of trace element partitioning between Opx and anhydrous silicate melts. Experiments were performed in air at atmospheric pressure and temperatures ranging from 1,326 to 1,420°C in the system CaO-MgO-A

f(R) theories

Over the past decade, f(R) theories have been extensively studied as one of the simplest modifications to General Relativity. In this article we review various applications of f(R) theories to cosmology and gravity - such as inflation, dark energy, local gravity constraints, cosmological perturbations, and spherically symmetric solutions in weak and strong gravitational backgrounds. We present a number of ways to distinguish those theories from General Relativity observationally and experimentally. We also discuss the extension to other modified gravity theories such as Brans-Dicke theory and Gauss-Bonnet gravity, and address models that can satisfy both cosmological and local gravity constraints.Comment: 156 pages, 14 figures, Invited review article in Living Reviews in Relativity, Published version, Comments are welcom

Diamonds, gold and crime displacement: Hatton Garden, and the evolution of organised crime in the UK

The 2015 Hatton Garden Heist was described as the ‘largest burglary in English legal history’. However, the global attention that this spectacular crime attracted to ‘The Garden’ tended to concentrate upon the value of the stolen goods and the vintage of the burglars. What has been ignored is how the burglary shone a spotlight into Hatton Garden itself, as an area with a unique ‘upperworld’ commercial profile and skills cluster that we identify as an incubator and facilitator for organised crime. The Garden is the UK’s foremost jewellery production and retail centre and this paper seeks to explore how Hatton Garden’s businesses integrated with a fluid criminal population to transition, through hosting lucrative (and bureaucratically complex) VAT gold frauds from 1980 to the early 1990s, to become a major base for sophisticated acquisitive criminal activities. Based on extensive interviews over a thirty year period, evidence from a personal research archive and public records, this paper details a cultural community with a unique criminal profile due to the particularities of its geographical location, ethnic composition, trading culture, skills base and international connections. The processes and structures that facilitate criminal markets are largely under-researched (Antonopoulos et al. 2015: 11), and this paper considers how elements of Hatton Garden’s ‘upperworld’ businesses integrated with project criminals, displaced by policing strategies, to effect this transition

Conditional targeting of MAD1 to kinetochores is sufficient to reactivate the spindle assembly checkpoint in metaphase

Fidelity of chromosome segregation is monitored by the spindle assembly checkpoint (SAC). Key components of the SAC include MAD1, MAD2, BUB1, BUB3, BUBR1, and MPS1. These proteins accumulate on kinetochores in early prometaphase but are displaced when chromosomes attach to microtubules and/or biorient on the mitotic spindle. As a result, stable attachment of the final chromosome satisfies the SAC, permitting activation of the anaphase promoting complex/cyclosome (APC/C) and subsequent anaphase onset. SAC satisfaction is reversible, however, as addition of taxol during metaphase stops cyclin B1 degradation by the APC/C. We now show that targeting MAD1 to kinetochores during metaphase is sufficient to reestablish SAC activity after initial silencing. Using rapamycin-induced heterodimerization of FKBP-MAD1 to FRB-MIS12 and live monitoring of cyclin B1 degradation, we show that timed relocalization of MAD1 during metaphase can stop cyclin B1 degradation without affecting chromosome-spindle attachments. APC/C inhibition represented true SAC reactivation, as FKBP-MAD1 required an intact MAD2-interaction motif and MPS1 activity to accomplish this. Our data show that MAD1 kinetochore localization dictates SAC activity and imply that SAC regulatory mechanisms downstream of MAD1 remain functional in metaphase. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00412-014-0458-9) contains supplementary material, which is available to authorized users

Response perseveration and ventral prefrontal sensitivity to reward and punishment in male problem gamblers and smokers

Pathological gambling (PG) is associated with maladaptive perseverative behavior, but the underlying mechanism and neural circuitry is not completely clear. Here, the hypothesis was tested that PG is characterized by response perseveration and abnormalities in reward and/or punishment sensitivity in the ventral frontostriatal circuit. Executive functioning was assessed to verify if these effects are independent of the dorsal frontostriatal circuit. A group of smokers was also included to examine whether impairments in PG generalize to substance use disorders. Response perseveration and reward/punishment sensitivity were measured with a probabilistic reversal-learning task, in which subjects could win and lose money. Executive functioning was measured with a planning task, the Tower of London. Performance and fMRI data were acquired in 19 problem gamblers, 19 smokers, and 19 healthy controls. Problem gamblers showed severe response perseveration, associated with reduced activation of right ventrolateral prefrontal cortex in response to both monetary gain and loss. Results did not fully generalize to smokers. Planning performance and related activation of the dorsal frontostriatal circuit were intact in both problem gamblers and smokers. PG is related to response perseveration and diminished reward and punishment sensitivity as indicated by hypoactivation of the ventrolateral prefrontal cortex when money is gained and lost. Moreover, intact planning abilities and normal dorsal frontostriatal responsiveness indicate that this deficit is not due to impaired executive functioning. Response perseveration and ventral prefrontal hyporesponsiveness to monetary loss may be markers for maladaptive behavior seen in chemical and nonchemical addictions. © 2009 Nature Publishing Group All rights reserved

Long-term efficacy and tolerability of TNFα inhibitors in the treatment of non-infectious ocular inflammation: an 8-year prospective surveillance study

Background/Aim To report the efficacy and tolerability of antitumour necrosis factor-alpha therapy (TNF inhibitors [TNFi]) in the management of non-infectious ocular inflammation, including uveitis and scleritis, in adult patients over an 8-year period. Materials and methods This is a prospective cohort study of infliximab and adalimumab in the treatment of non-infectious ocular inflammatory disease. 43 of 85 adult patients on TNFi (34 infliximab, 9 adalimumab) for ≥1 year with non-infectious uveitis or scleritis were followed from 2006 to 2014. Clinical assessments, medication, adverse events and history of steroid rescues were collected at 6 monthly intervals. General quality of life (Short Form Health Survey (SF-36)) and visual quality of life (Vision-related quality of life Core Measure (VCM1)) were assessed annually. Outcome measures included rate of sustained remission, rate of relapse, systemic corticosteroid reduction, adverse events, and VCM1 and SF-36 scores. Results The median time on infliximab was 3.2 years (IQR 4.3) and on adalimumab was 2.4 years (IQR 1.8). Sustained remission was induced in 39 patients (91%) (0.5 per patient year) after a median of 1.2 years on a TNFi. 22 (51%) experienced one relapse, and 5 (12%) had two relapses. 23 (54%) had at least one adverse event; serious adverse events necessitating hospitalisation or cessation of medication occurred in four (9%) patients. 10 patients (23%) switched from the initiation of TNFi, at 1.7 years after starting, to another TNFi or another class of biologic therapy. Conclusion TNFi treatment is associated with longterm drug-induced remission of ocular inflammation, visual stability and corticosteroid reduction. Adverse events were common and no new safety signals occurred. Relapse of inflammation occurs in half of the treated population