108 research outputs found
Actin cytoskeleton remodeling during early Drosophila furrow formation requires recycling endosomal components Nuclear-fallout and Rab11
Cytokinesis requires a dramatic remodeling of the cortical cytoskeleton as well as membrane addition. The Drosophila pericentrosomal protein, Nuclear-fallout (Nuf), provides a link between these two processes. In nuf-derived embryos, actin remodeling and membrane recruitment during the initial stages of metaphase and cellular furrow formation are disrupted. Nuf is a homologue of arfophilin-2, an ADP ribosylation factor effector that binds Rab11 and influences recycling endosome (RE) organization. Here, we show that Nuf is an important component of the RE, and that these phenotypes are a consequence of Nuf activities at the RE. Nuf exhibits extensive colocalization with Rab11, a key RE component. GST pull-downs and the presence of a conserved Rab11-binding domain in Nuf demonstrate that Nuf and Rab11 physically associate. In addition, Nuf and Rab11 are mutually required for their localization to the RE. Embryos with reduced levels of Rab11 produce membrane recruitment and actin remodeling defects strikingly similar to nuf-derived embryos. These analyses support a common role for Nuf and Rab11 at the RE in membrane trafficking and actin remodeling during the initial stages of furrow formation
Annual Cycle of Turbulent Dissipation Estimated from Seagliders
The rate of dissipation of turbulent kinetic energy is estimated using Seaglider observations of vertical water velocity in the midlatitude North Atlantic. This estimate is based on the largeâeddy method, allowing the use of measurements of turbulent energy at large scales O(1â10 m) to diagnose the rate of energy dissipated through viscous processes at scales O(1 mm). The Seaglider data considered here were obtained in a region of high stratification (1 Ă 10â4<N < 1Ă10â2sâ1), where previous implementations of this method fail. The largeâeddy method is generalized to highâstratification by highâpass filtering vertical velocity with a cutoff dependent on the local buoyancy frequency, producing a yearâlong time series of dissipation rate spanning the uppermost 1,000 m with subdaily resolution. This is compared to the dissipation rate estimated from a moored 600 kHz acoustic Doppler current profiler. The variability of the Seagliderâbased dissipation correlates with oneâdimensional scalings of windâ and buoyancyâdriven mixedâlayer turbulence.
Plain Language Summary
Measuring ocean turbulence is crucial for understanding how heat and carbon dioxide are transferred from the atmosphere to the deep ocean. However, measurements of ocean turbulence are sparse. Here autonomous Seagliders are used to estimate turbulence in the surface kilometer of the North Atlantic Ocean. Using an estimate of the vertical water velocity from the flight of the Seaglider through the water, we estimate turbulence by assuming the energy of the largest turbulent fluctuations is representative of the energy dissipated at molecular scales. This approach has been used previously in an ocean region where the vertical gradient of density is small. Our results show that this previous approach fails when the vertical density gradient increases, as it does not account for other processes that are unrelated to turbulence. We introduce a generalized method that isolates only the turbulent processes by accounting for the strength of the vertical density gradient. We show that this new estimate agrees with other turbulence measurements. Our estimate also agrees well with a simple estimates of turbulence from atmospheric processes. This study therefore presents method that can be applied to existing and new Seaglider data to greatly increase our measurements of ocean turbulence
High Plasmid Gene Protein 3 (Pgp3) Chlamydia trachomatis Seropositivity, Pelvic Inflammatory Disease, and Infertility Among Women, National Health and Nutrition Examination Survey, United States, 2013-2016
BACKGROUND. Chlamydia trachomatis causes pelvic inflammatory disease (PID) and tubal infertility. Plasmid gene protein 3 antibody (Pgp3Ab) detects prior chlamydial infections. We evaluated for an association of high chlamydial seropositivity with sequelae using a Pgp3Ab multiplex bead array (Pgp3AbMBA). METHODS. We performed chlamydia Pgp3AbMBA on sera from women 18â39 years old participating in the 2013â2016 National Health and Nutrition Examination Survey (NHANES) with urine chlamydia nucleic acid amplification test results. High chlamydial seropositivity was defined as a median fluorescence intensity (MFI â„ 50 000; low-positive was MFI > 551â<50 000. Weighted US population high-positive, low-positive, and negative Pgp3Ab chlamydia seroprevalence and 95% confidence intervals (CI) were compared for women with chlamydial infection, self-reported PID, and infertility. RESULTS. Of 2339 women aged 18â39 years, 1725 (73.7%) had sera, and 1425 were sexually experienced. Overall, 104 women had high positive Pgp3Ab (5.4% [95% CI 4.0â7.0] of US women); 407 had lowpositive Pgp3Ab (25.1% [95% CI 21.5â29.0]), and 914 had negative Pgp3Ab (69.5% [95% CI 65.5â73.4]). Among women with high Pgp3Ab, infertility prevalence was 2.0 (95% CI 1.1â3.7) times higher than among Pgp3Ab-negative women (19.6% [95% CI 10.5â31.7] versus 9.9% [95% CI 7.7â12.4]). For women with low Pgp3Ab, PID prevalence was 7.9% (95% CI 4.6â12.6) compared to 2.3% (95% CI 1.4â3.6) in negative Pgp3Ab. CONCLUSIONS. High chlamydial Pgp3Ab seropositivity was associated with infertility although small sample size limited evaluation of an association of high seropositivity with PID. In infertile women, Pgp3Ab may be a marker of prior chlamydial infection
Impact of Community Treatment With Ivermectin for the Control of Scabies on the Prevalence of Antibodies to Strongyloides stercoralis in Children.
The prevalence of antibodies to Strongyloides stercoralis was measured in 0-12-year-olds using a bead-based immunoassay before and after ivermectin mass drug administration (MDA) for scabies in the Solomon Islands. Seroprevalence was 9.3% before and 5.1% after MDA (Pâ
=â
.019), demonstrating collateral benefits of ivermectin MDA in this setting
Defining Seropositivity Thresholds for Use in Trachoma Elimination Studies.
BACKGROUND: Efforts are underway to eliminate trachoma as a public health problem by 2020. Programmatic guidelines are based on clinical signs that correlate poorly with Chlamydia trachomatis (Ct) infection in post-treatment and low-endemicity settings. Age-specific seroprevalence of anti Ct Pgp3 antibodies has been proposed as an alternative indicator of the need for intervention. To standardise the use of these tools, it is necessary to develop an analytical approach that performs reproducibly both within and between studies. METHODOLOGY: Dried blood spots were collected in 2014 from children aged 1-9 years in Laos (n = 952) and Uganda (n = 2700) and from people aged 1-90 years in The Gambia (n = 1868). Anti-Pgp3 antibodies were detected by ELISA. A number of visual and statistical analytical approaches for defining serological status were compared. PRINCIPAL FINDINGS: Seroprevalence was estimated at 11.3% (Laos), 13.4% (Uganda) and 29.3% (The Gambia) by visual inspection of the inflection point. The expectation-maximisation algorithm estimated seroprevalence at 10.4% (Laos), 24.3% (Uganda) and 29.3% (The Gambia). Finite mixture model estimates were 15.6% (Laos), 17.1% (Uganda) and 26.2% (The Gambia). Receiver operating characteristic (ROC) curve analysis using a threshold calibrated against external reference specimens estimated the seroprevalence at 6.7% (Laos), 6.8% (Uganda) and 20.9% (The Gambia) when the threshold was set to optimise Youden's J index. The ROC curve analysis was found to estimate seroprevalence at lower levels than estimates based on thresholds established using internal reference data. Thresholds defined using internal reference threshold methods did not vary substantially between population samples. CONCLUSIONS: Internally calibrated approaches to threshold specification are reproducible and consistent and thus have advantages over methods that require external calibrators. We propose that future serological analyses in trachoma use a finite mixture model or expectation-maximisation algorithm as a means of setting the threshold for ELISA data. This will facilitate standardisation and harmonisation between studies and eliminate the need to establish and maintain a global calibration standard
OSSOS. IX. Two Objects in Neptune's 9: 1 Resonance - Implications for Resonance Sticking in the Scattering Population
We discuss the detection in the Outer Solar System Origins Survey (OSSOS) of
two objects in Neptune's distant 9:1 mean motion resonance at semimajor axis
~au. Both objects are securely resonant on 10~Myr timescales,
with one securely in the 9:1 resonance's leading asymmetric libration island
and the other in either the symmetric or trailing asymmetric island. These
objects are the largest semimajor axis objects with secure resonant
classifications, and their detection in a carefully characterized survey allows
for the first robust resonance population estimate beyond 100~au. The detection
of these objects implies a 9:1 resonance population of objects
with (~km) on similar orbits (95\% confidence range
of ). Integrations over 4~Gyr of an ensemble of clones
spanning these objects' orbit fit uncertainties reveal that they both have
median resonance occupation timescales of ~Gyr. These timescales are
consistent with the hypothesis that these objects originate in the scattering
population but became transiently stuck to Neptune's 9:1 resonance within the
last ~Gyr of solar system evolution. Based on simulations of a model of
the current scattering population, we estimate the expected resonance sticking
population in the 9:1 resonance to be 1000-4500 objects with ; this
is marginally consistent with the OSSOS 9:1 population estimate. We conclude
that resonance sticking is a plausible explanation for the observed 9:1
population, but we also discuss the possibility of a primordial 9:1 population,
which would have interesting implications for the Kuiper belt's dynamical
history.Comment: accepted for publication in A
Genomes from Verteba cave suggest diversity within the Trypillians in Ukraine
The transition to agriculture occurred relatively late in Eastern Europe, leading researchers to debate whether it was a gradual, interactive process or a colonisation event. In the forest and forest-steppe regions of Ukraine, farming appeared during the fifth millennium BCE, associated with the Cucuteni-Trypillia cultural complex (CTCC,â~â5000-3000 BCE). Across Europe, the Neolithisation process was highly variable across space and over time. Here, we investigate the population dynamics of early agriculturalists from the eastern forest-steppe region based on the analyses of 20 ancient genomes from the site of Verteba Cave (3935-825Â cal BCE). Results reveal that the CTCC individuals' ancestry is related to both western hunter-gatherers and Near Eastern farmers, has no local ancestry associated with Ukrainian Neolithic hunter-gatherers and has steppe ancestry. An Early Bronze Age individual has an ancestry profile related to the Yamnaya expansions but with 20% of ancestry related to the other Trypillian individuals, which suggests admixture between the Trypillians and the incoming populations carrying steppe-related ancestry. A Late Bronze Age individual dated to 980-825Â cal BCE has a genetic profile indicating affinity to Beaker-related populations, detected close to 1000Â years after the end of the Bell Beaker phenomenon during the third millennium BCE
Surveillance for peri-elimination trachoma recrudescence: Exploratory studies in Ghana.
INTRODUCTION: To date, eleven countries have been validated as having eliminated trachoma as a public health problem, including Ghana in 2018. Surveillance for recrudescence is needed both pre- and post-validation but evidence-based guidance on appropriate strategies is lacking. We explored two potential surveillance strategies in Ghana. METHODOLOGY/PRINCIPAL FINDINGS: Amongst randomly-selected communities enrolled in pre-validation on-going surveillance between 2011 and 2015, eight were identified as having had trachomatous-inflammation follicular (TF) prevalence â„5% in children aged 1-9 years between 2012 and 2014. These eight were re-visited in 2015 and 2016 and neighbouring communities were also added ("TF trigger" investigations). Resident children aged 1-9 years were then examined for trachoma and had a conjunctival swab to test for Chlamydia trachomatis (Ct) and a dried blood spot (DBS) taken to test for anti-Pgp3 antibodies. These investigations identified at least one community with evidence of probable recent Ct ocular transmission. However, the approach likely lacks sufficient spatio-temporal power to be reliable. A post-validation surveillance strategy was also evaluated, this reviewed the ocular Ct infection and anti-Pgp3 seroprevalence data from the TF trigger investigations and from the pre-validation surveillance surveys in 2015 and 2016. Three communities identified as having ocular Ct infection >0% and anti-Pgp3 seroprevalence â„15.0% were identified, and along with three linked communities, were followed-up as part of the surveillance strategy. An additional three communities with a seroprevalence â„25.0% but no Ct infection were also followed up ("antibody and infection trigger" investigations). DBS were taken from all residents aged â„1 year and ocular swabs from all children aged 1-9 years. There was evidence of transmission in the group of communities visited in one district (Zabzugu-Tatale). There was no or little evidence of continued transmission in other districts, suggesting previous infection identified was transient or potentially not true ocular Ct infection. CONCLUSIONS/SIGNIFICANCE: There is evidence of heterogeneity in Ct transmission dynamics in northern Ghana, even 10 years after wide-scale MDA has stopped. There is added value in monitoring Ct infection and anti-Ct antibodies, using these indicators to interrogate past or present surveillance strategies. This can result in a deeper understanding of transmission dynamics and inform new post-validation surveillance strategies. Opportunities should be explored for integrating PCR and serological-based markers into surveys conducted in trachoma elimination settings
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