Downregulation of NAC transcription factors modifies cell wall composition and increases strawberry fruit firmness

The strawberry is a soft fruit with a very short post-harvest shelf life. The changes in texture during fruit ripening are mainly due to the dissolution of the middle lamellae, reducing cell-to-cell adhesion, and the weakening of parenchymal cell walls as result of the action of cell wall modifying enzymes. At present, no master regulator of this process has been discovered yet. NAC transcription factors have been involved in numerous physiological processes, including fruit ripening. In strawberry, the NAC family comprises more than 110 genes, and at least 6 of them are expressed during fruit development. In this research, we performed a functional analysis of two ripening-related NAC genes, FaNAC2 and FaNAC3, in Fragaria x ananassa Duch. cv. Chandler. Several RNAi transgenic lines showing low FaNAC2 or FaNAC3 mRNA levels in fruit were obtained through Agrobacterium-mediated transformation. These lines produced fruits significantly firmer than control at the ripe stage, being the increase in firmness higher in FaNAC2 silenced plants. Cell walls were extracted from ripe transgenic fruits and characterized by ELISA and Epitope Detection Chromatography (EDC), using monoclonal antibodies against different polysaccharide epitopes. FaNAC2 transgenic lines showed more extensive changes than FaNAC3; these modifications involved increased amounts of demethylated pectins (LM19) in water and CDTA fractions and an alteration of the lateral branches of RG-I, decreasing the amount of arabinan epitopes and increasing galactan epitopes detected by LM6 and LM5, respectively. The amount of arabinogalactan proteins recognized by the JIM13 antibody was also affected, decreasing in the Na2CO3 fraction and increasing in the 4M KOH and cellulase fraction of the transgenic lines.The results obtained indicate that NAC genes could be involved in the regulation of cell wall disassembly associated to strawberry fruit softening.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Cell wall disassembly is delayed by rhamnogalacturonate lyase gene silencing: potential role in fruit firmness

Strawberry fruits greatly reduce their quality due to softening during ripening with economically important losses. Texture changes of fleshy fruits during ripening are mainly due to middle lamellae dissolution, cell-to-cell adhesion losses and wall weakening of parenchyma cells by the coordinated action of several cell wall enzymes. Pectin degradation has been proven a key factor in strawberry softening by functional analysis of several pectinase genes (polygalacturonase, pectate lyase and -galactosidase). The complexity and highly dynamic nature of pectins remains a challenge to fully elucidate structure-function relationships of pectins. In this work, we present the functional analysis of two independent strawberry transgenic lines with more than 95% silencing of a rhamnogalacturonate lyase gene (FaRGLyase1). Firmness of ripe fruit was significantly higher in both transgenic lines than in the control. Cell walls from these fruits were extracted and analyzed by glycan microarray profiling. This high‐throughput technique allows a wide screening of cell-wall glycan occurrence based on the detection of specific cell wall oligosaccharide epitopes by monoclonal antibodies and reveals profiles which can be used as potential fingerprints specific for a singular organ and/or developmental stage. Our microarray results showed that the silencing of FaRGLyase1 reduced degradation of several rhamnogalacturonan-I related epitopes, as expected. Additionally, comparison of transgenic cell walls from ripe fruits with those extracted from control fruits at different developmental stages (green, white and red) by hierarchical clustering, demonstrated a higher similarity of transgenic fruit cell walls with the control cell walls from fruits at the white stage. Glycan microarray profiles revealed less degraded fruit cell walls as result of FaRGLyase1 down-regulation which could contribute to the increased firmness of transgenic fruitsUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Search for Tensor, Vector, and Scalar Polarizations in the Stochastic Gravitational-Wave Background

The detection of gravitational waves with Advanced LIGO and Advanced Virgo has enabled novel tests of general relativity, including direct study of the polarization of gravitational waves. While general relativity allows for only two tensor gravitational-wave polarizations, general metric theories can additionally predict two vector and two scalar polarizations. The polarization of gravitational waves is encoded in the spectral shape of the stochastic gravitational-wave background, formed by the superposition of cosmological and individually unresolved astrophysical sources. Using data recorded by Advanced LIGO during its first observing run, we search for a stochastic background of generically polarized gravitational waves. We find no evidence for a background of any polarization, and place the first direct bounds on the contributions of vector and scalar polarizations to the stochastic background. Under log-uniform priors for the energy in each polarization, we limit the energy densities of tensor, vector, and scalar modes at 95% credibility to Ω0T<5.58×10-8, Ω0V<6.35×10-8, and Ω0S<1.08×10-7 at a reference frequency f0=25 Hz. © 2018 American Physical Society

Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47×10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society

EPIdemiology of Surgery-Associated Acute Kidney Injury (EPIS-AKI) : Study protocol for a multicentre, observational trial

More than 300 million surgical procedures are performed each year. Acute kidney injury (AKI) is a common complication after major surgery and is associated with adverse short-term and long-term outcomes. However, there is a large variation in the incidence of reported AKI rates. The establishment of an accurate epidemiology of surgery-associated AKI is important for healthcare policy, quality initiatives, clinical trials, as well as for improving guidelines. The objective of the Epidemiology of Surgery-associated Acute Kidney Injury (EPIS-AKI) trial is to prospectively evaluate the epidemiology of AKI after major surgery using the latest Kidney Disease: Improving Global Outcomes (KDIGO) consensus definition of AKI. EPIS-AKI is an international prospective, observational, multicentre cohort study including 10 000 patients undergoing major surgery who are subsequently admitted to the ICU or a similar high dependency unit. The primary endpoint is the incidence of AKI within 72 hours after surgery according to the KDIGO criteria. Secondary endpoints include use of renal replacement therapy (RRT), mortality during ICU and hospital stay, length of ICU and hospital stay and major adverse kidney events (combined endpoint consisting of persistent renal dysfunction, RRT and mortality) at day 90. Further, we will evaluate preoperative and intraoperative risk factors affecting the incidence of postoperative AKI. In an add-on analysis, we will assess urinary biomarkers for early detection of AKI. EPIS-AKI has been approved by the leading Ethics Committee of the Medical Council North Rhine-Westphalia, of the Westphalian Wilhelms-University Münster and the corresponding Ethics Committee at each participating site. Results will be disseminated widely and published in peer-reviewed journals, presented at conferences and used to design further AKI-related trials. Trial registration number NCT04165369

Erratum: "A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo" (2021, ApJ, 909, 218)

[no abstract available

Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3b

We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC-2020 March 27 17:00 UTC). We conduct two independent searches: A generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence for subthreshold gravitational-wave signals associated with this GRB ensemble either. We use several source types and signal morphologies during the searches, resulting in lower bounds on the estimated distance to each GRB. Finally, we constrain the population of low-luminosity short GRBs using results from the first to the third observing runs of Advanced LIGO and Advanced Virgo. The resulting population is in accordance with the local binary neutron star merger rate. © 2022. The Author(s). Published by the American Astronomical Society

Narrowband Searches for Continuous and Long-duration Transient Gravitational Waves from Known Pulsars in the LIGO-Virgo Third Observing Run

Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo's third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours-months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets. © 2022. The Author(s). Published by the American Astronomical Society