Double-faced role of Bcl-2-associated athanogene 7 in plant-Phytophthora interaction.

Due to their sessile nature, plants must respond to various environmental assaults in a coordinated manner. The endoplasmic reticulum is a central hub for plant responses to various stresses. We previously showed that Phytophthora utilizes effector PsAvh262-mediated binding immunoglobulin protein (BiP) accumulation for suppressing endoplasmic reticulum stress-triggered cell death. As a BiP binding partner, Bcl-2-associated athanogene 7 (BAG7) plays a crucial role in the maintenance of the unfolded protein response, but little is known about its role in plant immunity. In this work, we reveal a double-faced role of BAG7 in Arabidopsis-Phytophthora interaction in which it regulates endoplasmic reticulum stress-mediated immunity oppositely in different cellular compartments. In detail, it acts as a susceptibility factor in the endoplasmic reticulum, but plays a resistance role in the nucleus against Phytophthora. Phytophthora infection triggers the endoplasmic reticulum-to-nucleus translocation of BAG7, the same as abiotic heat stress; however, this process can be prevented by PsAvh262-mediated BiP accumulation. Moreover, the immunoglobulin/albumin-binding domain in PsAvh262 is essential for both pathogen virulence and BiP accumulation. Taken together, our study uncovers a double-faced role of BAG7; Phytophthora advances its colonization in planta by utilizing an effector to detain BAG7 in the endoplasmic reticulum.

Hydrothermal 15N15N abundances constrain the origins of mantle nitrogen.

Nitrogen is the main constituent of the Earth's atmosphere, but its provenance in the Earth's mantle remains uncertain. The relative contribution of primordial nitrogen inherited during the Earth's accretion versus that subducted from the Earth's surface is unclear1-6. Here we show that the mantle may have retained remnants of such primordial nitrogen. We use the rare 15N15N isotopologue of N2 as a new tracer of air contamination in volcanic gas effusions. By constraining air contamination in gases from Iceland, Eifel (Germany) and Yellowstone (USA), we derive estimates of mantle δ15N (the fractional difference in 15N/14N from air), N2/36Ar and N2/3He. Our results show that negative δ15N values observed in gases, previously regarded as indicating a mantle origin for nitrogen7-10, in fact represent dominantly air-derived N2 that experienced 15N/14N fractionation in hydrothermal systems. Using two-component mixing models to correct for this effect, the 15N15N data allow extrapolations that characterize mantle endmember δ15N, N2/36Ar and N2/3He values. We show that the Eifel region has slightly increased δ15N and N2/36Ar values relative to estimates for the convective mantle provided by mid-ocean-ridge basalts11, consistent with subducted nitrogen being added to the mantle source. In contrast, we find that whereas the Yellowstone plume has δ15N values substantially greater than that of the convective mantle, resembling surface components12-15, its N2/36Ar and N2/3He ratios are indistinguishable from those of the convective mantle. This observation raises the possibility that the plume hosts a primordial component. We provide a test of the subduction hypothesis with a two-box model, describing the evolution of mantle and surface nitrogen through geological time. We show that the effect of subduction on the deep nitrogen cycle may be less important than has been suggested by previous investigations. We propose instead that high mid-ocean-ridge basalt and plume δ15N values may both be dominantly primordial features.

Movement Kinematics Dynamically Modulates the Rolandic ~ 20-Hz Rhythm During Goal-Directed Executed and Observed Hand Actions.

This study investigates whether movement kinematics modulates similarly the rolandic α and ß rhythm amplitude during executed and observed goal-directed hand movements. It also assesses if this modulation relates to the corticokinematic coherence (CKC), which is the coupling observed between cortical activity and movement kinematics during such motor actions. Magnetoencephalography (MEG) signals were recorded from 11 right-handed healthy subjects while they performed or observed an actor performing the same repetitive hand pinching action. Subjects' and actor's forefinger movements were monitored with an accelerometer. Coherence was computed between acceleration signals and the amplitude of α (8-12 Hz) or ß (15-25 Hz) oscillations. The coherence was also evaluated between source-projected MEG signals and their ß amplitude. Coherence was mainly observed between acceleration and the amplitude of ß oscillations at movement frequency within bilateral primary sensorimotor (SM1) cortex with no difference between executed and observed movements. Cross-correlation between the amplitude of ß oscillations at the SM1 cortex and movement acceleration was maximal when acceleration was delayed by ~ 100 ms, both during movement execution and observation. Coherence between source-projected MEG signals and their ß amplitude during movement observation and execution was not significantly different from that during rest. This study shows that observing others' actions engages in the viewer's brain similar dynamic modulations of SM1 cortex ß rhythm as during action execution. Results support the view that different neural mechanisms might account for this modulation and CKC. These two kinematic-related phenomena might help humans to understand how observed motor actions are actually performed.

Neural Basis of Early Somatosensory Change Detection: A Magnetoencephalography Study.

The mismatch negativity (MMN) reflects the early detection of changes in sensory stimuli at the cortical level. The mechanisms underlying its genesis remain debated. This magnetoencephalography study investigates the spatio-temporal dynamics and the neural mechanisms of the magnetic somatosensory MMN. Somatosensory evoked magnetic fields elicited by tactile stimulation of the right fingertip (Single), tactile stimulation of the right middle phalanx and fingertip (Double) or omissions (Omitted) of tactile stimuli were studied in different paradigms: in oddballs where Double/Omitted followed a sequence of four Single, in sequences of two stimuli where Double occurred after one Single, and in random presentation of Double only. The predictability of Double occurrence in oddballs was also manipulated. Cortical sources of evoked responses were identified using equivalent current dipole modeling. Evoked responses elicited by Double were significantly different from those elicited by Single at the contralateral secondary somatosensory (cSII) cortex. Double elicited higher cSII cortex responses than Single when preceded by a sequence of four Single, compared to when they were preceded by one Single. Double elicited higher cSII cortex response when presented alone compared to when Double were preceded by one or a sequence of Single. Omitted elicited similar cSII cortex response than Single. Double in oddballs led to higher cSII cortex responses when less predictable. These data suggest that early tactile change detection involves mainly cSII cortex. The predictive coding framework probably accounts for the SII cortex response features observed in the different tactile paradigms.

Fast, precise, and accurate myocardial T1 mapping using a radial MOLLI sequence with FLASH readout.

PURPOSE: Quantitative cardiac MRI, and more particularly T1 mapping, has become a most important modality to characterize myocardial tissue. In this work, the value of a radial variant of the conventional modified Look-Locker inversion recovery sequence (raMOLLI) is demonstrated. METHODS: The raMOLLI acquisition scheme consisted of five radial echo trains of 80 spokes acquired using either a fast low-angle shot (FLASH) or a true fast imaging with steady-state-precession (TrueFISP) readout at different time points after a single magnetization inversion. View sharing combined with a compressed sensing algorithm allowed the reconstruction of 50 images along the T1 relaxation recovery curve, to which a dictionary-fitting approach was applied to estimate T1 . The sequence was validated on a nine-vial phantom, on 19 healthy subjects, and one patient suffering from dilated cardiomyopathy. RESULTS: The raMOLLI sequence allowed a significant decrease of myocardial T1 map acquisition time down to five heartbeats, while exhibiting a higher degree of accuracy and a comparable precision on T1 value estimation than the conventional modified Look-Locker inversion recovery sequence. The FLASH readout demonstrated a better robustness to B0 inhomogeneities than TrueFISP, and was therefore preferred for in vivo acquisitions. CONCLUSIONS: This sequence represents a good candidate for ultrafast acquisition of myocardial T1 maps. Magn Reson Med 79:1387-1398, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Xenon isotopes in 67P/Churyumov-Gerasimenko show that comets contributed to Earth's atmosphere.

The origin of cometary matter and the potential contribution of comets to inner-planet atmospheres are long-standing problems. During a series of dedicated low-altitude orbits, the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) on the Rosetta spacecraft analyzed the isotopes of xenon in the coma of comet 67P/Churyumov-Gerasimenko. The xenon isotopic composition shows deficits in heavy xenon isotopes and matches that of a primordial atmospheric component. The present-day Earth atmosphere contains 22 ± 5% cometary xenon, in addition to chondritic (or solar) xenon.

Effect of movement rate on corticokinematic coherence.

AIMS OF THE STUDY: This study investigates the effect of movement rate on the coupling between cortical magnetoencephalographic (MEG) signals and the kinematics of repetitive active finger movements, i.e., the corticokinematic coherence (CKC). MATERIAL AND METHODS: CKC was evaluated in ten right-handed healthy adults performing repetitive flexion-extension of the right-hand fingers in three different movement rate conditions: slow (∼1 Hz, duration: 11 min), medium (∼2 Hz, duration: 5 min) and fast (∼3 Hz, duration: 3 min). Neuromagnetic signals were recorded with a whole-scalp-covering MEG (Elekta Oy) and index acceleration was monitored with a 3-axis accelerometer. Coherent sources were estimated on the time-course of the cross-correlogram using equivalent current dipole (ECD) modeling. RESULTS: Significant coherence was found at movement frequency or its first harmonics in all subjects and movement conditions. ECDs clustered at the primary sensorimotor cortex contralateral to hand movements. Movement rate had no effect on the coherence levels and the location of coherent sources. CONCLUSIONS: This study demonstrates that the movement rate does not affect coherence levels and CKC source location during active finger movements. This finding has direct implications for CKC functional mapping applications and studies investigating the pathophysiology of central nervous disorders affecting proprioceptive pathways.

Abundant molecular oxygen in the coma of comet 67P/Churyumov-Gerasimenko.

The composition of the neutral gas comas of most comets is dominated by H2O, CO and CO2, typically comprising as much as 95 per cent of the total gas density. In addition, cometary comas have been found to contain a rich array of other molecules, including sulfuric compounds and complex hydrocarbons. Molecular oxygen (O2), however, despite its detection on other icy bodies such as the moons of Jupiter and Saturn, has remained undetected in cometary comas. Here we report in situ measurement of O2 in the coma of comet 67P/Churyumov-Gerasimenko, with local abundances ranging from one per cent to ten per cent relative to H2O and with a mean value of 3.80 ± 0.85 per cent. Our observations indicate that the O2/H2O ratio is isotropic in the coma and does not change systematically with heliocentric distance. This suggests that primordial O2 was incorporated into the nucleus during the comet's formation, which is unexpected given the low upper limits from remote sensing observations. Current Solar System formation models do not predict conditions that would allow this to occur.

The IS200/IS605 Family and "Peel and Paste" Single-strand Transposition Mechanism.

This chapter presents an analysis of the organization and distribution of the IS200/IS605 family of insertion sequences (IS). Members of this family are widespread in both bacteria and archaea. They are unusual because they use obligatory single-strand DNA intermediates, which distinguishes them from classical IS. We summarize studies of the experimental model systems IS608 (from Helicobacter pylori) and ISDra2 (from Deinococcus radiodurans) and present biochemical, genetic, and structural data that describe their transposition pathway and the way in which their transposase (an HuH rather than a DDE enzyme) catalyzes this process. The transposition of IS200/IS605 family members can be described as a "Peel-and-Paste" mechanism. We also address the probable domestication of IS200/IS605 family transposases as enzymes involved in multiplication of repeated extragenic palindromes and as potential homing endonucleases in intron-IS chimeras.

Molecular nitrogen in comet 67P/Churyumov-Gerasimenko indicates a low formation temperature.

Molecular nitrogen (N2) is thought to have been the most abundant form of nitrogen in the protosolar nebula. It is the main N-bearing molecule in the atmospheres of Pluto and Triton and probably the main nitrogen reservoir from which the giant planets formed. Yet in comets, often considered the most primitive bodies in the solar system, N2 has not been detected. Here we report the direct in situ measurement of N2 in the Jupiter family comet 67P/Churyumov-Gerasimenko, made by the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis mass spectrometer aboard the Rosetta spacecraft. A N2/CO ratio of (5.70 ± 0.66) × 10(-3) (2σ standard deviation of the sampled mean) corresponds to depletion by a factor of ~25.4 ± 8.9 as compared to the protosolar value. This depletion suggests that cometary grains formed at low-temperature conditions below ~30 kelvin.

Cometary science. Time variability and heterogeneity in the coma of 67P/Churyumov-Gerasimenko.

Comets contain the best-preserved material from the beginning of our planetary system. Their nuclei and comae composition reveal clues about physical and chemical conditions during the early solar system when comets formed. ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) onboard the Rosetta spacecraft has measured the coma composition of comet 67P/Churyumov-Gerasimenko with well-sampled time resolution per rotation. Measurements were made over many comet rotation periods and a wide range of latitudes. These measurements show large fluctuations in composition in a heterogeneous coma that has diurnal and possibly seasonal variations in the major outgassing species: water, carbon monoxide, and carbon dioxide. These results indicate a complex coma-nucleus relationship where seasonal variations may be driven by temperature differences just below the comet surface.

Constraints from Comets on the Formation and Volatile Acquisition of the Planets and Satellites.

Comets play a dual role in understanding the formation and evolution of the solar system. First, the composition of comets provides information about the origin of the giant planets and their moons because comets formed early and their composition is not expected to have evolved significantly since formation. They, therefore serve as a record of conditions during the early stages of solar system formation. Once comets had formed, their orbits were perturbed allowing them to travel into the inner solar system and impact the planets. In this way they contributed to the volatile inventory of planetary atmospheres. We review here how knowledge of comet composition up to the time of the Rosetta mission has contributed to understanding the formation processes of the giant planets, their moons and small icy bodies in the solar system. We also discuss how comets contributed to the volatile inventories of the giant and terrestrial planets.

Cometary science. 67P/Churyumov-Gerasimenko, a Jupiter family comet with a high D/H ratio.

The provenance of water and organic compounds on Earth and other terrestrial planets has been discussed for a long time without reaching a consensus. One of the best means to distinguish between different scenarios is by determining the deuterium-to-hydrogen (D/H) ratios in the reservoirs for comets and Earth's oceans. Here, we report the direct in situ measurement of the D/H ratio in the Jupiter family comet 67P/Churyumov-Gerasimenko by the ROSINA mass spectrometer aboard the European Space Agency's Rosetta spacecraft, which is found to be (5.3 ± 0.7) × 10(-4)­that is, approximately three times the terrestrial value. Previous cometary measurements and our new finding suggest a wide range of D/H ratios in the water within Jupiter family objects and preclude the idea that this reservoir is solely composed of Earth ocean-like water.

The iodine-plutonium-xenon age of the Moon-Earth system revisited.

Iodine-plutonium-xenon isotope systematics have been used to re-evaluate time constraints on the early evolution of the Earth-atmosphere system and, by inference, on the Moon-forming event. Two extinct radionuclides ((129)I, T1/2=15.6 Ma and (244)Pu, T1/2=80 Ma) have produced radiogenic (129)Xe and fissiogenic (131-136)Xe, respectively, within the Earth, the related isotope fingerprints of which are seen in the compositions of mantle and atmospheric Xe. Recent studies of Archaean rocks suggest that xenon atoms have been lost from the Earth's atmosphere and isotopically fractionated during long periods of geological time, until at least the end of the Archaean eon. Here, we build a model that takes into account these results. Correction for Xe loss permits the computation of new closure ages for the Earth's atmosphere that are in agreement with those computed for mantle Xe. The corrected Xe formation interval for the Earth-atmosphere system is [Formula: see text] Ma after the beginning of Solar System formation. This time interval may represent a lower limit for the age of the Moon-forming impact.

Characterization of organic matter in beef feedyard manure by ultraviolet-visible and fourier transform infrared spectroscopies.

Manure from beef cattle feedyards is a valuable source of nutrients and assists with maintaining soil quality. However, humification and decomposition processes occurring during feedyard manure's on-farm life cycle influence the forms, concentrations, and availability of carbon (C) and nutrients such as nitrogen (N) and phosphorus (P). Improved understanding of manure organic matter (OM) chemistry will provide better estimates of potential fertilizer value of manure from different feedyard sources (e.g., manure accumulated in pens, stockpiled manure after pen scraping) and in settling basin and retention pond sediments. This will also assist with identifying factors related to nutrient loss and environmental degradation via volatilization of ammonia and nitrous oxide and nitrate leaching. We used Fourier-transform infrared (FTIR) and ultraviolet-visible (UV-vis) spectroscopies to characterize structural and functional properties of OM and water-extractable OM (WEOM) from different sources (surface manure, manure pack, settling basin, retention pond) on a typical commercial beef feedyard in the Texas Panhandle. Results showed that as beef manure completes its on-farm life cycle, concentrations of dissolved organic C and N decrease up to 98 and 95%, respectively. The UV-vis analysis of WEOM indicated large differences in molecular weight, lignin content, and proportion of humified OM between manures from different sources. The FTIR spectra of OM and WEOM indicate preferential decomposition of fats, lipids, and proteins over aromatic polysaccharides such as lignin. Further work is warranted to evaluate how application of feedyard manure from different sources influences soil metabolic functioning and fertility.

Hindered diffusion of MRI contrast agents in rat brain extracellular micro-environment assessed by acquisition of dynamic T1 and T2 maps.

The knowledge of brain tissues characteristics (such as extracellular space and tortuosity) represents valuable information for the design of optimal MR probes for specific biomarkers targeting. This work proposes a methodology based on dynamic acquisition of relaxation time maps to quantify in vivo MRI contrast agent concentration after intra-cerebral injection in rat brain. It was applied to estimate the hindered diffusion in brain tissues of five contrast agents with different hydrodynamic diameters (Dotarem(®) ≈ 1 nm, P846 ≈ 4 nm, P792 ≈ 7 nm, P904 ≈ 22 nm and Gd-based emulsion ≈ 170 nm). In vivo apparent diffusion coefficients were compared with those estimated in an obstacle-free medium to determine brain extracellular space and tortuosity. At a 2 h imaging timescale, all contrast agents except the Gd-based emulsion exhibited significant diffusion through brain tissues, with characteristic times compatible with MR molecular imaging (<70 min to diffuse between two capillaries). In conclusion, our experiments indicate that MRI contrast agents with sizes up to 22 nm can be used to perform molecular imaging on intra-cerebral biomarkers. Our quantification methodology allows a precise estimation of apparent diffusion coefficients, which is helpful to calibrate optimal timing between contrast agent injection and MRI observation for molecular imaging studies.

Tissint martian meteorite: a fresh look at the interior, surface, and atmosphere of Mars.

Tissint (Morocco) is the fifth martian meteorite collected after it was witnessed falling to Earth. Our integrated mineralogical, petrological, and geochemical study shows that it is a depleted picritic shergottite similar to EETA79001A. Highly magnesian olivine and abundant glass containing martian atmosphere are present in Tissint. Refractory trace element, sulfur, and fluorine data for the matrix and glass veins in the meteorite indicate the presence of a martian surface component. Thus, the influence of in situ martian weathering can be unambiguously distinguished from terrestrial contamination in this meteorite. Martian weathering features in Tissint are compatible with the results of spacecraft observations of Mars. Tissint has a cosmic-ray exposure age of 0.7 ± 0.3 million years, consistent with those of many other shergottites, notably EETA79001, suggesting that they were ejected from Mars during the same event.

A 15N-poor isotopic composition for the solar system as shown by Genesis solar wind samples.

The Genesis mission sampled solar wind ions to document the elemental and isotopic compositions of the Sun and, by inference, of the protosolar nebula. Nitrogen was a key target element because the extent and origin of its isotopic variations in solar system materials remain unknown. Isotopic analysis of a Genesis Solar Wind Concentrator target material shows that implanted solar wind nitrogen has a (15)N/(14)N ratio of 2.18 ± 0.02 × 10(-3) (that is, ≈40% poorer in (15)N relative to terrestrial atmosphere). The (15)N/(14)N ratio of the protosolar nebula was 2.27 ± 0.03 × 10(-3), which is the lowest (15)N/(14)N ratio known for solar system objects. This result demonstrates the extreme nitrogen isotopic heterogeneity of the nascent solar system and accounts for the (15)N-depleted components observed in solar system reservoirs.

Daily, monthly, seasonal, and annual ammonia emissions from Southern High Plains cattle feedyards.

Ammonia emitted from beef cattle feedyards adds excess reactive N to the environment, contributes to degraded air quality as a precursor to secondary particulate matter, and represents a significant loss of N from beef cattle feedyards. We used open path laser spectroscopy and an inverse dispersion model to quantify daily, monthly, seasonal, and annual NH emissions during 2 yr from two commercial cattle feedyards in the Panhandle High Plains of Texas. Annual patterns of NH fluxes correlated with air temperature, with the greatest fluxes (>100 kg ha d) during the summer and the lowest fluxes (<15 kg ha d) during the winter. Mean monthly per capita emission rate (PCER) of NH-N at one feedyard ranged from 31 g NH-N head d (January) to 207 g NH-N head d (October), when increased dietary crude protein from wet distillers grains elevated emissions. Ammonia N emissions at the other feedyard ranged from 36 g NH-N head d (January) to 121 g NH-N head d (September). Monthly fractional NH-N loss ranged from a low of 19 to 24% to a high of 80 to 85% of fed N at the two feedyards. Seasonal PCER at the two feedyards averaged 60 to 71 g NH-N head d during winter and 103 to 158 g NH-N head d during summer. Annually, PCER was 115 and 80 g NH-N head d at the two feedyards, which represented 59 and 52% of N fed to the cattle. Detailed studies are needed to determine the effect of management and environmental variables such as diet, temperature, precipitation, and manure water content on NH emissions.