Developer ducks are ducks being reared for breeding. Like breeder candidate chickens, they are raised with appropriate light and feed programs. A commercial Pekin duck (
) developer flock experienced ...an extraordinary, elevated mortality event at 6 wk of age. Weekly mortality rate that week was 162 ducklings out of a flock of 6420 (2.5%). Mortality jumped to 988 (15.4%) ducklings the next week. On first elevated mortality, six dead ducks from that flock were submitted for diagnostic investigation at Michigan State University Veterinary Diagnostic Laboratory. Myocarditis, pale striping or diffuse pallor of the epicardium, was grossly evident in five of the six submitted ducklings. All of the ducklings had hydropericardium, three had ascites, and three had congested meninges. Histology confirmed myocarditis with myocardial necrosis. Cerebrum and brainstem had lymphocytic vasculitis with rare neuronal necrosis in affected areas, as well as Purkinje cells in the cerebellum. West Nile virus was confirmed by PCR the day after submittal and by immunohistochemistry soon thereafter.
The infusion of donor regulatory T cells (Tregs) has been used to prevent acute graft-versus-host disease (GVHD) in mice and has shown promise in phase 1 clinical trials. Previous work suggested that ...early Treg migration into lymphoid tissue was important for GVHD prevention. However, it is unclear how and where Tregs function longitudinally to affect GVHD. To better understand their mechanism of action, we studied 2 Treg-associated chemokine receptors in murine stem cell transplant models. CC chemokine receptor (CCR) 4 was dispensable for donor Treg function in the transplant setting. Donor Tregs lacking CCR8 (CCR8−/−), however, were severely impaired in their ability to prevent lethal GVHD because of increased cell death. By itself, CCR8 stimulation was unable to rescue Tregs from apoptosis. Instead, CCR8 potentiated Treg survival by promoting critical interactions with dendritic cells. In vivo, donor bone marrow–derived CD11c+ antigen-presenting cells (APCs) were important for promoting donor Treg maintenance after transplant. In contrast, host CD11c+ APCs appeared to be dispensable for early activation and expansion of donor Tregs. Collectively, our data indicate that a sustained donor Treg presence is critical for their beneficial properties, and that their survival depends on CCR8 and donor but not host CD11c+ APCs.
•Extended donor Treg survival is required for protection from GVHD; donor Treg longevity depends on Treg CCR8 expression.•Donor CD11c+ APCs promote Treg longevity in vivo; host CD11c+ APCs do not appear to contribute to donor Treg reconstitution.
Polar flagella from mesophilic
strains have previously been shown to be modified with a range of glycans. Mass spectrometry studies of purified polar flagellins suggested the glycan typically ...includes a putative pseudaminic acid like derivative; while some strains are modified with this single monosaccharide, others modified with a heterologous glycan. In the current study, we demonstrate that genes involved in polar flagella glycosylation are clustered in highly polymorphic genomic islands flanked by pseudaminic acid biosynthetic genes (
). Bioinformatic analysis of mesophilic
genomes identified three types of polar flagella glycosylation islands (FGIs), denoted Group I, II and III. FGI Groups I and III are small genomic islands present in
strains with flagellins modified with a single monosaccharide pseudaminic acid derivative. Group II were large genomic islands, present in strains found to modify polar flagellins with heterogeneous glycan moieties. Group II, in addition to
genes, contained numerous glycosyltransferases and other biosynthetic enzymes. All Group II strains shared a common glycosyltransferase downstream of
that we named flagella glycosylation island 1,
, in
AH-3. We demonstrate that Fgi-1 transfers the first sugar of the heterogeneous glycan to the pseudaminic acid derivative linked to polar flagellins and could be used as marker for polysaccharidic glycosylation of
polar flagella.
The carbon and nitrogen isotopic signatures of chloropigments and porphyrins from the sediments of redox‐stratified lakes and marine basins reveal details of past biogeochemical nutrient cycling. ...Such interpretations are strengthened by modern calibration studies, and here, we report on the C and N isotopic composition of pigments and nutrients in the water column and surface sediment of redox‐stratified Fayetteville Green Lake (FGL; New York). We also report δ13C and δ15N values for pyropheophytin a (Pphe a) and bacteriochlorophyll e (Bchl e) deposited in the Black Sea during its transition to a redox‐stratified basin ca. 7.8 ka. We propose a model for evolving nutrient cycling in the Black Sea from 7.8 to 6.4 ka, informed by the new pigment data from FGL. The seasonal study of water column nutrients and pigments at FGL revealed population dynamics in surface and deep waters that were also captured in the sediments. Biomass was greatest near the chemocline, where cyanobacteria, purple sulfur bacteria (PSB), and green sulfur bacteria (GSB) had seasonally variable populations. Bulk organic matter in the surface sediment, however, was derived mainly from the oxygenated surface waters. Surface sediment pigment δ13C and δ15N values indicate intact chlorophyll a (Chl a) was derived from near the chemocline, but its degradation product pheophytin a (Phe a) was derived primarily from surface waters. Bacteriopheophytin a (Bphe a) and Bchl e in the sediments came from chemocline populations of PSB and GSB, respectively. The distinctive δ13C and δ15N values for Chl a, Phe a, and Bphe a in the surface sediment are inputs to an isotopic mixing model that shows their decomposition to a common porphyrin derivative can produce non‐specific sedimentary isotope signatures. This model serves as a caveat for paleobiogeochemical interpretations in basins that had diverse populations near a shallow chemocline.
The detection of frictional heating effects along faults provides key insight into the dynamics of earthquakes and faulting. Thermal maturity of organic matter has been considered a possible ...fault‐thermometer that records the frictional heat signature of ancient earthquakes. However, whether or not organic matter can mature on the order of seconds, typical earthquake rise time, remains uncertain. Here we present the results of experiments aimed at revealing coal maturation by frictional heat generated at slip velocities representative of natural earthquakes of up to 1.3 m/s. Our results show that coal can mature coseismically in ∼11 seconds at temperatures induced by frictional heat ranging from 26 to 266°C. Even with a temperature rise to only 28.7°C over 15 m displacement in ∼3.2 hours, coal can slightly mature within a shear localized zone. The commonly used kinetic model of vitrinite maturation cannot predict the experimental results. A kinetic model involving the effect of flash temperature at grain contacts and mechanochemical effects on reaction kinetics is necessary to better estimate heat generation along a fault.
Key Points
Vitrinite can mature during rapid faulting in the order of seconds
Thermal maturity of vitrinite occurs typically in shear localized zone
Commonly used kinetic models of vitrinite cannot predict fault temperature
Viruses play a key role in controlling the population dynamics of algae, including Emiliania huxleyi, a globally distributed haptophyte with calcite coccoliths that comprise ca. 50% of the sinking ...carbonate flux from the surface ocean. Emiliania huxleyi viruses (EhVs) routinely infect and terminate E. huxleyi blooms. EhVs are surrounded by a lipid envelope, which we found to be comprised largely of glycosphingolipids (GSLs) with lesser amounts of polar glycerolipids. Infection appears to involve membrane fusion between the virus and host, and we hypothesized that specific polar lipids may facilitate virus attachment. We identified three novel intact polar lipids in E. huxleyi strain CCMP 374 and EhV86, including a GSL with a monosaccharide sialic acid headgroup (sGSL); for all 11 E. huxleyi strains we tested, there was a direct relationship between sGSL content and sensitivity to infection by EhV1, EhV86 and EhV163. In mesocosms, the E. huxleyi population with greatest initial sGSL content had the highest rate of virus‐induced mortality. We propose potential physiological roles for sGSL that would be beneficial for growth but leave cells susceptible to infection, thus furthering the discussion of Red Queen‐based co‐evolution and the cost(s) of sensitivity and resistance in the dynamic E. huxleyi‐EhV system.
Because of the influence pore pressures have on effective stress, understanding hydrogeologic properties that control fluid flow and pressure distribution is important in characterizing earthquake ...and deformation processes. Here, we utilize borehole pressure changes in response to earth tides to determine hydrogeologic properties and their time variations for 17 boreholes within the NSF Earthscope’s Plate Boundary Observatory (PBO) network along the San Andreas fault and Cascadia subduction zone. Our analysis considers solutions for both confined and unconfined aquiares. Resulting permeability and hydraulic diffusivity values range from 6.4×10−16–8.4×10−14 m2 and 1×10−4–9×10−1 m2s−1, respectively, whereas specific storage values are generally ~1×10−6 m−1. The values are fairly consistent through time, reasonable given lithology, and are comparable to other regional studies. For one borehole, values are also comparable to those determined with traditional aquifer test data. In contrast with previous determinations of the high-frequency poroelastic response to seismic waves, no obvious spatial trends in hydrogeologic properties determined from long-wavelength tidal perturbations are observed. Within the recurring time-series estimates, only one borehole exhibits clear permeability enhancement by earthquakes, whereas nearby boreholes with similar lithology and hydrogeologic property values do not. This highlights the variable susceptibility of rocks to permeability enhancement. Together, these results provide quantitative constraints useful for models of large-scale groundwater flow around large fault systems and the potential hydrologic influence on deformation and fault slip behavior.
ABSTRACT
We present multiwavelength follow-up observations of the ATLAS discovered faint Iax supernova SN 2020kyg that peaked at an absolute magnitude of Mg ≈ −14.9 ± 0.2, making it another member of ...the faint Iax supernova population. The bolometric light curve requires only ≈7 × 10−3 M⊙ of radioactive 56Ni, with an ejected mass of Mej ∼ 0.4 M⊙ and a low kinetic energy of E ≈ 0.05 ± 0.02 × 1051 erg. We construct a homogeneous volume-limited sample of 902 transients observed by ATLAS within 100 Mpc during a 3.5 yr span. Using this sample, we constrain the rates of faint Iax (Mr ≳ −16) events within 60 Mpc at $12^{+14}_{-8}{{\ \rm per\ cent}}$ of the SN Ia rate. The overall Iax rate, at $15^{+17}_{-9}{{\ \rm per\ cent}}$ of the Ia rate, is dominated by the low-luminosity events, with luminous SNe Iax (Mr ≲ −17.5) like 2002cx and 2005hk, accounting for only $0.9^{+1.1}_{-0.5}{{\ \rm per\ cent}}$ of the Ia rate (a 2σ upper limit of approximately 3 per cent). We favour the hybrid CONe WD + He star progenitor channel involving a failed deflagration of a near Chandrasekhar mass white dwarf, expected to leave a bound remnant and a surviving secondary companion, as a candidate explanation for faint Iax explosions. This scenario requires short delay times, consistent with the observed environments of SNe Iax. Furthermore, binary population synthesis calculations have suggested rates of $1\!-\!18{{\ \rm per\ cent}}$ of the SN Ia rate for this channel, consistent with our rate estimates.
We previously reported a novel polymeric surface coating, namely, HaloFilm™ that can immobilize and extend the antimicrobial activity of chlorine on surfaces. In this study, we demonstrated the ...continuous antiviral efficacy of HaloFilm when applied on stainless steel and cotton gauze as two representative models for non‐porous and porous surfaces against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). Forty‐eight hours post HaloFilm application and chlorination and 2 h post the viral challenge, the inoculum titre was reduced by 2.25 ± 0.33 and ≥4.36 ± 0.23 log10 TCID50 on non‐porous and porous surfaces, respectively. The half‐life of the virus was shorter (13.86 min) on a HaloFilm‐coated surface than what has been reported on copper (46.44 min).
Significance and Impact of Study: Chlorine is a widely used antimicrobial agent due to its broad spectrum and potent efficacy, low cost, abundancy, and history of safe use. This work describes a unique, non‐antimicrobial polymeric coating, Halofilm™, which, in conjunction with chlorine disinfectants, demonstrates extended activity against SARS‐CoV‐2 virus on a stainless steel and cotton gauze. Ease of application combined with the quick drying properties of HaloFilm solutions would enable its use in many standard cleaning and disinfection practices across a variety of institutional and home settings.
The lack of substantial frictional heat anomalies across major fault zones has been a key observation suggesting that faults support low shear stress during slip. Some studies have suggested that the ...lack of large thermal anomalies across faults may be a result of considerably less energy going to frictional heat than generally thought and that a large fraction of energy is dissipated by other processes such as the creation of new surface area. We evaluate this hypothesis through the analysis of laboratory shear experiments for both stick–slip (seismic) and stably sliding (aseismic) analog fault gouges. These experiments differ from previous laboratory studies in that they 1) provide independent constraints on frictional heat generation and energy consumed generating new surface area, 2) cover a broader range of shear stresses (2–20
MPa) than most previous studies, and 3) evaluate both stick–slip and stable sliding within granular material. Based on the analysis of high-precision temperature measurements and comparisons with numerical model simulations >
90% of the total energy appears to go to frictional heat generation (
E
H
) for all of our experiments. We also show based on grain size analysis that ~
1% of total work is consumed generating new surface area (
E
SA
). These results are consistent with assumptions allowing frictional resistance to be inferred from thermal data. Furthermore, we observe no resolvable difference in the fraction of energy going to fracturing or frictional heat between stick–slip and stable sliding experiments.
► The different components of energy during slip are independently constrained. ► Shear stress conditions ranging from 2 to 20
MPa are prescribed for stable and unstable sliding. ► There is no resolvable difference in thermal efficiency between sliding styles. ► >
90% of energy goes to frictional heat and ~
1% to generating new surface area. ► Results support assumptions allowing fault friction to be inferred from thermal data.
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