Asparaginyl endopeptidases (AEPs) are proteases that have crucial roles in plant defense and seed storage protein maturation. Select plant AEPs, however, do not function as proteases but as ...transpeptidases (ligases) catalyzing the intra-molecular ligation of peptide termini, which leads to peptide cyclization. These ligase-type AEPs have potential biotechnological applications ranging from in vitro peptide engineering to plant molecular farming, but the structural features enabling these enzymes to catalyze peptide ligation/cyclization rather than proteolysis are currently unknown. Here, we compare the sequences, structures, and functions of diverse plant AEPs by combining molecular modeling, sequence space analysis, and functional testing in planta. We find that changes within the substrate-binding pocket and an adjacent loop, here named the "marker of ligase activity", together play a key role for AEP ligase efficiency. Identification of these structural determinants may facilitate the discovery of more ligase-type AEPs and the engineering of AEPs with tailored catalytic properties.
Seaweed farming in the United States is gaining significant financial and political support due to prospects to sustainably expand domestic economies with environmentally friendly products. Several ...networks are seeking appropriate synthesis of available science to both inform policy and substantiate the sector's sustainability claims. Significant knowledge gaps remain regarding seaweed-specific food hazards and their mitigation; a resource-intensive challenge that can inhibit sustainable policies. This is particularly concerning for rapidly expanding Saccharina latissima (sugar kelp) crops, a brown seaweed that is known to accumulate heavy metals linked to food hazards. Here, we present baseline information about concentrations of arsenic, cadmium, lead, and mercury, in both wild and farmed sugar kelp from the New England region. We interpret our findings based on proximity to potential sources of contamination, location on blade, and available heavy metals standards. Contrary to our expectations, high concentrations were widespread in both wild and farmed populations, regardless of proximity to contamination. We find, like others, that cadmium and arsenic consistently reach levels of regulatory concern, and that dried seaweeds could harbor higher concentrations compared to raw products. We also share unique findings that suggest some toxins concentrate at the base of kelp blades. Our results are one step towards aggregating vital data for the region to expand its seaweed farming footprint.
We present the first wide area (19 deg2), deep (≈120–150 μJy beam−1), high-resolution (5.6 × 7.4 arcsec) LOFAR High Band Antenna image of the Boötes field made at 130–169 MHz. This image is at least ...an order of magnitude deeper and 3–5 times higher in angular resolution than previously achieved for this field at low frequencies. The observations and data reduction, which includes full direction-dependent calibration, are described here. We present a radio source catalogue containing 6 276 sources detected over an area of 19 deg2, with a peak flux density threshold of 5σ. As the first thorough test of the facet calibration strategy, introduced by van Weeren et al., we investigate the flux and positional accuracy of the catalogue. We present differential source counts that reach an order of magnitude deeper in flux density than previously achieved at these low frequencies, and show flattening at 150-MHz flux densities below 10 mJy associated with the rise of the low flux density star-forming galaxies and radio-quiet AGN.
Pulmonary exposure to multi-walled carbon nanotubes (MWCNTs) has been linked to an increased risk of developing cardiovascular disease in addition to the well-documented physicochemical-dependent ...adverse lung effects. A proposed mechanism is through a strong and sustained pulmonary secretion of acute phase proteins to the blood. We identified physicochemical determinants of MWCNT-induced systemic acute phase response by analyzing effects of pulmonary exposure to 14 commercial, well-characterized MWCNTs in female C57BL/6J mice pulmonary exposed to 0, 6, 18 or 54 μg MWCNT/mouse. Plasma levels of acute phase response proteins serum amyloid A1/2 (SAA1/2) and SAA3 were determined on day 1, 28 or 92. Expression levels of hepatic Saa1 and pulmonary Saa3 mRNA levels were assessed to determine the origin of the acute phase response proteins. Pulmonary Saa3 mRNA expression levels were greater and lasted longer than hepatic Saa1 mRNA expression. Plasma SAA1/2 and SAA3 protein levels were related to time and physicochemical properties using adjusted, multiple regression analyses. SAA3 and SAA1/2 plasma protein levels were increased after exposure to almost all of the MWCNTs on day 1, whereas limited changes were observed on day 28 and 92. SAA1/2 and SAA3 protein levels did not correlate and only SAA3 protein levels correlated with neutrophil influx. The multiple regression analyses revealed a protective effect of MWCNT length on SAA1/2 protein level on day 1, such that a longer length resulted in lowered SAA1/2 plasma levels. Increased SAA3 protein levels were positively related to dose and content of Mn, Mg and Co on day 1, whereas oxidation and diameter of the MWCNTs were protective on day 28 and 92, respectively. The results of this study reveal very differently controlled pulmonary and hepatic acute phase responses after MWCNT exposure. As the responses were influenced by the physicochemical properties of the MWCNTs, this study provides the first step towards designing MWCNT that induce less SAA.
The 3rd September 2010 Mw 7.1 Darfield and 21st February 2011 Mw 6.3 Christchurch (New Zealand) earthquakes occurred on previously unknown faults. We use InSAR ground displacements, SAR amplitude ...offsets, field mapping, aerial photographs, satellite optical imagery, a LiDAR DEM and teleseismic body‐wave modeling to constrain the pattern of faulting in these earthquakes. The InSAR measurements reveal slip on multiple strike‐slip segments and secondary reverse faults associated with the Darfield main shock. Fault orientations are consistent with those expected from the GPS‐derived strain field. The InSAR line‐of‐sight displacement field indicates the main fault rupture is about 45 km long, and is confined largely to the upper 10 km of the crust. Slip on the individual fault segments of up to 8 m at 4 km depth indicate stress drops of 6–10 MPa. In each event, rupture initiated on a reverse fault segment, before continuing onto a strike‐slip segment. The non‐double couple seismological moment tensors for each event are matched well by the sum of double couple equivalent moment tensors for fault slip determined by InSAR. The slip distributions derived from InSAR observations of both the Darfield and Christchurch events show a 15‐km‐long gap in fault slip south‐west of Christchurch, which may present a continuing seismic hazard if a further unknown fault structure of significant size should exist there.
Key Points
Earthquake source determined for recent New Zealand 2010‐2011 earthquakes
Seismic gap in faulting found between the two ruptures is potentially hazardous
Mechanism of fault segment ruptures is consistent with velocity field
Highlights • Cold stress protein RBM3 is increased by 36 °C in primary neurons and astrocytes. • 33 °C is a stronger inducer of RBM3 in young neurons and astrocytes. • Increased RBM3 at 36 °C is ...associated with increased global protein synthesis. • FGF21 and Melatonin are novel RBM3 inducers.
A recent epidemiological study suggested that higher caffeine intake over decades reduces the risk of Alzheimer’s disease (AD). The present study sought to determine any long-term protective effects ...of dietary caffeine intake in a controlled longitudinal study involving AD transgenic mice. Caffeine (an adenosine receptor antagonist) was added to the drinking water of amyloid precursor protein, Swedish mutation (APPsw) transgenic (Tg) mice between 4 and 9 months of age, with behavioral testing done during the final 6 weeks of treatment. The average daily intake of caffeine per mouse (1.5 mg) was the human equivalent of 500 mg caffeine, the amount typically found in five cups of coffee per day. Across multiple cognitive tasks of spatial learning/reference memory, working memory, and recognition/identification, Tg mice given caffeine performed significantly better than Tg control mice and similar to non-transgenic controls. In both behaviorally-tested and aged Tg mice, long-term caffeine administration resulted in lower hippocampal β-amyloid (Aβ) levels. Expression of both Presenilin 1 (PS1) and β-secretase (BACE) was reduced in caffeine-treated Tg mice, indicating decreased Aβ production as a likely mechanism of caffeine’s cognitive protection. The ability of caffeine to reduce Aβ production was confirmed in SweAPP N2a neuronal cultures, wherein concentration-dependent decreases in both Aβ1–40 and Aβ1–42 were observed. Although adenosine A
1 or A
2A receptor densities in cortex or hippocampus were not affected by caffeine treatment, brain adenosine levels in Tg mice were restored back to normal by dietary caffeine and could be involved in the cognitive protection provided by caffeine. Our data demonstrate that moderate daily intake of caffeine may delay or reduce the risk of AD.
Summary
Exosomes in plasma of head and neck squamous cell carcinoma (HNSCC) patients comprise subsets of vesicles derived from various cells. Recently, we separated CD3(+) from CD3(–) exosomes by ...immune capture. CD3(–) exosomes were largely tumour‐derived (CD44v3+). Both subsets carried immunosuppressive proteins and inhibited functions of human immune cells. The role of these subsets in immune cell reprogramming by the tumour was investigated by focusing on the adenosine pathway components. Spontaneous adenosine production by CD3(+) or CD3(–) exosomes was measured by mass spectrometry, as was the production of adenosine by CD4+CD39+ regulatory T cells (Treg) co‐incubated with these exosomes. The highest level of CD39/CD73 ectoenzymes and of adenosine production was found in CD3(–) exosomes in patients with the stages III/IV HNSCCs). Also, the production of 5′‐AMP and purines was significantly higher in Treg co‐incubated with CD3(–) than CD3(+) exosomes. Consistently, CD26 and adenosine deaminase (ADA) levels were higher in CD3(+) than CD3(–) exosomes. ADA and CD26 levels in CD3(+) exosomes were significantly higher in patients with early (stages I/II) than advanced (stages III/IV) disease. HNSCC patients receiving and responding to photodynamic therapy had increased ADA levels in CD3(+) exosomes with no increase in CD3(–) exosomes. The opposite roles of CD3(+) ADA+CD26+ and CD3(–)CD44v3+ adenosine‐producing exosomes in early versus advanced HNSCC suggest that, like their parent cells, these exosomes serve as surrogates of immune suppression in cancer.
Separation of plasma‐derived exosomes in a CD3 (+) T cell derived exosome fraction and a CD3 (−) fraction enriched in tumor derived exosomes have the potential to serve as biomarkers of tumor activities and also as biomarkers of immune competence/suppression.
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