Photorespiration recycles ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) oxygenation product, 2-phosphoglycolate, back into the Calvin Cycle. Natural photorespiration, however, limits ...agricultural productivity by dissipating energy and releasing CO₂. Several photorespiration bypasses have been previously suggested but were limited to existing enzymes and pathways that release CO₂. Here, we harness the power of enzyme and metabolic engineering to establish synthetic routes that bypass photorespiration without CO₂ release. By defining specific reaction rules, we systematically identified promising routes that assimilate 2-phosphoglycolate into the Calvin Cycle without carbon loss. We further developed a kinetic–stoichiometric model that indicates that the identified synthetic shunts could potentially enhance carbon fixation rate across the physiological range of irradiation and CO₂, even if most of their enzymes operate at a tenth of Rubisco’s maximal carboxylation activity. Glycolate reduction to glycolaldehyde is essential for several of the synthetic shunts but is not known to occur naturally. We, therefore, used computational design and directed evolution to establish this activity in two sequential reactions. An acetyl-CoA synthetase was engineered for higher stability and glycolyl-CoA synthesis. A propionyl-CoA reductase was engineered for higher selectivity for glycolyl-CoA and for use of NADPH over NAD⁺, thereby favoring reduction over oxidation. The engineered glycolate reduction module was then combined with downstream condensation and assimilation of glycolaldehyde to ribulose 1,5-bisphosphate, thus providing proof of principle for a carbon-conserving photorespiration pathway.
Disasters disproportionally affect vulnerable, technology-dependent people, including preterm and critically ill newborn infants. It is important for health care providers to be aware of and prepared ...for the potential consequences of disasters for the NICU. Neonatal intensive care personnel can provide specialized expertise for their hospital, community, and regional emergency preparedness plans and can help develop institutional surge capacity for mass critical care, including equipment, medications, personnel, and facility resources.
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•Triclosan (TCS) sources determined in a rural to urban watershed.•Streamwater TCS concentrations amongst highest in literature.•TCS concentrations/yields linked to a multitude of low ...volume sources.•Relative contribution of TCS loading delineated between low and high-volume sources.
Triclosan (TCS), an emerging contaminant linked to antimicrobial resistance, has been the focus of many surface water studies to date. However, these initial studies have predominantly used sampling locations downstream of large volume (i.e., >0.5 million gallons per day) wastewater treatment plants (WWTPs). This approach overlooks potential inputs from their low volume counterparts as well as non-point sources, such as sewage network leaks, biosolid application to agricultural fields and leach fields associated with septic systems. Here we examine the range of concentrations, overall loading, and potential controls on TCS delivery to the East Branch of the Brandywine Creek (EBBC), a rural to suburban watershed located in southeastern Pennsylvania. TCS measurements were collected from 13 locations in the EBBC during baseflow conditions and immediately following a storm event. A regulatory database review identified WWTP density an order of magnitude greater than the national average, thereby confirming their pervasiveness in rural to urban systems. Detectable concentrations of TCS in the EBBC ranged from 0.2 to 0.6 ng/L during baseflow conditions and 0.5 to over 1000 ng/L following a storm event. The lack of a statistical relationship between TCS concentrations and yields with the number of upstream WWTPs and/or volume of treated effluent during both sampling periods confirm the importance of individual WWTP practices and the volume of the receiving water body, while a positive statistically-significant relationship between TCS concentrations and upstream developed open space following the storm event was likely influenced by runoff of spray-applied treated wastewater and/or sewage network leaks. Furthermore, the presence of detectable concentrations of TCS in sub-watersheds with no WWTP systems implies field applied biosolids or treated wastewater, as well as septic tank related leach fields are all viable sources of TCS. These findings suggest we must greatly expand our consideration of sources for emerging contaminants in waterways.
For prey animals to negotiate successfully the fundamental trade-off between predation and starvation, a realistic assessment of predation risk is vital. Prey responses to conspicuous indicators of ...risk (such as looming predators or fleeing conspecifics) are well documented, but there should also be strong selection for the detection of more subtle cues. A predator's head orientation and eye-gaze direction are good candidates for subtle but useful indicators of risk, since many predators orient their head and eyes towards their prey as they attack. We describe the first explicit demonstration of a bird responding to a live predator's eye-gaze direction. We present wild-caught European starlings (Sturnus vulgaris) with human 'predators' whose frontal appearance and gaze direction are manipulated independently, and show that starlings are sensitive to the predator's orientation, the presence of eyes and the direction of eye-gaze. Starlings respond in a functionally significant manner: when the predator's gaze was averted, starlings resumed feeding earlier, at a higher rate and consumed more food overall. By correctly assessing lower risk and returning to feeding activity earlier (as in this study), the animal gains a competitive advantage over conspecifics that do not respond to the subtle predator cue in this way.
Quantitative fractography (QF) may be used for measuring service- and test-induced fatigue crack growth (FCG) in metallic components and structures. The QF compares progression and striation markings ...on fatigue fracture surfaces with known occurrences in the components' load histories. This paper concisely surveys fatigue-related QF, followed by a case study for a crack in a component from a maritime patrol aircraft. The case study illustrates how a FCG versus time history can be estimated. This was achieved using (i) knowledge of when the crack was detected, (ii) a reconstruction of the aircraft usage history from counting accelerometer (g-meter) data, (iii) an exponential FCG model of how cracking could have progressed, and (iv) QF of progression markings. Comparison of the reconstructed usage data and the QF information showed that the model provided a useful correlation.
•Quantitative fractography can be a powerful post-failure forensics tool;•A step-by-step description of the analyses of a in-service aircraft crack is provide;•The example included the reconstruction of the service load history.
The brains of 158 consecutively admitted very preterm infants were repeatedly examined with real time ultrasound. Abnormalities, most commonly periventricular haemorrhage, were detected in 79 (50%). ...The 109 infants who survived were followed up until they were 16-23 months old. Major or minor neurological or developmental sequelae were found in 5 of 62 infants (8%) with normal ultrasound scans and in an identical proportion, 2 of 25 infants (8%), with uncomplicated periventricular haemorrhage. By contrast, 15 of 21 infants (71%) whose ventricles became enlarged (with or without periventricular haemorrhage) had abnormalities at follow up. The proportion with sequelae depended on the cause and extent of the enlargement. Three of 8 infants (38%) with mild (usually transient) ventricular distension had sequelae, compared with 3 of 4 (75%) with hydrocephalus and 9 of 9 (100%) with cerebral atrophy (2 of whom also had hydrocephalus). Adverse neurodevelopmental sequelae at follow up appeared more often to be attributable to cerebral ischaemia and infarction than to periventricular haemorrhage.
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Curcumin, a natural product isolated from the spice turmeric, has been shown to exhibit a wide range of pharmacological activities including certain anti-cancer properties. It has ...been specifically shown to be an effective inhibitor of angiogenesis both in vitro and in vivo. Using curcumin as a lead compound for anti-angiogenic analog design, a series of structurally related compounds utilizing a substituted chalcone backbone have been synthesized and tested via an established SVR cell proliferation assay. The results have yielded a wide range of compounds that equal or exceed curcumin’s ability to inhibit endothelial cell growth in vitro. Due to both their commercial availability and their fairly straightforward synthetic preparation, these low molecular weight compounds are attractive leads for developing future angiogenic inhibitors.
The formation of peroxorhenium complexes by activation of H2O2 is key in selective oxidation reactions catalyzed by CH3ReO3 (methyltrioxorhenium, MTO). Previous reports on the thermodynamics and ...kinetics of these reactions are inconsistent with each other and sometimes internally inconsistent. New experiments and calculations using density functional theory with the ωB97X-D and augmented def2-TZVP basis sets were conducted to better understand these reactions and to provide a strong experimental foundation for benchmarking computational studies involving MTO and its derivatives. Including solvation contributions to the free energies as well as tunneling corrections, we compute negative reaction enthalpies for each reaction and correctly predict the hydration state of all complexes in aqueous CH3CN. New rate constants for each of the forward and reverse reactions were both measured and computed as a function of temperature, providing a complete set of consistent activation parameters. New, independent measurements of equilibrium constants do not indicate strong cooperativity in peroxide ligand binding, as was previously reported. The free energy barriers for formation of both CH3ReO2(η2-O2) (A) and CH3ReO(η2-O2)2(H2O) (B) are predominantly entropic, and the former is much smaller than a previously reported value. Computed rate constants for a direct ligand-exchange mechanism, and for a mechanism in which a water molecule facilitates ligand-exchange via proton transfer in the transition state, differ by at least 7 orders of magnitude. The latter, water-assisted mechanism is predicted to be much faster and is consequently in much closer agreement with the experimentally measured kinetics. Experiments confirm the predicted catalytic role of water: the kinetics of both steps are strongly dependent on the water concentration, and water appears directly in the rate law.
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