Oxygen

Describes motivation process for creativity with emphasis on intrinsic motivation by Corey K Katir

Protein synthesis involves the translation of ribonucleic acid information into proteins, the building blocks of life. The initial step of protein synthesis is the binding of the eukaryotic translation initiation factor 4E (eIF4E) to the 7-methylguanosine (m7-GpppG) 5a2acap of messenger RNAs. Low oxygen tension (hypoxia) represses cap-mediated translation by sequestering eIF4E through mammalian target of rapamycin (mTOR)-dependent mechanisms. Although the internal ribosome entry site is an alternative translation initiation mechanism, this pathway alone cannot account for the translational capacity of hypoxic cells. This raises a fundamental question in biology as to how proteins are synthesized in periods of oxygen scarcity and eIF4E inhibition. Here we describe an oxygen-regulated translation initiation complex that mediates selective cap-dependent protein synthesis. We show that hypoxia stimulates the formation of a complex that includes the oxygen-regulated hypoxia-inducible factor 2I+- (HIF-2I+-), the RNA-binding protein RBM4 and the cap-binding eIF4E2, an eIF4E homologue. Photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation (PAR-CLIP) analysis identified an RNA hypoxia response element (rHRE) that recruits this complex to a wide array of mRNAs, including that encoding the epidermal growth factor receptor. Once assembled at the rHRE, the HIF-2I+-aRBM4aeIF4E2 complex captures the 5a2acap and targets mRNAs to polysomes for active translation, thereby evading hypoxia-induced repression of protein synthesis. These findings demonstrate that cells have evolved a program by which oxygen tension switches the basic translation initiation machinery.

The Earth acts as a gigantic heat engine driven by the decay of radiogenic isotopes and slow cooling, which gives rise to plate tectonics, volcanoes and mountain building. Another key product is the geomagnetic field, generated in the liquid iron core by a dynamo running on heat released by cooling and freezing (as the solid inner core grows), and on chemical convection (due to light elements expelled from the liquid on freezing). The power supplied to the geodynamo, measured by the heat flux across the coreamantle boundary (CMB), places constraints on Earthas evolution. Estimates of CMB heat flux depend on properties of iron mixtures under the extreme pressure and temperature conditions in the core, most critically on the thermal and electrical conductivities. These quantities remain poorly known because of inherent experimental and theoretical difficulties. Here we use density functional theory to compute these conductivities in liquid iron mixtures at core conditions from first principlesaunlike previous estimates, which relied on extrapolations. The mixtures of iron, oxygen, sulphur and silicon are taken from earlier work and fit the seismologically determined core density and inner-core boundary density jump. We find both conductivities to be two to three times higher than estimates in current use. The changes are so large that core thermal histories and power requirements need to be reassessed. New estimates indicate that the adiabatic heat flux is 15 to 16 terawatts at the CMB, higher than present estimates of CMB heat flux based on mantle convection; the top of the core must be thermally stratified and any convection in the upper core must be driven by chemical convection against the adverse thermal buoyancy or lateral variations in CMB heat flow. Power for the geodynamo is greatly restricted, and future models of mantle evolution will need to incorporate a high CMB heat flux and explain the recent formation of the inner core.

How Long Does Whey Protein Last For? We Take A Look At The Shelf Life of That Cannister of Whey Protein

I have a quick question about the shelf life of whey protein powder.A My ex boyfriend left…

What is VO2 Max and How Does It Work?

Vo2 max is considered the standardA indicator of cardiovascularA or cardiorespiratory endurance and fitness.A Vo2 Max determines a…

What Is EPOC orA Excess Post-ExerciseA Oxygen Consumption?

EPOC, or Excess Post-Exercise Oxygen Consumptionis a measure of increased oxygen consumption after exercise or strenuous activity.A EPOC is also accompaniedA by a post-exerciseA increase in energy or fuelA consumptionA (also characterized as an increase in…

The first heavier main-group-14-element analogue of a ketone, which contains a three-coordinate germanium atom multiply bonded to oxygen, has been prepared and characterized.

Heavier analogues of ketones a containing a double bond between a group 14 element and oxygen a have so far not been isolated as stable compounds. Now, a stable monomeric germanone with a highly polarized Ge=O double bond has been isolated, stabilized by rigid bulky ligands.

Increasing the efficiency and speed of the water-oxidation reaction is crucial to realizing light-driven water splitting. Now, a mononuclear ruthenium complex achieves fast water-oxidation catalysis with a high reaction rate of more than 300 turnovers per second, comparable to the activity of the oxygen-evolving complex in photosystem II.

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