Temporal covariation of island arc Sr isotopes and seawater chemistry over the past 2 billion years.

The chemical compositions of island arc basalts (IAB) reflect contributions from the mantle as well as fluids and melts from the subducting slab. Addition of radiogenic seawater Sr to oceanic crust through hydrothermal alteration and subsequent subduction is often invoked to explain elevated Sr/Sr signatures in modern IAB. However, changes in the Sr/Sr of island arc magmatic rocks through time has not been investigated, limiting our understanding of the factors influencing the Sr budgets of arcs throughout Earth's history.

Isotopic clumping in wood as a proxy for photorespiration in trees.

Photorespiration can limit gross primary productivity in terrestrial plants. The rate of photorespiration relative to carbon fixation increases with temperature and decreases with atmospheric [CO]. However, the extent to which this rate varies in the environment is unclear.

The origin of carbonate mud and implications for global climate.

Carbonate mud represents one of the most important geochemical archives for reconstructing ancient climatic, environmental, and evolutionary change from the rock record. Mud also represents a major sink in the global carbon cycle. Yet, there remains no consensus about how and where carbonate mud is formed.

Nitrogen isotope evidence for expanded ocean suboxia in the early Cenozoic.

The million-year variability of the marine nitrogen cycle is poorly understood. Before 57 million years (Ma) ago, the N/N ratio (δN) of foraminifera shell-bound organic matter from three sediment cores was high, indicating expanded water column suboxia and denitrification. Between 57 and 50 Ma ago, δN declined by 13 to 16 per mil in the North Pacific and by 3 to 8 per mil in the Atlantic.

Neoproterozoic to early Phanerozoic rise in island arc redox state due to deep ocean oxygenation and increased marine sulfate levels.

A rise in atmospheric O levels between 800 and 400 Ma is thought to have oxygenated the deep oceans, ushered in modern biogeochemical cycles, and led to the diversification of animals. Over the same time interval, marine sulfate concentrations are also thought to have increased to near-modern levels. We present compiled data that indicate Phanerozoic island arc igneous rocks are more oxidized (Fe/ΣFe ratios are elevated by 0.

A record of deep-ocean dissolved O from the oxidation state of iron in submarine basalts.

The oxygenation of the deep ocean in the geological past has been associated with a rise in the partial pressure of atmospheric molecular oxygen (O) to near-present levels and the emergence of modern marine biogeochemical cycles. It has also been linked to the origination and diversification of early animals. It is generally thought that the deep ocean was largely anoxic from about 2,500 to 800 million years ago, with estimates of the occurrence of deep-ocean oxygenation and the linked increase in the partial pressure of atmospheric oxygen to levels sufficient for this oxygenation ranging from about 800 to 400 million years ago.

Targeting a DNA binding motif of the EVI1 protein by a pyrrole-imidazole polyamide.

The zinc finger protein EVI1 is causally associated with acute myeloid leukemogenesis, and inhibition of its function with a small molecule therapeutic may provide effective therapy for EVI1-expressing leukemias. In this paper we describe the development of a pyrrole-imidazole polyamide to specifically block EVI1 binding to DNA. We first identify essential domains for leukemogenesis through structure-function studies on both EVI1 and the t(3;21)(q26;q22)-derived RUNX1-MDS1-EVI1 (RME) protein, which revealed that DNA binding to the cognate motif GACAAGATA via the first of two zinc finger domains (ZF1, encompassing fingers 1-7) is essential transforming activity.

Aerobic growth at nanomolar oxygen concentrations.

Molecular oxygen (O(2)) is the second most abundant gas in the Earth's atmosphere, but in many natural environments, its concentration is reduced to low or even undetectable levels. Although low-oxygen-adapted organisms define the ecology of low-oxygen environments, their capabilities are not fully known. These capabilities also provide a framework for reconstructing a critical period in the history of life, because low, but not negligible, atmospheric oxygen levels could have persisted before the "Great Oxidation" of the Earth's surface about 2.