Evidence for widespread hydrated minerals on asteroid (101955) Bennu

Early spectral data from the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission reveal evidence for abundant hydrated minerals on the surface of near-Earth asteroid (101955) Bennu in the form of a near-infrared absorption near 2.7 µm and thermal infrared spectral features that are most similar to those of aqueously altered CM-type carbonaceous chondrites. We observe these spectral features across the surface of Bennu, and there is no evidence of substantial rotational variability at the spatial scales of tens to hundreds of metres observed to date. In the visible and near-infrared (0.4 to 2.4 µm) Bennu’s spectrum appears featureless and with a blue (negative) slope, confirming previous ground-based observations. Bennu may represent a class of objects that could have brought volatiles and organic chemistry to Earth

The dynamic geophysical environment of (101955) Bennu based on OSIRIS-REx measurements

The top-shaped morphology characteristic of asteroid (101955) Bennu, often found among fast-spinning asteroids and binary asteroid primaries, may have contributed substantially to binary asteroid formation. Yet a detailed geophysical analysis of this morphology for a fast-spinning asteroid has not been possible prior to the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission. Combining the measured Bennu mass and shape obtained during the Preliminary Survey phase of the OSIRIS-REx mission, we find a notable transition in Bennu’s surface slopes within its rotational Roche lobe, defined as the region where material is energetically trapped to the surface. As the intersection of the rotational Roche lobe with Bennu’s surface has been most recently migrating towards its equator (given Bennu’s increasing spin rate), we infer that Bennu’s surface slopes have been changing across its surface within the last million years. We also find evidence for substantial density heterogeneity within this body, suggesting that its interior is a mixture of voids and boulders. The presence of such heterogeneity and Bennu’s top shape are consistent with spin-induced failure at some point in its past, although the manner of its failure cannot yet be determined. Future measurements by the OSIRIS-REx spacecraft will provide insight into and may resolve questions regarding the formation and evolution of Bennu’s top-shape morphology and its link to the formation of binary asteroids

The Saccharomyces cerevisiae NPR1 gene required for the activity of ammonia-sensitive amino acid permeases encodes a protein kinase homologue.

The NPR1 gene of Saccharomyces cerevisiae plays a central role in controlling permease activity; its product is required to promote the activity of at least six distinct transport systems for nitrogenous nutrients under conditions of nitrogen catabolite derepression. We report here the nucleotide sequence of the cloned NPR1 gene. The predicted amino acid sequence indicates that NPR1 encodes a protein of 86 kDa which appears to be organized into two distinct structural domains. The amino-terminal domain of NPR1 (residues 1 to 440) contains 26% serine residues and several regions strongly enriched for PEST residues and several regions strongly enriched for PEST residues suggesting a short half-life for the NPR1 protein. The carboxy-terminal region of NPR1 contains consensus sequences characteristic of the catalytic domains of protein kinases. Therefore, NPR1-dependent positive control of nitrogen transport systems most likely involves protein phosphorylation. Northern analysis indicates that the absence of general amino acid permease (GAP1) activity in npr1 mutants is not due to reduction in transcription or messenger stability. Hence, the NPR1 protein probably acts at the post-transcriptional level. Proteins that may serve as substrates for phosphorylation are discussed.SCOPUS: ar.jinfo:eu-repo/semantics/publishe