ACS Chemical Health & Safety最新文献

The James Webb Space Telescope can potentially explore the geological diversity of the surfaces of rocky exoplanets, especially due to its access to mid-infrared wavelengths. Here we investigate the level of geological detail that it could be possible to observe with the low-resolution spectroscopy and photometric modes of the mid-infrared instrument onboard the James Webb Space Telescope. We used new emissivity measurements of 15 basaltic samples between 2 μm and 25 μm to produce synthetic spectra and photometric fluxes. We found that the mid-infrared instrument can, in principle, distinguish several specific mineralogical and bulk chemical signals among relatively similar rocks. In particular, hydrous minerals, such as amphibole and serpentine, which would signal the existence of past or present water, can have observable characteristics in both low-resolution spectroscopy observations (with the precision of 5 eclipses) and the integrated fluxes over mid-infrared instrument filter bandwidths (20–100 eclipses). Photometric fluxes are also sensitive to bulk compositions (for example, wt% Al₂O₃), which reflect magmatic processes. Our work demonstrates the potential for the James Webb Space Telescope and future observatories to access a fuller picture of exoplanet surface geology.

Genetically encoded DNA recorders noninvasively convert transient biological events into durable mutations in a cell’s genome, allowing for the later reconstruction of cellular experiences by DNA sequencing. We present a DNA recorder, peCHYRON, that achieves high-information, durable, and temporally resolved multiplexed recording of multiple cellular signals in mammalian cells. In each step of recording, prime editor, a Cas9-reverse transcriptase fusion protein, inserts a variable triplet DNA sequence alongside a constant propagator sequence that deactivates the previous and activates the next step of insertion. Insertions accumulate sequentially in a unidirectional order, editing can continue indefinitely, and high information is achieved by coexpressing a variety of prime editing guide RNAs (pegRNAs), each harboring unique triplet DNA sequences. We demonstrate that the constitutive expression of pegRNA collections generates insertion patterns for the straightforward reconstruction of cell lineage relationships and that the inducible expression of specific pegRNAs results in the accurate recording of exposures to biological stimuli.

The post-translational modification of intracellular proteins through O-linked β-N-acetylglucosamine (O-GlcNAc) is a conserved regulatory mechanism in multicellular organisms. Catalyzed by O-GlcNAc transferase (OGT), this dynamic modification has an essential role in signal transduction, gene expression, organelle function and systemic physiology. Here, we present Opto-OGT, an optogenetic probe that allows for precise spatiotemporal control of OGT activity through light stimulation. By fusing a photosensitive cryptochrome protein to OGT, Opto-OGT can be robustly and reversibly activated with high temporal resolution by blue light and exhibits minimal background activity without illumination. Transient activation of Opto-OGT results in mTORC activation and AMPK suppression, which recapitulate nutrient-sensing signaling. Furthermore, Opto-OGT can be customized to localize to specific subcellular sites. By targeting OGT to the plasma membrane, we demonstrate the downregulation of site-specific AKT phosphorylation and signaling outputs in response to insulin stimulation. Thus, Opto-OGT is a powerful tool for defining the role of O-GlcNAcylation in cell signaling and physiology.