Day–Night Monitoring of Volcanic SO2 and Ash Clouds for Aviation Avoidance at Northern Polar Latitudes

We describe NASA’s Applied Sciences Disasters Program, which is a collaborative project between the Direct Readout Laboratory (DRL), ozone processing team, Jet Propulsion Laboratory, Geographic Information Network of Alaska (GINA), and Finnish Meteorological Institute (FMI), to expedite the processing and delivery of direct readout (DR) volcanic ash and sulfur dioxide (SO2) satellite data. We developed low-latency quantitative retrievals of SO2 column density from the solar backscattered ultraviolet (UV) measurements using the Ozone Mapping and Profiler Suite (OMPS) spectrometers as well as the thermal infrared (TIR) SO2 and ash indices using Visible Infrared Imaging Radiometer Suite (VIIRS) instruments, all flying aboard US polar-orbiting meteorological satellites. The VIIRS TIR indices were developed to address the critical need for nighttime coverage over northern polar regions. Our UV and TIR SO2 and ash software packages were designed for the DRL’s International Planetary Observation Processing Package (IPOPP); IPOPP runs operationally at GINA and FMI stations in Fairbanks, Alaska, and Sodankylä, Finland. The data are produced within 30 min of satellite overpasses and are distributed to the Alaska Volcano Observatory and Anchorage Volcanic Ash Advisory Center. FMI receives DR data from GINA and posts composite Arctic maps for ozone, volcanic SO2, and UV aerosol index (UVAI, proxy for ash or smoke) on its public website and provides DR data to EUMETCast users. The IPOPP-based software packages are available through DRL to a broad DR user community worldwide.

Incorporation of sensing modalities into de novo designed fluorescence-activating proteins

Through the efforts of many groups, a wide range of fluorescent protein reporters and sensors based on green fluorescent protein and its relatives have been engineered in recent years. Here we explore the incorporation of sensing modalities into de novo designed fluorescence-activating proteins, called mini-fluorescence-activating proteins (mFAPs), that bind and stabilize the fluorescent cis-planar state of the fluorogenic compound DFHBI. We show through further design that the fluorescence intensity and specificity of mFAPs for different chromophores can be tuned, and the fluorescence made sensitive to pH and Ca2+ for real-time fluorescence reporting. Bipartite split mFAPs enable real-time monitoring of protein–protein association and (unlike widely used split GFP reporter systems) are fully reversible, allowing direct readout of association and dissociation events. The relative ease with which sensing modalities can be incorporated and advantages in smaller size and photostability make de novo designed fluorescence-activating proteins attractive candidates for optical sensor engineering.

FREQUENCY COMB-COUPLED METROLOGY LASERS FOR NANOPOSITIONING AND NANO MEASURING MACHINES

This article shows how a direct readout of the interferometric length measurement in nanopositioning machines can be transferred by connecting the metrology laser to a frequency comb line. The approach is based on a GPS-referenced frequency comb with which the stability of the timer (atomic clock via GPS) is transferred to the metrology laser of the nanopositioning and nano measuring machine NPMM-200. The necessary prerequisites for ensuring traceability are discussed. It is demonstrated that with this approach an improvement in the long-term stability of the metrology laser by three orders of magnitude can be achieved.

An Activity-Based Fluorescent Sensor for the Detection of the Phenol Sulfotransferase SULT1A1 in Living Cells

<p>The biological activation and incorporation of inorganic sulfate proceeds via a process known as sulfurylation. Transfer of a sulfuryl moiety from the activated sulfate donor, 3’-phosphoadenosine-5’-phosphosulfate (PAPS), to hydroxy-containing substrates by human phenol sulfotransferases (SULT1 family) alters substrate solubility and charge to affect the metabolism of endogenous metabolites, xenobiotics, and drugs. Current methods to monitor SULT1 activity in living cells primarily rely on radiolabeling and/or cell extractions, but these methods do not provide a direct readout of enzyme activity with a dynamic, temporally resolved spatial map in live, intact cells. To fill this gap, here, we present the development, computational modeling, <i>in vitro</i> enzymology, and biological application of Sulfotransferase Sensor-3, STS-3, an activity-based fluorescent sensor for SULT1A1, the most widely expressed and promiscuous SULT1 isoform. </p>

An Activity-Based Fluorescent Sensor for the Detection of the Phenol Sulfotransferase SULT1A1 in Living Cells

<p>The biological activation and incorporation of inorganic sulfate proceeds via a process known as sulfurylation. Transfer of a sulfuryl moiety from the activated sulfate donor, 3’-phosphoadenosine-5’-phosphosulfate (PAPS), to hydroxy-containing substrates by human phenol sulfotransferases (SULT1 family) alters substrate solubility and charge to affect the metabolism of endogenous metabolites, xenobiotics, and drugs. Current methods to monitor SULT1 activity in living cells primarily rely on radiolabeling and/or cell extractions, but these methods do not provide a direct readout of enzyme activity with a dynamic, temporally resolved spatial map in live, intact cells. To fill this gap, here, we present the development, computational modeling, <i>in vitro</i> enzymology, and biological application of Sulfotransferase Sensor-3, STS-3, an activity-based fluorescent sensor for SULT1A1, the most widely expressed and promiscuous SULT1 isoform. </p>

Direct readout of heterochromatic H3K9me3 regulates DNMT1-mediated maintenance DNA methylation

In mammals, repressive histone modifications such as trimethylation of histone H3 Lys9 (H3K9me3), frequently coexist with DNA methylation, producing a more stable and silenced chromatin state. However, it remains elusive how these epigenetic modifications crosstalk. Here, through structural and biochemical characterizations, we identified the replication foci targeting sequence (RFTS) domain of maintenance DNA methyltransferase DNMT1, a module known to bind the ubiquitylated H3 (H3Ub), as a specific reader for H3K9me3/H3Ub, with the recognition mode distinct from the typical trimethyl-lysine reader. Disruption of the interaction between RFTS and the H3K9me3Ub affects the localization of DNMT1 in stem cells and profoundly impairs the global DNA methylation and genomic stability. Together, this study reveals a previously unappreciated pathway through which H3K9me3 directly reinforces DNMT1-mediated maintenance DNA methylation.