Leveraging the ALMA Atacama Compact Array for Cometary Science: An Interferometric Survey of Comet C/2015 ER61 (PanSTARRS) and Evidence for a Distributed Source of Carbon Monosulfide

We report the first survey of molecular emission from cometary volatiles using standalone Atacama Compact Array (ACA) observations of the Atacama Large Millimeter/Submillimeter Array (ALMA) toward comet C/2015 ER61 (PanSTARRS) carried out on UT 2017 April 11 and 15, shortly after its April 4 outburst. These measurements of HCN, CS, CH$_3$OH, H$_2$CO, and HNC (along with continuum emission from dust) probed the inner coma of C/2015 ER61, revealing asymmetric outgassing and discerning parent from daughter/distributed source species. This work presents spectrally integrated flux maps, autocorrelation spectra, production rates, and parent scale lengths for each molecule, and a stringent upper limit for CO. HCN is consistent with direct nucleus release in C/2015 ER61, whereas CS, H$_2$CO, HNC, and potentially CH$_3$OH are associated with distributed sources in the coma. Adopting a Haser model, parent scale lengths determined for H$_2$CO (L$_p$ $\sim$ 2200 km) and HNC (L$_p$ $\sim$ 3300 km) are consistent with previous work in comets, whereas significant extended source production (L$_p$ $\sim$ 2000 km) is indicated for CS, suggesting production from an unknown parent in the coma. The continuum presents a point-source distribution, with a flux density implying an excessively large nucleus, inconsistent with other estimates of the nucleus size. It is best explained by the thermal emission of slowly-moving outburst ejectas, with total mass 5--8 $\times$ 10$^{10}$ kg. These results demonstrate the power of the ACA for revealing the abundances, spatial distributions, and locations of molecular production for volatiles in moderately bright comets such as C/2015 ER61

ALMA Observations of the DART Impact: Characterizing the Ejecta at Sub-Millimeter Wavelengths

We report observations of the Didymos-Dimorphos binary asteroid system using the Atacama Large Millimeter/Submillimeter Array (ALMA) and the Atacama Compact Array (ACA) in support of the Double Asteroid Redirection Test (DART) mission. Our observations on UT 2022 September 15 provided a pre-impact baseline and the first measure of Didymos-Dimorphos' spectral emissivity at $\lambda=0.87$ mm, which was consistent with the handful of siliceous and carbonaceous asteroids measured at millimeter wavelengths. Our post-impact observations were conducted using four consecutive executions each of ALMA and the ACA spanning from T$+$3.52 to T$+$8.60 hours post-impact, sampling thermal emission from the asteroids and the impact ejecta. We scaled our pre-impact baseline measurement and subtracted it from the post-impact observations to isolate the flux density of mm-sized grains in the ejecta. Ejecta dust masses were calculated for a range of materials that may be representative of Dimorphos' S-type asteroid material. The average ejecta mass over our observations is consistent with 1.3--6.4$\times10^7$ kg, with the lower and higher values calculated for amorphous silicates and for crystalline silicates, respectively. Owing to the likely crystalline nature of S-type asteroid material, the higher value is favored. These ejecta masses represent 0.3--1.5\% of Dimorphos' total mass and are in agreement with lower limits on the ejecta mass based on measurements at optical wavelengths. Our results provide the most sensitive measure of mm-sized material in the ejecta and demonstrate the power of ALMA for providing supporting observations to spaceflight missions

The maternal and early embryonic transcriptome of the milkweed bug Oncopeltus fasciatus

<p>Abstract</p> <p>Background</p> <p>Most evolutionary developmental biology ("evo-devo") studies of emerging model organisms focus on small numbers of candidate genes cloned individually using degenerate PCR. However, newly available sequencing technologies such as 454 pyrosequencing have recently begun to allow for massive gene discovery in animals without sequenced genomes. Within insects, although large volumes of sequence data are available for holometabolous insects, developmental studies of basally branching hemimetabolous insects typically suffer from low rates of gene discovery.</p> <p>Results</p> <p>We used 454 pyrosequencing to sequence over 500 million bases of cDNA from the ovaries and embryos of the milkweed bug <it>Oncopeltus fasciatus</it>, which lacks a sequenced genome. This indirectly developing insect occupies an important phylogenetic position, branching basal to Diptera (including fruit flies) and Hymenoptera (including honeybees), and is an experimentally tractable model for short-germ development. 2,087,410 reads from both normalized and non-normalized cDNA assembled into 21,097 sequences (isotigs) and 112,531 singletons. The assembled sequences fell into 16,617 unique gene models, and included predictions of splicing isoforms, which we examined experimentally. Discovery of new genes plateaued after assembly of ~1.5 million reads, suggesting that we have sequenced nearly all transcripts present in the cDNA sampled. Many transcripts have been assembled at close to full length, and there is a net gain of sequence data for over half of the pre-existing <it>O. fasciatus </it>accessions for developmental genes in GenBank. We identified 10,775 unique genes, including members of all major conserved metazoan signaling pathways and genes involved in several major categories of early developmental processes. We also specifically address the effects of cDNA normalization on gene discovery in <it>de novo </it>transcriptome analyses.</p> <p>Conclusions</p> <p>Our sequencing, assembly and annotation framework provide a simple and effective way to achieve high-throughput gene discovery for organisms lacking a sequenced genome. These data will have applications to the study of the evolution of arthropod genes and genetic pathways, and to the wider evolution, development and genomics communities working with emerging model organisms.</p> <p>[The sequence data from this study have been submitted to GenBank under study accession number SRP002610 (<url>http://www.ncbi.nlm.nih.gov/sra?term=SRP002610</url>). Custom scripts generated are available at <url>http://www.extavourlab.com/protocols/index.html</url>. Seven Additional files are available.]</p

Computational Identification of Transcriptional Regulators in Human Endotoxemia

One of the great challenges in the post-genomic era is to decipher the underlying principles governing the dynamics of biological responses. As modulating gene expression levels is among the key regulatory responses of an organism to changes in its environment, identifying biologically relevant transcriptional regulators and their putative regulatory interactions with target genes is an essential step towards studying the complex dynamics of transcriptional regulation. We present an analysis that integrates various computational and biological aspects to explore the transcriptional regulation of systemic inflammatory responses through a human endotoxemia model. Given a high-dimensional transcriptional profiling dataset from human blood leukocytes, an elementary set of temporal dynamic responses which capture the essence of a pro-inflammatory phase, a counter-regulatory response and a dysregulation in leukocyte bioenergetics has been extracted. Upon identification of these expression patterns, fourteen inflammation-specific gene batteries that represent groups of hypothetically ‘coregulated’ genes are proposed. Subsequently, statistically significant cis-regulatory modules (CRMs) are identified and decomposed into a list of critical transcription factors (34) that are validated largely on primary literature. Finally, our analysis further allows for the construction of a dynamic representation of the temporal transcriptional regulatory program across the host, deciphering possible combinatorial interactions among factors under which they might be active. Although much remains to be explored, this study has computationally identified key transcription factors and proposed a putative time-dependent transcriptional regulatory program associated with critical transcriptional inflammatory responses. These results provide a solid foundation for future investigations to elucidate the underlying transcriptional regulatory mechanisms under the host inflammatory response. Also, the assumption that coexpressed genes that are functionally relevant are more likely to share some common transcriptional regulatory mechanism seems to be promising, making the proposed framework become essential in unravelling context-specific transcriptional regulatory interactions underlying diverse mammalian biological processes

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field

Achievement of the planetary defense investigations of the Double Asteroid Redirection Test (DART) mission

NASA's Double Asteroid Redirection Test (DART) mission was the first to demonstrate asteroid deflection, and the mission's Level 1 requirements guided its planetary defense investigations. Here, we summarize DART's achievement of those requirements. On 2022 September 26, the DART spacecraft impacted Dimorphos, the secondary member of the Didymos near-Earth asteroid binary system, demonstrating an autonomously navigated kinetic impact into an asteroid with limited prior knowledge for planetary defense. Months of subsequent Earth-based observations showed that the binary orbital period was changed by –33.24 minutes, with two independent analysis methods each reporting a 1σ uncertainty of 1.4 s. Dynamical models determined that the momentum enhancement factor, β, resulting from DART's kinetic impact test is between 2.4 and 4.9, depending on the mass of Dimorphos, which remains the largest source of uncertainty. Over five dozen telescopes across the globe and in space, along with the Light Italian CubeSat for Imaging of Asteroids, have contributed to DART's investigations. These combined investigations have addressed topics related to the ejecta, dynamics, impact event, and properties of both asteroids in the binary system. A year following DART's successful impact into Dimorphos, the mission has achieved its planetary defense requirements, although work to further understand DART's kinetic impact test and the Didymos system will continue. In particular, ESA's Hera mission is planned to perform extensive measurements in 2027 during its rendezvous with the Didymos–Dimorphos system, building on DART to advance our knowledge and continue the ongoing international collaboration for planetary defense

Selectivity and Mechanism of Hydrogen Atom Transfer by an Isolable Imidoiron(III) Complex

This article discusses a mechanistic study of hydrogen atom transfer by an isolable iron (III) imido complex, LᴹᵉFeNAd (Lᴹᵉ = bulky β-diketiminate ligand, 2,4-bis(2,6-diisopropylphenylimido)pentyl; Ad = 1-adamantyl)