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Context. The fundamental process of star formation in galaxies involves the intricate interplay between the fueling of star formation via molecular gas and the feedback from recently formed massive stars that can, in turn, hinder the conversion of gas into stars. This process, by which galaxies evolve, is also closely connected to the intrinsic properties of the interstellar medium (ISM), such as structure, density, pressure, and metallicity. Aims. To study the role that different molecular and atomic phases of the ISM play in star formation, and to characterize their physical conditions, we zoom into our nearest neighboring galaxy, the Large Magellanic Cloud (LMC; 50 kpc), the most convenient laboratory in which to study the effects of the lower metal abundance on the properties of the ISM. The LMC offers a view of the ISM and star formation conditions in a low-metallicity (Z~ 0.5 Z_⊙) environment similar, in that regard, to the epoch of the peak of star formation in the earlier Universe (z~ 1.5). Following up on studies carried out at galactic scales in low-Z galaxies, we present an unprecedentedly detailed analysis of well-known star-forming regions (SFRs) at a spatial resolution of a few parsecs. Methods. We mapped a 610pc× 260pc region in the LMC molecular ridge in [C II]λ158 µm and the [O III]λ88 µm using the FIFI-LS instrument on the SOFIA telescope. We compared the data with the distribution of the CO(2−1) emission from ALMA, the modeled total infrared luminosity, and the Spitzer/MIPS 24 µm continuum and Hα. Results. We present new large maps of [CII] and [OIII] and perform a first comparison with CO(2−1) line and LTIR emission. We also provide a detailed description of the observing strategy with SOFIA/FIFI-LS and the data reduction process. Conclusions. We find that [CII] and [OIII] emission is associated with the SFRs in the molecular ridge, but also extends throughout the mapped region, and is not obviously associated with ongoing star formation. The CO emission is clumpier than the [C II] emission and we find plentiful [C II] present where there is little CO emission, possibly holding important implications for “CO-dark” gas. We find a clear trend of the L_[C II]/L_TIRratio decreasing with increasing L_TIRin the full range. This suggests a strong link between the “[C II]-deficit” and the local physical conditions instead of global properties. 

Summary This work revisits a publication by Beanet al.(2018) that reports seven amino acid substitutions are essential for the evolution ofl‐DOPA 4,5‐dioxygenase (DODA) activity in Caryophyllales. In this study, we explore several concerns which led us to replicate the analyses of Beanet al.(2018).Our comparative analyses, with structural modelling, implicate numerous residues additional to those identified by Beanet al.(2018), with many of these additional residues occurring around the active site of BvDODAα1. We therefore replicated the analyses of Beanet al.(2018) to re‐observe the effect of their original seven residue substitutions in a BvDODAα2 background, that is the BvDODAα2‐mut3 variant.Multiplein vivoassays, in bothSaccharomyces cerevisiaeandNicotiana benthamiana, did not result in visible DODA activity in BvDODAα2‐mut3, with betalain production always 10‐fold below BvDODAα1.In vitroassays also revealed substantial differences in both catalytic activity and pH optima between BvDODAα1, BvDODAα2 and BvDODAα2‐mut3 proteins, explaining their differing performancein vivo.In summary, we were unable to replicate thein vivoanalyses of Beanet al.(2018), and our quantitativein vivoandin vitroanalyses suggest a minimal effect of these seven residues in altering catalytic activity of BvDODAα2. We conclude that the evolutionary pathway to high DODA activity is substantially more complex than implied by Beanet al.(2018). 

We use a combination of new NOrthern Extended Millimeter Array (NOEMA) observations of the pair of [CI] transitions, the CO(7-6) line, and the dust continuum, in addition to ancillary CO(1-0) and CO(3-2) data, to study the molecular gas properties of Q1700-MD94. This is a massive, main-sequence galaxy at z  ≈ 2. We find that for a reasonable set of assumptions for a typical massive star-forming galaxy, the CO(1-0), the [CI](1-0) and the dust continuum yield molecular gas masses that are consistent within a factor of ∼2. The global excitation properties of the molecular gas as traced by the [CI] and CO transitions are similar to those observed in other massive star-forming galaxies at z  ∼ 2. Our large velocity gradient modeling using RADEX of the CO and [CI] spectral line energy distributions suggests the presence of relatively warm ( T kin  = 41 K), dense ( n H 2  = 8 × 10 3  cm −3 ) molecular gas, comparable to the high-excitation molecular gas component observed in main-sequence star-forming galaxies at z  ∼ 1. The galaxy size in the CO(1-0) and CO(7-6) line emission is comparable, which suggests that the highly excited molecular gas is distributed throughout the disk, powered by intense star formation activity. A confirmation of this scenario will require spatially resolved observations of the CO and [CI] lines, which can now be obtained with NOEMA upgraded capabilities.