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The recent COVID-19 pandemic underscored the limitations of currently available direct-acting antiviral treatments against acute respiratory RNA-viral infections and stimulated major research initiatives targeting anticoronavirus agents. Two novel nsp5 protease (MPro) inhibitors have been approved, nirmatrelvir and ensitrelvir, along with two existing nucleos(t)ide analogues repurposed as nsp12 polymerase inhibitors, remdesivir and molnupiravir, but a need still exists for therapies with improved potency and systemic exposure with oral dosing, better metabolic stability, and reduced resistance and toxicity risks. Herein, we summarize our research toward identifying nsp12 inhibitors that led to nucleoside analogues 10e and 10n , which showed favorable pan-coronavirus activity in cell-infection screens, were metabolized to active triphosphate nucleotides in cell-incubation studies, and demonstrated target (nsp12) engagement in biochemical assays.

Rift Valley fever virus (RVFV) is an important mosquito-borne virus that can cause severe disease manifestations in humans including ocular damage, vision loss, late-onset encephalitis, and hemorrhagic fever. In ruminants, RVFV can cause high mortality rates in young animals and high rates of abortion in pregnant animals resulting in an enormous negative impact on the economy of affected regions. To date, no licensed vaccines in humans or anti-RVFV therapeutics for animal or human use are available. The development of reverse genetics has facilitated the generation of recombinant infectious viruses that serve as powerful tools for investigating the molecular biology and pathogenesis of RVFV. Infectious recombinant RVFV can be rescued entirely from cDNAs containing predetermined mutations in their genomes to investigate virus-host interactions and mechanisms of pathogenesis and generate live-attenuated vaccines. In this chapter, we will describe the experimental procedures for the implementation of RVFV reverse genetics., (© 2024. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

The nearby radio galaxy M87 is a prime target for studying black hole accretion and jet formation 1,2 . Event Horizon Telescope observations of M87 in 2017, at a wavelength of 1.3 mm, revealed a ring-like structure, which was interpreted as gravitationally lensed emission around a central black hole 3 . Here we report images of M87 obtained in 2018, at a wavelength of 3.5 mm, showing that the compact radio core is spatially resolved. High-resolution imaging shows a ring-like structure of [Formula: see text] Schwarzschild radii in diameter, approximately 50% larger than that seen at 1.3 mm. The outer edge at 3.5 mm is also larger than that at 1.3 mm. This larger and thicker ring indicates a substantial contribution from the accretion flow with absorption effects, in addition to the gravitationally lensed ring-like emission. The images show that the edge-brightened jet connects to the accretion flow of the black hole. Close to the black hole, the emission profile of the jet-launching region is wider than the expected profile of a black-hole-driven jet, suggesting the possible presence of a wind associated with the accretion flow., (© 2023. The Author(s).)

Rift Valley fever virus (RVFV), a bunyavirus, has a single-stranded, negative-sense tri-segmented RNA genome, consisting of L, M and S RNAs. An infectious virion carries two envelope glycoproteins, Gn and Gc, along with ribonucleoprotein complexes composed of encapsidated viral RNA segments. The antigenomic S RNA, which serves as the template of the mRNA encoding a nonstructural protein, NSs, an interferon antagonist, is also efficiently packaged into RVFV particles. An interaction between Gn and viral ribonucleoprotein complexes, including the direct binding of Gn to viral RNAs, drives viral RNA packaging into RVFV particles. To understand the mechanism of efficient antigenomic S RNA packaging in RVFV, we identified the regions in viral RNAs that directly interact with Gn by performing UV-crosslinking and immunoprecipitation of RVFV-infected cell lysates with anti-Gn antibody followed by high-throughput sequencing analysis (CLIP-seq analysis). Our data suggested the presence of multiple Gn-binding sites in RVFV RNAs, including a prominent Gn-binding site within the 3' noncoding region of the antigenomic S RNA. We found that the efficient packaging of antigenomic S RNA was abrogated in a RVFV mutant lacking a part of this prominent Gn-binding site within the 3' noncoding region. Also, the mutant RVFV, but not the parental RVFV, triggered the early induction of interferon-β mRNA expression after infection. These data suggest that the direct binding of Gn to the RNA element within the 3' noncoding region of the antigenomic S RNA promoted the efficient packaging of antigenomic S RNA into virions. Furthermore, the efficient packaging of antigenomic S RNA into RVFV particles, driven by the RNA element, facilitated the synthesis of viral mRNA encoding NSs immediately after infection, resulting in the suppression of interferon-β mRNA expression., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Tercero, Terasaki, Narayanan and Makino.)

Rift Valley fever phlebovirus (RVFV) has a single-stranded, negative-sense RNA genome, consisting of L, M, and S segments. The virion carries two envelope glycoproteins, Gn and Gc, along with ribonucleoprotein complexes (RNPs), composed of encapsidated genomes carrying N protein and the viral polymerase, L protein. A quantitative analysis of the profile of viral RNA segments packaged into RVFV particles showed that all three genomic RNA segments had similar packaging abilities, whereas among antigenomic RNA segments, the antigenomic S RNA, which serves as the template for the transcription of mRNA expressing the RVFV virulence factor, NSs, displayed a significantly higher packaging ability. To delineate the factor(s) governing the packaging of RVFV RNA segments, we characterized the interactions between Gn and viral RNPs in RVFV-infected cells. Coimmunoprecipitation analysis demonstrated the interaction of Gn with N protein, L protein, and viral RNAs in RVFV-infected cells. Furthermore, UV-cross-linking and immunoprecipitation analysis revealed, for the first time in bunyaviruses, the presence of a direct interaction between Gn and all the viral RNA segments in RVFV-infected cells. Notably, analysis of the ability of Gn to bind to RVFV RNA segments indicated a positive correlation with their respective packaging abilities and highlighted a binding preference of Gn for antigenomic S RNA, among the antigenomic RNA segments, suggesting the presence of a selection mechanism for antigenomic S RNA incorporation into infectious RVFV particles. Collectively, the results of our study illuminate the importance of a direct interaction between Gn and viral RNA segments in determining their efficiency of incorporation into RVFV particles. IMPORTANCE Rift Valley fever phlebovirus, a bunyavirus, is a mosquito-borne, segmented RNA virus that can cause severe disease in humans and ruminants. An essential step in RVFV life cycle is the packaging of viral RNA segments to produce infectious virus particles for dissemination to new hosts. However, there are key gaps in knowledge regarding the mechanisms that regulate viral RNA packaging efficiency in bunyaviruses. Our studies investigating the mechanism of RNA packaging in RVFV revealed the presence of a direct interaction between the viral envelope glycoprotein, Gn, and the viral RNA segments in infected cells, for the first time in bunyaviruses. Furthermore, our data strongly indicate a critical role for the direct interaction between Gn and viral RNAs in determining the efficiency of incorporation of viral RNA segments into RVFV particles. Clarifying the fundamental mechanisms of RNA packaging in RVFV would be valuable for the development of antivirals and live-attenuated vaccines.

We report the first detection in space of the single deuterated isotopologue of methylcyanoacetylene, CH 2 DC 3 N. A total of fifteen rotational transitions, with J = 8-12 and K a = 0 and 1, were identified for this species in TMC-1 in the 31.0-50.4 GHz range using the Yebes 40m radio telescope. The observed frequencies were used to derive for the first time the spectroscopic parameters of this deuterated isotopologue. We derive a column density of (8.0 ± 0.4) × 10 10 cm -2 . The abundance ratio between CH 3 C 3 N and CH 2 DC 3 N is ∼22. We also theoretically computed the principal spectroscopic constants of 13 C isotopologues of CH 3 C 3 N and CH 3 C 4 H and those of the deuterated isotopologues of CH 3 C 4 H for which we could expect a similar degree of deuteration enhancement. However, we have not detected either CH 2 DC 4 H nor CH 3 C 4 D nor any 13 C isotopologue. The different observed deuterium ratios in TMC-1 are reasonably accounted for by a gas phase chemical model where the low temperature conditions favor deuteron transfer through reactions with H 2 D + .

Cell membranes are a key element of life because they keep the genetic material and metabolic machinery together. All present cell membranes are made of phospholipids, yet the nature of the first membranes and the origin of phospholipids are still under debate. We report here the presence of ethanolamine in space, [Formula: see text]OH, which forms the hydrophilic head of the simplest and second-most-abundant phospholipid in membranes. The molecular column density of ethanolamine in interstellar space is N = (1.51[Formula: see text]0.07)[Formula: see text], implying a molecular abundance with respect to [Formula: see text] of [Formula: see text] Previous studies reported its presence in meteoritic material, but they suggested that it is synthesized in the meteorite itself by decomposition of amino acids. However, we find that the proportion of the molecule with respect to water in the interstellar medium is similar to the one found in the meteorite ([Formula: see text]). These results indicate that ethanolamine forms efficiently in space and, if delivered onto early Earth, could have contributed to the assembling and early evolution of primitive membranes., Competing Interests: The authors declare no competing interest., (Copyright © 2021 the Author(s). Published by PNAS.)

We report the detection of the oxygen-bearing complex organic molecules propenal (C 2 H 3 CHO), vinyl alcohol (C 2 H 3 OH), methyl formate (HCOOCH 3 ), and dimethyl ether (CH 3 OCH 3 ) toward the cyanopolyyne peak of the starless core TMC-1. These molecules are detected through several emission lines in a deep Q-band line survey of TMC-1 carried out with the Yebes 40m telescope. These observations reveal that the cyanopolyyne peak of TMC-1, which is the prototype of cold dark cloud rich in carbon chains, contains also O-bearing complex organic molecules like HCOOCH 3 and CH 3 OCH 3 , which have been previously seen in a handful of cold interstellar clouds. In addition, this is the first secure detection of C 2 H 3 OH in space and the first time that C 2 H 3 CHO and C 2 H 3 OH are detected in a cold environment, adding new pieces in the puzzle of complex organic molecules in cold sources. We derive column densities of (2.2 ± 0.3) × 10 11 cm ™2 , (2.5 ± 0.5) × 10 12 cm -2 , (1.1 ± 0.2) × 10 12 cm -2 , and (2.5 ± 0.7) × 10 12 cm -2 for C 2 H 3 CHO, C 2 H 3 OH, HCOOCH 3 , and CH 3 OCH 3 , respectively. Interestingly, C 2 H 3 OH has an abundance similar to that of its well known isomer acetaldehyde (CH 3 CHO), with C 2 H 3 OH/CH 3 CHO ~ 1 at the cyanopolyyne peak. We discuss potential formation routes to these molecules and recognize that further experimental, theoretical, and astronomical studies are needed to elucidate the true mechanism of formation of these O-bearing complex organic molecules in cold interstellar sources.

The chemical compounds carrying the thiol group (-SH) have been considered essential in recent prebiotic studies regarding the polymerization of amino acids. We have searched for this kind of compounds toward the Galactic Centre quiescent cloud G+0.693-0.027. We report the first detection in the interstellar space of the trans-isomer of monothioformic acid (t-HC(O)SH) with an abundance of ~ 1 × 10 -10 . Additionally, we provide a solid confirmation of the gauche isomer of ethyl mercaptan (g-C 2 H 5 SH) with an abundance of ~ 3 × 10 -10 , and we also detect methyl mercaptan (CH 3 SH) with an abundance of ~ 5 × 10 -9 . Abundance ratios were calculated for the three SH-bearing species and their OH-analogues, revealing similar trends between alcohols and thiols with increasing complexity. Possible chemical routes for the interstellar synthesis of t-HC(O)SH, CH 3 SH and C 2 H 5 SH are discussed, as well as the relevance of these compounds in the synthesis of prebiotic proteins in the primitive Earth.

We report the detection of the sulfur-bearing species NCS, HCCS, H 2 CCS, H 2 CCCS, and C 4 S for the first time in space. These molecules were found towards TMC-1 through the observation of several lines for each species. We also report the detection of C 5 S for the first time in a cold cloud through the observation of five lines in the 31-50 GHz range. The derived column densities are N (NCS) = (7.8±0.6)×10 11 cm -2 , N (HCCS) = (6.8±0.6)×10 11 cm -2 , N(H 2 CCS) = (7.8±0.8)×10 11 cm -2 , N(H 2 CCCS) = (3.7±0.4)×10 11 cm -2 , N(C 4 S) = (3.8±0.4)×10 10 cm -2 , and N(C 5 S) = (5.0±1.0)×10 10 cm -2 . The observed abundance ratio between C 3 S and C 4 S is 340, that is to say a factor of approximately one hundred larger than the corresponding value for CCS and C 3 S. The observational results are compared with a state-of-the-art chemical model, which is only partially successful in reproducing the observed abundances. These detections underline the need to improve chemical networks dealing with S-bearing species.

We present the first identification in interstellar space of the propargyl radical (CH 2 CCH). This species was observed in the cold dark cloud TMC-1 using the Yebes 40m telescope. The six strongest hyperfine components of the 2 0,2 -1 0,1 rotational transition, lying at 37.46 GHz, were detected with signal-to-noise ratios in the range 4.6-12.3 σ. We derive a column density of 8.7 × 10 13 cm -2 for CH 2 CCH, which translates to a fractional abundance relative to H 2 of 8.7 × 10 -9 . This radical has a similar abundance to methyl acetylene, with an abundance ratio CH 2 CCH/CH 3 CCH close to one. The propargyl radical is thus one of the most abundant radicals detected in TMC-1, and it is probably the most abundant organic radical with a certain chemical complexity ever found in a cold dark cloud. We constructed a gas-phase chemical model and find calculated abundances that agree with, or fall two orders of magnitude below, the observed value depending on the poorly constrained low-temperature reactivity of CH 2 CCH with neutral atoms. According to the chemical model, the propargyl radical is essentially formed by the C + C 2 H 4 reaction and by the dissociative recombination of C 3 H n + ions with n = 4-6. The propargyl radical is believed to control the synthesis of the first aromatic ring in combustion processes, and it probably plays a key role in the synthesis of large organic molecules and cyclization processes to benzene in cold dark clouds.

We present the discovery in TMC-1 of allenyl acetylene, H 2 CCCHCCH, through the observation of nineteen lines with a signal-to-noise ratio ~4-15. For this species, we derived a rotational temperature of 7±1K and a column density of 1.2±0.2×10 13 cm -2 . The other well known isomer of this molecule, methyl diacetylene (CH 3 C 4 H), has also been observed and we derived a similar rotational temperature, T r =7.0±0.3 K, and a column density for its two states ( A and E ) of 6.5±0.3×10 12 cm -2 . Hence, allenyl acetylene and methyl diacetylene have a similar abundance. Remarkably, their abundances are close to that of vinyl acetylene (CH 2 CHCCH). We also searched for the other isomer of C 5 H 4 , HCCCH 2 CCH (1.4-Pentadiyne), but only a3σ upper limit of 2.5×10 12 cm -2 to the column density can be established. These results have been compared to state-of-the-art chemical models for TMC-1, indicating the important role of these hydrocarbons in its chemistry. The rotational parameters of allenyl acetylene have been improved by fitting the existing laboratory data together with the frequencies of the transitions observed in TMC-1.

We present the discovery in TMC-1 of vinyl acetylene, CH 2 CHCCH, and the detection, for the first time in a cold dark cloud, of HCCN, HC 4 N, and CH 3 CH 2 CN. A tentative detection of CH 3 CH 2 CCH is also reported. The column density of vinyl acetylene is (1.2±0.2)×10 13 cm -2 , which makes it one of the most abundant closed-shell hydrocarbons detected in TMC-1. Its abundance is only three times lower than that of propylene, CH 3 CHCH 2 . The column densities derived for HCCN and HC 4 N are (4.4±0.4)×10 11 cm -2 and (3.7±0.4)×10 11 cm -2 , respectively. Hence, the HCCN/HC 4 N abundance ratio is 1.2±0.3. For ethyl cyanide we derive a column density of (1.1 ±0.3)×10 11 cm -2 . These results are compared with a state-of-the-art chemical model of TMC-1, which is able to account for the observed abundances of these molecules through gas-phase chemical routes.

We present Yebes 40m telescope observations of the three most stable C 4 H 3 N isomers towards the cyanopolyyne peak of TMC-1. We have detected 13 transitions from CH 3 C 3 N (A and E species), 16 lines from CH 2 CCHCN, and 27 lines (a-type and b-type) from HCCCH 2 CN. We thus provide a robust confirmation of the detection of HCCCH 2 CN and CH 2 CCHCN in space. We have constructed rotational diagrams for the three species, and obtained rotational temperatures between 4-8 K and similar column densities for the three isomers, in the range (1.5-3)×10 12 cm -2 . Our chemical model provides abundances of the order of the observed ones, although it overestimates the abundance of CH 3 CCCN and underestimates that of HCCCH 2 CN. The similarity of the observed abundances of the three isomers suggests a common origin, most probably involving reactions of the radical CN with the unsaturated hydrocarbons methyl acetylene and allene. Studies of reaction kinetics at low temperature and further observations of these molecules in different astronomical sources are needed to draw a clear picture of the chemistry of C 4 H 3 N isomers in space.

Using the Yebes 40m and IRAM 30m radiotelescopes, we detected two series of harmonically related lines in space that can be fitted to a symmetric rotor. The lines have been seen towards the cold dense cores TMC-1, L483, L1527, and L1544. High level of theory ab initio calculations indicate that the best possible candidate is the acetyl cation, CH 3 CO + , which is the most stable product resulting from the protonation of ketene. We have produced this species in the laboratory and observed its rotational transitions J u = 10 up to J u = 27. Hence, we report the discovery of CH 3 CO + in space based on our observations, theoretical calculations, and laboratory experiments. The derived rotational and distortion constants allow us to predict the spectrum of CH 3 CO + with high accuracy up to 500 GHz. We derive an abundance ratio N (H 2 CCO)/ N (CH 3 CO + )~44. The high abundance of the protonated form of H 2 CCO is due to the high proton affinity of the neutral species. The other isomer, H 2 CCOH + , is found to be 178.9 kJ mol -1 above CH 3 CO + . The observed intensity ratio between the K =0 and K =1 lines, ~2.2, strongly suggests that the A and E symmetry states have suffered interconversion processes due to collisions with H and/or H 2 , or during their formation through the reaction of H 3 + with H 2 CCO.

Rotational spectroscopy provides the most powerful means of identifying molecules of biological interest in the interstellar medium (ISM), but despite their importance, the detection of carbohydrates has remained rather elusive. Here, we present a comprehensive Fourier transform rotational spectroscopic study of elusive erythrulose, a sugar building block likely to be present in the ISM, employing a novel method of transferring the hygroscopic oily carbohydrate into the gas phase. The high sensitivity of the experiment allowed the rotational spectra of all monosubstituted isotopologue species of 13 C- 12 C 3 H 8 O 4 to be recorded, which, together with quantum chemical calculations, enabled us to determine their equilibrium geometries ( r e SE ) with great precision. Searches employing the new experimental data for erythrulose have been undertaken in different ISM regions, so far including the cold areas Barnard 1, the pre-stellar core TMC-1, Sagittarius B2. Although no lines of erythrulose were found, this data will serve to enable future searches and possible detections in other ISM regions.

Context: S-methyl thioformate CH 3 SC(O)H is a monosulfur derivative of methyl formate, a relatively abundant component of the interstellar medium (ISM). S-methyl thioformate being, thermodynamically, the most stable isomer, it can be reasonably proposed for detection in the ISM., Aims: This work aims to experimentally study and theoretically analyze the ground and first torsional excited states for CH 3 SC(O)H in a large spectral range for astrophysical use., Methods: S-methyl thioformate was synthesized as a result of a reaction of methyl mercaptan with acetic-formic anhydride. The millimeter-wave spectrum was then recorded for the first time from 150 to 660 GHz with the solid-state spectrometer located at Lille., Results: A set of 3545 lines is determined and combined with 54 previously measured lines in the microwave region, belonging to ground state ν t = 0 as well as 1391 transitions in the first excited state of torsion ν 18 = 1. Some 164 lines were also assigned to ν 18 = 2 for the A-species. A global fit was performed using the BELGI-C s code taking into account the large splitting of A and E lines due to methyl internal rotation motion with a relatively low barrier, V 3 = 127.4846(15) cm -1 ., Conclusions: Using our spectroscopy work, a deep search of S-methyl thioformate was carried out in the IRAM 30m and ALMA data of different high-mass star-forming regions (Orion KL and Sgr B2). We derived an upper limit to the CH 3 SC(O)H column density in these regions.

Using the Yebes 40m radio telescope, we report the detection of a series of seven lines harmonically related with a rotational constant B 0 =1295.81581 ± 0.00026 MHz and a distortion constant D 0 = 27.3 ± 0.5 Hz towards the cold dense cloud TMC-1. Ab initio calculations indicate that the best possible candidates are the cations HC 5 NH + and NC 4 NH + . From a comparison between calculated and observed rotational constants and other arguments based on proton affinities and dipole moments, we conclude that the best candidate for a carrier of the observed lines is the protonated cyanodiacetylene cation, HC 5 NH + . The HC 5 N/HC 5 NH + ratio derived in TMC-1 is 240, which is very similar to the HC 3 N/HC 3 NH + ratio. Results are discussed in the framework of a chemical model for protonated molecules in cold dense clouds.

Using the Yebes 40m and IRAM 30m radio telescopes, we detected a series of harmonically related lines with a rotational constant B 0 =4460.590±0.001 MHz and a distortion constant D 0 =0.511 ±0.005 kHz towards the cold dense core TMC-1. High-level-of-theory ab initio calculations indicate that the best possible candidate is protonated tricarbon monoxide, HC 3 O + . We have succeeded in producing this species in the laboratory and observed its J u - J l = 2-1 and 3-2 rotational transitions. Hence, we report the discovery of HC 3 O + in space based on our observations, theoretical calculations, and laboratory experiments. We derive an abundance ratio N (C 3 O)/ N (HC 3 O + )~7. The high abundance of the protonated form of C 3 O is due to the high proton affinity of the neutral species. The chemistry of O-bearing species is modelled, and predictions are compared to the derived abundances from our data for the most prominent O-bearing species in TMC-1.

We present a study of the isocyano isomers of the cyanopolyynes HC 3 N, HC 5 N, and HC 7 N in TMC-1 and IRC+10216 carried out with the Yebes 40m radio telescope. This study has enabled us to report the detection, for the first time in space, of HCCCCNC in TMC-1 and to give upper limits for HC 6 NC in the same source. In addition, the deuterated isotopologues of HCCNC and HNCCC were detected, along with all 13 C substitutions of HCCNC, also for the first time in space. The abundance ratios of HC 3 N and HC 5 N, with their isomers, are very different in TMC-1 and IRC+10216, namely, N (HC 5 N)/ N (HC 4 NC) is ~300 and ≥2100, respectively. We discuss the chemistry of the metastable isomers of cyanopolyynes in terms of the most likely formation pathways and by comparing observational abundance ratios between different sources.

The Bunyavirales order is the largest group of RNA viruses, which includes important human and animal pathogens, that cause serious diseases. Licensed vaccines are often not available for many of these pathogens. The establishment of bunyavirus reverse genetics systems has facilitated the generation of recombinant infectious viruses, which have been employed as powerful tools for understanding bunyavirus biology and identifying important virulence factors. Technological advances in this area have enabled the development of novel strategies, including codon-deoptimization, viral genome rearrangement and single-cycle replicable viruses, for the generation of live-attenuated vaccine candidates. In this review, we have summarized the current knowledge of the bunyavirus reverse genetics approaches for the generation of live-attenuated vaccine candidates and their evaluation in animal models., (Copyright © 2020 Elsevier B.V. All rights reserved.)

We report on the first detection of C 3 N - and C 5 N - towards the cold dark core TMC-1 in the Taurus region, using the Yebes 40 m telescope. The observed C 3 N/C 3 N - and C 5 N/C 5 N - abundance ratios are ~140 and ~2, respectively; that is similar to those found in the circumstellar envelope of the carbon-rich star IRC +10216. Although the formation mechanisms for the neutrals are different in interstellar (ion-neutral reactions) and circumstellar clouds (photodissociation and radical-neutral reactions), the similarity of the C 3 N/C 3 N - and C 5 N/C 5 N - abundance ratios strongly suggests a common chemical path for the formation of these anions in interstellar and circumstellar clouds. We discuss the role of radiative electronic attachment, reactions between N atoms and carbon chain anions C n - , and that of H - reactions with HC 3 N and HC 5 N as possible routes to form C n N - . The detection of C 5 N - in TMC-1 gives strong support for assigning to this anion the lines found in IRC +10216, as it excludes the possibility of a metal-bearing species, or a vibrationally excited state. New sets of rotational parameters have been derived from the observed frequencies in TMC-1 and IRC +10216 for C 5 N - and the neutral radical C 5 N.

Observations of IRC +10216 with the Yebes 40m telescope between 31 and 50 GHz have revealed more than 150 unidentified lines. Some of them can be grouped into a new series of 26 doublets, harmonically related with integer quantum numbers ranging from J up =54 to 80. The separation of the doublets increases systematically with J , i.e., as expected for a linear species in one of its bending modes. The rotational parameters resulting from the fit to these data are B = 290.8844 ± 0.0004 MHz, D = 0.88 ± 0.04 Hz, q = 0.1463 ± 0.0001 MHz. The rotational constant is very close to that of the ground state of HC 9 N. Ab initio calculations show an excellent agreement between these parameters and those predicted for the lowest energy vibrationally excited state, ν 19 =1, of HC 9 N. This is the first detection, and complete characterization in space, of vibrationally excited HC 9 N. An energy of 41.5 cm -1 is estimated for the ν 19 state. In addition, 17 doublets of HC 7 N in the ν 15 =1 state, for which laboratory spectroscopy is available, have been detected for the first time in IRC+10216. Several doublets of HC 5 N in its ν 11 =1 state have been also observed. The column density ratio between the ground and the lowest excited vibrational states are ≈127, 9.5, and 1.5 for HC 5 N, HC 7 N, and HC 9 N, respectively. We find that these lowest-lying vibrational states are most probably populated via infrared pumping to vibrationally excited states lying at ≈600 cm -1 . The lowest vibrationally excited states thus need to be taken into account to precisely determine absolute abundances and abundanceratios for long carbon chains. The abundance ratios N(HC 5 N)/N(HC 7 N) and N(HC 7 N)/N(HC 9 N) are 2.4 and 7.7 respectively.

Rift Valley Fever phlebovirus (RVFV), genus Phlebovirus, family Phenuiviridae, order Bunyavirales, has a single-stranded, negative-sense RNA genome, consisting of L, M and S segments. Here, we report the establishment of a strand-specific, quantitative reverse transcription (RT)-PCR assay system that can selectively distinguish between the genomic and antigenomic RNAs of each of the three viral RNA segments produced in RVFV-infected cells. To circumvent the obstacle of primer-independent cDNA synthesis during RT, we used a tagged, strand-specific RT primer, carrying a non-viral 'tag' sequence at the 5' end, which ensured the strand-specificity through the selective amplification of only the tagged cDNA in the real-time PCR assay. We used this assay system to examine the kinetics of intracellular accumulation of genomic and antigenomic viral RNAs in mammalian cells infected with the MP-12 strain of RVFV. The genomic RNA copy numbers, for all three viral RNA segments, were higher than that of their corresponding antigenomic RNAs throughout the time-course of infection, with a notable exception, wherein the M segment genomic and antigenomic RNAs exhibited similar copy numbers at specific times post-infection. Overall, this assay system could be a useful tool to gain an insight into the mechanisms of RNA replication and packaging in RVFV., (Copyright © 2019 Elsevier B.V. All rights reserved.)

GEMS is an IRAM 30m Large Program whose aim is determining the elemental depletions and the ionization fraction in a set of prototypical star-forming regions. This paper presents the first results from the prototypical dark cloud TMC 1. Extensive millimeter observations have been carried out with the IRAM 30m telescope (3 mm and 2 mm) and the 40m Yebes telescope (1.3 cm and 7 mm) to determine the fractional abundances of CO, HCO + , HCN, CS, SO, HCS + , and N 2 H + in three cuts which intersect the dense filament at the well-known positions TMC 1-CP, TMC 1-NH3, and TMC 1-C, covering a visual extinction range from A V ~ 3 to ~20 mag. Two phases with differentiated chemistry can be distinguished: i) the translucent envelope with molecular hydrogen densities of 1-5×10 3 cm -3 ; and ii) the dense phase, located at A V > 10 mag, with molecular hydrogen densities >10 4 cm -3 . Observations and modeling show that the gas phase abundances of C and O progressively decrease along the C + /C/CO transition zone (A V ~ 3 mag) where C/H ~ 8×10 -5 and C/O~0.8-1, until the beginning of the dense phase at A V ~ 10 mag. This is consistent with the grain temperatures being below the CO evaporation temperature in this region. In the case of sulfur, a strong depletion should occur before the translucent phase where we estimate a S/H ~ (0.4 - 2.2) ×10 -6 , an abundance ~7-40 times lower than the solar value. A second strong depletion must be present during the formation of the thick icy mantles to achieve the values of S/H measured in the dense cold cores (S/H ~8×10 -8 ). Based on our chemical modeling, we constrain the value of ζ H 2 to ~ (0.5 - 1.8) ×10 -16 s -1 in the translucent cloud.

As many organic molecules, formic acid (HCOOH) has two conformers ( trans and cis ). The energy barrier to internal conversion from trans to cis is much higher than the thermal energy available in molecular clouds. Thus, only the most stable conformer ( trans ) is expected to exist in detectable amounts. We report the first interstellar detection of cis -HCOOH. Its presence in ultraviolet (UV) irradiated gas exclusively (the Orion Bar photodissociation region), with a low trans -to- cis abundance ratio of 2.8 ± 1.0, supports a photoswitching mechanism: a given conformer absorbs a stellar photon that radiatively excites the molecule to electronic states above the interconversion barrier. Subsequent fluorescent decay leaves the molecule in a different conformer form. This mechanism, which we specifically study with ab initio quantum calculations, was not considered in Space before but likely induces structural changes of a variety of interstellar molecules submitted to UV radiation.

Context: Despite the fact that many sulfur-bearing molecules, ranging from simple diatomic species up to astronomical complex molecules, have been detected in the interstellar medium, the sulfur chemistry in space is largely unknown and a depletion in the abundance of S-containing species has been observed in the cold, dense interstellar medium (ISM). The chemical form of the missing sulfur has yet to be identified., Aims: For these reasons, in view of the fact that there is a large abundance of triatomic species harbouring sulfur, oxygen, and hydrogen, we decided to investigate the HSO radical in the laboratory to try its astronomical detection., Methods: High-resolution measurements of the rotational spectrum of the HSO radical were carried out within a frequency range well up into the THz region. Subsequently, a rigorous search for HSO in the two most studied high-mass star-forming regions, Orion KL and Sagittarius (Sgr) B2, and in the cold dark cloud Barnard 1 (B1-b) was performed., Results: The frequency coverage and the spectral resolution of our measurements allowed us to improve and extend the existing dataset of spectroscopic parameters, thus enabling accurate frequency predictions up to the THz range. These were used to derive the synthetic spectrum of HSO, by means of the MADEX code, according to the physical parameters of the astronomical source under consideration. For all sources investigated, the lack of HSO lines above the confusion limit of the data is evident., Conclusions: The derived upper limit to the abundance of HSO clearly indicates that this molecule does not achieve significant abundances in either the gas phase or in the ice mantles of dust grains.

The recent analysis of the composition of the frozen surface of comet 67P/Churyumov-Gerasimenko has revealed a significant number of complex organic molecules. Methyl isocyanate (CH 3 NCO) is one of the more abundant species detected on the comet surface. In this work we report extensive characterization of its rotational spectrum resulting in a list of 1269 confidently assigned laboratory lines and its detection in space towards the Orion clouds where 399 lines of the molecule have been unambiguously identified. We find that the limited mm-wave laboratory data reported prior to our work require some revision. The abundance of CH 3 NCO in Orion is only a factor of ten below those of HNCO and CH 3 CN. Unlike the molecular abundances in the coma of comets, which correlate with those of warm molecular clouds, molecular abundances in the gas phase in Orion are only weakly correlated with those measured on the comet surface. We also compare our abundances with those derived recently for this molecule towards Sgr B2 (Halfen et al. 2015). A more accurate abundance of CH 3 NCO is provided for this cloud based on our extensive laboratory work.

CH2D+, the singly deuterated counterpart of CH3(+), offers an alternative way to mediate formation of deuterated species at temperatures of several tens of Kelvin, as compared to the release of deuterated species from grains. We report a longstanding observational search for this molecular ion, whose rotational spectroscopy is not yet completely secure. We summarize the main spectroscopic properties of this molecule and discuss the chemical network leading to the formation of CH2D+, with explicit account of the ortho/para forms of H2, H3(+), and CH3(+). Astrochemical models support the presence of this molecular ion in moderately warm environments at a marginal level.