Microbial cycling of isoprene, the most abundantly produced biological volatile organic compound on Earth

Isoprene (2-methyl-1,3-butadiene), the most abundantly produced biogenic volatile organic compound (BVOC) on Earth, is highly reactive and can have diverse and often detrimental atmospheric effects, which impact on climate and health. Most isoprene is produced by terrestrial plants, but (micro)algal production is important in aquatic environments, and the relative bacterial contribution remains unknown. Soils are a sink for isoprene, and bacteria that can use isoprene as a carbon and energy source have been cultivated and also identified using cultivation-independent methods from soils, leaves and coastal/marine environments. Bacteria belonging to the Actinobacteria are most frequently isolated and identified, and Proteobacteria have also been shown to degrade isoprene. In the freshwater-sediment isolate, Rhodococcus strain AD45, initial oxidation of isoprene to 1,2-epoxy-isoprene is catalyzed by a multicomponent isoprene monooxygenase encoded by the genes isoABCDEF. The resultant epoxide is converted to a glutathione conjugate by a glutathione S-transferase encoded by isoI, and further degraded by enzymes encoded by isoGHJ. Genome sequence analysis of actinobacterial isolates belonging to the genera Rhodococcus, Mycobacterium and Gordonia has revealed that isoABCDEF and isoGHIJ are linked in an operon, either on a plasmid or the chromosome. In Rhodococcus strain AD45 both isoprene and epoxy-isoprene induce a high level of transcription of 22 contiguous genes, including isoABCDEF and isoGHIJ. Sequence analysis of the isoA gene, encoding the large subunit of the oxygenase component of isoprene monooxygenase, from isolates has facilitated the development of PCR primers that are proving valuable in investigating the ecology of uncultivated isoprene-degrading bacteria

The wind and the magnetospheric accretion onto the T Tauri star S Coronae Australis at sub-Au resolution

This is the author accepted manuscript. The final version is available from EDP Sciences via the DOI in this record.Aims. To investigate the inner regions of protoplanetary discs, we performed near-infrared interferometric observations of the classical T Tauri binary system S CrA. Methods. We present the first VLTI-GRAVITY high spectral resolution (R - 4000) observations of a classical T Tauri binary, S CrA (composed of S CrAN and S CrAS and separated by -10:04), combining the four 8m telescopes in dual-field mode. Results. Our observations in the near-infrared K-band continuum reveal a disc around each binary component, with similar halfflux radii of about 0.1 au at d - 130 pc, inclinations (i = 28 - 3-and i = 22 - 6-), and position angles (PA = 0- 6- and PA = -2-12-), suggesting that they formed from the fragmentation of a common disc. The S CrAN spectrum shows bright He i and Br line emission exhibiting inverse P Cygni profiles, typically associated with infalling gas. The continuum-compensated Br line visibilities of S CrAN show the presence of a compact Br emitting region whose radius is about -0.06 au, which is twice as big as the truncation radius. This component is mostly tracing a wind. Moreover, a slight radius change between the blue-And red-shifted Br line components is marginally detected. Conclusions. The presence of an inverse P Cygni profile in the He i and Br lines, along with the tentative detection of a slightly larger size of the blue-shifted Br line component, hint at the simultaneous presence of a wind and magnetospheric accretion in S CrA N.Science Foundation IrelandAlexander von Humboldt Foundation Fellowship ProgrammeFrench PNPSLabEx OSUG@202

Multiple star systems in the Orion nebula

This is the author accepted manuscript. The final fersion is available from EDP Sciences via the DOI in this record.This work presents an interferometric study of the massive-binary fraction in the Orion Trapezium cluster with the recently comissioned GRAVITY instrument. We observed a total of 16 stars of mainly OB spectral type. We find three previously unknown companions for θ1 Ori B, θ2 Ori B, and θ2 Ori C. We determined a separation for the previously suspected companion of NU Ori. We confirm four companions for θ1 Ori A, θ1 Ori C, θ1 Ori D, and θ2 Ori A, all with substantially improved astrometry and photometric mass estimates. We refined the orbit of the eccentric high-mass binary θ1 Ori C and we are able to derive a new orbit for θ1 Ori D. We find a system mass of 21.7 M⊙ and a period of 53 days. Together with other previously detected companions seen in spectroscopy or direct imaging, eleven of the 16 high-mass stars are multiple systems. We obtain a total number of 22 companions with separations up to 600 AU. The companion fraction of the early B and O stars in our sample is about two, significantly higher than in earlier studies of mostly OB associations. The separation distribution hints toward a bimodality. Such a bimodality has been previously found in A stars, but rarely in OB binaries, which up to this point have been assumed to be mostly compact with a tail of wider companions. We also do not find a substantial population of equal-mass binaries. The observed distribution of mass ratios declines steeply with mass, and like the direct star counts, indicates that our companions follow a standard power law initial mass function. Again, this is in contrast to earlier findings of flat mass ratio distributions in OB associations. We excluded collision as a dominant formation mechanism but find no clear preference for core accretion or competitive accretion.Marie Skłodowska-Curie Grant AgreementFCT-PortugalERC Starting Gran

Volatile organic compounds in truffle (Tuber magnatum Pico): comparison of samples from different regions of Italy and from different seasons

In this paper volatile organic compounds (VOCs) from Tuber magnatum fruiting bodies were analyzed using a PTR-TOF-MS instrument. The aim was to characterize the VOC's profile of the fruiting bodies and identify if any VOCs were specific to a season and geographical areas. Multiple factorial analysis (MFA) was carried out on the signals obtained by MS. Experiments using ITS region sequencing proved that the T. magnatum life cycle includes the formation of fruiting bodies at two different times of the year. The VOCs profiles diverge when different seasonal and geographical productions are considered. Using PTR-TOF-MS, compounds present at levels as low pptv were detected. This made it possible to determine both the origin of fruiting bodies (Alba and San Miniato) and the two biological phases of fruiting bodies formation in San Miniato truffles

m(6)A mRNA Methylation in the Mammalian Brain: Distribution, Function and Implications for Brain Functions

RNA is abundantly modified by a range of covalent modifications, collectively termed the epitranscriptome. Of these modifications, N-6-methyladenosine (m(6)A) is the most prevalent internal chemical tag in eukaryotic mRNA. Being cotranscriptionally deposited, it regulates almost all aspects of mRNA's lifetime including maturation into mRNA, stability, distribution and protein translation. While m(6)A is likely present in all developing and adult mammalian tissues, here we highlight its distribution and reported functions in the mammalian brain. Additionally, we describe its potential to act as an encoding mechanism for activity- and experience-dependent adaptation and memory-formation. Such alterations may be positive when adjusting to outer challenges or negative when involved in maladaptive processes of the brain such as in the development of psychopathologies. Consequently, studying this layer of gene expression control in the brain, alongside posttranslational regulation of proteins and epigenetics may inform us as to the molecular mechanisms underlying normal and pathological behaviors. Unfortunately, measuring m(6)A levels, patterns and especially dynamics still poses a major technological challenge especially in such a complicated organ as the brain