The Genus Piscirickettsia

Marshall, Sergio H.; Gómez, Fernando; Klose, Karl E.

doi:10.1007/978-3-642-38922-1_234

Cited by 10 publications

(16 citation statements)

References 41 publications

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“…the distance bin labelled "10" contains stars up to 10 pc distance from the Sun). The green and red bars represent the stars that have both known planets and detected debris discs based on recent Herschel surveys (Marshall et al 2014a;Moro-Martín et al 2015) and the SONS survey, respectively.…”

Section: Disc Mass Evolutionmentioning

confidence: 99%

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SONS: The JCMT legacy survey of debris discs in the submillimetre

Holland

Matthews

Kennedy

et al. 2017

Monthly Notices of the Royal Astronomical Society

129

111

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Debris discs are evidence of the ongoing destructive collisions between planetesimals, and their presence around stars also suggests that planets exist in these systems. In this paper, we present submillimetre images of the thermal emission from debris discs that formed the SCUBA-2 Observations of Nearby Stars (SONS) survey, one of seven legacy surveys undertaken on the James Clerk Maxwell telescope between 2012 and 2015. The overall results of the survey are presented in the form of 850 µm (and 450 µm, where possible) images and fluxes for the observed fields. Excess thermal emission, over that expected from the stellar photosphere, is detected around 49 stars out of the 100 observed fields. The discs are characterised in terms of their flux density, size (radial distribution of the dust) and derived dust properties from their spectral energy distributions. The results show discs over a range of sizes, typically 1-10 times the diameter of the Edgeworth-Kuiper Belt in our Solar System. The mass of a disc, for particles up to a few millimetres in size, is uniquely obtainable with submillimetre observations and this quantity is presented as a function of the host stars' age, showing a tentative decline in mass with age. Having doubled the number of imaged discs at submillimetre wavelengths from ground-based, single dish telescope observations, one of the key legacy products from the SONS survey is to provide a comprehensive target list to observe at high angular resolution using submillimetre/millimetre interferometers (e.g., ALMA, SMA).

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Section: Disc Mass Evolutionmentioning

confidence: 99%

“…The majority of stars with known planets and a debris disc are naturally chosen to be close to the Sun, as shown in Fig. 36 for both SONS and recent Herschel surveys (Marshall et al 2014a;Moro-Martín et al 2015). It is also the case that the few directly-imaged exoplanets (i.e.…”

Section: Planet Hostsmentioning

confidence: 99%

SONS: The JCMT legacy survey of debris discs in the submillimetre

Holland

Matthews

Kennedy

et al. 2017

Monthly Notices of the Royal Astronomical Society

129

111

View full text Add to dashboard Cite

show abstract

“…For single E-mail: bastien@astro.umontreal.ca (PB) vandeportal.julien@gmail.com (JV) and multiple stars, the rates are 21 ± 3 per cent and 11 ± 3 per cent respectively (Rodriguez et al 2015a). Marshall et al (2014) found a fraction of 29 ± 9 per cent debris disks associated with planetary systems, combining the DUNES and DEBRIS samples. Such high proportions of stars hosting debris disks indicate that belts of small bodies (asteroids, comets) are common outcomes of the planet formation process, and survive over long timescales.…”

Section: Introductionmentioning

confidence: 91%

“…Moreover, Beichman et al (2005) found a correlation between the presence of debris disks and the presence of planets. However, it is still a subject of debate (Kóspál et al 2009;Maldonado et al 2015;Marshall et al 2014). In any case, for spatially-resolved disks, their wide extension and the presence of structures indicates that planetesimals and probably even planets are present and perturb the disk (Backman & Paresce 1993;Ertel et al 2012;Schneider et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Polarization of stars with debris discs: comparing observations with models

Vandeportal

Bastien

Simon

et al. 2018

Monthly Notices of the Royal Astronomical Society

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The Herschel Space telescope carried out an unprecedented survey of nearby stars for debris disks. The dust present in these debris disks scatters and polarizes stellar light in the visible part of the spectrum. We explore what can be learned with aperture polarimetry and detailed radiative transfer modelling about stellar systems with debris disks. We present a polarimetric survey, with measurements from the literature, of candidate stars observed by DEBRIS and DUNES Herschel surveys. We perform a statistical analysis of the polarimetric data with the detection of far-infrared excess by Herschel and S pitzer with a sample of 223 stars. Monte Carlo simulations were performed to determine the effects of various model parameters on the polarization level and find the mass required for detection with current instruments. Eighteen stars were detected with a polarization 0.01 ≤ P 0.1 per cent and ≥ 3σ P , but only two of them have a debris disk. No statistically significant difference is found between the different groups of stars, with, without, and unknown status for far-infrared excess, and presence of polarization. The simulations show that the integrated polarization is rather small, usually < 0.01 per cent for typical masses detected by their far-infrared excess for hot and most warm disks. Masses observed in cold disks can produce polarization levels above 0.01 per cent since there is usually more dust in them than in closer disks. We list five factors which can explain the observed low-polarization detection rate. Observations with high-precision polarimeters should lead to additional constraints on models of unresolved debris disks.

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“…In this work, we provide the first description and characterization of the coding and expression of two different chaperone Hfq paralogs in Piscirickettsia salmonis . This Gram‐negative bacterium is a facultative intracellular pathogen and is the aetiological agent of Piscirickettsiosis, the most important bacterial disease that affecting the Chilean salmon industry (Marshall, Gómez, & Klose, ; Tobar et al., ). Although the complete genome sequences of different P. salmonis isolates were recently reported (Bohle et al., ; Eppinger et al., ; Pulgar et al., ; Yañez et al., ), relevant aspects, such as metabolism, virulence and life cycle, remain poorly understood.…”

Section: Introductionmentioning

confidence: 99%

Identification and characterization of two variants of the Hfq‐sRNA‐chaperone in the fish pathogen Piscirickettsia salmonis

Marshall

Flores-Herrera

Henríquez

et al. 2017

Journal of Fish Diseases

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Small RNA and chaperone proteins form synergistic duos that play pivotal roles in controlling gene expression in bacteria. This is the case for Hfq, a highly pleiotropic pretranslational modulator of general protein expression, which responds to harsh environmental conditions and influences fitness and virulence in a wide range of pathogenic Enterobacteria. Given this relevancy, we evaluated the presence and potential role of Hfq in the fish pathogen Piscirickettsia salmonis, a Gram-negative bacterium that threatens the sustainability of Chilean salmon production. Using bioinformatics tools were identified and characterized two variants of Hfq, which share the consensus RNA-binding domains and the active sites described functional Hfq other bacteria. Additionally, we demonstrated that hfq-1 and hfq-2 were transcriptionally active when growing in cell-free media and in infected susceptible fish cell line. Expression of both genes differed under different growth conditions and under stress, suggesting that their roles might be independent and different, depending on the bacterial physiological status. In conclusion, we demonstrate the existence of two different and functional ORF coding for the hfq marker in marine bacteria and a preliminary analysis indicating that these two novel proteins might have relevant roles in the biology and pathogenic potential of P. salmonis.

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The Genus Piscirickettsia

Cited by 10 publications

References 41 publications

SONS: The JCMT legacy survey of debris discs in the submillimetre

SONS: The JCMT legacy survey of debris discs in the submillimetre

Polarization of stars with debris discs: comparing observations with models

Identification and characterization of two variants of the Hfq‐sRNA‐chaperone in the fish pathogen Piscirickettsia salmonis

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