106 research outputs found
Type VI Secretion: Not Just for Pathogenesis Anymore
Type VI Secretion Systems (T6SS) have been studied primarily in the context of pathogenic bacterial-host interactions. Recent data suggest, however, that these versatile secretion systems may also function to promote commensal or mutualistic relationships between bacteria and eukaryotes, or to mediate cooperative or competitive interactions between bacteria
Recommended from our members
Self-assembly, nematic phase formation and organocatalytic behaviour of a proline-functionalized lipopeptide
The self-assembly of the amphiphilic lipopeptide PAEPKI-C16 (P = proline, A = alanine, E = glutamic acid, K = lysine, I = isoleucine, C16 = hexadecyl) was investigated using a combination of spectroscopic, microscopic and scattering methods and compared to C16-IKPEAP with the same (reversed) peptide sequence and the alkyl chain positioned N-terminally and which lacks a free N-terminal proline residue. The catalytic activity of these peptides were then compared using a model aldol reaction system. For PAEPKI-C16, Cryo-TEM images showed the formation of micrometer length fibers, which by Small-angle X-ray scattering (SAXS) were found to have a radius of 2.5 - 2.6 nm. Spectroscopic analysis shows these fibers are built from -sheets. This behaviour is in complete contrast to that of C16-IKPEAP which forms spherical micelles with peptides in a disordered conformation [Hutchinson, J. A. et al. J. Phys. Chem. B 2019, 123, 613]. For PAEPKI-C16, the spontaneous alignment of fibers was observed upon increasing pH, which was accompanied by observed birefringence and anisotropy of SAXS patterns. This shows the formation of a nematic liquids and unprecedented nematic hydrogel formation was also observed these lipopeptides at sufficiently high concentrations. SAXS shows retention of an ultrafine (1.7 nm core radius) fibrillar network within the hydrogel. PAEPKI-C16 with free N-terminal proline shows enhanced anti:syn diastereoselectivity and better conversion compared to C16-IKPEAP. The cytotoxicity of PAEPKI-C16 was also lower than C16-IKPEAP for both fibroblast and cancer cell lines. These results highlight the sensitivity of lipopeptide properties to the presence of a free proline residue. The spontaneous nematic phase formation by PAEPKI-C16 points to the highly anisotropy of its ultrafine fibrillar structure and the formation of such a phase at low concentration in aqueous solution may be valuable for future applications
Predicting habitat suitability for Ixodes ricinus and Ixodes persulcatus ticks in Finland
Background Ticks are responsible for transmitting several notable pathogens worldwide. Finland lies in a zone where two human-biting tick species co-occur: Ixodesricinus and Ixodespersulcatus. Tick densities have increased in boreal regions worldwide during past decades, and tick-borne pathogens have been identified as one of the major threats to public health in the face of climate change. Methods We used species distribution modelling techniques to predict the distributions of I.ricinus and I.persulcatus, using aggregated historical data from 2014 to 2020 and new tick occurrence data from 2021. By aiming to fill the gaps in tick occurrence data, we created a new sampling strategy across Finland. We also screened for tick-borne encephalitis virus (TBEV) and Borrelia from the newly collected ticks. Climate, land use and vegetation data, and population densities of the tick hosts were used in various combinations on four data sets to estimate tick species' distributions across mainland Finland with a 1-km resolution. Results In the 2021 survey, 89 new locations were sampled of which 25 new presences and 63 absences were found for I.ricinus and one new presence and 88 absences for I.persulcatus. A total of 502 ticks were collected and analysed; no ticks were positive for TBEV, while 56 (47%) of the 120 pools, including adult, nymph, and larva pools, were positive for Borrelia (minimum infection rate 11.2%, respectively). Our prediction results demonstrate that two combined predictor data sets based on ensemble mean models yielded the highest predictive accuracy for both I.ricinus (AUC = 0.91, 0.94) and I.persulcatus (AUC = 0.93, 0.96). The suitable habitats for I.ricinus were determined by higher relative humidity, air temperature, precipitation sum, and middle-infrared reflectance levels and higher densities of white-tailed deer, European hare, and red fox. For I.persulcatus, locations with greater precipitation and air temperature and higher white-tailed deer, roe deer, and mountain hare densities were associated with higher occurrence probabilities. Suitable habitats for I.ricinus ranged from southern Finland up to Central Ostrobothnia and North Karelia, excluding areas in Ostrobothnia and Pirkanmaa. For I.persulcatus, suitable areas were located along the western coast from Ostrobothnia to southern Lapland, in North Karelia, North Savo, Kainuu, and areas in Pirkanmaa and Paijat-Hame. Conclusions This is the first study conducted in Finland that estimates potential tick species distributions using environmental and host data. Our results can be utilized in vector control strategies, as supporting material in recommendations issued by public health authorities, and as predictor data for modelling the risk for tick-borne diseases.Peer reviewe
MITS: the Multi-Imaging Transient Spectrograph for SOXS
The Son Of X-Shooter (SOXS) is a medium resolution spectrograph R~4500
proposed for the ESO 3.6 m NTT. We present the optical design of the UV-VIS arm
of SOXS which employs high efficiency ion-etched gratings used in first order
(m=1) as the main dispersers. The spectral band is split into four channels
which are directed to individual gratings, and imaged simultaneously by a
single three-element catadioptric camera. The expected throughput of our design
is >60% including contingency. The SOXS collaboration expects first light in
early 2021. This paper is one of several papers presented in these proceedings
describing the full SOXS instrument
Optical design of the SOXS spectrograph for ESO NTT
An overview of the optical design for the SOXS spectrograph is presented.
SOXS (Son Of X-Shooter) is the new wideband, medium resolution (R>4500)
spectrograph for the ESO 3.58m NTT telescope expected to start observations in
2021 at La Silla. The spectroscopic capabilities of SOXS are assured by two
different arms. The UV-VIS (350-850 nm) arm is based on a novel concept that
adopts the use of 4 ion-etched high efficiency transmission gratings. The NIR
(800- 2000 nm) arm adopts the '4C' design (Collimator Correction of Camera
Chromatism) successfully applied in X-Shooter. Other optical sub-systems are
the imaging Acquisition Camera, the Calibration Unit and a pre-slit Common
Path. We describe the optical design of the five sub-systems and report their
performance in terms of spectral format, throughput and optical quality. This
work is part of a series of contributions describing the SOXS design and
properties as it is about to face the Final Design Review.Comment: 9 pages, 9 figures, published in SPIE Proceedings 1070
The VIS detector system of SOXS
SOXS will be a unique spectroscopic facility for the ESO NTT telescope able
to cover the optical and NIR bands thanks to two different arms: the UV-VIS
(350-850 nm), and the NIR (800-1800 nm). In this article, we describe the
design of the visible camera cryostat and the architecture of the acquisition
system. The UV-VIS detector system is based on a e2v CCD 44-82, a custom
detector head coupled with the ESO continuous ow cryostats (CFC) cooling system
and the NGC CCD controller developed by ESO. This paper outlines the status of
the system and describes the design of the different parts that made up the
UV-VIS arm and is accompanied by a series of contributions describing the SOXS
design solutions.Comment: 9 pages, 13 figures, to be published in SPIE Proceedings 1070
The Acquisition Camera System for SOXS at NTT
SOXS (Son of X-Shooter) will be the new medium resolution (R4500 for a
1 arcsec slit), high-efficiency, wide band spectrograph for the ESO-NTT
telescope on La Silla. It will be able to cover simultaneously optical and NIR
bands (350-2000nm) using two different arms and a pre-slit Common Path feeding
system. SOXS will provide an unique facility to follow up any kind of transient
event with the best possible response time in addition to high efficiency and
availability. Furthermore, a Calibration Unit and an Acquisition Camera System
with all the necessary relay optics will be connected to the Common Path
sub-system. The Acquisition Camera, working in optical regime, will be
primarily focused on target acquisition and secondary guiding, but will also
provide an imaging mode for scientific photometry. In this work we give an
overview of the Acquisition Camera System for SOXS with all the different
functionalities. The optical and mechanical design of the system are also
presented together with the preliminary performances in terms of optical
quality, throughput, magnitude limits and photometric properties.Comment: 9 pages, 7 figures, SPIE conferenc
Maximizing the value of Solar System data through Planetary Spatial Data Infrastructures
Planetary spatial data returned by spacecraft, including images and
higher-order products such as mosaics, controlled basemaps, and digital
elevation models (DEMs), are of critical importance to NASA, its commercial
partners and other space agencies. Planetary spatial data are an essential
component of basic scientific research and sustained planetary exploration and
operations. The Planetary Data System (PDS) is performing the essential job of
archiving and serving these data, mostly in raw or calibrated form, with less
support for higher-order, more ready-to-use products. However, many planetary
spatial data remain not readily accessible to and/or usable by the general
science user because particular skills and tools are necessary to process and
interpret them from the raw initial state. There is a critical need for
planetary spatial data to be more accessible and usable to researchers and
stakeholders. A Planetary Spatial Data Infrastructure (PSDI) is a collection of
data, tools, standards, policies, and the people that use and engage with them.
A PSDI comprises an overarching support system for planetary spatial data.
PSDIs (1) establish effective plans for data acquisition; (2) create and make
available higher-order products; and (3) consider long-term planning for
correct data acquisition, processing and serving (including funding). We
recommend that Planetary Spatial Data Infrastructures be created for all bodies
and key regions in the Solar System. NASA, with guidance from the planetary
science community, should follow established data format standards to build
foundational and framework products and use those to build and apply PDSIs to
all bodies. Establishment of PSDIs is critical in the coming decade for several
locations under active or imminent exploration, and for all others for future
planning and current scientific analysis.Comment: 8 pages, 0 figures. White paper submitted to the Planetary Science
and Astrobiology Decadal Survey 2023-203
Effectiveness of antifungal treatments during chytridiomycosis epizootics in populations of an endangered frog
The recently-emerged amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) has had an unprecedented impact on global amphibian populations, and highlights the urgent need to develop effective mitigation strategies. We conducted in-situ antifungal treatment experiments in wild populations of the endangered mountain yellow-legged frog during or immediately after Bd-caused mass die-off events. The objective of treatments was to reduce Bd infection intensity (“load”) and in doing so alter frog-Bd dynamics and increase the probability of frog population persistence despite ongoing Bd infection. Experiments included treatment of early life stages (tadpoles and subadults) with the antifungal drug itraconazole, treatment of adults with itraconazole, and augmentation of the skin microbiome of subadults with Janthinobacterium lividum, a commensal bacterium with antifungal properties. All itraconazole treatments caused immediate reductions in Bd load, and produced longer-term effects that differed between life stages. In experiments focused on early life stages, Bd load was reduced in the 2 months immediately following treatment and was associated with increased survival of subadults. However, Bd load and frog survival returned to pre-treatment levels in less than 1 year, and treatment had no effect on population persistence. In adults, treatment reduced Bd load and increased frog survival over the entire 3-year post-treatment period, consistent with frogs having developed an effective adaptive immune response against Bd. Despite this protracted period of reduced impacts of Bd on adults, recruitment into the adult population was limited and the population eventually declined to near-extirpation. In the microbiome augmentation experiment, exposure of subadults to a solution of J. lividum increased concentrations of this potentially protective bacterium on frogs. However, concentrations declined to baseline levels within 1 month and did not have a protective effect against Bd infection. Collectively, these results indicate that our mitigation efforts were ineffective in causing long-term changes in frog-Bd dynamics and increasing population persistence, due largely to the inability of early life stages to mount an effective immune response against Bd. This results in repeated recruitment failure and a low probability of population persistence in the face of ongoing Bd infection
Predicting habitat suitability for Ixodesricinus and Ixodespersulcatus ticks in Finland
Background Ticks are responsible for transmitting several notable pathogens worldwide. Finland lies in a zone where two human-biting tick species co-occur: Ixodesricinus and Ixodespersulcatus. Tick densities have increased in boreal regions worldwide during past decades, and tick-borne pathogens have been identified as one of the major threats to public health in the face of climate change. Methods We used species distribution modelling techniques to predict the distributions of I.ricinus and I.persulcatus, using aggregated historical data from 2014 to 2020 and new tick occurrence data from 2021. By aiming to fill the gaps in tick occurrence data, we created a new sampling strategy across Finland. We also screened for tick-borne encephalitis virus (TBEV) and Borrelia from the newly collected ticks. Climate, land use and vegetation data, and population densities of the tick hosts were used in various combinations on four data sets to estimate tick species' distributions across mainland Finland with a 1-km resolution. Results In the 2021 survey, 89 new locations were sampled of which 25 new presences and 63 absences were found for I.ricinus and one new presence and 88 absences for I.persulcatus. A total of 502 ticks were collected and analysed; no ticks were positive for TBEV, while 56 (47%) of the 120 pools, including adult, nymph, and larva pools, were positive for Borrelia (minimum infection rate 11.2%, respectively). Our prediction results demonstrate that two combined predictor data sets based on ensemble mean models yielded the highest predictive accuracy for both I.ricinus (AUC = 0.91, 0.94) and I.persulcatus (AUC = 0.93, 0.96). The suitable habitats for I.ricinus were determined by higher relative humidity, air temperature, precipitation sum, and middle-infrared reflectance levels and higher densities of white-tailed deer, European hare, and red fox. For I.persulcatus, locations with greater precipitation and air temperature and higher white-tailed deer, roe deer, and mountain hare densities were associated with higher occurrence probabilities. Suitable habitats for I.ricinus ranged from southern Finland up to Central Ostrobothnia and North Karelia, excluding areas in Ostrobothnia and Pirkanmaa. For I.persulcatus, suitable areas were located along the western coast from Ostrobothnia to southern Lapland, in North Karelia, North Savo, Kainuu, and areas in Pirkanmaa and Paijat-Hame. Conclusions This is the first study conducted in Finland that estimates potential tick species distributions using environmental and host data. Our results can be utilized in vector control strategies, as supporting material in recommendations issued by public health authorities, and as predictor data for modelling the risk for tick-borne diseases.</p
- …