2,564 research outputs found
Genomic analysis of two novel bacteriophages infecting Acinetobacter beijerinckii and halotolerans species
Bacteriophages are the most diverse genetic entities on Earth. In this study, two novel bacteriophages, nACB1 (Podoviridae morphotype) and nACB2 (Myoviridae morphotype), which infect Acinetobacter beijerinckii and Acinetobacter halotolerans, respectively, were isolated from sewage samples. The genome sequences of nACB1 and nACB2 revealed that their genome sizes were 80,310 bp and 136,560 bp, respectively. Comparative analysis showed that both genomes are novel members of the Schitoviridae and the Ackermannviridae families, sharing ≤ 40% overall nucleotide identities with any other phages. Interestingly, among other genetic features, nACB1 encoded a very large RNA polymerase, while nACB2 displayed three putative depolymerases (two capsular depolymerases and one capsular esterase) encoded in tandem. This is the first report of phages infecting A. halotolerans and beijerinckii human pathogenic species. The findings regarding these two phages will allow us to further explore phage—Acinetobacter interactions and the genetic evolution for this group of phages.This study was supported by the Portuguese Foundation for Science and Technology (FCT)
under the scope of the strategic funding of UIDB/04469/2020 unit, and by LABBELS—Associate
Laboratory in Biotechnology, Bioengineering and Microelectromechnical Systems, LA/P/0029/2020.info:eu-repo/semantics/publishedVersio
Anxiety and burnout in young athletes: The mediating role of cognitive appraisal
This study tested the relationship between trait anxiety, cognitive appraisal, and athletes’ burnout proposing two hypotheses: (a) there is a direct relationship between athletes’ trait anxiety and cognitive appraisal and burnout; and (b) cognitive appraisal mediates the relationship between trait anxiety and burnout and this mediation occurs despite the competitive level and sport records of athletes. The study included 673 young athletes and provided measures of trait anxiety, cognitive appraisal, and burnout. Structural equation modelling indicated that cognitive appraisal mediates the relationship between trait anxiety and burnout, confirming hypothesis 2, and this model provided better fit than the direct model of hypothesis 1. However, the mediation also indicated that the direct relationship between trait anxiety and burnout should be considered. The mediating model was invariant according to competitive levels and sport records. In conclusion, cognitive appraisal is an important variable in explaining athletes’ burnout.This study was conducted at Psychology Research Centre (UID/PSI/01662/2013), University of Minho, and supported by the Portuguese Foundation for Science and Technology, the Portuguese Ministry of Science, Technology and Higher Education through national funds and co-financed by FEDER through COMPETE2020 under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007653), and "Guimaraes, European City of Sport 2013".info:eu-repo/semantics/publishedVersio
Toward scalable biocatalytic conversion of 5-hydroxymethylfurfural by galactose oxidase using coordinated reaction and enzyme engineering
5-Hydroxymethylfurfural (HMF) can be transformed to a range of industrially useful derivatives, such as 2,5-diformylfuran (DFF), but the reactions needed for efficient industrial production are hindered by several issues. Here, the authors perform reaction and enzyme engineering resulting in a galactose oxidase variant with high activity towards HMF, improved oxygen binding and high productivity
Troubling meanings of family and competing moral imperatives in the family lives of young people with a parent who is at the end of life
This article draws on a narrative study of young people with a parent who is at the end of life to examine how family lives are troubled by life-limiting parental illness. Young people struggled to reconcile the physical and emotional absence of family members with meanings of ‘family’; the extent to which young people could rely on family to ‘be there’ in these troubling circumstances was of practical, emotional and moral significance. Our discussion is situated in the context of an English end of life care policy predicated on the ideal of a good death as one that takes place at home accompanied by family members. We explore how the shift away from family as a site for nurturing children towards family as a space to care for the dying is experienced by young people, and consider how these competing moral imperatives are negotiated through relational practices of care
Modeling malaria infection and immunity against variant surface antigens in PrÃncipe Island, West Africa
After remarkable success of vector control campaigns worldwide, concerns about loss of immunity against Plasmodium falciparum due to lack of exposure to the parasite are relevant since an increase of severe cases in less immune individuals is expected. We present a mathematical model to investigate the impact of reducing exposure to the parasite on the immune repertoire against P. falciparum erythrocyte membrane protein 1 (PfEMP1) variants. The model was parameterized with data from PrÃncipe Island, West Africa, and applied to simulate two alternative transmission scenarios: one where control measures are continued to eventually drive the system to elimination; and another where the effort is interrupted after 6 years of its initiation and the system returns to the initial transmission potential. Population dynamics of parasite prevalence predict that in a few years infection levels return to the pre-control values, while the re-acquisition of the immune repertoire against PfEMP1 is slower, creating a window for increased severity. The model illustrates the consequences of loss of immune repertoire against PfEMP1 in a given setting and can be applied to other regions where similar data may be available
A Sawtooth-like Timeline for the First Billion Year of Lunar Bombardment
We revisit the early evolution of the Moon's bombardment. Our work combines
modeling (based on plausible projectile sources and their dynamical decay
rates) with constraints from the lunar crater record, radiometric ages of the
youngest lunar basins, and the abundance of highly siderophile elements in the
lunar crust and mantle. We deduce that the evolution of the impact flux did not
decline exponentially over the first billion years of lunar history, but also
there was no prominent and "narrow" impact spike some 3.9 Gy ago, unlike that
typically envisioned in the lunar cataclysm scenario. Instead, we show the
timeline of the lunar bombardment has a sawtooth-like profile, with an uptick
in the impact flux near 4.1 Gy ago. The impact flux at the beginning of this
weaker cataclysm was 5-10 times higher than the immediately preceding period.
The Nectaris basin should have been one of the first basins formed at the
sawtooth. We predict the bombardment rate since about 4.1Gy ago declined slowly
and adhered relatively close to classic crater chronology models (Neukum and
Ivanov (1994)). Overall we expect that the sawtooth event accounted for about
1/4 of the total bombardment suffered by the Moon since its formation.
Consequently, considering that about 12-14 basins formed during the sawtooth
event, we expect that the net number of basins formed on the Moon was about
45-50. From our expected bombardment timeline, we derived a new and improved
lunar chronology suitable for use on Pre-Nectarian surface units. According to
this chronology, a significant portion of the oldest lunar cratered terrains
has an age of 4.38-4.42 Gyr. Moreover, the largest lunar basin, South Pole
Aitken, is older than 4.3Gy, and therefore was not produced during the lunar
cataclysm.Comment: In press in EPS
A near-infrared interferometric survey of debris disk stars. I. Probing the hot dust content around epsilon Eridani and tau Ceti with CHARA/FLUOR
We probed the first 3AU around tau Ceti and epsilon Eridani with the CHARA
array (Mt Wilson, USA) in order to gauge the 2micron excess flux emanating from
possible hot dust grains in the debris disks and to also resolve the stellar
photospheres. High precision visibility amplitude measurements were performed
with the FLUOR single mode fiber instrument and telescope pairs on baselines
ranging from 22 to 241m of projected length. The short baseline observations
allow us to disentangle the contribution of an extended structure from the
photospheric emission, while the long baselines constrain the stellar diameter.
We have detected a resolved emission around tau Cet, corresponding to a
spatially integrated, fractional excess flux of 0.98 +/- 0.21 x 10^{-2} with
respect to the photospheric flux in the K'-band. Around eps Eri, our
measurements can exclude a fractional excess of greater than 0.6x10^{-2}
(3sigma). We interpret the photometric excess around tau Cet as a possible
signature of hot grains in the inner debris disk and demonstrate that a faint,
physical or background, companion can be safely excluded. In addition, we
measured both stellar angular diameters with an unprecedented accuracy:
Theta_LD(tau Cet)= 2.015 +/- 0.011 mas and Theta_LD(eps Eri)=2.126 +/- 0.014
mas.Comment: 8 pages, 5 figures, to appear in Astronomy and Astrophysic
Circumstellar material in the Vega inner system revealed by CHARA/FLUOR
Only a handful of debris disks have been imaged up to now. Due to the need
for high dynamic range and high angular resolution, very little is known about
the inner planetary region, where small amounts of warm dust are expected to be
found. We investigate the close neighbourhood of Vega with the help of infrared
stellar interferometry and estimate the integrated K-band flux originating from
the central 8 AU of the debris disk. We performed precise visibility
measurements at both short (~30 m) and long (~150 m) baselines with the FLUOR
beam-combiner installed at the CHARA Array (Mt Wilson, California) in order to
separately resolve the emissions from the extended debris disk (short
baselines) and from the stellar photosphere (long baselines). After revising
Vega's K-band angular diameter (3.202+/-0.005 mas), we show that a significant
deficit in squared visibility (1.88+/-0.34%) is detected at short baselines
with respect to the best-fit uniform disk stellar model. This deficit can be
either attributed to the presence of a low-mass stellar companion around Vega,
or as the signature of the thermal and scattered emissions from the debris
disk. We show that the presence of a close companion is highly unlikely, as
well as other possible perturbations (stellar morphology, calibration), and
deduce that we have most probably detected the presence of dust in the close
neighbourhood of Vega. The resulting flux ratio between the stellar photosphere
and the debris disk amounts to 1.29+/-0.19% within the FLUOR field-of-view
(~7.8 AU). Finally, we complement our K-band study with archival photometric
and interferometric data in order to evaluate the main physical properties of
the inner dust disk. The inferred properties suggest that the Vega system could
be currently undergoing major dynamical perturbations.Comment: A&A, accepted -- Press release available at
http://www2.cnrs.fr/presse/communique/848.ht
The use of gamification in the teaching of disease epidemics and pandemics.
With the launch of the teaching excellence framework, teaching in higher education (HE) is under greater scrutiny than ever before. Didactic lecture delivery is still a core element of many HE programmes but there is now a greater expectation for academics to incorporate alternative approaches into their practice to increase student engagement. These approaches may include a large array of techniques from group activities, problem-based learning, practical experience and mock scenarios to newly emerging approaches such as flipped learning practices and the use of gamification. These participatory forms of learning encourage students to become more absorbed within a topic that may otherwise be seen as rather ‘dry’ and reduce students engagement with, and therefore retention of, material. Here we use participatory-based teaching approaches in microbiology as an example to illustrate to University undergraduate students the potentially devastating effects that a disease can have on a population. The ‘threat’ that diseases may pose and the manner in which they may spread and/or evolve can be challenging to communicate, especially in relation to the timescales associated with these factors in the case of an epidemic or pandemic.N
The effects of symmetry on the dynamics of antigenic variation
In the studies of dynamics of pathogens and their interactions with a host
immune system, an important role is played by the structure of antigenic
variants associated with a pathogen. Using the example of a model of antigenic
variation in malaria, we show how many of the observed dynamical regimes can be
explained in terms of the symmetry of interactions between different antigenic
variants. The results of this analysis are quite generic, and have wider
implications for understanding the dynamics of immune escape of other
parasites, as well as for the dynamics of multi-strain diseases.Comment: 21 pages, 4 figures; J. Math. Biol. (2012), Online Firs
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