70 research outputs found
Elimination of a group II intron from a plastid gene causes a mutant phenotype
Group II introns are found in bacteria and cell organelles (plastids, mitochondria) and are thought to represent the evolutionary ancestors of spliceosomal introns. It is generally believed that group II introns are selfish genetic elements that do not have any function. Here, we have scrutinized this assumption by analyzing two group II introns that interrupt a plastid gene (ycf3) involved in photosystem assembly. Using stable transformation of the plastid genome, we have generated mutant plants that lack either intron 1 or intron 2 or both. Interestingly, the deletion of intron 1 caused a strong mutant phenotype. We show that the mutants are deficient in photosystem I and that this deficiency is directly related to impaired ycf3 function. We further show that, upon deletion of intron 1, the splicing of intron 2 is strongly inhibited. Our data demonstrate that (i) the loss of a group II intron is not necessarily phenotypically neutral and (ii) the splicing of one intron can depend on the presence of another
Blind test comparison on the wake behind a yawed wind turbine
This article summarizes the results of the Blind test 5
workshop, which was held in
Visby, Sweden, in May 2017. This study compares the numerical predictions of
the wake flow behind a model wind turbine operated in yaw to experimental
wind tunnel results. Prior to the workshop, research groups were invited to
predict the turbine performance and wake flow properties using computational
fluid dynamics (CFD) methods. For this purpose, the power, thrust, and yaw
moments for a 30° yawed model turbine, as well as the wake's mean and
turbulent streamwise and vertical flow components, were measured in the wind
tunnel at the Norwegian University of Science and Technology (NTNU). In order
to increase the complexity, a non-yawed downstream turbine was added in a
second test case, while a third test case challenged the modelers with a new
rotor and turbine geometry.Four participants submitted predictions using different flow solvers, three
of which were based on large eddy simulations (LES) while another one used an
improved delayed detached eddy simulation (IDDES) model. The performance of a
single yawed turbine was fairly well predicted by all simulations, both in
the first and third test cases. The scatter in the downstream turbine
performance predictions in the second test case, however, was found to be
significantly larger. The complex asymmetric shape of the mean streamwise and
vertical velocities was generally well predicted by all the simulations for
all test cases. The largest improvement with respect to previous blind tests
is the good prediction of the levels of TKE in the wake, even for the complex
case of yaw misalignment. These very promising results confirm the mature
development stage of LES/DES simulations for wind turbine wake modeling,
while competitive advantages might be obtained by faster computational
methods.</p
Cloaking nanoparticles with protein corona shield for targeted drug delivery
Targeted drug delivery using nanoparticles can minimize the side effects of conventional pharmaceutical agents and enhance their efficacy. However, translating nanoparticle-based agents into clinical applications still remains a challenge due to the difficulty in regulating interactions on the interfaces between nanoparticles and biological systems. Here, we present a targeting strategy for nanoparticles incorporated with a supramolecularly pre-coated recombinant fusion protein in which HER2-binding affibody combines with glutathione-S-transferase. Once thermodynamically stabilized in preferred orientations on the nanoparticles, the adsorbed fusion proteins as a corona minimize interactions with serum proteins to prevent the clearance of nanoparticles by macrophages, while ensuring systematic targeting functions in vitro and in vivo. This study provides insight into the use of the supramolecularly built protein corona shield as a targeting agent through regulating the interfaces between nanoparticles and biological systems
Sediment source fingerprinting: benchmarking recent outputs, remaining challenges and emerging themes
Abstract: Purpose: This review of sediment source fingerprinting assesses the current state-of-the-art, remaining challenges and emerging themes. It combines inputs from international scientists either with track records in the approach or with expertise relevant to progressing the science. Methods: Web of Science and Google Scholar were used to review published papers spanning the period 2013–2019, inclusive, to confirm publication trends in quantities of papers by study area country and the types of tracers used. The most recent (2018–2019, inclusive) papers were also benchmarked using a methodological decision-tree published in 2017. Scope: Areas requiring further research and international consensus on methodological detail are reviewed, and these comprise spatial variability in tracers and corresponding sampling implications for end-members, temporal variability in tracers and sampling implications for end-members and target sediment, tracer conservation and knowledge-based pre-selection, the physico-chemical basis for source discrimination and dissemination of fingerprinting results to stakeholders. Emerging themes are also discussed: novel tracers, concentration-dependence for biomarkers, combining sediment fingerprinting and age-dating, applications to sediment-bound pollutants, incorporation of supportive spatial information to augment discrimination and modelling, aeolian sediment source fingerprinting, integration with process-based models and development of open-access software tools for data processing. Conclusions: The popularity of sediment source fingerprinting continues on an upward trend globally, but with this growth comes issues surrounding lack of standardisation and procedural diversity. Nonetheless, the last 2 years have also evidenced growing uptake of critical requirements for robust applications and this review is intended to signpost investigators, both old and new, towards these benchmarks and remaining research challenges for, and emerging options for different applications of, the fingerprinting approach
Brief communication: On the influence of vertical wind shear on the combined power output of two model wind turbines in yaw
The effect of vertical wind shear on the total power output of two aligned
model wind turbines as a function of yaw misalignment of the upstream turbine
is studied experimentally. It is shown that asymmetries of the power output
of the downstream turbine and the combined power of both with respect to the
upstream turbine's yaw misalignment angle can be linked to the vertical wind
shear of the inflow
On the impact of non-Gaussian wind statistics on wind turbines – an experimental approach
The effect of intermittent and Gaussian inflow conditions on wind energy
converters is studied experimentally. Two different flow situations were
created in a wind tunnel using an active grid. Both flows exhibit nearly
equal mean velocity values and turbulence intensities but strongly differ in
their two point statistics, namely their distribution of velocity increments
on a variety of timescales, one being Gaussian distributed, and the other one
being strongly intermittent. A horizontal axis model wind turbine is exposed
to both flows, isolating the effect on the turbine of the differences not captured by mean
values and turbulence intensities. Thrust, torque and power
data were recorded and analyzed, showing that the model turbine does not
smooth out intermittency. Intermittent inflow is converted to similarly
intermittent turbine data on all scales considered, reaching down to
sub-rotor scales in space. This indicates that it is not correct to assume a
smoothing of intermittent wind speed increments below the size of the rotor
Autophagy supports color vision
Cones comprise only a small portion of the photoreceptors in mammalian retinas. However, cones are vital for color vision and visual perception, and their loss severely diminishes the quality of life for patients with retinal degenerative diseases. Cones function in bright light and have higher demand for energy than rods; yet, the mechanisms that support the energy requirements of cones are poorly understood. One such pathway that potentially could sustain cones under basal and stress conditions is macroautophagy. We addressed the role of macroautophagy in cones by examining how the genetic block of this pathway affects the structural integrity, survival, and function of these neurons. We found that macroautophagy was not detectable in cones under normal conditions but was readily observed following 24 h of fasting. Consistent with this, starvation induced phosphorylation of AMPK specifically in cones indicating cellular starvation. Inhibiting macroautophagy in cones by deleting the essential macroautophagy gene Atg5 led to reduced cone function following starvation suggesting that cones are sensitive to systemic changes in nutrients and activate macroautophagy to maintain their function. ATG5-deficiency rendered cones susceptible to light-induced damage and caused accumulation of damaged mitochondria in the inner segments, shortening of the outer segments, and degeneration of all cone types, revealing the importance of mitophagy in supporting cone metabolic needs. Our results demonstrate that macroautophagy supports the function and long-term survival of cones providing for their unique metabolic requirements and resistance to stress. Targeting macroautophagy has the potential to preserve cone-mediated vision during retinal degenerative diseases
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