1,557 research outputs found
Functional profiles of orphan membrane transporters in the life cycle of the malaria parasite
Assigning function to orphan membrane transport proteins and prioritizing candidates for detailed biochemical characterization remain fundamental challenges and are particularly important for medically relevant pathogens, such as malaria parasites. Here we present a comprehensive genetic analysis of 35 orphan transport proteins of Plasmodium berghei during its life cycle in mice and Anopheles mosquitoes. Six genes, including four candidate aminophospholipid transporters, are refractory to gene deletion, indicative of essential functions. We generate and phenotypically characterize 29 mutant strains with deletions of individual transporter genes. Whereas seven genes appear to be dispensable under the experimental conditions tested, deletion of any of the 22 other genes leads to specific defects in life cycle progression in vivo and/or host transition. Our study provides growing support for a potential link between heavy metal homeostasis and host switching and reveals potential targets for rational design of new intervention strategies against malaria
Copper-transporting ATPase is important for malaria parasite fertility
Homeostasis of the trace element copper is essential to all eukaryotic life. Copper serves as a cofactor in metalloenzymes and catalyses electron transfer reactions as well as the generation of potentially toxic reactive oxygen species. Here, we describe the functional characterization of an evolutionarily highly conserved, predicted copper-transporting P-type ATPase (CuTP) in the murine malaria model parasite Plasmodium berghei. Live imaging of a parasite line expressing a fluorescently tagged CuTP demonstrated that CuTP is predominantly located in vesicular bodies of the parasite. A P. berghei loss-of-function mutant line was readily obtained and showed no apparent defect in in vivo blood stage growth. Parasite transmission through the mosquito vector was severely affected, but not entirely abolished. We show that male and female gametocytes are abundant in cutp− parasites, but activation of male microgametes and exflagellation were strongly impaired. This specific defect could be mimicked by addition of the copper chelator neocuproine to wild-type gametocytes. A cross-fertilization assay demonstrated that female fertility was also severely abrogated. In conclusion, we provide experimental genetic and pharmacological evidence that a healthy copper homeostasis is critical to malaria parasite fertility of both genders of gametocyte and, hence, to transmission to the mosquito vector
lassopack: Model selection and prediction with regularized regression in Stata
This article introduces lassopack, a suite of programs for regularized
regression in Stata. lassopack implements lasso, square-root lasso, elastic
net, ridge regression, adaptive lasso and post-estimation OLS. The methods are
suitable for the high-dimensional setting where the number of predictors
may be large and possibly greater than the number of observations, . We
offer three different approaches for selecting the penalization (`tuning')
parameters: information criteria (implemented in lasso2), -fold
cross-validation and -step ahead rolling cross-validation for cross-section,
panel and time-series data (cvlasso), and theory-driven (`rigorous')
penalization for the lasso and square-root lasso for cross-section and panel
data (rlasso). We discuss the theoretical framework and practical
considerations for each approach. We also present Monte Carlo results to
compare the performance of the penalization approaches.Comment: 52 pages, 6 figures, 6 tables; submitted to Stata Journal; for more
information see https://statalasso.github.io
How do Cross-View and Cross-Modal Alignment Affect Representations in Contrastive Learning?
Various state-of-the-art self-supervised visual representation learning
approaches take advantage of data from multiple sensors by aligning the feature
representations across views and/or modalities. In this work, we investigate
how aligning representations affects the visual features obtained from
cross-view and cross-modal contrastive learning on images and point clouds. On
five real-world datasets and on five tasks, we train and evaluate 108 models
based on four pretraining variations. We find that cross-modal representation
alignment discards complementary visual information, such as color and texture,
and instead emphasizes redundant depth cues. The depth cues obtained from
pretraining improve downstream depth prediction performance. Also overall,
cross-modal alignment leads to more robust encoders than pre-training by
cross-view alignment, especially on depth prediction, instance segmentation,
and object detection
UniBEV: Multi-modal 3D Object Detection with Uniform BEV Encoders for Robustness against Missing Sensor Modalities
Multi-sensor object detection is an active research topic in automated
driving, but the robustness of such detection models against missing sensor
input (modality missing), e.g., due to a sudden sensor failure, is a critical
problem which remains under-studied. In this work, we propose UniBEV, an
end-to-end multi-modal 3D object detection framework designed for robustness
against missing modalities: UniBEV can operate on LiDAR plus camera input, but
also on LiDAR-only or camera-only input without retraining. To facilitate its
detector head to handle different input combinations, UniBEV aims to create
well-aligned Bird's Eye View (BEV) feature maps from each available modality.
Unlike prior BEV-based multi-modal detection methods, all sensor modalities
follow a uniform approach to resample features from the native sensor
coordinate systems to the BEV features. We furthermore investigate the
robustness of various fusion strategies w.r.t. missing modalities: the commonly
used feature concatenation, but also channel-wise averaging, and a
generalization to weighted averaging termed Channel Normalized Weights. To
validate its effectiveness, we compare UniBEV to state-of-the-art BEVFusion and
MetaBEV on nuScenes over all sensor input combinations. In this setting, UniBEV
achieves mAP on average over all input combinations, significantly
improving over the baselines ( mAP on average for BEVFusion,
mAP on average for MetaBEV). An ablation study shows the robustness benefits of
fusing by weighted averaging over regular concatenation, and of sharing queries
between the BEV encoders of each modality. Our code will be released upon paper
acceptance.Comment: 6 pages, 5 figure
Charge Induced Dynamics of Water in a Graphene-Mica Slit Pore
We use atomic force microscopy to in situ investigate the dynamic behavior of confined water at the interface between graphene and mica. The graphene is either uncharged, negatively charged, or positively charged. At high humidity, a third water layer will intercalate between graphene and mica. When graphene is negatively charged, the interface fills faster with a complete three layer water film, compared to uncharged graphene. As charged positively, the third water layer dewets the interface, either by evaporation into the ambient or by the formation of three-dimensional droplets under the graphene, on top of the bilayer. Our experimental findings reveal novel phenomena of water at the nanoscale, which are interesting from a fundamental point of view and demonstrate the direct control over the wetting properties of the graphene/water interface
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