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61.
Alba Nicolas‐Boluda Zhijie Yang Illia Dobryden Florent Carn Naomi Winckelmans Christine Pchoux Pierre Bonville Sara Bals Per Martin Claesson Florence Gazeau Marie Paule Pileni 《Advanced functional materials》2020,30(40)
Control of interactions between nanomaterials and cells remains a biomedical challenge. A strategy is proposed to modulate the intralysosomal distribution of nanoparticles through the design of 3D suprastructures built by hydrophilic nanocrystals (NCs) coated with alkyl chains. The intracellular fate of two water‐dispersible architectures of self‐assembled hydrophobic magnetic NCs: hollow deformable shells (colloidosomes) or solid fcc particles (supraballs) is compared. These two self‐assemblies display increased cellular uptake by tumor cells compared to dispersions of the water‐soluble NC building blocks. Moreover, the self‐assembly structures increase the NCs density in lysosomes and close to the lysosome membrane. Importantly, the structural organization of NCs in colloidosomes and supraballs are maintained in lysosomes up to 8 days after internalization, whereas initially dispersed hydrophilic NCs are randomly aggregated. Supraballs and colloidosomes are differently sensed by cells due to their different architectures and mechanical properties. Flexible and soft colloidosomes deform and spread along the biological membranes. In contrast, the more rigid supraballs remain spherical. By subjecting the internalized suprastructures to a magnetic field, they both align and form long chains. Overall, it is highlighted that the mechanical and topological properties of the self‐assemblies direct their intracellular fate allowing the control intralysosomal density, ordering, and localization of NCs. 相似文献
62.
Etya Amsalem Mario Padilla Paul M. Schreiber Naomi S. Altman Abraham Hefetz Christina M. Grozinger 《Journal of chemical ecology》2017,43(6):563-572
Reproduction in social insect societies reflects a delicate balance between cooperation and conflict over offspring production, and worker reproduction is widespread even in species showing strong reproductive skew in favor of the queen. To navigate these conflicts, workers are predicted to develop the means to estimate the queen’s fecundity - potentially through behavioral and/or chemical cues - and to adjust their reproduction to maximize their fitness. Here, we introduced bumble bee, Bombus impatiens, workers to queens of different mating and reproductive status and examined worker reproduction and expression levels of two genes which were previously shown to be sensitive to the presence of the queen, vitellogenin and Krüppel-homolog 1. We further explored whether the queen’s chemical secretion alone is sufficient to regulate worker reproduction, aggression and gene expression. We found that worker ovary activation was inhibited only in the presence of egg-laying queens, regardless of their mating status. Workers reared in the presence of newly-mated queens showed intermediate vitellogenin expression levels relative to workers reared with mated egg-laying and virgin queens. However, none of the whole-body chemical extracts of any of the queen treatment groups affected ovary activation, aggressive behavior, or gene expression in workers. Our findings indicate that only the presence of a freely-behaving, egg-laying queen can fully inhibit worker reproduction. It remains to be determined if workers detect differences in queen mating status and fecundity through differences in the queens’ behavior alone or through the queen’s behavior in concert with fertility signals. 相似文献
63.
Kuki KN Oliva MA Pereira EG Costa AC Cambraia J 《The Science of the total environment》2008,403(1-3):207-214
Particulate matter is a natural occurrence in the environment, but some industries, such as the iron ore sector, can raise the total amount of particles in the atmosphere. This industry is primarily a source of iron and sulfur dioxide particulates. The effects of the pollutants from the iron ore industries on representatives of restinga vegetation in a Brazilian coastal ecosystem were investigated using physiological and biochemical measures. Two species, Schinus terebinthifolius and Sophora tomentosa, were exposed to simulated deposition of acid mist and iron ore particulate matter in acrylic chambers in a greenhouse. Parameters such as gas exchange, fluorescence emission, chlorophyll content, total iron content, antioxidant enzyme activity and malondialdehyde content were assessed in order to evaluate the responses of the two species. Neither treatment was capable of inducing oxidative stress in S. terebinthifolius. Nevertheless, the deposition of iron ore particulates on this species increased chlorophyll content, the maximum quantum efficiency of photosystem II and the electron transport rate, while iron content was unaltered. On the other hand, S. tomentosa showed a greater sensitivity to the treatments. Plants of S. tomentosa that were exposed to acid mist had a decrease in photosynthesis, while the deposition of iron particulate matter led to an increase in iron content and membrane permeability of the leaves. The activities of antioxidant enzymes, such as catalases and superoxide dismutase, were enhanced by both treatments. The results suggested that the two restinga species use different strategies to overcome the stressful conditions created by the deposition of particulate matter, either solid or wet. It seems that while S. terebinthifolius avoided stress, S. tomentosa used antioxidant enzyme systems to partially neutralize oxidative stress. The findings also point to the potential use of S. tomentosa as a biomarker species under field conditions. 相似文献
64.
Taylor Shelley E.; Burklund Lisa J.; Eisenberger Naomi I.; Lehman Barbara J.; Hilmert Clayton J.; Lieberman Matthew D. 《Canadian Metallurgical Quarterly》2008,95(1):197
Psychosocial resources have been tied to lower psychological and biological responses to stress. The present research replicated this relationship and extended it by examining how differences in dispositional reactivity of certain neural structures may underlie this relationship. Two hypotheses were examined: (a) psychosocial resources are tied to decreased sensitivity to threat and/or (b) psychosocial resources are associated with enhanced prefrontal inhibition of threat responses during threat regulation. Results indicated that participants with greater psychosocial resources exhibited significantly less cortisol reactivity following a stress task, as predicted. Analyses using functional magnetic resonance imaging revealed that psychosocial resources were associated with greater right ventrolateral prefrontal cortex and less amygdala activity during a threat regulation task but were not associated with less amygdala activity during a threat sensitivity task. Mediational analyses suggest that the relation of psychosocial resources to low cortisol reactivity was mediated by lower amygdala activity during threat regulation. Results suggest that psychosocial resources are associated with lower cortisol responses to stress by means of enhanced inhibition of threat responses during threat regulation, rather than by decreased sensitivity to threat. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
65.
Objective
To accelerate super-selective arterial spin labeling (ASL) angiography by using a single control condition denoted as cycled super-selective arterial spin labeling.Materials and methods
A single non-selective control image is acquired that is shared by selective label images. Artery-selective imaging is possible by geometrically changing the position of the labeling focus to more than one artery of interest during measurement. The presented approach is compared to conventional super-selective imaging in terms of its labeling efficiency inside and outside the labeling focus using numerical simulations and in vivo measurements. Additionally, the signal-to-noise ratios of the images are compared to non-selective ASL angiography and analyzed using a two-way ANOVA test and calculating the Pearson’s correlation coefficients.Results
The results indicate that the labeling efficiency is not reduced within the labeled artery, but can increase as a function of distance to the artery of interest when compared to conventional super-selective ASL. In the final images, no statistically significant difference of image quality can be observed while the acquisition duration could be reduced when the major brain feeding arteries are being tagged.Conclusion
Using super-selective arterial spin labeling, a single non-selective control acquisition suffices for reconstructing selective angiograms of the cerebral vasculature, thereby accelerating image acquisition of the major intracranial arteries without notable loss of information.66.
67.
Lubick N 《Environmental science & technology》2007,41(23):7954-7955
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