9 research outputs found

    Biophysical Influence of Airborne Carbon Nanomaterials on Natural Pulmonary Surfactant

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    Inhalation of nanoparticles (NP), including lightweight airborne carbonaceous nanomaterials (CNM), poses a direct and systemic health threat to those who handle them. Inhaled NP penetrate deep pulmonary structures in which they first interact with the pulmonary surfactant (PS) lining at the alveolar air–water interface. In spite of many research efforts, there is a gap of knowledge between <i>in vitro</i> biophysical study and <i>in vivo</i> inhalation toxicology since all existing biophysical models handle NP–PS interactions in the liquid phase. This technical limitation, inherent in current <i>in vitro</i> methodologies, makes it impossible to simulate how airborne NP deposit at the PS film and interact with it. Existing <i>in vitro</i> NP–PS studies using liquid-suspended particles have been shown to artificially inflate the no-observed adverse effect level of NP exposure when compared to <i>in vivo</i> inhalation studies and international occupational exposure limits (OELs). Here, we developed an <i>in vitro</i> methodology called the constrained drop surfactometer (CDS) to quantitatively study PS inhibition by airborne CNM. We show that airborne multiwalled carbon nanotubes and graphene nanoplatelets induce a concentration-dependent PS inhibition under physiologically relevant conditions. The CNM aerosol concentrations controlled in the CDS are comparable to those defined in international OELs. Development of the CDS has the potential to advance our understanding of how submicron airborne nanomaterials affect the PS lining of the lung

    Fly courtship behavioral assay on a Helmholtz coil platform.

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    <p>(A-B) Diagrams of the Helmholtz coil platform. (C) Photograph of the Helmholtz coil platform, which is composed of two Helmholtz coil rings and a DC power supply. (D) The courtship chambers were placed in the middle of the Helmholtz coil platform, and a video camera on the top of the platform was used to record the fly courtship behaviors.</p

    Courtship indices under magnetic fields of various strengths.

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    <p>Courtship activities displayed by different <i>Drosophila</i> strains in various magnetic field strengths (10, 20, 40, 60, and 80 G) in full-spectrum light. The bars show the courtship indices of the three wild-type flies under different magnetic field intensities. (A) white-eyed Canton-S, (B) red-eyed Oregon-R, and (C) red-eyed Canton-S. Each value represents the mean + SEM (n ≥ 8; *<i>p</i> < 0.05, **<i>p</i> < 0.01, and ***<i>p</i> < 0.001; n.s., not statistically significant; ANOVA followed by Tukey’s tests).</p

    Activating large ventral lateral neurons (l-LNvs) and small ventral lateral neurons (s-LNvs) increases male courtship activity.

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    <p>(A) Activation of <i>cry-GAL4-</i>expressing neurons increased the male courtship index, whereas <i>cry-GAL80</i> suppressed this behavioral phenotype. Each value represents the mean + SEM (n ≥13; ***<i>p</i> < 0.001; n.s., not statistically significant; <i>t</i>-tests). Genotypes: (1) <i>w/Y; cry-GAL4/+; +/+</i>, (2) <i>w/Y; +/+; +/UAS-TrpA1</i>, (3) <i>w/Y; cry-GAL4/+; +/UAS-TrpA1</i>, (4) <i>w/Y; cry-GAL4/+; cry-GAL80/UAS-TrpA1</i>. (B) Activation of <i>pdf-GAL4-</i>expressing neurons increased the male courtship index. Each value represents the mean + SEM (n ≥ 8; ***<i>p</i> < 0.001; n.s., not statistically significant; <i>t</i>-tests). Genotypes: (1) <i>w/Y; pdf-GAL4/+; +/+</i>, (2) <i>w/Y; +/+; +/UAS-TrpA1</i>, (3) <i>w/Y; pdf-GAL4/+; +/UAS-TrpA1</i>.</p

    The increase in male courtship activity in a magnetic field is cryptochrome- (CRY-) and blue light-dependent.

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    <p>(A) Two CRY mutant flies did not show increased courtship indices in magnetic fields (20 G and 40 G) compared with the control (0 G). Each value represents the mean + SEM (n ≥ 9; n.s., not significant; ANOVA). Genotypes: (1) <i>w/Y; +/+; cry</i><sup><i>b</i></sup><i>/cry</i><sup><i>b</i></sup>, (2) <i>w/Y; +/+; cry</i><sup><i>m</i></sup><i>/cry</i><sup><i>m</i></sup>. (B) In white-eyed Canton-S male flies, the increase in courtship activity induced by the magnetic field was blue light-dependent. The bars show the courtship index values for naïve responses under full-spectrum light (left panel) and for light with wavelengths > 500 nm (right panel). Each value represents the mean + SEM (n ≥ 9; ***<i>p</i> < 0.001; n.s., not statistically significant; ANOVA followed by Tukey’s tests).</p

    Magnetoreception Regulates Male Courtship Activity in <i>Drosophila</i>

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    <div><p>The possible neurological and biophysical effects of magnetic fields on animals is an area of active study. Here, we report that courtship activity of male <i>Drosophila</i> increases in a magnetic field and that this effect is regulated by the blue light-dependent photoreceptor cryptochrome (CRY). Naïve male flies exhibited significantly increased courtship activities when they were exposed to a ≥ 20-Gauss static magnetic field, compared with their behavior in the natural environment (0 Gauss). CRY-deficient flies, <i>cry</i><sup><i>b</i></sup> and <i>cry</i><sup><i>m</i></sup>, did not show an increased courtship index in a magnetic field. RNAi-mediated knockdown of <i>cry</i> in <i>cry-GAL4</i>-positive neurons disrupted the increased male courtship activity in a magnetic field. Genetically expressing <i>cry</i> under the control of <i>cry-GAL4</i> in the CRY-deficient flies restored the increase in male courtship index that occurred in a magnetic field. Interestingly, artificially activating <i>cry-GAL4-</i>expressing neurons, which include large ventral lateral neurons and small ventral lateral neurons, via expression of thermosensitive cation channel <i>dTrpA1</i>, also increased the male courtship index. This enhancement was abolished by the addition of the <i>cry-GAL80</i> transgene. Our results highlight the phenomenon of increased male courtship activity caused by a magnetic field through CRY-dependent magnetic sensation in CRY expression neurons in <i>Drosophila</i>.</p></div

    Expression of cryptochrome (CRY) with <i>cry-GAL4</i> restores the increase in courtship activity in <i>cry</i> mutants in a magnetic field.

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    <p>(A) In the 20-G magnetic field environment, overexpression of the <i>cry</i> transgene in <i>cry-GAL4-</i>positive neurons restored the increase in courtship activity (indicated by courtship index) that was observed in flies with the <i>cry</i><sup><i>b</i></sup> background, compared with the 0-G control. Each value represents the mean + SEM (n ≥ 9; **<i>p</i> < 0.01; n.s., not statistically significant; <i>t</i>-tests). Genotypes: (1) <i>w/Y; cry-GAL4/+; cry</i><sup><i>b</i></sup><i>/cry</i><sup><i>b</i></sup>, (2) <i>w/Y; +/UAS-cry; cry</i><sup><i>b</i></sup><i>/cry</i><sup><i>b</i></sup>, (3) <i>w/Y; cry-GAL4/UAS-cry; cry</i><sup><i>b</i></sup><i>/cry</i><sup><i>b</i></sup>. (B) In the 20-G magnetic field, overexpression of the <i>cry</i> transgene in <i>cry-GAL4-</i>positive neurons restored the increase in courtship index that was observed in flies with the <i>cry</i><sup><i>m</i></sup> background compared with the 0-G control. Each value represents the mean + SEM (n ≥ 12; **<i>p</i> < 0.01; n.s., not statistically significant; <i>t</i>-tests). Genotypes: (1) <i>w/Y; cry-GAL4/+; cry</i><sup><i>m</i></sup><i>/cry</i><sup><i>m</i></sup>, (2) <i>w/Y; +/UAS-cry; cry</i><sup><i>m</i></sup><i>/cry</i><sup><i>m</i></sup>, (3) <i>w/Y; cry-GAL4/UAS-cry; cry</i><sup><i>m</i></sup><i>/cry</i><sup><i>m</i></sup>.</p

    Reactions of Persistent Carbenes with Hydrogen-Terminated Silicon Surfaces

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    Surface passivation has enabled the development of silicon-based solar cells and microelectronics. However, a number of emerging applications require a paradigm shift from passivation to functionalization, wherein surface functionality is installed proximal to the silicon surface. To address this need, we report here the use of persistent aminocarbenes to functionalize hydrogen-terminated silicon surfaces via Si–H insertion reactions. Through the use of model compounds (H–Si­(TMS)<sub>3</sub> and H–Si­(OTMS)<sub>3</sub>), nanoparticles (H–<b>SiNPs</b>), and planar Si(111) wafers (H–<b>Si­(111)</b>), we demonstrate that among different classes of persistent carbenes, the more electrophilic and nucleophilic ones, in particular, a cyclic (alkyl)­(amino)­carbene (CAAC) and an acyclic diaminocarbene (ADAC), are able to undergo insertion into Si–H bonds at the silicon surface, forming persistent C–Si linkages and simultaneously installing amine or aminal functionality in proximity to the surface. The CAAC (<b>6</b>) is particularly notable for its clean insertion reactivity under mild conditions that produces monolayers with 21 ± 3% coverage of Si(111) atop sites, commensurate with the expected maximum of ∼20%. Atomic force and transmission electron microscopy, nuclear magnetic resonance, X-ray photoelectron, and infrared spectroscopy, and time-of-flight secondary ion mass spectrometry provided evidence for the surface Si–H insertion process. Furthermore, computational studies shed light on the reaction energetics and indicated that CAAC <b>6</b> should be particularly effective at binding to silicon dihydride, trihydride, and coupled monohyride motifs, as well as oxidized surface sites. Our results pave the way for the further development of persistent carbenes as universal ligands for silicon and potentially other nonmetallic substrates
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