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1.
Insect Sci ; 2020 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-32365268

RESUMO

Rickettsia consists of some of the most prevalent symbionts of insects and often plays a significant role in the biology of its hosts. Recently, a maternally inherited Torix group Rickettsia, provisionally named as RiTBt, was recorded in a species of notorious pest whitefly, tentatively named as Asia II 1, from the Bemisia tabaci complex. The role of this Rickettsia in the biology of its host is unknown. Here we investigated the impact of RiTBt on the performance and virus transmission capacity of Asia II 1. RiTBt did not significantly affect the life history parameters of the whitefly when the host insect was reared on tobacco, tomato, and cotton, three host plants with relatively low, medium and high suitability to the whitefly. Intriguingly, RiTBt slightly enhanced whitefly transmission of cotton leaf curl Multan virus (CLCuMuV), a virus that is transmitted by the whitefly in the field and has caused extensive damage to cotton production. Specifically, compared with whiteflies without RiTBt, following a 48 h virus acquisition whiteflies with RiTBt had higher titer of virus and showed higher efficiency of virus transmission. A rickettsial secretory protein BtR242 was identified as a putative virus-binding protein, and was observed to interact with the coat protein of CLCuMuV in vitro. Viral infection of the whitefly downregulated gene transcript level of BtR242 gene. These observations indicate that RiTBt has limited impact on the biology of the Asia II 1 whitefly, and whether this symbiont has functions in the biology of other host whiteflies warrants future investigations. This article is protected by copyright. All rights reserved.

2.
Nano Lett ; 2020 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-32348146

RESUMO

Because of the toxicity of lead, searching for a lead-free halide perovskite semiconducting material with comparable optical and electronic properties is of great interest. Rare-earth-based halide perovskite represents a promising class of materials for this purpose. In this work, we demonstrate the solution-phase synthesis of single-crystalline CsEuCl3 nanocrystals with a uniform size distribution centered around 15 nm. The CsEuCl3 nanocrystals have photoluminescence emission centered at 435 nm, with a full width at half-maximum of 19 nm. Furthermore, CsEuCl3 nanocrystals can be embedded in a polymer matrix that provides enhanced stability under continuous laser irradiation. Lead-free rare-earth cesium europium halide perovskite nanocrystals represent a promising candidate to replace lead halide perovskites.

3.
Environ Microbiol ; 22(4): 1207-1221, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31997547

RESUMO

The bacterium Rickettsia is found widely in phytophagous insects and often exerts profound effects on the phenotype and fitness of its hosts. Here, we decrypt a new, independent, phylogenetically ancient Torix Rickettsia endosymbiont found constantly in a laboratory line of an economically important insect Asia II 7, a putative species of the Bemisia tabaci whitefly complex (Hemiptera: Aleyrodidae), and occasionally in field whitefly populations. This new Rickettsia distributes throughout the body of its whitefly host. Genetically, compared to Rickettsia_bellii_MEAM1 found earlier in whiteflies, the new Rickettsia species has more gene families and pathways, which may be important factors in shaping specific symbiotic relationships. We propose the name 'Candidatus Rickettsia_Torix_Bemisia_tabaci (RiTBt)' for this new endosymbiont associated with whiteflies. Comparative genomic analyses indicate that RiTBi may be a relatively recent intruder in whiteflies given its low abundance in the field and relatively larger genome compared to Rickettsia_bellii_MEAM1.

4.
Proc Natl Acad Sci U S A ; 116(47): 23404-23409, 2019 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-31685626

RESUMO

Phase transitions in halide perovskites triggered by external stimuli generate significantly different material properties, providing a great opportunity for broad applications. Here, we demonstrate an In-based, charge-ordered (In+/In3+) inorganic halide perovskite with the composition of Cs2In(I)In(III)Cl6 in which a pressure-driven semiconductor-to-metal phase transition exists. The single crystals, synthesized via a solid-state reaction method, crystallize in a distorted perovskite structure with space group I4/m with a = 17.2604(12) Å, c = 11.0113(16) Å if both the strong reflections and superstructures are considered. The supercell was further confirmed by rotation electron diffraction measurement. The pressure-induced semiconductor-to-metal phase transition was demonstrated by high-pressure Raman and absorbance spectroscopies and was consistent with theoretical modeling. This type of charge-ordered inorganic halide perovskite with a pressure-induced semiconductor-to-metal phase transition may inspire a range of potential applications.

5.
Mitochondrial DNA B Resour ; 4(2): 2765-2766, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31709305

RESUMO

A novel complete mitochondrial genome (mitogenome) of whitefly species, collected from Litchi chinensis at Fujian province of China (hereafter whitefly_Litchi chinensis _China) (GenBank accession number: MH999477), was described in this study. The mitogenome of whitefly_Litchi chinensis _China is 15,360 bp in length and contains 13 protein-coding genes, 21 transfer RNAs, 2 ribosomal RNAs and a non-coding AT-rich region (D-loop). The arrangement of mitochondrial genes of whitefly_Litchi chinensis_China are identical with Aleurochiton aceris, but remarkably different from the mitogenomes of the other whitefly genus. Most protein-coding genes (PCGs) start with ATN, except for nad2, cox2 and atp6 genes starting with TTG, GTG, and TTG, respectively; 10 of the 13 PCGs use the typical stop codon TAN, whereas cox1, and cox2 stop with a single T. Phylogenetic analyses based on 13 PCGs support the close relationship of the sample with Aleurochiton aceris, which would provide us further insights on the taxonomy and phylogeny of Aleyrodidae.

6.
J Am Chem Soc ; 141(33): 13028-13032, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31386354

RESUMO

The self-assembly of nanoparticles, a process whereby nanocrystal building blocks organize into even more ordered superstructures, is of great interest to nanoscience. Here we report the layer-by-layer assembly of 2D perovskite nanosheet building blocks. Structural analysis reveals that the assembled superlattice nanocrystals match with the layered Ruddlesden-Popper perovskite phase. This assembly proves reversible, as these superlattice nanocrystals can be reversibly exfoliated back into their building blocks via sonication. This study demonstrates the opportunity to further understand and exploit thermodynamics to increase order in a system of nanoparticles and to study emergent optical properties of a superlattice from 2D, weakly attracted, perovskite building blocks.

7.
Proc Natl Acad Sci U S A ; 116(26): 12648-12653, 2019 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-31189607

RESUMO

Ion exchange, as a postsynthetic transformation strategy, offers more flexibilities in controlling material compositions and structures beyond direct synthetic methodology. Observation of such transformation kinetics on the single-particle level with rich spatial and spectroscopic information has never been achieved. We report the quantitative imaging of anion exchange kinetics in individual single-crystalline halide perovskite nanoplates using confocal photoluminescence microscopy. We have systematically observed a symmetrical anion exchange pathway on the nanoplates with dependence on reaction time and plate thickness, which is governed by the crystal structure and the diffusion-limited transformation mechanism. Based on a reaction-diffusion model, the halide diffusion coefficient was estimated to be on the order of [Formula: see text] This diffusion-controlled mechanism leads to the formation of 2D perovskite heterostructures with spatially resolved coherent interface through the precisely controlled anion exchange reaction, offering a design protocol for tailoring functionalities of semiconductors at the nano-/microscale.

9.
Sci Rep ; 9(1): 6568, 2019 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-31024030

RESUMO

The 37 currently recognized Bemisia tabaci cryptic species are economically important species and contain both primary and secondary endosymbionts, but their diversity has never been mapped systematically across the group. To achieve this, PacBio sequencing of full-length bacterial 16S rRNA gene amplicons was carried out on 21 globally collected species in the B. tabaci complex, and two samples from B. afer were used here as outgroups. The microbial diversity was first explored across the major lineages of the whole group and 15 new putative bacterial sequences were observed. Extensive comparison of our results with previous endosymbiont diversity surveys which used PCR or multiplex 454 pyrosequencing platforms showed that the bacterial diversity was underestimated. To validate these new putative bacteria, one of them (Halomonas) was first confirmed to be present in MED B. tabaci using Hiseq2500 and FISH technologies. These results confirmed PacBio is a reliable and informative venue to reveal the bacterial diversity of insects. In addition, many new secondary endosymbiotic strains of Rickettsia and Arsenophonus were found, increasing the known diversity in these groups. For the previously described primary endosymbionts, one Portiera Operational Taxonomic Units (OTU) was shared by all B. tabaci species. The congruence of the B. tabaci-host and Portiera phylogenetic trees provides strong support for the hypothesis that primary endosymbionts co-speciated with their hosts. Likewise, a comparison of bacterial alpha diversities, Principal Coordinate Analysis, indistinct endosymbiotic communities harbored by different species and the co-divergence analyses suggest a lack of association between overall microbial diversity with cryptic species, further indicate that the secondary endosymbiont-mediated speciation is unlikely to have occurred in the B. tabaci species group.

10.
Virol J ; 16(1): 32, 2019 03 11.
Artigo em Inglês | MEDLINE | ID: mdl-30857562

RESUMO

BACKGROUND: Viruses in the genus Begomovirus (Family Geminiviridae) include many important economic plant viruses transmitted by whiteflies of the Bemisia tabaci species complex. In general, different begomoviruses may be acquired and transmitted by the same whitefly species with different efficiencies. For example, the species Mediterranean (MED) in this whitefly species complex transmits tomato yellow leaf curl virus (TYLCV) at a higher efficiency than papaya leaf curl China virus (PaLCuCNV). However, the proteomic responses of whitefly to the infection of different begomoviruses remain largely unknown. METHODS: We used iTRAQ-based proteomics coupled with RT-qPCR to investigate and compare responses of the MED whitefly to the infection of TYLCV and PaLCuCNV. RESULTS: Totally, 259, 395 and 74 differently expressed proteins (DEPs) were identified in the comparisons of TYLCV-infected vs. un-infected, PaLCuCNV-infected vs. un-infected, and TYLCV-infected vs. PaLCuCNV-infected whiteflies, respectively. These proteins appear associated with catabolic process, metabolic process, transport, defense response, cell cycle, and receptor. The comparisons of TYLCV-infected vs. un-infected and PaLCuCNV-infected vs. un-infected shared some similar DEPs, indicating possible involvement of laminin subunit alpha, dystroglycan, integrin alpha-PS2 and cuticle proteins in viral transport as well as the role of putative defense proteins 3 and PITH in anti-viral response. However, 20S proteasome subunits associated with regulation of virus degradation and accumulation were up-regulated in PaLCuCNV-infected but not in TYLCV-infected whiteflies, which may be related to the constraints of PaLCuCNV accumulation in MED. CONCLUSIONS: These findings provide valuable clues for unravelling the roles of some whitefly proteins in begomovirus transmission.


Assuntos
Begomovirus/genética , Hemípteros/virologia , Interações entre Hospedeiro e Microrganismos/genética , Proteômica/métodos , Viroses/transmissão , Animais , Doenças das Plantas/virologia , Vírus de Plantas/genética , Reação em Cadeia da Polimerase em Tempo Real
11.
Proc Natl Acad Sci U S A ; 115(47): 11929-11934, 2018 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-30397127

RESUMO

Facile ionic transport in lead halide perovskites plays a critical role in device performance. Understanding the microscopic origins of high ionic conductivities has been complicated by indirect measurements and sample microstructural heterogeneities. Here, we report the direct visualization of halide anion interdiffusion in CsPbCl3-CsPbBr3 single crystalline perovskite nanowire heterojunctions using wide-field and confocal photoluminescence measurements. The combination of nanoscale imaging techniques with these single crystalline materials allows us to measure intrinsic anionic lattice diffusivities, free from complications of microscale inhomogeneity. Halide diffusivities were found to be between 10-13 and ∼10-12 cm2/second at about 100 °C, which are several orders of magnitudes lower than those reported in polycrystalline thin films. Spatially resolved photoluminescence lifetimes and surface potential measurements provide evidence of the central role of halide vacancies in facilitating ionic diffusion. Vacancy formation free energies computed from molecular simulation are small due to the easily deformable perovskite lattice, accounting for the high equilibrium vacancy concentration. Furthermore, molecular simulations suggest that ionic motion is facilitated by low-frequency lattice modes, resulting in low activation barriers for vacancy-mediated transport. This work elucidates the intrinsic solid-state ion diffusion mechanisms in this class of semisoft materials and offers guidelines for engineering materials with long-term stability in functional devices.

12.
Nano Lett ; 18(11): 6967-6973, 2018 11 14.
Artigo em Inglês | MEDLINE | ID: mdl-30265549

RESUMO

Surface condition plays an important role in the optical performance of semiconductor materials. As new types of semiconductors, the emerging metal-halide perovskites are promising for next-generation optoelectronic devices. We discover significantly improved light-emission efficiencies in lead halide perovskites due to surface oxygen passivation. The enhancement manifests close to 3 orders of magnitude as the perovskite dimensions decrease to the nanoscale, improving external quantum efficiencies from <0.02% to over 12%. Along with about a 4-fold increase in spontaneous carrier recombination lifetimes, we show that oxygen exposure enhances light emission by reducing the nonradiative recombination channel. Supported by X-ray surface characterization and theoretical modeling, we propose that excess lead atoms on the perovskite surface create deep-level trap states that can be passivated by oxygen adsorption.

13.
Proc Natl Acad Sci U S A ; 115(36): 8889-8894, 2018 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-30127004

RESUMO

Semiconductor p-n junctions are fundamental building blocks for modern optical and electronic devices. The p- and n-type regions are typically created by chemical doping process. Here we show that in the new class of halide perovskite semiconductors, the p-n junctions can be readily induced through a localized thermal-driven phase transition. We demonstrate this p-n junction formation in a single-crystalline halide perovskite CsSnI3 nanowire (NW). This material undergoes a phase transition from a double-chain yellow (Y) phase to an orthorhombic black (B) phase. The formation energies of the cation and anion vacancies in these two phases are significantly different, which leads to n- and p- type electrical characteristics for Y and B phases, respectively. Interface formation between these two phases and directional interface propagation within a single NW are directly observed under cathodoluminescence (CL) microscopy. Current rectification is demonstrated for the p-n junction formed with this localized thermal-driven phase transition.

14.
Nano Lett ; 18(6): 3538-3542, 2018 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-29771532

RESUMO

Alloying different semiconductors is a powerful approach to tuning the optical and electronic properties of semiconductor materials. In halide perovskites (ABX3), alloys with different anions have been widely studied, and great band gap tunability in the visible range has been achieved. However, perovskite alloys with different cations at the "B" site are less understood due to the synthetic challenges. Herein, we first have developed the synthesis of single-crystalline CsPb xSn1- xI3 nanowires (NWs). The electronic band gaps of CsPb xSn1- xI3 NWs can be tuned from 1.3 to 1.78 eV by varying the Pb/Sn ratio, which leads to the tunable photoluminescence (PL) in the near-infrared range. More importantly, we found that the electrical conductivity increases as more Sn2+ is alloyed with Pb2+, possibly due to the increase of charge carrier concentration when more Sn2+ is introduced. The wide tunability of the optical and electronic properties makes CsPb xSn1- xI3 alloy NWs promising candidates for future optoelectronic device applications.

15.
Virology ; 515: 66-73, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29272747

RESUMO

Begomoviruses are transmitted by whiteflies in a persistent manner, but factors responsible for the variation of virus transmission by different species are poorly understood. We examined ingestion of papaya leaf curl China virus (PaLCuCNV) and tomato yellow leaf curl virus (TYLCV) by two species of the Bemisia tabaci complex, MEAM1 and MED, and then quantified the virion concentrations in different organs/tissues in each species. We found that PaLCuCNV penetrated the midgut wall of MED less efficiently than MEAM1, resulting in lower efficiency of PalCuCNV transmission by MED than that by MEAM1, while TYLCV penetrated the midgut wall of both species and was transmitted by them at similar levels of efficiency. Virus coat protein determined the virus capacity to cross the midgut wall of a given whitefly species. These data indicate that the level of midgut penetration determines virus acquisition and transmission by whiteflies in the first instance.


Assuntos
Begomovirus/fisiologia , Cucumis melo/virologia , Hemípteros/virologia , Insetos Vetores/virologia , Doenças das Plantas/virologia , Animais , Feminino , Trato Gastrointestinal/virologia , Masculino , Especificidade de Órgãos
16.
J Am Chem Soc ; 139(34): 11678-11681, 2017 08 30.
Artigo em Inglês | MEDLINE | ID: mdl-28787139

RESUMO

Platinum-based alloys are known to demonstrate advanced properties in electrochemical reactions that are relevant for proton exchange membrane fuel cells and electrolyzers. Further development of Pt alloy electrocatalysts relies on the design of architectures with highly active surfaces and optimized utilization of the expensive element, Pt. Here, we show that the three-dimensional Pt anisotropy of Pt-Ni rhombic dodecahedra can be tuned by controlling the ratio between Pt and Ni precursors such that either a completely hollow nanoframe or a new architecture, the excavated nanoframe, can be obtained. The excavated nanoframe showed ∼10 times higher specific and ∼6 times higher mass activity for the oxygen reduction reaction than Pt/C, and twice the mass activity of the hollow nanoframe. The high activity is attributed to enhanced Ni content in the near-surface region and the extended two-dimensional sheet structure within the nanoframe that minimizes the number of buried Pt sites.

17.
Nan Fang Yi Ke Da Xue Xue Bao ; 37(4): 431-437, 2016 Apr 20.
Artigo em Chinês | MEDLINE | ID: mdl-28446392

RESUMO

OBJECTIVE: To investigate the effect of HBP-A on meniscal injuries and the expressions of genes associated with pathological hypertrophy and calcification of the meniscusinduced by abnormal loading. METHODS: Bovine meniscus explants were subjected to 25% strain at 0.3 Hz for 3 h and treated with 0.6 mg/mL of HBP-A. The cell viability in the meniscus explants after 72 hin culture was determined using live/dead staining and the expression levels of genes associated with pathological hypertrophy and calcification of the meniscus (ANKH, ENPP1, ALP, MMP13, and IL-1) were measured using real-time PCR and Western blotting. The conditioned medium was collected for testing sulfated glycosaminoglycan (GAG) release. RESULTS: The number of dead cells, loss of proteoglycan content, and the expressions of ANKH, ENPP1, ALP and MMP13, and IL-1 at both the mRNA and protein levels were all significantly lower in the meniscus explants treated with 0.6 mg/mL HBP-A than in the explants with only 25% abnormal pressure stimulation (n=3, P<0.05). CONCLUSION: HBP-A can effectively alleviate meniscal injuries induced by abnormal loading and suppress the expressions of genes related with pathological hypertrophy and calcification of the meniscus, and can serve as a potential drug for treatment of knee osteoarthritis.


Assuntos
Calcinose/tratamento farmacológico , Glucanos/farmacologia , Meniscos Tibiais/efeitos dos fármacos , Lesões do Menisco Tibial/tratamento farmacológico , Animais , Bovinos , Hipertrofia , Osteoartrite do Joelho/tratamento farmacológico , Reação em Cadeia da Polimerase em Tempo Real
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