Identification of RNA silencing suppressor encoded by citrus chlorotic dwarf-associated virus.

Introduction: Citrus chlorotic dwarf-associated virus (CCDaV) is an economically important citrus virus associated with leaf curling, deformation, and chlorosis found in China. Plants have evolved RNA silencing to defend against viral infections; however, the mechanism by which CCDaV suppresses RNA silencing in citrus remains unknown. Methods: Six proteins encoded by CCDaV were ectopically expressed in Nicotiana benthamiana 16c using the pCHF3 vector to identify RNA-silencing suppression activities. Results: V2 protein encoded by CCDaV suppressed local RNA silencing and systemic RNA silencing triggered by GFP RNA, but did not impede short-distance movement of the RNA silencing signal in N. benthamiana 16c. GFP fluorescence observations showed that the ability of V2 protein to suppress RNA silencing was weaker than tomato bushy stunt virus P19. Deletion analysis showed that the putative nuclear localization signal (NLS, 25-54 aa) was involved in the RNA silencing suppression activity of V2 protein. Furthermore, V2 protein cannot block dsRNA-triggered RNA silencing. The subcellular localization assay suggested that V2 protein was localized to nucleus of N. benthamiana. Conclusion: Overall, the results of this study demonstrate that CCDaV-V2 acts as an activity of silencing suppression. This is the first reported RNA-silencing suppressor encoded by Citlodavirus and will be valuable in revealing the molecular mechanism of CCDaV infection.

Morphological Transformation and In Situ Polymerization of Caspase-3 Responsive Diacetylene-Containing Lipidated Peptide Amphiphile for Self-Amplified Cooperative Antitumor Therapy.

In order to artificially regulate cell behaviors, intracellular polymerization as an emerging chemical technique has attracted much attention. Yet, it is still a challenge to achieve effective intracellular polymerization to conquer tumors in the complex cellular environment. Herein, this work develops a tumor-targeting and caspase-3 responsive nanoparticle composed of a diacetylene-containing lipidated peptide amphiphile and mitochondria-targeting photosensitizer (C3), which undergoes nanoparticle-to-nanofiber transformation and efficient in situ polymerization triggered by photodynamic treatment and activation of caspase-3. The locational nanofibers on the mitochondria membranes lead to mitochondrial reactive oxygen species (mtROS) burst and self-amplified circulation, offering persistent high oxidative stress to induce cell apoptosis. This study provides a strategy for greatly enhanced antitumor therapeutic efficacy through mtROS burst and self-amplified circulation induced by intracellular transformation and in situ polymerization.

Anionic Cyanine J-Type Aggregate Nanoparticles with Enhanced Photosensitization for Mitochondria-Targeting Tumor Phototherapy.

Cyanines have been widely used as the photosensitizers (PSs) in the biomedical field, but controlling their molecular aggregates in nanoparticles (NPs) remains a major challenge. Moreover, the impact of aggregate behaviors of cyanines on the photosensitization is still unclear. Herein, the first anionic cyanine PSs based on a tricyanofuran end group have been designed by achieving supramolecular J-type aggregates in NPs via counterion engineering. Our results indicate that J-type aggregates in NPs can not only bring significantly red-shifted emission, negatively charged surface, and high photostability, but also enable a significant 5-fold increase in singlet oxygen generation efficiency compared to that in the nonaggregate state, providing strong experimental evidence for the superiority of J-aggregates in enhancing photosensitization. Thus, combined with the mitochondria-targeting ability, the J-type aggregate NPs show remarkable in vivo antitumor phototheranostic efficacy, making them have a potential for clinical use.

Molecular characterization of a novel citrivirus from citrus using next-generation sequencing.

A novel positive-strand RNA virus infecting citrus with the tentative name "citrus leaf blotch virus 2" (CLBV-2), was identified in the present work. The complete genome sequence of CLBV-2 comprises 8,697 nucleotides (nt) excluding a poly(A) tail and three open reading frames (ORFs), showing the highest nucleotide sequence identity with the Actinidia strain (JN983456) of citrus leaf blotch virus (CLBV). The putative movement protein (ORF2), coat protein (ORF3), and 3' untranslated region (UTR) shared high sequence similarity with those of the extant CLBV isolates. In contrast, only low sequence similarity was observed in the 5' UTR and putative replicase polyprotein (ORF1) regions. The distant phylogenetic relationship between CLBV-2 and CLBV was deduced based on whole-genome nucleotide and whole-ORF1 amino acid sequence comparisons. Sequence comparisons suggest that CLBV-2 acquired an ORF2-ORF3-3' UTR region homologous to CLBV by recombination with of an unknown citrivirus. In view of the fact that this genomic recombination event appears to have occurred between members of different species in the genus Citrivirus, we propose that CLBV-2 should be considered a member of a distinct species.

Fluorescence enhancements of benzene-cored luminophors by restricted intramolecular rotations: AIE and AIEE effects.

Photoluminescence of simple arylbenzenes with ready synthetic accessibility is enhanced by two orders of magnitude through aggregate formation; viscosity and temperature effects indicate that the emission enhancement is due to the restriction of their intramolecular rotations in the solid state.