High-Fidelity Spatiotemporal Recognition of Golgi ALP through an Initial-Accumulation and Postactivation Strategy.

Various signal molecules mediate complex physiological processes collectively in the Golgi. However, most currently accessible probes are questionable in illuminating the functions of these reactive species in Golgi because of the inability to irradiate these probes only at the desired Golgi location, which compromises specificity and accuracy. In this study, we rationally designed the first photocontrollable and Golgi-targeted fluorescent probe to in situ visualize the Golgi alkaline phosphatase (ALP). The designed probe with natural yellow fluorescence can provide access into Golgi and monitor the exact timing of accumulation in Golgi. On-demand photoactivation at only the desired Golgi location affords a significant emission response to ALP with illuminating red fluorescence at 710 nm. Through the photocontrollable fluorescence responsiveness to ALP, precise spatiotemporal recognition of Golgi ALP fluctuations is successfully performed. With this probe, for the first time, we revealed the Golgi ALP levels during cisplatin-induced acute kidney injury (AKI), which will further facilitate and complement the comprehensive exploration of ALP kinetics during physiological and pathological processes.

RSS and ROS Sequentially Activated Carbon Monoxide Release for Boosting NIR Imaging-Guided On-Demand Photodynamic Therapy.

Carbon monoxide shows great therapeutic potential in anti-cancer. In particular, the construction of multifunctional CO delivery systems can promote the precise delivery of CO and achieve ideal therapeutic effects, but there are still great challenges in design. In this work, a RSS and ROS sequentially activated CO delivery system is developed for boosting NIR imaging-guided on-demand photodynamic therapy. This designed system is composed of a CO releaser (BOD-CO) and a photosensitizer (BOD-I). BOD-CO can be specifically activated by hydrogen sulfide with simultaneous release of CO donor and NIR fluorescence that can identify H2S-rich tumors and guide light therapy, also depleting H2S in the process. Moreover, BOD-I generates 1O2 under long-wavelength light irradiation, enabling both PDT and precise local release of CO via a photooxidation mechanism. Such sequential activation of CO release by RSS and ROS ensured the safety and controllability of CO delivery, and effectively avoided leakage during delivery. Importantly, cytotoxicity and in vivo studies reveal that the release of CO combined with the depletion of endogenous H2S amplified PDT, achieving ideal anticancer results. It is believed that such theranostic nanoplatform can provide a novel strategy for the precise CO delivery and combined therapy involved in gas therapy and PDT.

Precise Spatiotemporal Identification of Mitochondrial H2S Fluctuations through Exploiting an On-Demand Photoactivated Probe.

Various signal molecules participate in complex biological processes in mitochondria. However, most currently available probes have problems in elucidating the functions of these active species in mitochondria due to the inability to light up these probes exclusively at the desired mitochondrial location, thereby compromising the specificity and accuracy. In this study, we present an on-demand photoactivation approach to the molecular design of optimized probes for precise spatiotemporal identification of mitochondrial H2S fluctuations. The designed probe with native yellow fluorescence can monitor the process into mitochondria but maintains nonfluorescent response to H2S during cellular delivery, providing the accurate timing of accumulation in mitochondria. On-demand photoactivation exclusively at the desired mitochondrial location affords a significant aggregation-enhanced and emissive response to H2S with lighting up red fluorescence at 690 nm, which is the only way to get such an emissive phenomenon and greatly improves the specificity and accuracy of targeting mitochondrial H2S. By using this photocontrolled fluorescence responsiveness to H2S, precise spatiotemporal identification of mitochondrial H2S fluctuations is successfully performed. Our work could facilitate advances toward interrogating the physiological and pathological consequences of mitochondrial H2S in various biological events.

Specific imaging of intracellular hydrogen sulfide by a positively charged NIR fluorescent probe.

The poor water solubility of traditional activatable organic molecular probes usually limits their detection ability in physiological environment. In this work, a positively charged H2S probe was designed, which exhibited a significantly enhanced responsiveness to H2S in the aggregated state due to the increased positive charge density on the aggregate surface. Under physiological conditions, the probe could be activated by H2S with specificity and sensitivity to release near-infrared fluorescence signal. Moreover, endogenous H2S levels in living cells were successfully monitored by using this probe. We expect that this probe can provide a new strategy for the design of activatable probes to break the limitation of poor water solubility of conventional organic molecular probes.

An activatable endoplasmic reticulum-targeted probe for NIR imaging-guided photothermal therapy.

An H2O2-activated, endoplasmic reticulum-targeted theranostic probe was developed. This designed probe could be activated by H2O2, resulting in increased NIR fluorescence and photothermal signals, thus achieving specific recognition of H2O2 and further photothermal therapy in the endoplasmic reticulum of H2O2-overexpressing cancer cells.

High-efficiency adsorption removal of CR and MG dyes using AlOOH fibers embedded with porous CoFe2O4 nanoparticles.

Owing to the toxicity and difficulty in degradation, how to the effective separation for the residual dyes in the aqueous solution is still an issue with great challenge in the area of environmental protection. Now, to high-efficiency removal of organic dyes from the aqueous solution, we design a unique AlOOH/CoFe2O4 adsorbent with porous CoFe2O4 nanoparticles embedded on the AlOOH fibers using a simple hydrothermal technique and calcination process. The structural properties and surface characteristics of the AlOOH/CoFe2O4 composites are detailedly analyzed by XRD, FTIR, XPS, TEM and SEM. Here, the high SBET and specific porous structure are beneficial to improve the adsorption performance of AlOOH/CoFe2O4 adsorbents. Especially, when the molar ratio of AlOOH to CoFe2O4 in the AlOOH/CoFe2O4 fibers is 1:1, an optimal performance on adsorbing anionic Congo red (CR) and cationic methyl green (MG) dyes can be obtained at pH = 6.29, where the corresponding maximum adsorption capacities reach up to 565.0 and 423.7 mg g-1, respectively. Factors leading to the change in the ability of adsorbing CR and MG dyes are systematically discussed, including contact time, temperature, initial concentrations, and pH values of the solutions. Meanwhile, the uptake of CR and MG dyes can best conform to Langmuir isotherm model and pseudo-second-order adsorption kinetics. The thermodynamic analysis verifies that the dye adsorption process is spontaneous and endothermic. Moreover, from the point view of practical application, the good reusability further makes the as-synthesized magnetic AlOOH/CoFe2O4 composite be a perfect adsorbent with efficiently removing both anionic and cationic dyes from aqueous solutions.

A water-soluble fluorescent probe for real-time visualization of γ-glutamyl transpeptidase activity in living cells.

γ-glutamyl transpeptidase (GGT) is a kind of cell-surface enzyme that is overexpressed in many cancer cells. It is of great significance to develop an ideal tool for the diagnosis of GGT-rich cancer cells. Here, we reported a simple-structured but effective imaging probe for the detection of GGT activity. In the presence of GGT, the γ-glutamyl linkage could be cleaved specifically to produce amino-substituted product, resulting in significant fluorescence enhancement at 578 nm. Moreover, we successfully employed the probe to monitor GGT activity in HepG2 cells. We envisaged that such a simple but effective imaging tool could improve the practical applications for bioimaging.

Real-Time Monitoring Renal Impairment Due to Drug-Induced AKI and Diabetes-Caused CKD Using an NAG-Activatable NIR-II Nanoprobe.

Real-time in vivo optical imaging of kidney function is important for the diagnosis of renal diseases, such as acute kidney injury (AKI) and chronic kidney disease (CKD), with high morbidity and mortality worldwide. However, the reported optical imaging agents still have limitations for identifying AKI or CKD in the early stage due to their low sensitivity, poor tissue penetration, and significant background interference. Herein, an N-acetyl-ß-d-glucosaminidase (NAG)-activatable second near-infrared (NIR-II) fluorescent nanoprobe (BOD-II-NAG-NP) is developed for monitoring the progression of drug-induced AKI and in vivo imaging of diabetes-caused CKD. NAG, as a biomarker of renal diseases, is able to specifically activate BOD-II-NAG-NP to release NIR-II fluorescence signals, enabling in vivo imaging of kidney dysfunctions in living mice. Importantly, such an active imaging mechanism allows BOD-II-NAG-NP to noninvasively detect the onset of drug-induced AKI at least 32 h earlier than the most existing assays, which indicates that BOD-II-NAG-NP has the potential to be an optical imaging agent for the early diagnosis of AKI. Moreover, NIR-II fluorescence produced by BOD-II-NAG-NP could deeply penetrate into the relatively thick layers of fat in diabetic nephropathy mice and provide in vivo imaging with high resolution, indicating that BOD-II-NAG-NP has clinical potential for precision diagnosis of CKD.

Probing the Intracellular Dynamics of Nitric Oxide and Hydrogen Sulfide Using an Activatable NIR II Fluorescence Reporter.

Understanding the complex interplay among gasotransmitters is of great significance but remains technically challenging. In this study, we present the design and synthesis of a dually responsive BOD-NH-SC reporter for probing the dynamic and alternating existence of NO and H2 S in living cells. This designed reporter can repeatedly cycle S-nitrosation and transnitrosation reactions when successively treated with NO and H2 S, thus affording the interchange of NIR fluorescence at 645 nm (NO) and NIR II fluorescence at 936 nm (H2 S). In light of this unique fluorescence alternation between two colors, we synthesized water-soluble BOD-NH-SC dots to visualize the intracellular dynamics of NO and H2 S. These molecular probes thus provide a toolbox to elucidate the interplaying roles of NO and H2 S in the complex interaction networks of various signal transduction pathways.

Aggregation Enhanced Responsiveness of Rationally Designed Probes to Hydrogen Sulfide for Targeted Cancer Imaging.

Activatable molecular probes hold great promise for targeted cancer imaging. However, the hydrophobic nature of most conventional probes makes them generate precipitated agglomerate in aqueous media, thereby annihilating their responsiveness to analytes and precluding their practical applications for bioimaging. This study reports the development of two small molecular probes with unprecedented aggregation enhanced responsiveness to H2S for in vivo imaging of H2S-rich cancers. The subtle modulation of the equilibrium between hydrophilicity and lipophilicity by N-methylpyridinium endows these designed probes with the capability of spontaneously self-assembling into nanoprobes under physiological conditions. Such probes in an aggregated state, rather than a molecular dissolved state, show NIR fluorescence light up and photoacoustic signals turn on upon H2S specific activation, allowing in vivo visualization and differentiation of cancers based on differences in H2S content. Thus, our study presents an effective design strategy which should pave the way to molecular design of optimized probes for precision cancer diagnostics.

PINOID Is Required for Formation of the Stigma and Style in Rice.

The stigma is the entry point for sexual reproduction in plants, but the mechanisms underlying stigma development are largely unknown. Here, we disrupted putative auxin biosynthetic and signaling genes to evaluate their roles in rice (Oryza sativa) development. Disruption of the rice PINOID (OsPID) gene completely eliminated the development of stigmas, and overexpression of OsPID led to overproliferation of stigmas, suggesting that OsPID is a key determinant for stigma development. Interestingly, ospid mutants did not display defects in flower initiation, nor did they develop any pin-like inflorescences, a characteristic phenotype observed in pid mutants in Arabidopsis (Arabidopsis thaliana) and maize (Zea mays). We constructed double mutants of OsPID and its closest homolog, OsPIDb, yet the double mutants still did not develop any pin-like inflorescences, indicating that either ospid is compensated by additional homologous genes or OsPID has different functions in rice compared with PID in other organisms. We then knocked out one of the NAKED PINS IN YUC MUTANTS (NPY) genes, which cause the formation of pin-like inflorescences in Arabidopsis when compromised, in the ospid background. The ospid osnpy2 double mutants developed pin-like inflorescences, which were phenotypically similar to pid mutants in Arabidopsis and maize, demonstrating that the roles of OsPID in inflorescence development are likely masked by redundant partners. This work identified a key determinant for stigma development in rice and revealed a complex picture of the PID gene in rice development. Furthermore, the stigma-less ospid mutants are potentially useful in producing hybrid rice.

Homeobox transcription factor OsZHD2 promotes root meristem activity in rice by inducing ethylene biosynthesis.

Root meristem activity is the most critical process influencing root development. Although several factors that regulate meristem activity have been identified in rice, studies on the enhancement of meristem activity in roots are limited. We identified a T-DNA activation tagging line of a zinc-finger homeobox gene, OsZHD2, which has longer seminal and lateral roots due to increased meristem activity. The phenotypes were confirmed in transgenic plants overexpressing OsZHD2. In addition, the overexpressing plants showed enhanced grain yield under low nutrient and paddy field conditions. OsZHD2 was preferentially expressed in the shoot apical meristem and root tips. Transcriptome analyses and quantitative real-time PCR experiments on roots from the activation tagging line and the wild type showed that genes for ethylene biosynthesis were up-regulated in the activation line. Ethylene levels were higher in the activation lines compared with the wild type. ChIP assay results suggested that OsZHD2 induces ethylene biosynthesis by controlling ACS5 directly. Treatment with ACC (1-aminocyclopropane-1-carboxylic acid), an ethylene precursor, induced the expression of the DR5 reporter at the root tip and stele, whereas treatment with an ethylene biosynthesis inhibitor, AVG (aminoethoxyvinylglycine), decreased that expression in both the wild type and the OsZHD2 overexpression line. These observations suggest that OsZHD2 enhances root meristem activity by influencing ethylene biosynthesis and, in turn, auxin.

Tumor microenvironment-activated nanosystems with selenophenol substituted BODIPYs as photosensitizers for photodynamic therapy.

NIR-light-absorbing photosensitizers with the capability of selective localization and activation in tumor regions are of great importance for practical photodynamic therapy (PDT). Here, selenophenol substituted BODIPYs were designed and synthesized as new photosensitizers for PDT. One of these obtained BODIPYs, IBSeOV, possesses an intense and low energy absorption with a high singlet oxygen quantum yield (ΦΔ = 60%). Considering manganese dioxide (MnO2) nanosheets as versatile nanocarriers in cancer theranostics, nanosystem IBSeOV/MnO2 was then fabricated to furnish tumor environment selective activation. Such designed nanoplatform allowed for GSH-controllable 1O2 production and exhibited low cytotoxicity in dark but good photocytotoxicity to cancer cells. The in vivo antitumor outcome suggested the high treatment efficiency of IBSeOV/MnO2 for tumor therapy.

The Arabidopsis NRG2 Protein Mediates Nitrate Signaling and Interacts with and Regulates Key Nitrate Regulators.

We show that NITRATE REGULATORY GENE2 (NRG2), which we identified using forward genetics, mediates nitrate signaling in Arabidopsis thaliana. A mutation in NRG2 disrupted the induction of nitrate-responsive genes after nitrate treatment by an ammonium-independent mechanism. The nitrate content in roots was lower in the mutants than in the wild type, which may have resulted from reduced expression of NRT1.1 (also called NPF6.3, encoding a nitrate transporter/receptor) and upregulation of NRT1.8 (also called NPF7.2, encoding a xylem nitrate transporter). Genetic and molecular data suggest that NRG2 functions upstream of NRT1.1 in nitrate signaling. Furthermore, NRG2 directly interacts with the nitrate regulator NLP7 in the nucleus, but nuclear retention of NLP7 in response to nitrate is not dependent on NRG2. Transcriptomic analysis revealed that genes involved in four nitrogen-related clusters including nitrate transport and response to nitrate were differentially expressed in the nrg2 mutants. A nitrogen compound transport cluster containing some members of the NRT/PTR family was regulated by both NRG2 and NRT1.1, while no nitrogen-related clusters showed regulation by both NRG2 and NLP7. Thus, NRG2 plays a key role in nitrate regulation in part through modulating NRT1.1 expression and may function with NLP7 via their physical interaction.

Hydrogen Sulfide-Activatable Second Near-Infrared Fluorescent Nanoassemblies for Targeted Photothermal Cancer Therapy.

Near-infrared (NIR)-II fluorescence agents hold great promise for deep-tissue photothermal therapy (PTT) of cancers, which nevertheless remains restricted by the inherent nonspecificity and toxicity of PTT. In response to this challenge, we herein develop a hydrogen sulfide (H2S)-activatable nanostructured photothermal agent (Nano-PT) for site-specific NIR-II fluorescence-guided PTT of colorectal cancer (CRC). Our in vivo studies reveal that this theranostic Nano-PT probe is specifically activated in H2S-rich CRC tissues, whereas it is nonfunctional in normal tissues. Activation of Nano-PT not only emits NIR-II fluorescence with deeper tissue penetration ability than conventional fluorescent probes but also generates high NIR absorption resulting in efficient photothermal conversion under NIR laser irradiation. Importantly, we establish NIR-II imaging-guided PTT of CRC by applying the Nano-PT agent in tumor-bearing mice, which results in complete tumor regression with minimal nonspecific damages. Our studies thus shed light on the development of cancer biomarker-activated PTT for precision medicine.

Theranostic Nanoplatform with Hydrogen Sulfide Activatable NIR Responsiveness for Imaging-Guided On-Demand Drug Release.

NIR light responsive nanoplatforms hold great promise for on-demand drug release in precision cancer medicine. However, currently available systems utilize "always-on" photothermal transducers that lack target specificity, and thus inaccurately differentiate tumors from normal tissues. Developed here is a theranostic nanoplatform featuring H2 S-mediated in situ production of NIR photothermal agents for imaging-guided and photocontrolled drug release. The system targets H2 S-rich cancers. This nanoplatform shows H2 S-activatable NIR-II emission and NIR light controllable release of the drug Camptothecin-11. Upon administering the system to HCT116 tumor-bearing mice, the tumor is greatly suppressed with minimal side effects, arising from the synergy of the cancer-specific and NIR light activated therapy. This theranostic nanoplatform thus sheds light on precision medicine with guidance through NIR-II imaging.

Recent advances in auxin research in rice and their implications for crop improvement.

Auxin is essential for various aspects of plant development, and modulation of auxin pathways has great potential for crop improvement. Although the current understanding of auxin biology including auxin biosynthesis, transport, and signaling mainly originated from studies in Arabidopsis, several key auxin genes were first discovered in rice, indicating that it is useful to employ several plant systems for auxin research. In this review, we summarize the recent advances in auxin biology in rice, highlight the main contributions of rice research to auxin biology, and discuss the potential for crop improvement through modulating auxin pathways.

Imaging of Colorectal Cancers Using Activatable Nanoprobes with Second Near-Infrared Window Emission.

Fluorescent probes in the second near-infrared window (NIR-II) allow high-resolution bioimaging with deep-tissue penetration. However, existing NIR-II materials often have poor signal-to-background ratios because of the lack of target specificity. Herein, an activatable NIR-II nanoprobe for visualizing colorectal cancers was devised. This designed probe displays H2 S-activated ratiometric fluorescence and light-up NIR-II emission at 900-1300 nm. By using this activatable and target specific probe for deep-tissue imaging of H2 S-rich colon cancer cells, accurate identification of colorectal tumors in animal models were performed. It is anticipated that the development of activatable NIR-II probes will find widespread applications in biological and clinical systems.

The Arabidopsis CPSF30-L gene plays an essential role in nitrate signaling and regulates the nitrate transceptor gene NRT1.1.

Plants have evolved sophisticated mechanisms to adapt to fluctuating environmental nitrogen availability. However, more underlying genes regulating the response to nitrate have yet to be characterized. We report here the identification of a nitrate regulatory mutant whose mutation mapped to the Cleavage and Polyadenylation Specificity Factor 30 gene (CPSF30-L). In the mutant, induction of nitrate-responsive genes was inhibited independent of the ammonium conditions and was restored by expression of the wild-type 65 kDa encoded by CPSF30-L. Molecular and genetic evidence suggests that CPSF30-L works upstream of NRT1.1 and independently of NLP7 in response to nitrate. Analysis of the 3'-UTR of NRT1.1 showed that the pattern of polyadenylation sites was altered in the cpsf30 mutant. Transcriptome analysis revealed that four nitrogen-related clusters were enriched in the differentially expressed genes of the cpsf30 mutant. Nitrate uptake was decreased in the mutant along with reduced expression of the nitrate transporter/sensor gene NRT1.1, while nitrate reduction and amino acid content were enhanced in roots along with increased expression of several nitrate assimilatory genes. These findings indicate that the 65 kDa protein encoded by CPSF30-L mediates nitrate signaling in part by regulating NRT1.1 expression, thus adding an important component to the nitrate signaling network.

Nitrate foraging by Arabidopsis roots is mediated by the transcription factor TCP20 through the systemic signaling pathway.

To compete for nutrients in diverse soil microenvironments, plants proliferate lateral roots preferentially in nutrient-rich zones. For nitrate, root foraging involves local and systemic signaling; however, little is known about the genes that function in the systemic signaling pathway. By using nitrate enhancer DNA to screen a library of Arabidopsis transcription factors in the yeast one-hybrid system, the transcription factor gene TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR1-20 (TCP20) was identified. TCP20, which belongs to an ancient, plant-specific gene family that regulates shoot, flower, and embryo development, was implicated in nitrate signaling by its ability to bind DNA in more than 100 nitrate-regulated genes. Analysis of insertion mutants of TCP20 showed that they had normal primary and lateral root growth on homogenous nitrate media but were impaired in preferential lateral root growth (root foraging) on heterogeneous media in split-root plates. Inhibition of preferential lateral root growth was still evident in the mutants even when ammonium was uniformly present in the media, indicating that the TCP20 response was to nitrate. Comparison of tcp20 mutants with those of nlp7 mutants, which are defective in local control of root growth but not in the root-foraging response, indicated that TCP20 function is independent of and distinct from NLP7 function. Further analysis showed that tcp20 mutants lack systemic control of root growth regardless of the local nitrate concentrations. These results indicate that TCP20 plays a key role in the systemic signaling pathway that directs nitrate foraging by Arabidopsis roots.