Activatable fluorescent probes for real-time imaging-guided tumor therapy.

Surgery and drug therapy are the two principal options for cancer treatment. However, their clinical benefits are hindered by the difficulty of accurate location of the tumors and timely monitoring of the treatment efficacy of drugs, respectively. Rapid development of imaging techniques provides promising tools to address these challenges. Compared with conventional imaging techniques such as magnetic resonance imaging and computed tomography etc., fluorescence imaging exhibits high spatial resolution, real-time imaging capability, and relatively low costs devices. The advancements in fluorescent probes further accelerate the implementation of fluorescence imaging in tumor diagnosis and treatment monitoring. In particular, the emergence of site-specifically activatable fluorescent probes fits the demands of tumor delineation and real-time feedback of the treatment efficacy. A variety of small molecule probes or nanoparticle-based probes have been developed and explored for the above-mentioned applications. This review will discuss recent advances in fluorescent probes with a special focus on activatable nanoprobes and highlight the potential implementation of activatable nanoprobes in fluorescence imaging-guided surgery as well as imaging-guided drug therapy.

Epidemiology of norovirus gastroenteritis in hospitalized children under five years old in western China, 2015-2019.

OBJECTIVES: Norovirus is associated with one-fifth of all gastroenteritis cases, but basic epidemiological data is lacking, especially in developing countries. As long-term surveillance on norovirus gastroenteritis is scarce in western China, this study aims to update the epidemiological knowledge of norovirus gastroenteritis and to characterize the genotypes of norovirus strains. METHODS: Stool samples were collected from hospitalized children under 5 years old with gastroenteritis in Chengdu, China. All samples were tested for norovirus as well as rotavirus, sapovirus, enteric adenovirus, and astrovirus by real-time RT-PCR. RdRp and VP1 genes were sequenced in norovirus-positive samples to investigate viral phylogenies. RESULTS: Of the 1181 samples collected from 2015 to 2019, 242 (20.5%) were positive for norovirus. Among norovirus-positive cases, 65 cases had co-infection with another virus; norovirus/enteric adenovirus was most frequently detected (50.8%, 33/65). The highest positive rate was observed in children aged 13-18 months (23.7%, 68/287). Norovirus infection peaked in autumn (36.6%, 91/249), followed by summer (20.3%, 70/345). Pearson correlation analysis showed significant correlation between the norovirus-positive rate and humidity (r = 0.773, P < 0.05). GII.4 Sydney 2012 [P31] (48.5%, 79/163) and GII.3 [P12] (35.6%, 58/163) were the dominant norovirus strains. CONCLUSIONS: Norovirus has become one of the most common causes of viral gastroenteritis in children under 5 years old in western China. Continuous monitoring is imperative for predicting the emergence of new epidemic strains and for current vaccine development.

Adenovirus-Mediated CRM197 Sensitizes Human Glioma Cells to Gemcitabine by the Mitochondrial Pathway.

PURPOSE: The cross-reacting material 197 (CRM197) is a mutation of the diphtheria toxin. The protein of CRM197 was used successfully for the therapy of various tumors in the recent studies. In this study, the recombinant adenoviruses containing the CRM197gene(AdCRM197) were used to enhance the cellar toxicity of gemcitabine in human glioma U87, U251, and H4 cells. PROCEDURES: MTT assay and flow cytometric analysis were performed to test the apoptosis of the U87, U251 and H4 cells with the combined treatment of AdCRM197 plus gemcitabine. Western blotting analyses were carried out to detect the cell apoptosis of the mitochondrial pathway. And the xenograft nude mice were used to observe the enhanced antitumor effect of AdCRM197 in vivo. RESULTS: AdCRM197 sensitizes human glioma cells to gemcitabine in vitro by the mitochondrial pathway. Tumor volume was inhibited and survival time was prolonged in the U251 or U87 xenografted nude mice with gemcitabine plus AdCRM197. The enhanced antitumor effect of AdCRM197 was also detected by the immunohistochemical analyses and TUNEL staining. CONCLUSION: The authors found that AdCRM197 sensitized the human glioma to gemcitabine not only in vitro but also in vivo. They provide the first evidence that adenovirus-mediated CRM197 may be a potential chemosensitizing agent for the treatment of cancer. The diphtheria toxin is of great toxicity that even one molecule of diphtheria toxin is enough to kill one cell. However, because of the high toxicity, the diphtheria toxin would kill the packing cells when it is being packaged into the recombinant viruses. Therefore, the diphtheria toxin is hard to be used in the gene therapy for virus vectors. The cross-reacting material 197 (CRM197) is a mutation of the diphtheria toxin. Unlike DTA, CRM197 exhibit a weak toxicity. The week toxicity of CRM197 is a good feature for the virus packaging. In the present study, we used a recombinant adenovirus which carried a CRM197 gene (AdCRM197) to enhance the cellar toxicity of gemcitabine in human glioma cells.

Arabidopsis cryptochrome 1 functions in nitrogen regulation of flowering.

The phenomenon of delayed flowering after the application of nitrogen (N) fertilizer has long been known in agriculture, but the detailed molecular basis for this phenomenon is largely unclear. Here we used a modified method of suppression-subtractive hybridization to identify two key factors involved in N-regulated flowering time control in Arabidopsis thaliana, namely ferredoxin-NADP(+)-oxidoreductase and the blue-light receptor cryptochrome 1 (CRY1). The expression of both genes is induced by low N levels, and their loss-of-function mutants are insensitive to altered N concentration. Low-N conditions increase both NADPH/NADP(+) and ATP/AMP ratios, which in turn affect adenosine monophosphate-activated protein kinase (AMPK) activity. Moreover, our results show that the AMPK activity and nuclear localization are rhythmic and inversely correlated with nuclear CRY1 protein abundance. Low-N conditions increase but high-N conditions decrease the expression of several key components of the central oscillator (e.g., CCA1, LHY, and TOC1) and the flowering output genes (e.g., GI and CO). Taken together, our results suggest that N signaling functions as a modulator of nuclear CRY1 protein abundance, as well as the input signal for the central circadian clock to interfere with the normal flowering process.

The roles of two transcription factors, ABI4 and CBFA, in ABA and plastid signalling and stress responses.

Genetic and physiological studies have revealed evidences for multiple signaling pathways by which the plastid exerts retrograde control over photosynthesis-associated-nuclear-genes. In this study we have examined the mechanisms of control of transcription by plastid signals, focusing on transcription factors. We have also further addressed the physical nature of plastid signals and the physiological role, in stress acclimation of this regulatory pathway. ABI4, a master Apetala 2 (AP2)-type transcription factor (TF), is targeted by multiple signalling pathways in plant cells, such as abscisic acid (ABA) signals, sugar signals and plastid signals derived from reactive oxygen species (ROS) and chlorophyll intermediates. ABI4 binds the promoter of target genes to prevent their transcription by competing with other competitive TFs. However, we found that once ABI4 bound the element (CCACGT), it may not be bound by other TFs, therefore making the signalling long-lasting. Downstream of ABI4, CBFA (CCAAT binding factor A) is a subunit of the HAP2/HAP3/HAP5 (Heme activator protein) trimeric transcription complex. CBFA however is a redundant HAP3 subunit. When emergency occurs (such as herbicide treatments or environmental stresses followed by ABA and ROS accumulation), the master transcription factor ABI4 down-regulates some TFs, like CBFA, and then some other TF subunits enter the transcription complex and transcriptional efficiency of stress-responsive genes (including the transcription co-factor CBP) is improved instantaneously. abi4, cbfA and cbp mutants showed weaker drought-tolerance after a herbicide norflurazon treatment, which indicated the physiological role of these key transcription factors.

The significance of CP29 reversible phosphorylation in thylakoids of higher plants under environmental stresses.

Reversible phosphorylation of proteins is a key event in many fundamental cellular processes. Under stressful conditions, many thylakoid membrane proteins in photosynthetic apparatus of higher plants undergo rapid phosphorylation and dephosphorylation in response to environmental changes. CP29 is the most frequently phosphorylated protein among three minor antennae complexes in higher plants. CP29 phosphorylation in dicotyledons has been known for several decades and is well characterized. However, CP29 phosphorylation in monocotyledons is less studied and appears to have a different phosphorylation pattern. In this review, we discuss recent advancements in CP29 phosphorylation and dephosphorylation studies and its physiological significance under environmental stresses in higher plants, especially in the monocotyledonous crops. Physiologically, the phosphorylation of CP29 is likely to be a prerequisite for state transitions and the disassembly of photosystem II supercomplexes, but not involved in non-photochemical quenching (NPQ). CP29 is phosphorylated in monocots exposed to environmental cues, with its subsequent lateral migration from grana stacks to stroma lamellae. However, neither CP29 phosphorylation nor its lateral migration occurs in dicotyledonous plants after drought, cold, or salt stress. Since the molecular mechanisms of differential CP29 phosphorylation under stresses are not fully understood, this review provides insights for future studies regarding the physiological function of CP29 reversible phosphorylation.

Light regulation to chlorophyll synthesis and plastid development of the chlorophyll-less golden-leaf privet.

Ligustrum vicaryi L. is a hybrid of Ligustrum ovalifolium Hassk. var. aureo-marginatum and Ligustrum vulgale L., and displays a chlorophyll-less phenotype. Therefore it is widely used as a horticultural shrub because of its golden-color leaves. Its putative mechanism, light responses, chlorophyll synthesis and plastid development were studied. L. vicaryi has a higher level of 5-aminolevulinic acid (ALA), but lower levels of chlorophylls compared with L. quihoui. The yellowish phenotype of L. vicaryi upper leaves could be attributed to their hampered conversion from chlorophyllide into chlorophyll a. Despite the enhanced ALA level and the decreased thylakoid stacking in plastids, L. vicaryi golden leaves contain normal levels of Lhcb transcripts and photosystem apoproteins. Furthermore, reactive oxygen species (ROS) accumulation is almost the same in L. vicaryi and L. quihoui. The golden leaves often turn green and the contents of chlorophylls increase with decreasing light intensity. Dynamic changes of chlorophyll-synthesis-system under the light transition were also analyzed.

[Fluorometric determination of fructose in the presence of glucose using zirconyl chloride-ammonium chloride].

According to the principle that Zn(OH)+ produced by ZrOCl2 upon hydrolysis in water can react to form a fluorescent derivative with fructose, a method for the quantitative determination of fructose has been proposed. The fluorescence of the derivative enhanced at 408 nm in NH4Cl medium has a direct ratio with fructose in the linear range of 0.5-25 microg x mL(-1). When reaction conditions such as a temperature of 70 degrees C and a time of 15 min are used, the detection limits is 0.071 mg x mL(-1). The proposed method was also applied successfully to the determination of fruit, satisfaction with high accuracy and good reproduction.