Identifying habitat modification by Chinese pangolin in subtropical forests of southern China.

The excavation of Chinese pangolin (Manis pentadactyla) is expected to alter habitat heterogeneity and thus affect the functioning and structure of forest ecosystems. In this study, the bioturbation of Chinese pangolin on forest soils in three regions (Heping, Tianjingshan, and Wuqinzhang) across Guangdong province was quantified. Overall, a mean of 2.66 m3·ha-1 and 83.1 m2·ha-1 of burrows and bare mounds, respectively, was excavated by Chinese pangolin; the disturbed soils had significantly lower water content and P, C, available N concentrations, but higher bulk density, pH, and microbial abundance than those undisturbed soils. The unevenness of habitat heterogeneity improvement was mainly ascribed to the stronger soil disturbance caused in resting burrows by pangolins. Patterns of altering habitat heterogeneity were site-specific, with high-intensity soil disturbance occurring most in shrubs, meadows, steep habitats at high elevations, and mountain tops in Heping, while in broad-leaved, coniferous and mixed coniferous and broad-leaved forests away from human settlements in Tianjingshan and upper mountains at high elevations far away from roads and human settlements in Wuqinzhang. Road networks are the main interference for the burrow distribution in Heping and Wuqinzhang and should be programmed.

Metformin Inhibits the Urea Cycle and Reduces Putrescine Generation in Colorectal Cancer Cell Lines.

The urea cycle (UC) removes the excess nitrogen and ammonia generated by nitrogen-containing compound composites or protein breakdown in the human body. Research has shown that changes in UC enzymes are not only related to tumorigenesis and tumor development but also associated with poor survival in hepatocellular, breast, and colorectal cancers (CRC), etc. Cytoplasmic ornithine, the intermediate product of the urea cycle, is a specific substrate for ornithine decarboxylase (ODC, also known as ODC1) for the production of putrescine and is required for tumor growth. Polyamines (spermidine, spermine, and their precursor putrescine) play central roles in more than half of the steps of colorectal tumorigenesis. Given the close connection between polyamines and cancer, the regulation of polyamine metabolic pathways has attracted attention regarding the mechanisms of action of chemical drugs used to prevent CRC, as the drug most widely used for treating type 2 diabetes (T2D), metformin (Met) exhibits antitumor activity against a variety of cancer cells, with a vaguely defined mechanism. In addition, the influence of metformin on the UC and putrescine generation in colorectal cancer has remained unclear. In our study, we investigated the effect of metformin on the UC and putrescine generation of CRC in vivo and in vitro and elucidated the underlying mechanisms. In nude mice bearing HCT116 tumor xenografts, the administration of metformin inhibited tumor growth without affecting body weight. In addition, metformin treatment increased the expression of monophosphate (AMP)-activated protein kinase (AMPK) and p53 in both HCT116 xenografts and colorectal cancer cell lines and decreased the expression of the urea cycle enzymes, including carbamoyl phosphate synthase 1 (CPS1), arginase 1 (ARG1), ornithine trans-carbamylase (OTC), and ODC. The putrescine levels in both HCT116 xenografts and HCT116 cells decreased after metformin treatment. These results demonstrate that metformin inhibited CRC cell proliferation via activating AMPK/p53 and that there was an association between metformin, urea cycle inhibition and a reduction in putrescine generation.

Homoharringtonine inhibits melanoma cells proliferation in vitro and vivo by inducing DNA damage, apoptosis, and G2/M cell cycle arrest.

Homoharringtonine (HHT), an approved anti-leukemic alkaloid, has been reported effectively in many types of tumor cells. However, its effect on melanoma cells has not been investigated. And the anti-melanoma mechanism of HHT is still unknown. In this study, we detected the effects of HHT on two melanoma cell lines (A375 and B16F10) and on the A375 xenograft mouse model. HHT significantly inhibited the proliferation of melanoma cells as investigated by the CCK8 method, cell cloning assay, and EdU experiment. HHT induced A375 and B16F10 cells DNA damage, apoptosis, and G2/M cell cycle arrest as proved by TdT-mediated dUTP Nick-End Labeling (TUNEL) and flow cytometry assay. Additionally, the loss of mitochondrial membrane potential in HHT-treated cells were visualized by JC-1 fluorescent staining. For the molecule mechanism study, western blotting results indicated the protein expression levels of ATM, P53, p-P53, p-CHK2, γ-H2AX, PARP, cleaved-PARP, cleaved caspase-3, cleaved caspase-9, Bcl-2, Bax, Aurka, p-Aurka, Plk1, p-Plk1, Cdc25c, CDK1, cyclin B1, and Myt1 were regulated by HHT. And the relative mRNA expression level of Aurka, Plk1, Cdc25c, CDK1, cyclin B1, and Myt1 were ascertained by q-PCR assay. The results in vivo experiment showed that HHT can slow down the growth rate of tumors. At the same time, the protein expression levels in vivo were consistent with that in vitro. Collectively, our study provided evidence that HHT could be considered an effective anti-melanoma agent by inducing DNA damage, apoptosis, and cell cycle arrest.

Establishment and validation of a mathematical diagnosis model to distinguish benign pulmonary nodules from early non-small cell lung cancer in Chinese people.

BACKGROUND: In this study, we aimed to establish and validate a mathematical diagnosis model to distinguish benign pulmonary nodules (BPNs) from early non-small cell lung cancer (eNSCLC) based on clinical characteristics, radiomics features, and hematological biomarkers. METHODS: Medical records from 81 patients (27 BPNs, 54 eNSCLC) were used to establish a novel mathematical diagnosis model and an additional 61 patients (21 BPNs, 40 eNSCLC) were used to validate this new model. To establish a clinical diagnosis model, a least absolute shrinkage and selection operator (LASSO) regression was applied to select predictors for eNSCLC, then multivariate logistic regression analysis was performed to determine independent predictors of the probability of eNSCLC, and to establish a clinical diagnosis model. The diagnostic accuracy and discriminative ability of our model were compared with the PKUPH and Mayo models using the following 4 indices: area under the receiver-operating characteristics curve (ROC), net reclassification improvement index (NRI), integrated discrimination improvement index (IDI), and decision curve analysis (DCA). RESULTS: Multivariate logistic regression analysis identified age, border, and albumin (ALB) as independent diagnostic markers of eNSCLC. In the training cohort, the AUC of our model was 0.740, which was larger than the AUCs for the PKUPH model (0.717, P=0.755) and the Mayo model (0.652, P=0.275). Compared with the PKUPH and Mayo models, the NRI of our model increased by 3.7% (P=0.731) and 27.78% (P=0.008), respectively, while the IDI changed -4.77% (P=0.437) and 11.67% (P=0.015), respectively. Moreover, the DCA demonstrated that our model had a higher overall net benefit compared to previously published models. Importantly, similar findings were confirmed in the validation cohort. CONCLUSIONS: Age, border, and serum ALB levels were independent diagnostic markers of eNSCLC. Thus, our model could more accurately distinguish BPNs from eNSCLC and outperformed previously published models.

Terminal-conjugated non-aggregated constraints of gold nanoparticles on lateral flow strips for mobile phone readouts of enrofloxacin.

Antibiotics abuse now poses a global threat to public health. Monitoring their residual levels as well as metabolites are of great importance, still challenges remain in in situ tracing during the circulation. Herein, taking the typical antibacterial Enrofloxacin (ENR) as a subject, a paper-based aptasensor was tailored by manipulating a duo of aptameric moieties to "sandwich" the target in a lateral-flow regime. To visualize the tight-binding sandwich motif more vividly, an irregular yet robust DNA-bridged gold nanoparticles (AuNPs) proximity strategy was developed with recourse to terminal deoxynucleotidyl transferase, of which the nonaggregate constraining feature was unveiled via optical absorption and scanning probe topography. This complex performed exceptionally better in the test strip context than single-particle tags, leading to an enhanced on-chip focusing. Rather than qualitative color developing, further efforts were taken to visualize the readouts in a quantitative manner by exploiting the smartphone camera for pattern recognition along with data processing in a professional App. Overall, this prototyped contraption realized a rapid and ultrasensitive quantification of ENR down to 0.1 µg/L along with a broad linear range over 5 orders of magnitude, plus excellent selectivity and precision even for real samples. Such innovative fusion across DNA-structured nanomanufacturing and intelligent perception provides a prospective and invigorating solution to point-of-care inspection.

Multiplexed aptasensing of food contaminants by using terminal deoxynucleotidyl transferase-produced primer-triggered rolling circle amplification: application to the colorimetric determination of enrofloxacin, lead (II), Escherichia coli O157:H7 and tropomyosin.

A colorimetric assay is described for simultaneous detection of multiple analytes related to food safety. It is based on the use of a sandwich aptasensor and terminal deoxynucleotidyl transferase (TdT) which produces a primer for subsequent rolling circle amplification (RCA). Two split aptamer fragments (Apt1 and Apt2) are firstly immobilized, Apt1 on gold nanoparticles (AuNPs), and Apt2 on magnetic beads (MBs). They are then used in a sandwich aptasensor. In the presence of analyte, two probes could specifically recognize target and form a ternary assembly, and the magnetic beads also act to separate rapidly and enrich the target. Then, the extension of template-free DNA is triggered by TdT at the exposed 3'-hydroxy terminals of Apt1. This produces polyA sequences that serve as primers for subsequent RCA. The product of RCA is hybridized with a complementary horse radish peroxidase (HRP) DNA probe. HRP catalyzes the H2O2-mediated oxidation of tetramethylbenzidine (TMB) and forms a blue chromogenic product. After magnetic separation, the absorption values of the blue product in the supernatant are measured at a wavelength of 600 nm. Based on this dual amplification mechanism, the assay was applied to multiplexed determination of enrofloxacin (ENR), lead(II), Escherichia coli O157:H7 and tropomyosin. Exemplarily, ENR is detectable at concentrations down to 2.5 pg mL-1 with a linear range that extends from 1 pg mL-1 to 1 µg·mL-1. The assay was validated by analysis of spiked fish samples. Recoveries range between 87.5 and 92.1%. Graphical abstractSchematic representation of a TdT-RCA based aptasensor for multiple analytes related to food safety. It makes use of sandwich aptasensors and TdT-produced universal primer-triggered RCA reaction. dATP: deoxyadenosine triphosphate, TdT: Terminal Deoxynucleotidyl Transferase, RCA: rolling circle amplification, TMB: 3,3',5,5'-Tetramethylbenzidine.

Hsp90 Interacts With Tm-22 and Is Essential for Tm-22-Mediated Resistance to Tobacco mosaic virus.

The tomato resistance gene Tm-22 encodes a coiled coil-nucleotide binding site-leucine rich repeat type resistance protein and confers effective immune response against tobamoviruses by detecting the presence of viral movement proteins (MPs). In this study, we show that the Nicotiana benthamiana Heat shock protein 90-kD (Hsp90) interacts with Tm-22. Silencing of Hsp90 reduced Tm-22-mediated resistance to Tobacco mosaic virus (TMV) and the steady-state levels of Tm-22 protein. Further, Hsp90 associates with SGT1 in yeast and in plant cells. These results suggest that Hsp90-SGT1 complex takes part in Tm-22-mediated TMV resistance by functioning as chaperone to regulate Tm-22 stability.

In situ analysis of foliar zinc absorption and short-distance movement in fresh and hydrated leaves of tomato and citrus using synchrotron-based X-ray fluorescence microscopy.

BACKGROUND AND AIMS: Globally, zinc deficiency is one of the most important nutritional factors limiting crop yield and quality. Despite widespread use of foliar-applied zinc fertilizers, much remains unknown regarding the movement of zinc from the foliar surface into the vascular structure for translocation into other tissues and the key factors affecting this diffusion. METHODS: Using synchrotron-based X-ray fluorescence microscopy (µ-XRF), absorption of foliar-applied zinc nitrate or zinc hydroxide nitrate was examined in fresh leaves of tomato (Solanum lycopersicum) and citrus (Citrus reticulatus). KEY RESULTS: The foliar absorption of zinc increased concentrations in the underlying tissues by up to 600-fold in tomato but only up to 5-fold in citrus. The magnitude of this absorption was influenced by the form of zinc applied, the zinc status of the treated leaf and the leaf surface to which it was applied (abaxial or adaxial). Once the zinc had moved through the leaf surface it appeared to bind strongly, with limited further redistribution. Regardless of this, in these underlying tissues zinc moved into the lower-order veins, with concentrations 2- to 10-fold higher than in the adjacent tissues. However, even once in higher-order veins, the movement of zinc was still comparatively limited, with concentrations decreasing to levels similar to the background within 1-10 mm. CONCLUSIONS: The results advance our understanding of the factors that influence the efficacy of foliar zinc fertilizers and demonstrate the merits of an innovative methodology for studying foliar zinc translocation mechanisms.

Hepatitis B virus X protein inhibits tumor suppressor miR-205 through inducing hypermethylation of miR-205 promoter to enhance carcinogenesis.

The infection of hepatitis B virus (HBV) is closely associated with the development of hepatocellular carcinoma (HCC), in which HBV X protein (HBx) plays crucial roles. MicroRNAs are involved in diverse biologic functions and in carcinogenesis by regulating gene expression. In the present study, we aim to investigate the underlying mechanism by which HBx enhances hepatocarcinogenesis. We found that miR-205 was downregulated in 33 clinical HCC tissues in comparison with adjacent noncancerous hepatic tissues. The expression levels of miR-205 were inversely correlated with those of HBx in abovementioned tissues. Then, we demonstrated that HBx was able to suppress miR-205 expression in hepatoma and liver cells. We validated that miR-205 directly targeted HBx mRNA. Ectopic expression of miR-205 downregulated HBx, whereas depletion of endogenous miR-205 upregulated HBx in hepatoma cells. Notably, our data revealed that HBx downregulated miR-205 through inducing hypermethylation of miR-205 promoter in the cells. In terms of function, the forced miR-205 expression remarkably inhibited the HBx-enhanced proliferation of hepatoma cells in vitro and in vivo, suggesting that miR-205 is a potential tumor-suppressive gene in HCC. HBx-transgenic mice showed that miR-205 was downregulated in the liver. Importantly, HBx was able to abrogate the effect of miR-205 on tumor suppression in carcinogenesis. Therefore, we conclude that HBx is able to inhibit tumor suppressor miR-205 to enhance hepatocarcinogenesis through inducing hypermethylation of miR-205 promoter during their interaction. Therapeutically, miR-205 may be useful in the treatment of HCC.

Type I J-domain NbMIP1 proteins are required for both Tobacco mosaic virus infection and plant innate immunity.

Tm-2² is a coiled coil-nucleotide binding-leucine rich repeat resistance protein that confers durable extreme resistance against Tomato mosaic virus (ToMV) and Tobacco mosaic virus (TMV) by recognizing the viral movement protein (MP). Here we report that the Nicotiana benthamiana J-domain MIP1 proteins (NbMIP1s) associate with tobamovirus MP, Tm-2² and SGT1. Silencing of NbMIP1s reduced TMV movement and compromised Tm-2²-mediated resistance against TMV and ToMV. Furthermore, silencing of NbMIP1s reduced the steady-state protein levels of ToMV MP and Tm-2². Moreover, NbMIP1s are required for plant resistance induced by other R genes and the nonhost pathogen Pseudomonas syringae pv. tomato (Pst) DC3000. In addition, we found that SGT1 associates with Tm-2² and is required for Tm-2²-mediated resistance against TMV. These results suggest that NbMIP1s function as co-chaperones during virus infection and plant immunity.

Autophagy contributes to leaf starch degradation.

Transitory starch, a major photosynthetic product in the leaves of land plants, accumulates in chloroplasts during the day and is hydrolyzed to maltose and Glc at night to support respiration and metabolism. Previous studies in Arabidopsis thaliana indicated that the degradation of transitory starch only occurs in the chloroplasts. Here, we report that autophagy, a nonplastidial process, participates in leaf starch degradation. Excessive starch accumulation was observed in Nicotiana benthamiana seedlings treated with an autophagy inhibitor and in autophagy-related (ATG) gene-silenced N. benthamiana and in Arabidopsis atg mutants. Autophagic activity in the leaves responded to the dynamic starch contents during the night. Microscopy showed that a type of small starch granule-like structure (SSGL) was localized outside the chloroplast and was sequestered by autophagic bodies. Moreover, an increased number of SSGLs was observed during starch depletion, and disruption of autophagy reduced the number of vacuole-localized SSGLs. These data suggest that autophagy contributes to transitory starch degradation by sequestering SSGLs to the vacuole for their subsequent breakdown.

Hepatitis B virus X protein protects hepatoma and hepatic cells from complement-dependent cytotoxicity by up-regulation of CD46.

The involvement of hepatitis B virus X protein (HBx) in anti-complement-dependent cytotoxicity (CDC) activity during hepatocarcinogenesis is poorly understood. Here, we report that HBx is able to up-regulate membrane-bound complement regulatory protein CD46 in hepatoma cells and human immortalized liver cells through activating the promoter activity involving cAMP response element-binding protein (CREB)/cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE2)/signal transducers and activators of transcription 3 (STAT3) signaling pathway. In contrast, the down-regulation of CD46 abolishes the resistance capability of hepatoma cells to CDC. Thus, we conclude that HBx contributes to the protection of hepatoma and hepatic cells from CDC by up-regulation of CD46.

Involvement of hepatitis B virus X gene (HBx) integration in hepatocarcinogenesis via a recombination of HBx/Alu core sequence/subtelomeric DNA.

The significance of hepatitis B virus (HBV) DNA-based integration in hepatocarcinogenesis is poorly understood. In the present study, we investigated whether the integration of HBV X gene (HBx) is involved in the event. Our finding showed that the integration of HBx fragment (316-462 bp/262-462 bp) was able to transform human immortalized normal liver LO2 cells using a cell model of HBx-integration. We identified that the recombination, HBx/Alu core sequence/subtelomeric DNA, was required for the transformation, which could be detected in 5 out of 44 clinical HBx-positive hepatocellular carcinoma tissues. Thus, we conclude that HBx integration is involved in the hepatocarcinogenesis.

Elevation of highly up-regulated in liver cancer (HULC) by hepatitis B virus X protein promotes hepatoma cell proliferation via down-regulating p18.

Long noncoding RNAs (lncRNAs) play crucial roles in human cancers. It has been reported that lncRNA highly up-regulated in liver cancer (HULC) is dramatically up-regulated in hepatocellular carcinoma (HCC). Hepatitis B virus X protein (HBx) contributes importantly to the development of HCC. However, the function of HULC in HCC mediated by HBx remains unclear. Here, we report that HULC is involved in HBx-mediated hepatocarcinogenesis. We found that the expression levels of HULC were positively correlated with those of HBx in clinical HCC tissues. Moreover, we revealed that HBx up-regulated HULC in human immortalized normal liver L-O2 cells and hepatoma HepG2 cells. Luciferase reporter gene assay and chromatin immunoprecipitation (ChIP) assay showed that HBx activated the HULC promoter via cAMP-responsive element-binding protein. We further demonstrated that HULC promoted cell proliferation by methyl thiazolyl tetrazolium, 5-ethynyl-2'-deoxyuridine, colony formation assay, and tumorigenicity assay. Next, we hypothesized that HULC might function through regulating a tumor suppressor gene p18 located near HULC in the same chromosome. We found that the mRNA levels of p18 were inversely correlated with those of HULC in the above clinical HCC specimens. Then, we validated that HULC down-regulated p18, which was involved in the HULC-enhanced cell proliferation in vitro and in vivo. Furthermore, we observed that knockdown of HULC could abolish the HBx-enhanced cell proliferation through up-regulating p18. Thus, we conclude that the up-regulated HULC by HBx promotes proliferation of hepatoma cells through suppressing p18. This finding provides new insight into the roles of lncRNAs in HBx-related hepatocarcinogenesis.

Hepatitis B virus X protein modulates oncogene Yes-associated protein by CREB to promote growth of hepatoma cells.

UNLABELLED: Hepatitis B virus X protein (HBx) plays critical roles in the development of hepatocellular carcinogenesis (HCC). Yes-associated protein (YAP), a downstream effector of the Hippo-signaling pathway, is an important human oncogene. In the present article, we report that YAP is involved in the hepatocarcinogenesis mediated by HBx. We demonstrated that the expression of YAP was dramatically elevated in clinical HCC samples, hepatitis B virus (HBV)-infected hepatoma HepG2.2.15 cell line, and liver cancer tissues of HBx-transgenic mice. Meanwhile, we found that overexpression of HBx resulted in the up-regulation of YAP in stably HBx-transfected HepG2/H7402 hepatoma cell lines, whereas HBx RNA interference reduced YAP expression in a dose-dependent manner in the above-mentioned cell lines, suggesting that HBx up-regulates YAP. Then, we investigated the mechanism underlying the up-regulation of YAP by HBx. Luciferase reporter gene assays revealed that the promoter region of YAP regulated by HBx was located at nt -232/+115 containing cyclic adenosine monophosphate response element-binding protein (CREB) element. Chromatin immunoprecipitation (ChIP) demonstrated that HBx was able to bind to the promoter of YAP, whereas it failed to work when CREB was silenced. Moreover, we confirmed that HBx activated the YAP promoter through CREB by electrophoretic mobility shift assay and luciferase reporter gene assays. Surprisingly, we found that YAP short interfering RNA was able to remarkably block the HBx-enhanced growth of hepatoma cells in vivo and in vitro. CONCLUSION: YAP is a key driver gene in HBx-induced hepatocarcinogenesis in a CREB-dependent manner. YAP may serve as a novel target in HBV-associated HCC therapy.

Hepatitis B virus X protein drives multiple cross-talk cascade loops involving NF-κB, 5-LOX, OPN and Capn4 to promote cell migration.

Hepatitis B virus X protein (HBx) plays an important role in the development of hepatocellular carcinoma (HCC). However, the mechanism remains unclear. Recently, we have reported that HBx promotes hepatoma cell migration through the upregulation of calpain small subunit 1 (Capn4). In addition, several reports have revealed that osteopontin (OPN) plays important roles in tumor cell migration. In this study, we investigated the signaling pathways involving the promotion of cell migration mediated by HBx. We report that HBx stimulates several factors in a network manner to promote hepatoma cell migration. We showed that HBx was able to upregulate the expression of osteopontin (OPN) through 5-lipoxygenase (5-LOX) in HepG2-X/H7402-X (stable HBx-transfected cells) cells. Furthermore, we identified that HBx could increase the expression of 5-LOX through nuclear factor-κB (NF-κB). We also found that OPN could upregulate Capn4 through NF-κB. Interestingly, we showed that Capn4 was able to upregulate OPN through NF-κB in a positive feedback manner, suggesting that the OPN and Capn4 proteins involving cell migration affect each other in a network through NF-κB. Importantly, NF-κB plays a crucial role in the regulation of 5-LOX, OPN and Capn4. Thus, we conclude that HBx drives multiple cross-talk cascade loops involving NF-κB, 5-LOX, OPN and Capn4 to promote cell migration. This finding provides new insight into the mechanism involving the promotion of cell migration by HBx.

Aluminum induces neurodegeneration and its toxicity arises from increased iron accumulation and reactive oxygen species (ROS) production.

The neurotoxicity of aluminum (Al) - the most abundant metal element on earth - has been known for years. However, the mechanism of Al-induced neurodegeneration and its relationship to Alzheimer's disease are still controversial. In particular, in vivo functional data are lacking. In a Drosophila model with chronic dietary Al overloading, general neurodegeneration and several behavioral changes were observed. Al-induced neurodegeneration is independent of ß-amyloid or tau-associated toxicity, suggesting they act in different molecular pathways. Interestingly, Drosophila frataxin (dfh), which causes Friedreich's ataxia if mutated in humans, displayed an interacting effect with Al, suggesting Friedreich's ataxia patients might be more susceptible to Al toxicity. Al-treated flies accumulated large amount of iron and reactive oxygen species (ROS), and exhibited elevated SOD2 activity. Genetic and pharmacological efforts to reduce ROS or chelate excess Fe significantly mitigated Al toxicity. Our results indicate that Al toxicity is mediated through ROS production and iron accumulation and suggest a remedial route to reduce toxicity due to Al exposure.

Hepatitis B virus X protein activates CD59 involving DNA binding and let-7i in protection of hepatoma and hepatic cells from complement attack.

Emerging evidence has shown that hepatitis B virus (HBV) X protein (HBx) plays a crucial role in the development of hepatocellular carcinoma. Complement regulatory proteins including CD46, CD55 and CD59 contribute to escape of tumor cells from complement-dependent cytotoxicity (CDC). However, little is known about the potential role of HBx in anti-CDC activity during hepatocarcinogenesis. In the present study, we for the first time report that HBx decreases the sensitivity of hepatoma and hepatic cells to CDC. Coincidentally, we demonstrated that HBx increased the promoter activity of CD59, as well as their messenger RNA and protein levels. Moreover, flow cytometry showed the increased expression level of CD59 protein on the surface of HBx-positive cells. Of interest, we found that HBx up-regulated CD59 by binding with cAMP response element-binding to the promoter region of the CD59 gene using chromatin immunoprecipitation assay. In addition, we showed that HBx up-regulated CD59 by let-7i at post-transcriptional regulation level. Our data showed that the deposition of C5b-9 were decreased on the cell surface in HepG2-X cells relative to HepG2 cells, suggesting that increased CD59 mediated by HBx prevents the formation of functional membrane attack complex. Furthermore, we demonstrated that down-regulation of CD59 was sufficient to abolish the resistance capability of CDC in HBx-positive cells by RNA interference (siRNA) in vitro and in vivo. Thus, we conclude that HBx contributes to cells resistance to CDC through CD59. Therapeutically, CD59 may serve as a target in HBV-associated hepatoma patients.

Aluminium tolerance and high phosphorus efficiency helps Stylosanthes better adapt to low-P acid soils.

BACKGROUND AND AIMS: Stylosanthes spp. (stylo) is one of the most important pasture legumes used in a wide range of agricultural systems on acid soils, where aluminium (Al) toxicity and phosphorus (P) deficiency are two major limiting factors for plant growth. However, physiological mechanisms of stylo adaptation to acid soils are not understood. METHODS: Twelve stylo genotypes were surveyed under field conditions, followed by sand and nutrient solution culture experiments to investigate possible physiological mechanisms of stylo adaptation to low-P acid soils. KEY RESULTS: Stylo genotypes varied substantially in growth and P uptake in low P conditions in the field. Three genotypes contrasting in P efficiency were selected for experiments in nutrient solution and sand culture to examine their Al tolerance and ability to utilize different P sources, including Ca-P, K-P, Al-P, Fe-P and phytate-P. Among the three tested genotypes, the P-efficient genotype 'TPRC2001-1' had higher Al tolerance than the P-inefficient genotype 'Fine-stem' as indicated by relative tap root length and haematoxylin staining. The three genotypes differed in their ability to utilize different P sources. The P-efficient genotype, 'TPRC2001-1', had superior ability to utilize phytate-P. CONCLUSIONS: The findings suggest that possible physiological mechanisms of stylo adaptation to low-P acid soils might involve superior ability of plant roots to tolerate Al toxicity and to utilize organic P and Al-P.