Effects of manganese and zinc on the growth process of Phytophthora nicotianae and the possible inhibitory mechanisms.

BACKGROUND: Phytophthora nicotianae is a fungal soil-borne pathogen that damages various plant species. Mancozeb and Zineb, fungicides containing manganese (Mn) and zinc (Zn) as the main components, are widely used to control the diseases caused by Phytophthora. However, the inhibition mechanism is still unclear. The purpose of this study was to examine the effects of Mn and Zn on P. nicotianae and to determine possible inhibitory mechanisms of Mn and Zn on sporangiogenesis of P. nicotianae. METHODS: The mycelial growth, sporangium generation, zoosporogenesis and zoospore germination of P. nicotianae were observed under Mn and Zn treatments. The gene (csn4 and csn7) expression levels of P. nicotianae in different growth stages were examined. Csn4 and csn7 gene expression, superoxide dismutase (SOD) activity, catalase (CAT) activity and malondialdehyde (MDA) content were tested at the stage of sporangiogenesis under different Mn and Zn concentrations. RESULTS: Mycelial growth of P. nicotianae was significantly inhibited by Mn from ≥1 mg/L concentration and by Zn from ≥10 mg/L. The sporangia production, sporangia release, and zoospore germination of P. nicotianae were significantly reduced by Mn at all concentrations, while treatment with Zn from ≥0.5 mg/L concentration significantly inhibited the same processes. At the same concentration, the inhibition rate of Mn on the growth process of P. nicotianae was higher than that of Zn. The csn4 and csn7 gene transcription of P. nicotianae were significantly reduced by all treatments with Mn and Zn at the stage of sporangiogenesis. With the increase of Mn concentration, the activities of SOD and CAT increased to maxima and then decreased, and the content of MDA gradually increased during sporangiogenesis of P. nicotianae. The sporangia production of P. nicotianae was significantly positively correlated with the expression levels of the genes csn4 and csn7. CONCLUSION: The inhibitory effect of Mn on the growth process of P. nicotianae was stronger than that of Zn, especially on sporangiogenesis and zoosporogenesis. A possible mechanism of the inhibitory effect on sporangiogenesis of P. nicotianae was that Mn and Zn acted by inhibiting the expression levels of the genes csn4 and csn7 and by affecting antioxidant enzyme activity (further resulting in lipid peroxidation) in the sporangium of P. nicotianae.

[Effects of wine processed Rheum palmatum on tissue distribution of aloe-emodin, rhein and emodin in rats].

Under the traditional processing theory "wine processing could promote the efficacy", Rhubarb after wine processing could treat the upper energizer diseases such as red swelling, and breath sores. Processing changes the medicinal properties of rhubarb, and thus results in different focuses in clinical application. In this study, a sensitive and specific method was developed for the determination of aloe-emodin, rhein and emodin in rats tissue. Rhubarb raw materials and its wine processed decoction were given to SD rats respectively by gavage administration, and then the contents of aloe-emodin, rhein and emodin in the tissues (heart, lung, brain, liver, kidney) were determined by HPLC-MS to explore the effect of wine processing on free anthraquinones in rat tissues. Experimental results showed that wine processing can significantly change the distribution of aloe emodin, rhein and emodin in rats in vivo, and the distribution of these components was increased in heart and lung tissues.There was no significant change of distribution in the liver and the kidney as compared with raw product group, and these three ingredients were not detected in the brain, indicating that aloe-emodin, rhein, emodin can not pass through the blood brain barrier.Therefore, wine processing had greater effect on distribution of free anthraquinones in rat tissues.This also verified the theory of traditional Chinese medicine, providing experimental basis for rhubarb processing mechanism.

Expression, purification, and characterization of a novel acid phosphatase that displays protein tyrosine phosphatases activity from Metarhizium anisopliae strain CQMa102.

The protein tyrosine phosphatase (PTPase) plays an important role in insect immune system. Our group has purified a type of acid phosphatase that could specifically dephosphorylate trans-Golgi p230 in vitro. In order to study this phosphatase further, we have identified and cloned the phosphatase gene from a locust specific Metarhizium anisopliae Strain CQMa102. The CQMa102 phosphatase was expressed in Pichia pastoris to verify its protease activity. The molecular weight (MW) and the isoelectric point (pI) of the phosphatase were about 85 kDa and 6.15, respectively. Substrate specificity evaluation showed that the purified enzyme exhibited high activity on O-phospho-L-tyrosine. At its optimal pH of 6.5 and optimum temperature of 70 °C, the protein showed the highest activity respectively. It can be activated by Ca2+, Mg2+, Mn2+, Ba2+, Co2+ and phosphate analogs, but inhibited by Zn2+, Cu2+, fluoride, dithiothreitol, ß-mercaptoethanol and N-ethylmaleimide.

Identification of ACTG2 functions as a promoter gene in hepatocellular carcinoma cells migration and tumor metastasis.

Metastatic hepatocellular carcinoma (HCC) remains a mostly incurable disease. The fact that the identity of the mechanisms that regulate metastasis in HCC is known hampers the development of anti-metastatic therapies. Currently, there is no effective treatment for HCC once it is progressed to metastatic stage. Therefore, further study to elucidate the molecular mechanism underlying the metastasis of HCC is urgently required for the improvement of HCC treatment. Here, we describes actin gamma smooth muscle 2 (ACTG2) over-express in HCC and demonstrates high-expression of ACTG2 as a promising therapeutic target in HCC metastasis. The use of shRNA to knock-down ACTG2 impaired cells migration and invasion in vitro. Moreover, silencing of ACTG2 causes almost complete inhibition of metastasis in vivo. In contrast, overexpression ACTG2 significantly enforces HCC cells migration and metastasis. Finally, ACTG2 boosts the metastatic potential of HCC cells in a Notch homolog 1 (Notch1) dependent manner. Collectively, our study reveals a critical role of ACTG2 in HCC tumor metastasis, and renders it a novel target for the treatment of HCC.

A novel GFP-based approach for screening biocontrol microorganisms in vitro against Dothistroma septosporum.

Dothistroma septosporum is the causal agent of Dothistroma needle blight of pine trees. A novel green fluorescent protein (GFP)-based screening method was developed to assess the potential of microorganisms for biocontrol of Dothistroma. The screen utilizes GFP expression as an indicator of metabolic activity in the pathogen and hygromycin resistance selection to determine if the interaction is fungistatic or fungicidal. Results suggested that six of eight Trichoderma isolates tested have the potential to control Dothistroma in vitro, via a fungicidal action. Because D. septosporum produces a broad-spectrum toxin, dothistromin, the inhibition of Trichoderma spp. by D. septosporum was determined by growth rate measurements compared to controls. Inhibition of the Trichoderma spp. ranged from no inhibition to 30% inhibition and was influenced by the assay medium used. The GFP screening method was also assessed to determine if it was suitable for screening bacteria as potential biocontrol candidates. Although a method involving indirect-contact had to be used, two of four Bacillus strains showed antagonistic activity against D. septosporum in vitro, via a fungistatic interaction. The four bacterial strains inhibited D. septosporum growth by 14.0 to 39.8%. This GFP-based method represents a novel approach to screening fungi and bacteria for antagonistic activity.