ROS meditated paralytic shellfish toxins production changes of Alexandrium tamarense caused by microplastic particles.

A variety of studies have investigated the toxic effects of microplastics (MPs) on microalgae, but few of them considered their influence on dinoflagellate toxins production, which could cause significant ecological safety concerns in coastal areas. This research investigated the impacts of 5 µg L-1 and 5 mg L-1 polystyrene (PS) MPs on the changes of paralytic shellfish toxins (PSTs) production and their relationship with cellular oxidative stress of Alexandrium tamarense, a common harmful algal blooms causative dinoflagellate. The results showed elevation of reactive oxygen species (ROS) levels, activation of antioxidant system and overproduction of PSTs were positively correlated under PS MPs exposure (especially under 5 mg L-1 PS MPs), and the PSTs changes were eliminated by the ROS inhibitor. Further transcriptomic analysis revealed that ROS could enhance biosynthesis of glutamate, providing raw materials for PSTs precursor arginine, accompanied with enhanced acetyl-CoA and ATP production, finally leading to the overproduction of PSTs. Moreover, the oxidative intracellular environments might block the reduction process from STX to C1&C2, leading to the increase of STX and decrease of C1&C2 proportions. This work brings the first evidence that ROS could mediate PSTs production and compositions of Alexandrium under MPs exposure, with important scientific and ecological significance.

Luteolin potentiates low-dose oxaliplatin-induced inhibitory effects on cell proliferation in gastric cancer by inducing G2/M cell cycle arrest and apoptosis.

Although the reduction of oxaliplatin doses may alleviate deleterious side effects of gastrointestinal and gynecological cancer treatment, it also limits the anticancer therapeutic effects. As a high-efficient and low-priced herbal medicine ingredient, luteolin is an agent with a broad spectrum of anticancer activities and acts as a potential enhancer of therapeutic effects of chemotherapy agents in cancer treatment. This study focused on the antitumor effects and mechanism of combined treatment with luteolin and oxaliplatin on a mouse forestomach carcinoma (MFC) cell line. The study used CCK-8 assay, flow cytometry, Annexin V-FITC/PI double staining assay, reactive oxygen species testing assay, mitochondrial membrane potential testing assay, and western blot assay. The results showed that luteolin and oxaliplatin exerted synergistic effects on inhibiting MFC cell proliferation by inducing G2/M cell cycle arrest and apoptosis. Inhibiting the tumor necrosis factor receptor-associated protein 1/phosphorylated-extracellular-regulated protein kinases1/2/cell division cycle 25 homolog C/cyclin-dependent kinase-1/cyclin B1 pathway was indispensable to the combined treatment with luteolin and oxaliplatin to induce G2/M cell cycle arrest. In addition, luteolin increased oxidative stress in MFC cells treated with a low dose of oxaliplatin. The combined therapy damaged mitochondrial membrane potential and regulated BCL-2-associated X protein and B-cell lymphoma 2 protein expression, leading to apoptosis. Findings of the present study suggest that luteolin may be a qualified chemotherapy enhancer to potentiate the anticancer effects of low-dose oxaliplatin in MFC cells. This work provides a theoretical foundation for future research on applications of luteolin in clinical chemotherapy.

The effect of naphthenic acids on physiological characteristics of the microalgae Phaeodactylum tricornutum and Platymonas helgolandica var. tsingtaoensis.

Naphthenic acids (NAs) account for 1-2% of crude oil and represent its main acidic component. However, the aquatoxic effects of NAs on marine phytoplankton and their ecological risks have remained largely unknown. Using the marine microalgae Phaeodactylum tricornutum and Platymonas helgolandica var. tsingtaoensis as the target, we studied the effects of NAs on their growth, cell morphology and physiological characteristics. The cell density decreased as the concentrations of NAs increased, indicating that they had an adverse effect on growth of the investigated algae in a concentration-dependent manner. Moreover, scanning electron microscopy revealed NAs exposure caused damage such as deformed cells, shrunken surface and ruptured cell structures. Exposure to NAs at higher concentrations for 48 h significantly increased the content of chlorophyll (Chl) a and b in P. tricornutum, but decreased their levels in P. helgolandica var. tsingtaoensis. NAs with concentrations no higher than 4 mg/L gradually enhanced the Chl fluorescence (ChlF) parameters and decreased the ChlF parameters at higher concentrations for the two marine microalgae. Additionally, NAs induced hormesis on photosynthetic efficiency of the two microalgae and also have the species difference in their aquatic toxicity. Overall, the results of this study provide a better understanding of the physiological responses of phytoplankton and will enable better risk assessments of NAs.

Protective roles of cornuside in acute myocardial ischemia and reperfusion injury in rats.

Cornuside is a secoiridoid glucoside isolated from the fruit of Cornus officinalis SIEB. et ZUCC. In this study, we investigated the anti-myocardial ischemia and reperfusion (I/R) injury effects of cornuside in vivo and elucidated the potential mechanism. Rat models of myocardial I/R were induced by coronary occlusion followed by reperfusion or by Isoproterenol (ISO), treatment of rats with cornuside (20 and 40 mg/kg, i.v.) protected the animals from myocardial I/R injury as indicated by a decrease in infarct volume, improvement in hemodynamics and reduction of myocardial damage severity. Treatment with cornuside also attenuated polymorphonuclear leukocytes (PMNs) infiltration, decreased myeloperoxidase (MPO) activity in the heart, lowered serum levels of pro-inflammatory factors and reduced phosphorylated IκB-α and nuclear factor kappa B (NF-κB) levels in the heart. Additionally, cornuside was shown to have remarkable antioxidant activity and inhibited ISO-induced myocardial cell necrosis. Thus, cornuside appeared to protect the rat from myocardial I/R injury by acting as an anti-inflammatory agent. These findings suggested that cornuside may be used therapeutically in the setting of myocardial I/R where inflammation and oxidant injury are prominent.

[Effects of artificial seawater with different N/P ratio on early development of Laminaria japonica embryo spore].

The embryo spores of Laminaria japonica were cultured in artificial seawater with different N/P ratio to observe their early development. 80 percent of the spores cultivated in whole-ingredient artificial seawater developed normally, but the time of spore germination and gametophyte formation was lagged significantly and the amount of female gametes was significantly higher than that of male gametes (P<0.001), as compared to the control cultivated in natural seawater. Artificial seawater with different N/P ratio showed different effects on the spore germination rate. The artificial seawater with N/P > 15 decreased the spore germination rate, while that without N or P inhibited the spore germination significantly (P<0.001). It was concluded that L. japonica spores could develop normally in artificial seawater, but their germination rate was affected by the seawater N/P. The deficiency of N or P in artificial seawater would lag the time of gametophyte formation and affect the differentiation ratio of female-male gametes.

Effects of scorpion venom bioactive polypolypeptides on platelet aggregation and thrombosis and plasma 6-keto-PG F1alpha and TXB2 in rabbits and rats.

Effects of scorpion venom active polypeptide (SVAP) from scorpion venom of Buthus Martensii Karsch of Chinese on platelet aggregation in ex vivo and vitro in rabbits, thrombosis in carotid artery of rats and plasma 6-keto-PG F1alpha and TXB2 in rats were studied by the turbidimetry, the duplicated thrombosis model by electrostimulation and RIA, respectively. The results showed that SVAP 0.125, 0.25, 0.5 mg/ml inhibited significantly the rabbit platelet aggregation triggered by 0.3 U/ml thrombin, 10 microM ADP in vitro (P<0.05 or 0.01) and SVAP at the dose of 0.32, 0.64 mg/kg iv prolonged distinctively the occlusion time of thrombosis that were induced by electrical stimulation. Increased% of 0.16, 0.32 and 0.64 mg/kg were 30.16, 71.74, 98.27%, respectively, which showed a good dose-effect relationship. SVAP 0.22 mg/ml (in vitro) or 0.2, 0.4 mg/kg (in ex vivo) could obviously increase the plasma concentration of 6-keto-PG F1alpha, but slightly effect rats plasma concentration of TXB2 in vitro and in ex vivo and significantly increase of value of PG I2/TXA2, which suggested that the mechanism of the antithrombotic action of SVAP is related to the resistance against platelet aggregation, increase of the concentration of PG I2 in plasma.