ABSTRACT
The particles suspended in seawater have great influence on pollutant migration and transformation in marine environment, while the lipophilic algae toxins enriched by the particles suspended in seawater will lead more serious toxicity to marine filter feeders. In this study, a new method was developed for the simultaneous determination of eight lipophilic algae toxins in suspended particles by ultra performance liquid chromatography-tandem mass spectrometry ( UPLC-MS/MS ) . After extracted with methanol by ultrasonic-assisted extraction, the sample was separated on an Acquity UPLC BEH C18 column (50 mm×2. 1 mm, 1. 7 μm) using gradient elution of acetonitrile and water containing 5 mmol/L ammonium acetate as eluent modifiers. The qualitative and quantitative analyses were carried out by electrospray ionization ( ESI) tandem mass spectrometry in multiple reaction monitoring ( MRM) mode. Under the optimal conditions, satisfactory precision (relative standard deviations (RSD≤14. 1%), recoveries (83. 8%-110. 4%) and detection limits (2. 9-103 pg/g) of the method were achieved. Good linearity (R2≥0. 99) was also obtained for all studied analytes. Then, the method was applied to determine the amounts of the eight lipophilic marine toxins in authentic suspended particle samples collected from Qingdao near-shore area. Pectenotoxin 2 ( PTX2 ) was detected in the samples from Shilaoren beach and No. 3 bathing beach with concentration ranges of 717 and 790 pg/g, respectively.
ABSTRACT
We previously reported that the p53 tumor suppressor protein plays an essential role in the induction of tetraploid G1 arrest in response to perturbation of the actin cytoskeleton, termed actin damage. In this study, we investigated the role of p53, ataxia telangiectasia mutated protein (ATM), and catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) in tetraploid G1 arrest induced by actin damage. Treatment with actin-damaging agents including pectenotoxin-2 (PTX-2) increases phosphorylation of Ser-15 and Ser-37 residues of p53, but not Ser-20 residue. Knockdown of ATM and DNA-PKcs do not affect p53 phosphorylation induced by actin damage. However, while ATM knockdown does not affect tetraploid G1 arrest, knockdown of DNA-PKcs not only perturbs tetraploid G1 arrest, but also results in formation of polyploidy and induction of apoptosis. These results indicate that DNA-PKcs is essential for the maintenance of actin damage induced-tetraploid G1 arrest in a p53-independent manner. Furthermore, actin damage-induced p53 expression is not observed in cells synchronized at G1/S of the cell cycle, implying that p53 induction is due to actin damage-induced tetraploidy rather than perturbation of actin cytoskeleton. Therefore, these results suggest that p53 and DNA-PKcs independently function for tetraploid G1 arrest and preventing polyploidy formation.