Uv mini 1240 uv spectrophotometer

Ca²⁺-ATPase assay kit (Genmed Scientifics Inc., USA) were used to measure Ca²⁺-ATPase activities according to the manufacturer’s protocol. The intracellular enzymes activities with and without MPEF treatment were determined by an APIZYM kit (BioMérieux Co, France) monitoring 19 enzymatic activities from a complex system. Substrates were mixed with the cell suspension and incubated at 37 °C for 4 h, and colors were developed by adding reagent of ZYMA and AYMB [34 ]. The color changes were measured by a UV-mini-1240 UV spectrophotometer (Shimadzu, Japan), and enzyme activities were expressed as a percentage of color changes.
SOD, Catalase and GSH-Px Assay Kit (Sigma) were used to detect the changes of SOD, CAT and GSH-Px activities after MPEF treatment. All results were expressed as relative enzyme activity (R%),
$\mathrm{R}\mathrm{\%}=\frac{A}{A_0}$
where A represents the enzyme activity of MPEF-treated samples, A₀ represents the enzyme activity of samples without MPEF treatment.

The samples were centrifuged at 4,500 r/min for 15 min using an Avanti JXN-30 floor-standing centrifuge (Beckman, USA). The supernatant was diluted by 200 times, then 1 ml of the diluted solution was added with 5 ml of G250 Coomassie Brilliant Blue, mixed uniformly, and the absorbance was measured at 595 nm using an UVmini-1240 UV Spectrophotometer (Shimadzu, Japan). The samples were measured within 2–30 min. BSA was used as the standard curve to calculate the protein content.

80 nm Al₂O₃ powder (99.99%, Beijing dekedaojin technology Co., Ltd., Beijing, China) was used, which should be dried at 60 °C to constant weight before use. Artificial seawater (ASW) was prepared according to the artificial seawater formula of Bidwell and Spotte [22 ], salinity(S) = 31.50, pH = 8.00. Natural seawater (NSW) was collected from Xiaogao Fishing Port in Fujian Province, China. The concentration of total organic carbon (TOC) was 117 μmol/L, analyzed by TOC-VCPH total organic carbon analyzer (Shimadzu Co., Kyoto, Japan). S was 29.8 at 25 °C by Cond 3110 conductivity meter (WTW Co., Munich, Germany). pH was 7.95 at 25 °C by pH meter (WTW Co., Munich, Germany). The absorbances (A) of nano-Al₂O₃ suspensions were test by UV mini-1240 UV spectrophotometer (Shimadzu Co., Kyoto, Japan).