Effects of elevated CO2 concentration on silicatein gene expression and ability to filtering diatom Natzchia closterum of marine sponge Hymeniacidon perlevis
LI Dongzi1, WANG Xiaoyu2, XU Ming2, SHEN Sisi1, DING Xiaohan1, GUO Junning1, LI Juncheng1, ZHANG Shijie1, FU Wantao1,3*
1.College of Marine Science and Environment,Dalian Ocean University, Dalian 116023, China; 2.College of Fisheries and Life Science, Dalian Ocean University, Dalian 116023, China; 3.Key Laboratory of Offshore Marine Environmental Science and Technology of Liaoning Province’s University, Dalian 116023, China
Abstract: Marine sponge Hymeniacidonperlevis was held in a 25 L inter-tidal zone ecological environment simulation system and exposed to CO2 level of 500, 750, and 1000 mg/L prepared by an air bag at a rate of 0 (control group) and 25 g of sponge to investigate effect of elevated CO2 concentration on silicatein gene expression in marine sponge. Then the marine sponge recovered for 1 h from the stress of elevated atmospheric CO2 concentration were reared in a 500 mL Erlenmeyer flask containing diatom Natzchiaclosterum at (105.5±8.6)×106 cells/mL at 20 ℃ and light intensity of 80 μmol /(m2·s) to probe into effect of high CO2 level on ability to filter the diatom of sponge. The results showed that there were 24.8%, 14.8% and 19.2% higher silicatein gene expression levels in the marine sponge exposed to atmospheric CO2 concentration of 500 mg/L at 12, 24 and 48 h than those in the control group (CO2 concentration of 390 mg/L), 40.0%, 71.9%, and 82.3% lower in the marine sponge exposed to atmospheric CO2 concentration of 750 mg/L than those in the control group and 55.2%, 83.6%, and 80.8% lower in the marine sponge exposed to atmospheric CO2 concentration of 1000 mg/L CO2 than those in the control group. The marine sponge recovered for 1 h from the 24 h stress of elevated atmospheric CO2 concentration in the control group had average filtering rates (FR) of 198.2×104 cells /(h·g)and clearance rates (CR) of 4.09 mL/(h·g), as 104.8% and 96.6% in 500 mg/L CO2 group, 58.5% and 65.3% in 750 mg/L CO2, and 30.8% and 20.0% in 1000 mg/L CO2 in as those the control group within 24 h. The findings demonstrated that above 750 mg/L CO2 concentration led to markedly inhibit silicatein gene expression in the marine sponge and to result in decrease in FR and CR of the sponge.