Interactive effects of temperature, pH and phenanthrene on matrix protein nacrein gene expression in Persian Gulf pearl oyster Pinctada radiata

In the present study, the interaction effect of climate change accomplished by phenanthrene as a representative of contaminants was investigated on the expression of nacrein gene in the mantle tissue of Pinctada radiata. To determine the studied gene expression pattern changes, pearl oysters were exposed to isolated/ combined warming in two levels (24 and 28 °C), acidification in two levels (8.1 and 7.6) and phenanthrene concentration in two levels (0 and 8 ng/L) for 4 weeks. Experimental setup was arranged in eight exposure treatments with triplicate aquaria per treatment and each aquaria containing 15 animals in 20 L. Sampling was performed three times, i.e.,24 h 48 h and 28 days after exposure. After 28 days of exposure, although no mortalities were observed in any treatments, the studied parameters caused significant reduction of nacrein expression in isolated exposure except for temperature, double interactions except for temperature and phenanthrene combination, and triple interaction. The quadruple interaction showed no significant effect on nacrein gene expression. These results demonstrated that the decreased seawater pH and elevated temperature in presence of contaminants caused downregulation of the nacrein gene and might impact the quality of pearl and shell of pearl oyster, P. radiata.