Abstract
Gender differences in the hemocyte immune response of Hong Kong oyster Crassostrea hongkongensis to Vibrio harveyi and lipopolysaccharide (LPS) infection exist. To determine if a gender difference also exists, we use a 1H NMR-based metabolomics method to investigate responses in C. hongkongensis hepatopancreas tissues to V. harveyi and LPS infection. Both infections induced pronounced gender- and immune-specific metabolic responses in hepatopancreas tissues. Responses are mainly presented in changes in substances involved in energy metabolism (decreased glucose, ATP, and AMP in males and increased ATP and AMP in LPS-infected females), oxidative stress (decreased glutathione in males and decreased tryptophan and phenylalanine and increased choline and proline in LPS-infected females), tricarboxylic acid (TCA) cycle (decreased α-ketoglutarate acid and increased fumarate in LPS-infected males, and decreased fumarate in LPS-infected females), and osmotic regulation (decreased trigonelline and increased taurine in V. harveyi-infected males and decreased betaine in V. harveyi-infected females). Results suggest that post-spawning-phase male oysters have a more significant energy metabolic response and greater ability to cope with oxidative stress than female oysters. We propose that the impact of oyster gender should be taken into consideration in the aftermath of oyster farming or oyster disease in natural seas.