CgHb-like modulates the energy metabolism, histone acetylation and inflammatory responses in oysters during Vibrio splendidus stimulation.

Hemoglobin (Hb) is the iron-containing oxygen-transport metalloprotein in red blood cells of vertebrates and some invertebrates. In the present study, a Hb homolog was identified from oyster Crassostrea gigas (defined as CgHb-like). CgHb-like transcripts were detected in all the tested tissues. After Vibrio splendidus stimulation, the mRNA expressions of CgHb-like increased significantly in gills. Recombinant CgHb-like had the ability to bind various pathogen-associated molecular patterns (PAMPs) and bacteria. In gills of CgHb-like-knockdown oysters, the content of lactate and the ratio of NAD+/NADH increased significantly in theglycolysis pathway, the contents of citric acid (CA) and acetyl-CoA (CoASH) decreased significantly, and the levels of histone acetylation decreased significantly after V. splendidus stimulation. In addition, the mRNA expressions of inflammatory cytokines also decreased significantly. The recombinant CgHb-like could significantly promote the growth and survival of bacteria. The results demonstrated that CgHb-like modulated the energy metabolism, histone acetylation and inflammatory responses in oysters in response to V. splendidus stimulation.