Differential Responses of the Nitric Oxide Synthase (NOS) Gene to Immunological Challenges in Noble Scallop Chlamys nobilis

Abstract

AbstractNitric oxide synthase (NOS) plays important roles in the immune system of animals. As an important marine bivalve cultured in south China, the noble scallop Chlamys nobilis is subject to diseases of various kinds, leading to decrease harvest. To investigate whether NOS in the noble scallop (hereafter, CnNOS) plays a significant role in immune defense, the full‐length open‐reading frame (ORF) of the CnNOS gene was cloned, and its expression levels in different tissues were determined. The complementary DNA nucleotide sequence of CnNOS encompassed 5,345 bp, with a full‐length ORF of 4,647 bp. The gene consisted of the typical NOS structure, including an NOS domain, a flavodoxin 1 domain, a flavin adenine dinucleotide binding domain, and a conservative nicotinamide adenine dinucleotide binding domain. Subsequently, transcript levels of CnNOS in hemocytes were determined by real‐time quantitative reverse transcription PCR, indicating that CnNOS expression was significantly up‐regulated in noble scallops injected with different immunostimulants, including lipopolysaccharides; the synthetic double‐stranded RNA, polyinosinic: polycytidylic acid; and Vibrio parahaemolyticus. The present results suggest that the CnNOS might play a crucial role in the noble scallop's defense against exogenous stimuli.