Histological, physiological, and transcriptomic responses of hepatopancreas to air exposure in asian freshwater clam Corbicula fluminea

Abstract

Corbicula fluminea (C. fluminea) is an important freshwater economy shellfish in China, but it often suffers from air exposure during transportation. In this study, we investigated the histological, physiological (mainly including respiratory metabolism, antioxidant capacity, and immune function), and transcriptomic responses of hepatopancreas in C. fluminea to different times of air exposure. At histological level, air exposure caused vacuolation of digestive cells (24–96 h) and enlargement of digestive tubule lumen (6–96 h) in hepatopancreas. At physiological level, the activities of enzymes related to glycolysis (hexokinase and pyruvate kinase) and anaerobic respiration (lactate dehydrogenase) were increased first (6–24 h) of air exposure, then came back to normal level or even decreased. The activity of aerobic respiration-related enzyme (succinic dehydrogenase) began to reduce from 24 h of air exposure. The activities of antioxidant enzymes (superoxide dismutase and catalase) were enhanced during 6–48 h of air exposure and then returned to control level or even inhibited. The content of malondialdehyde (MDA) increased from 96 h of air exposure. The activities of immune-related enzymes (acid phosphatase and alkaline phosphatase) increased during 6–48 h, then returned to normal or began to decline. At transcriptome level, 44 differentially expressed genes (DEGs) in the hepatopancreas were identified after 96-h air exposure. Among these DEGs, 8 were associated with glycolysis, TCA cycle, immune, and antioxidant, and were downregulated after 96-h air exposure. Taken together, these findings illuminated the response of C. fluminea to air exposure at histological, physiological, and transcriptomic levels, which will be beneficial to the aquaculture and transportation of C. fluminea.

Transcriptome Analysis of Juvenile Black Rockfish Sebastes schlegelii under Air Exposure Stress

“…Transcriptome sequencing methods have been employed to detect the gene expression profiles of aquatic animals under air exposure [12][13][14]. For instance, the transcriptome of the Eriocheir sinensis (Chinese mitten crab) under air exposure is a common stressor for this species, particularly during the periods of harvest and transportation [12].…”

“…For instance, the transcriptome of the Eriocheir sinensis (Chinese mitten crab) under air exposure is a common stressor for this species, particularly during the periods of harvest and transportation [12]. Another study investigated the effects of air exposure on the hepatopancreatic tissue of clams, including changes in tissue structure, physiological responses (mainly including respiratory metabolism, antioxidant capacity, and immune function), and alterations in the transcriptome [13]. Furthermore, the majority of the literature has focused on the physiological responses, behavioral changes, and survival rates of fish under air exposure [15][16][17][18][19][20].…”