Abstract
Okadaic acid (OA) is produced by dinoflagellates during harmful algal blooms and is a diarrhetic shellfish poisoning toxin. This toxin is particularly problematic for bivalves that are cultured for human consumption. This study aimed to reveal the effects of exposure to OA on the immune responses of bay scallop, Argopecten irradians. Various immunological parameters were assessed (total hemocyte counts (THC), reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), lactate dehydrogenase (LDH), and nitric oxide (NO) in the hemolymph of scallops at 3, 6, 12, 24, and 48 h post-exposure (hpe) to different concentrations of OA (50, 100, and 500 nM). Moreover, the expression of immune-system-related genes (CLT-6, FREP, HSP90, MT, and Cu/ZnSOD) was also measured. Results showed that ROS, MDA, and NO levels and LDH activity were enhanced after exposure to different concentrations of OA; however, both THC and GSH decreased between 24–48 hpe. The expression of immune-system-related genes was also assessed at different time points during the exposure period. Overall, our results suggest that exposure to OA had negative effects on immune system function, increased oxygenic stress, and disrupted metabolism of bay scallops.
Highlights
Harmful algal blooms (HABs), caused by pollution of water bodies and global climate change, can result in ecological and economic losses in coastal areas [1]
The main marine phycotoxins which can be consumed by humans, causing a variety of gastrointestinal and neurological illnesses through the food chain are shellfish toxins, including paralytic shellfish poisoning (PSP), diarrhetic shellfish poisoning (DSP), amnesic shellfish poisoning (ASP), neurotoxic shellfish poisoning (NSP), and azaspiracid shellfish poisoning (AZP) [3]
Selective inhibitor of serine/threonine phosphatases, has been shown to be cytotoxic in a var Previous reports revealed that constant contact with okadaic acid (OA) induced chromosome loss, apoptosis, cell lines [20]
Summary
Harmful algal blooms (HABs), caused by pollution of water bodies and global climate change, can result in ecological and economic losses in coastal areas [1]. HABs have various negative impacts on public health and threaten the aquaculture industry [2], as they cause mass mortality of cultivated animals from the algal toxins they produce [1]. The DSP toxins include okadaic acid (OA), the dinophysistoxins-1 (DTX-1), DTX22, DTX-3, and their derivative forms [4]. These are produced by some microalgae of the genera Dinophysis and Prorocentrum, such as P. lima, P. concavum, P. maculosum, D. acuminata, P. rhathymum, and D. fortii etc. Huang et al [3] revealed that P. lima, a dinoflagellate producing
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