Characterization of the Domoic Acid Uptake Mechanism of the Mussel (Mytilus galloprovincialis) Digestive Gland

Abstract

Cultures of the mussel Mytilus galloprovincialis are frequently affected by accumulation of the amnesic shellfish poisoning toxin domoic acid (DA). This species is characterized by a fast uptake and release of the toxin. In this work, the main characteristics of the uptake mechanism have been studied by incubation of digestive gland thin slices in media with different composition and DA concentration. DA uptake seems to follow Michaelis–Menten kinetics, with a very high estimated KM (1722 µg DA mL−1) and a Vmax of 71.9 µg DA g−1 h−1, which is similar to those found for other amino acids in invertebrates. Replacement of NaCl from the incubation media by Cl-choline (Na+-free medium) did not significantly reduce the uptake, but replacement by sorbitol (Na+-free and Cl−-depleted medium) did. A new experiment replacing all chlorides with their equivalent gluconates (Na+- and Cl−-free medium) showed an important reduction in the uptake that should be attributed to the absence of chloride, pointing to a Na+-independent, Cl− (or anion-) dependent transporter. In media with Na+ and Cl−, neither decreasing the pH nor adding cyanide (a metabolic inhibitor) had significant effect on DA uptake, suggesting that the transport mechanism is not H+- or ATP-dependent. In a chloride depleted medium, lowering pH or adding CN increased the uptake, suggesting that other anions could, at least partially, substitute chloride.

Occurrence and Seasonal Monitoring of Domoic Acid in Three Shellfish Species from the Northern Adriatic Sea

“…The differences elaborated above are species-specific and can be attributed to different accumulation [16,34,35] and elimination rates [18,22,36], gut assimilation [16,37], tissue The presence of DA in bivalve and ascidian species investigated in this study and the demonstration of differences between their DA accumulation are in line with the previous results obtained for naturally contaminated bivalves gathered from various world seas. Differences in DA accumulation between marine species collected at the same time at the same locality were observed by Ujević et al [12] in rough cockle Acanthocardia tuberculata and smooth clam Callista chione collected from the Cetina River estuary in the Central Adriatic Sea.…”

“…The differences elaborated above are species-specific and can be attributed to different accumulation [16,34,35] and elimination rates [18,22,36], gut assimilation [16,37], tissue distribution [19,20,22], and environmental conditions [38]. DA depuration in bivalves is usually explained by two kinetic models [20].…”

“…There are differences in the occurrence and concentration of DA between species, even when the latter are exposed to the same environmental influences [12][13][14][15]. These differences are attributed to the differences in DA absorption and depuration rates [16]. Some species such as M. edulis [17], M. galoprovincialis [18], Mesodesma donacium [19], and Argopecten purpuratus [20] depurate DA very quickly, unlike Siliqua patula [21] and Pecten maximus [22], which retain this phycotoxin for a long period of time.…”

Toxicological Evaluation of Acetylsalicylic Acid in Non-Target Organisms: Chronic Exposure on Mytilus galloprovincialis (Lamarck, 1819)

“…This barrier can be crossed both by substances important for the organism and contaminants present in water ( Canesi et al, 2012 ; Phuong et al, 2017 ; Azizi et al, 2018 ). Despite that gills are the primary site of contact with the pollutants, as reported by many authors, the main target of their accumulation and detoxification in bivalve molluscs is represented by the digestive gland ( Faggio et al, 2016 ; Blanco et al, 2021 ; Stollberg et al, 2021 ). In addition, the digestive gland is also involved in the metabolism of heavy metals ( Viarengo et al, 1981 ; Caricato et al, 2018 ).…”