Changes in Subcellular Responses in the Digestive Gland of the Freshwater Mussel <i>Unio crassus</i> from a Historically Contaminated Environment

Utilizing a multi-biomarker approach, we assessed the potential adverse effects of pollutants on subcellular responses in the digestive gland of the freshwater mussel <i>Unio crassus</i> from a historically contaminated lowland section (KIZ) of the river Mrežnica compared to its less imp...

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Main Authors: Zoran Kiralj, Zrinka Dragun, Jasna Lajtner, Krešimira Trgovčić, Tatjana Mijošek Pavin, Bruno Bušić, Dušica Ivanković
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Fishes
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Online Access:https://www.mdpi.com/2410-3888/10/7/317
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author Zoran Kiralj
Zrinka Dragun
Jasna Lajtner
Krešimira Trgovčić
Tatjana Mijošek Pavin
Bruno Bušić
Dušica Ivanković
author_facet Zoran Kiralj
Zrinka Dragun
Jasna Lajtner
Krešimira Trgovčić
Tatjana Mijošek Pavin
Bruno Bušić
Dušica Ivanković
author_sort Zoran Kiralj
collection DOAJ
description Utilizing a multi-biomarker approach, we assessed the potential adverse effects of pollutants on subcellular responses in the digestive gland of the freshwater mussel <i>Unio crassus</i> from a historically contaminated lowland section (KIZ) of the river Mrežnica compared to its less impacted upstream karstic section (REF) and their seasonality (spring vs. autumn). This approach accounted for the diverse modes of action of pollutants by including biomarkers of metal exposure (metallothioneins, MT), general stress (total cytosolic proteins, TP), antioxidative capacity (catalase, CAT; glutathione, GSH; glutathione-S-transferase, GST), oxidative damage (malondialdehyde, MDA), and neurotoxicity (acetylcholinesterase, AChE). Only in spring, MT concentrations were 15% higher at the REF site (4.38 ± 1.06 µg mg proteins<sup>−1</sup>) compared to the KIZ site (3.69 ± 0.63 µg mg proteins<sup>−1</sup>), likely related to elevated Cd bioaccumulation due to the karstic substrate. Regardless of the season, mussels from KIZ showed consistently lower TP and GSH, with significantly higher CAT, GST, and MDA levels, indicating elevated stress, activation of antioxidant defenses, and oxidative damage from chronic exposure to pro-oxidant pollutants, including metal(loid)s and organic contaminants (e.g., ibuprofen, nicotine). Compared to the REF site, AChE activity at the KIZ site was higher in late spring and lower in early autumn, indicating seasonal variability in AChE activity at the contamination-impacted location driven by fluctuating exposure to neurotoxicants, such as drugs and insecticides. Overall, biomarker responses indicated that mild historical pollution, reinforced by current low-capacity sources, has an observable impact on mussel health, posing long-term risks to sediment-dwelling aquatic organisms.
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spelling doaj-art-d3c6ed0e788549d5a30dc99f3ce1ab9a2025-08-20T02:45:38ZengMDPI AGFishes2410-38882025-07-0110731710.3390/fishes10070317Changes in Subcellular Responses in the Digestive Gland of the Freshwater Mussel <i>Unio crassus</i> from a Historically Contaminated EnvironmentZoran Kiralj0Zrinka Dragun1Jasna Lajtner2Krešimira Trgovčić3Tatjana Mijošek Pavin4Bruno Bušić5Dušica Ivanković6Ruđer Bošković Institute, Division for Marine and Environmental Research, Bijenička Cesta 54, 10000 Zagreb, CroatiaRuđer Bošković Institute, Division for Marine and Environmental Research, Bijenička Cesta 54, 10000 Zagreb, CroatiaDepartment of Biology, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000 Zagreb, CroatiaVodovod i Kanalizacija d.o.o. Karlovac, Gažanski Trg 8, 47000 Karlovac, CroatiaRuđer Bošković Institute, Division for Marine and Environmental Research, Bijenička Cesta 54, 10000 Zagreb, CroatiaFaculty of Chemical Engineering and Technology, University of Zagreb, Trg Marka Marulića 19, 10000 Zagreb, CroatiaRuđer Bošković Institute, Division for Marine and Environmental Research, Bijenička Cesta 54, 10000 Zagreb, CroatiaUtilizing a multi-biomarker approach, we assessed the potential adverse effects of pollutants on subcellular responses in the digestive gland of the freshwater mussel <i>Unio crassus</i> from a historically contaminated lowland section (KIZ) of the river Mrežnica compared to its less impacted upstream karstic section (REF) and their seasonality (spring vs. autumn). This approach accounted for the diverse modes of action of pollutants by including biomarkers of metal exposure (metallothioneins, MT), general stress (total cytosolic proteins, TP), antioxidative capacity (catalase, CAT; glutathione, GSH; glutathione-S-transferase, GST), oxidative damage (malondialdehyde, MDA), and neurotoxicity (acetylcholinesterase, AChE). Only in spring, MT concentrations were 15% higher at the REF site (4.38 ± 1.06 µg mg proteins<sup>−1</sup>) compared to the KIZ site (3.69 ± 0.63 µg mg proteins<sup>−1</sup>), likely related to elevated Cd bioaccumulation due to the karstic substrate. Regardless of the season, mussels from KIZ showed consistently lower TP and GSH, with significantly higher CAT, GST, and MDA levels, indicating elevated stress, activation of antioxidant defenses, and oxidative damage from chronic exposure to pro-oxidant pollutants, including metal(loid)s and organic contaminants (e.g., ibuprofen, nicotine). Compared to the REF site, AChE activity at the KIZ site was higher in late spring and lower in early autumn, indicating seasonal variability in AChE activity at the contamination-impacted location driven by fluctuating exposure to neurotoxicants, such as drugs and insecticides. Overall, biomarker responses indicated that mild historical pollution, reinforced by current low-capacity sources, has an observable impact on mussel health, posing long-term risks to sediment-dwelling aquatic organisms.https://www.mdpi.com/2410-3888/10/7/317subcellular responsesmulti-biomarkersbivalvefreshwaterlong-term pollution
spellingShingle Zoran Kiralj
Zrinka Dragun
Jasna Lajtner
Krešimira Trgovčić
Tatjana Mijošek Pavin
Bruno Bušić
Dušica Ivanković
Changes in Subcellular Responses in the Digestive Gland of the Freshwater Mussel <i>Unio crassus</i> from a Historically Contaminated Environment
Fishes
subcellular responses
multi-biomarkers
bivalve
freshwater
long-term pollution
title Changes in Subcellular Responses in the Digestive Gland of the Freshwater Mussel <i>Unio crassus</i> from a Historically Contaminated Environment
title_full Changes in Subcellular Responses in the Digestive Gland of the Freshwater Mussel <i>Unio crassus</i> from a Historically Contaminated Environment
title_fullStr Changes in Subcellular Responses in the Digestive Gland of the Freshwater Mussel <i>Unio crassus</i> from a Historically Contaminated Environment
title_full_unstemmed Changes in Subcellular Responses in the Digestive Gland of the Freshwater Mussel <i>Unio crassus</i> from a Historically Contaminated Environment
title_short Changes in Subcellular Responses in the Digestive Gland of the Freshwater Mussel <i>Unio crassus</i> from a Historically Contaminated Environment
title_sort changes in subcellular responses in the digestive gland of the freshwater mussel i unio crassus i from a historically contaminated environment
topic subcellular responses
multi-biomarkers
bivalve
freshwater
long-term pollution
url https://www.mdpi.com/2410-3888/10/7/317
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