Differential Cellular Response to Mercury in Non-Farmed Fish Species Based on Mitochondrial DNA Copy Number Variation Analysis
by
, ,
Marta Giuga
1,2,*, 
Venera Ferrito
1,
Giada Santa Calogero
1,
Anna Traina
3,
Maria Bonsignore
4,
Mario Sprovieri
5 and
Anna Maria Pappalardo
1,* 
1
Department of Biological, Geological and Environmental Sciences, Section of Animal Biology “M. La Greca”, University of Catania, Via Androne 81, 95124 Catania, Italy
2
National Research Council of Italy, Institute of Anthropic Impacts and Sustainability in Marine Environment (CNR-IAS), Via De Marini 16, 16149 Genova, Italy
3
National Research Council of Italy, Institute of Anthropic Impacts and Sustainability in Marine Environment (CNR-IAS), Lungomare Cristoforo Colombo 452, 90149 Palermo, Italy
4
National Research Council of Italy, Institute of Anthropic Impacts and Sustainability in Marine Environment (CNR-IAS), Via del Mare, 91021 Campobello di Mazara, Italy
5
National Research Council of Italy, Institute of Marine Sciences (ISMAR-CNR), Tesa 104—Arsenale, Castello 2737/F, 30122 Venezia, Italy
*
Authors to whom correspondence should be addressed.
Biology 2024, 13(9), 691; https://doi.org/10.3390/biology13090691
Submission received: 24 July 2024
/
Revised: 27 August 2024
/
Accepted: 31 August 2024
/
Published: 3 September 2024
(This article belongs to the Special Issue Mitochondria: The Signaling Organelle)
Simple Summary
Mercury represent a serious threat for marine ecosystems due to its persistence in the environment. Fishes are the most numerous and widely distributed group of vertebrates, living in the sea with different species often studied and used as bioindicators of the quality of aquatic systems being able to reflect even small changes in environmental parameters. Mitochondria are small cell organelles with their own DNA and the number of mitochondria within a cell is highly variable in different animal tissues, depending on metabolic requirements. Mitochondrial genome is vulnerable to reactive oxygen species (ROS) which in turn impair mitochondrial function. Therefore, the aim of the present study was the validation of the variation in the number of mitochondrial DNA copies (mtDNAcn) as biomarker of oxidative stress in aquatic environment. Three selected fish species were collected in Augusta Bay, a contaminated area remarkable by past Hg inputs, and in a control area (Marzamemi and Portopalo di Capo Passero), both in the South-East of Sicily. Based on the evidence found, the assessment of mtDNAcn variation emerges as a valid biomarker of oxidative stress deriving from contaminant exposure.
Abstract
Mercury (Hg) pro-oxidant role on biological systems and its biogeochemical cycle represent a serious threat due to its persistence in marine environment. As the mitochondrial genome is exposed to reactive oxygen species (ROS), the aim of the present study is the validation of the variation in the number of mitochondrial DNA copies (mtDNAcn) as biomarker of oxidative stress in aquatic environment. During summer 2021, three selected fish species (Mullus barbatus, Diplodus annularis and Pagellus erythrinus) were collected in Augusta Bay, one of the most Mediterranean contaminated areas remarkable by past Hg inputs, and in a control area, both in the south-east of Sicily. The relative mtDNAcn was evaluated by qPCR on specimens of each species from both sites, characterized respectively by higher and lower Hg bioaccumulation. M. barbatus and P. erythrinus collected in Augusta showed a dramatic mtDNAcn reduction compared to their control groups while D. annularis showed an incredible mtDNAcn rising suggesting a higher resilience of this species. These results align with the mitochondrial dynamics of fission and fusion triggered by environmental toxicants. In conclusion, we suggest the implementation of the mtDNAcn variation as a valid tool for the early warning stress-related impacts in aquatic system.
Keywords:
mtDNAcn; biomarker; teleost; marine monitoring; environmental contaminants; early warning
