Abstract
Fish skin is a multifunctional barrier tissue with high regeneration capacity that interacts with the surrounding environment and provides protection. Functional importance, high complexity and activity make skin an attractive tissue for studying the effects of environmental challenges and chemical stressors in fish. The aim of this work was to characterize skin from polar cod (Boreogadus saida) and Atlantic cod (Gadus morhua), and to test cod skin as an in vitro model in exposure studies. Both species have similar skin structures including epidermis, mucous cells, club cells and scales. However, microarchitectural differences were detected; Atlantic cod has a smooth epidermal surface and overlapping scales, whereas polar cod has a folded outer surface and discontinuous scales. Genome-wide microarray found 6.5k genes with expression differences, which suggested more active turnover of proteins, proliferation and motility of cells in skin of polar cod. Hydrogen peroxide (H2O2) was used to examine skin responses. Transcriptome response was stronger in the skin of polar cod, with 155 differentially expressed genes. The skin from Atlantic cod was further used to develop a cell culture. H2O2 decreased the cell migration rate in a dose-dependent manner, which could indicate reduced skin healing capacity. The results revealed novel skin structures and confirmed that the skin from cod is a promising tissue for evaluation of stressors.
Highlights
Insight into the molecular, cellular and physiological responses to environmental challenges is vital for sustainable growth of aquaculture and preservation of wild populations
Polar cod is not commercially exploited. This sentinel Arctic fish occurring in large numbers directly underneath the Arctic sea ice [6,7] is used in numerous environmental studies with a focus on pollution and thermal stress [8,9,10]
Polar cod has disjointed scales and bony plates located mostly in the dermis which do not extend into the epidermis, unlike the scales in Atlantic cod (Figure 1A,C)
Summary
Cellular and physiological responses to environmental challenges is vital for sustainable growth of aquaculture and preservation of wild populations. Atlantic cod is of great importance for commercial fisheries in the. Atlantic cod catches and spawning stock biomass have been declining over the last several decades, and fisheries of cod may further reduce due to climate change and increased oil drilling activity [3,4]. This sentinel Arctic fish occurring in large numbers directly underneath the Arctic sea ice [6,7] is used in numerous environmental studies with a focus on pollution and thermal stress [8,9,10]. The decrease of wild populations, growing potential for cod Fishes 2020, 5, 34; doi:10.3390/fishes5040034 www.mdpi.com/journal/fishes
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