Morphofunctional Alterations in Zebrafish (Danio rerio) Gills after Exposure to Mercury Chloride

• Published in: International journal of molecular sciences 2017-04, Vol.18 (4), p.824-824
• Main Authors: Macirella, Rachele, Brunelli, Elvira
• Format: Article
• Language: English
• Subjects: Acid-base regulation; Animals; Apoptosis; Aquatic ecosystems; Aquatic environment; Chlorides; Danio rerio; Degeneration; Detoxification; Epithelium; Excretion; Exposure; Functional morphology; Gas exchange; Gills; Gills - drug effects; Gills - metabolism; Gills - ultrastructure; Hyperplasia; Immunohistochemistry; Low concentrations; Mercuric Chloride - toxicity; Mercury; Mercury compounds; Metallothionein - genetics; Metallothionein - metabolism; Microscopy, Electron, Scanning; Na+/K+-exchanging ATPase; Osmoregulation; Polymerase chain reaction; Real time; Real-Time Polymerase Chain Reaction; Sodium-Potassium-Exchanging ATPase - genetics; Sodium-Potassium-Exchanging ATPase - metabolism; Terrestrial ecosystems; Water Pollutants, Chemical - toxicity; Zebrafish; Zebrafish - metabolism
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms18040824

Mercury (Hg) is a global pollutant that may exert its toxic effects on living organisms and is found in both aquatic and terrestrial ecosystems in three chemical forms; elemental, organic, and inorganic. The inorganic form (iHg) tends to predominantly accumulate in aquatic environments. The gill apparatus is a very dynamic organ that plays a fundamental role in gas exchange, osmoregulation, acid-base regulation, detoxification, and excretion, and the gills are the primary route of waterborne iHg entrance in fish. In the present work we investigated the morphofunctional and ultrastructural effects in gills after 96 h exposure to two low HgCl₂ concentrations (7.7 and 38.5 µg/L). Our results clearly demonstrated that a short-term exposure to low concentrations of mercury chloride resulted in gill morphology alterations and in the modifications of both Na K⁺-ATPase and metallothioneins (MTs) expression pattern. The main morphological effects recorded in this work were represented by hyperplasia and ectopia of chloride cells (CCs), lamellar fusion, increased mucous secretion, alteration of pavement cells (PVCs), detachment of the secondary epithelium, pillar cell degeneration, degeneration, and apoptosis. Trough immunohistochemistry and real-time PCR analysis also showed a dose-related modulation of Na⁺/K⁺-ATPase and MTs.