Mercury is present in the body of organisms as inorganic mercury (generally Hg 2+ ), metal mercury (element, HgO), and organic mercury (generally methylmercury; MeHg). Metal mercury is usually derived from dental amalgam and industrial exposure. Another possible source of metal mercury is fluorescent light bulbs.
Furthermore, Hg emissions have increased every year due to rapid industrialization. The accumulation of heavy metals in fish depends on many factors, including some chemical interactions, bioavailability and pollutant sources, sex, size, species, nutrition, their concentration in water, time of exposure, and other environmental factors such as salinity, pH, and water temperature. Some researchers chose fish as an experimental model to assess the effects of mercury in organisms to study mercury accumulation in freshwater fish.
In this study, the tilapia fish, Oreochromis niloticus strain of East Java, was chosen as a fish species model not only because of the presence of Hg from gold mining activities in East Java and other Indonesian regions, but also because it is one of the most consumed freshwater fish in Java and Indonesia. Tilapia has been used in ecotoxicological studies by Handayani et al., (2017); Nursanti et al., (2017); Soegianto et al., (2017).
Their ability to adapt to various temperatures and estuarine conditions makes tilapia an interesting species to measure changes in Na + / K + -ATPase (NKA) and H-ATPase activity due to salinity and temperature change. It is generally agreed that sodium transport from intracellular fluid of gill epithelial cells into interstitial fluid and then blood is driven by NKA transporters on the basolateral membrane. Fish gills are known as the main effector sites for active and passive exchanges between organisms and their environment (Gilles and Delpire 1997); therefore, it is likely a place for metal entry and exit. Therefore, this study experimentally explored the accumulation of Hg and its effects on gill tilapia by observing NKA expression and gill damage during a 96-hour exposure time.
The purpose of this study was to analyze and compare the effects of mercury accumulation (Hg) and their effects on the chloride cells (CC) of the tilapia gill strain of East Java ( Oreochromis niloticus ). Fish specimens were exposed to concentrations of 0 mg / L Hg, 0.1 mg / L, and 1 mg / L. After 96 hours of exposure, accumulation of Hg in fish gills was measured, gill structure and NKA immunohistochemistry were observed using a light microscope. The concentration of mercury in the gills of fish exposed to mercury was significantly higher with the 1 mg / L compared to 0.1 mg / L and the control group. Positive NKA expression in CC was observed along the primary and secondary lamella gill tilapia. Microscopic observations showed the most significant gill damage in higher Hg concentrations.
Author: KIKI SYAPUTRI HANDAYANI, BAMBANG IRAWAN DAN AGOES SOEGIANTO *
Details of research: ACCUMULATION OF MERCURY AND ITS IMPACT ON THE CHLORIDE CELL OF GILLS OF TILAPIA (OREOCHROMIS NILOTICUS LINNAEUS, 1758)