Veterinarska stanica, Vol. 48 No. 6, 2017.
Pregledni rad
Biochemical functions and toxicity of manganese and its concentration in marine mammal tissues
Maja Đokić
Nina Bilandžić
Martina Đuras
Tomislav Gomerčić
Marija Sedak
Sažetak
Manganese is an essential element involved in a number of metabolic functions, including skeletal system development, energy metabolism, specific enzyme activation, nervous system function, connective tissue growth, blood clotting, immune function, and proper function of reproductive hormones. It is also an antioxidant that protects cells from free radicals, and is a cofactor in a series of enzymatic reactions. Deficiency of manganese in animals affects carbohydrate metabolism, decreased glucose metabolism, poor lipid metabolism and decreased synthesis and insulin activity. Manganese accumulates in mitochondrial cells, and therefore, tissues rich in these organelles, such as the pancreas, liver, kidneys and intestine, have the highest concentrations of manganese. It also easily crosses the blood-brain barrier and accumulates in specific regions of the brain. Therefore, chronic inhalation of high concentrations of manganese affects the brain, causing central nervous system disorders and neurobehavioral disorders. The effects of manganese as a trace element with potential toxicity to marine mammals, such as dolphins, have not yet been explored. The main load factor of manganese in mammals is diet, with metal content varying widely among species and tissues. The expected range of manganese in marine mammal tissues is up to 7 mg/kg wet weight. The highest concentrations, ranging from 2.15 to 5.34 mg/kg, were determined
in the livers of the three species of kite whale (Cetacea) dolphins present in all seas, including the Mediterranean and Adriatic Sea: bottlenose (Tursiops truncatus), striped (Stenella coeruleoalba), and Risso’s (Grampus griseus) dolphins. Studies conducted for the determination of manganese concentrations in dolphin tissues have shown the concentration order liver > kidneys > muscles. Also, manganese concentrations in the tissues of the three dolphin species from the Mediterranean showed similar values in tissues, especially liver, kidneys, muscles and lungs. There are few reports on manganese concentrations in dolphins from the Italian coast of the Adriatic Sea. Comparison of manganese concentrations in the tissues of bottlenose and striped dolphins from other world seas, i.e., the American, Brazilian and Portuguese coasts of the Atlantic and the Pacific islands of Hawaii and Japan, showed similar values to those determined in the dolphin tissue from the Mediterranean. There were no available literature data for Risso’s dolphins from the world seas. Significant differences in manganese concentrations were found in the skin due to the global geographical position of the bottlenose dolphins, suggesting that geographic location may be an important factor influencing manganese concentrations.
Ključne riječi
manganese; marine mammals; dolphins; tissues
Hrčak ID:
222679
URI
Datum izdavanja:
4.12.2017.
Posjeta: 1.597 *