engleski

The effect of metal exposure on melanomacrophage agregates and their pigment content in the spleen of the Vardar chub (Squalius vardarensis)

Macrophage aggregates (MACs) are pigment- containing cells accumulations that are presented in fish spleen, kidney and liver. Their number, size and pigment content may change depending on environmental degradation and therefore can be used as bioindicators of water quality. There are some indications that metals have inhibitory effect on fish immune system, but little is known of the effect of complex mixture of pollutants on MACs pool in fish spleen. In this study quantitative influence of heavy metals pollution on the MACs amount in the spleen tissue will be evaluated for the first time. For this study female (n=26) and male (n=30) Vardar chub (Squalius vardarensis) were collected at three rivers: Bregalnica, Zletovska and Kriva Reka, with difference in pollution impact ; organic, heavy metals, and mixture of both, respectively. Using stereological technique, relative (Vv) and total volume (V) of the MACs were estimated as well as the amount of the pigments within MACs. The results showed that when V and Vv of MACs and the contributing pigments in the spleen were estimated, male fish appeared more impacted by pollution compared to female and also showed significant decrease of V of MACs in Zletovska compared to Bregalnica. Moreover, statisticaly lower value of Vv and V of MACs containing melanin/lipofuscin pigments were recorded in Zletovska when compared to the two other sites. In comparison, Bregalnica, which has mainly organic pollution impact, had highest values of V of MACs compared with other two rivers. Male fish from Kriva Reka showed low V of MACs, with the lowest amount of MACs which contains haemosiderin/lipofuscin pigments. Female fish showed lowest Vv of MACs in Kriva Reka which can be attributed to the significantly lower Vv for the lipofuscin containing MACs in the same locality. In conclusion, pigment content, as well as the amount of MACs in the chub can change concerning the type of pollutants. Metals reduce the appearance of the MACs pool, mostly through reduction of lipofuscin and melanin/lipofuscin pigments, and probably induce immunosuppression in these cells.

pollution ; bioindicator ; stereology ; immunotoxicity ; melanin ; lipofuscin ; haemosiderin

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