Assessment of contamination based on trace element concentrations in Gomphus flavipes (Odonata: Insect) larvae of the Upper Tisza Region

Odonata larvae are frequently used to assess the contamination of aquatic systems, because they tolerate a wide range of chemical and biological conditions in freshwater systems. In early 2000, the sediments of the Hungarian section of the River Tisza and the River Szamos were strongly enriched with heavy metals by an accidental mining spill. Earlier studies demonstrated higher contamination levels in the Szamos than in the Tisza, based on sediment analysis. The aim of our study was to assess the contamination in the Upper Tisza Region, along the upper reach of the Tisza, and the lower reach of the Szamos, based on the trace element concentrations of the Gomphus flavipes larvae. We collected 269 dragonfly specimens for the analyses. The Al, Ba, Cr, Cu, Fe, Mn, Pb, Sr and Zn element contents were analysed in the dragonfly larvae by microwave plasma atomic emission spectrometry (MP-AES). Significantly higher Ba and Cu concentrations were found in the dragonfly larvae of the Tisza than the Szamos. In spite of this, the Cr, Mn, Pb, Sr and Zn concentration was significantly lower in the dragonfly larvae of the Tisza than the Szamos. For all trace elements significant differences were found along the Tisza. Significant differences were also found in all trace element concentrations of dragonfly larvae among studied localities in the Szamos, except in the cases of Al and Ba. Our results demonstrated that the Szamos was more contaminated with Cr, Mn, Pb, Sr and Zn than the Tisza, but that the Tisza was more contaminated with Ba and Cu than the Szamos, based on the trace element concentrations in Gomphus flavipes larvae, which was likely to have been caused by the tributaries of the Tisza. In summary, our results indicated a continuous pollution of the Tisza and the Szamos and their tributaries.

The effect of unilateral papillectomy on the juxtaglomerular granulated cells

The changes of the juxtaglomerular index values in the superficial, deep and whole cortical areas of rat kidneys after unilateral papillectomy were analyzed. On the papillectomized side the JGI values showed an increase in the deep, and a decrease in the superficial cortical zone. The changes proved to be significant during the whole experimental period in the juxtamedullary index and between the 4--14 postoperative days in the superficial index values. The tendency of the changes of JGI in the contralateral kidneys was similar to those of the papillectomized kidneys, but significant differences were registered less constantly. These changes are probably the consequences of haemodynamic factors. Papillectomy is considered an incompetent model for studying the regulatory function of macula densa in the synthesis of renin.