University of Zagreb. Faculty of Science. Department of Biology.
Abstract
Vodena leća Lemna minor L. je kozmopolitska jednosupnica pogodna za ekotoksikološka istraživanja. U ovom je radu u uvjetima in vitro analiziran učinak teških metala na aktivnost i sastav esteraza u vodenoj leći Lemna minor L. uzgajanoj sedam dana u površinskim vodama Sava Županja, Sava Jasenice i Sutla Prišlin sakupljenim jednom mjesečno unutar tri mjeseca, otpadnim vodama ZGOS sakupljenim svaka 4h unutar 24h te otpadnoj vodi Jakuševac. Sadržaj teških metala poput cinka, žive i kroma bio je povišen u gotovo svim uzorcima ispitivanih voda, dok je sadržaj željeza, nikla, kadmija, arsena i mangana bio ispod najviših dopuštenih vrijednosti. Korištenjem 2-naftilacetata kao supstrata esteraza, u odnosu na kontrolne biljke, zapažena je povećana aktivnost esteraza u vodenim lećama izloženim otpadnim vodama ZGOS (1-3), Jakuševcu te površinskim vodama SŽ (1-3) i SJ (2-3). Elektroforetskom analizom razdvojene su ukupno tri izoforme esteraza koje se javljaju u svim uzorcima pri čemu nije zabilježena pojava novih izoformi. Sadržaj ukupnih proteina u vodenoj leći snižen je u svim uzorcima, naročito kod onih izloženih otpadnoj vodi ZGOS. Dobiveni rezultati ukazuju na moguću uključenost esteraza u prilagodbi vodene leće na stres izazvan teškim metalima. Aktivnost esteraza mogla bi se koristiti kao biomarker toksičnosti uzrokovane različitim onečišćivačima.Duckweed (Lemna minor L.) is a widely spread monocot often used as a model organism in ecotoxicological studies. The effects of heavy metals present in certain surface and wastewater samples on esterase activity and isoesterase patterns of duckweed cultured in vitro were investigated. Duckweed plants were exposed to surface - Sava Županja, Sava Jasenice and Sutla Prišlin (collected monthly over a 3-month monitoring period) and wastewater samples - ZGOS (collected every 4h during one day) and Jakuševac for seven days. The contents of zinc, mercury and chromium were elevated while those of iron, nickel, cadmium, arsenic and manganese were below the maximum allowed value. Esterase activities, measured with 2-naphtylacetate, increased in duckweed exposed to ZGOS (1-3), Jakuševac, SŽ (1-3) and SJ (2-3) water samples. In total, three isoforms of esterase were present in both control and treated duckweed and appearance of new bands was not noticed. The content of soluble proteins was decreased in duckweed exposed to all tested water samples though especially in plants exposed to ZGOS. Results obtained indicate a possible involvement of esterases in duckweed's adaptation to stress caused by heavy metals. Esterase activity could be used as a potential marker of toxicity induced by various agents
