Cadmium (Cd) or nickel (Ni) were applied as a foliar spray (1 µM solution over one month) to mimic air pollution and to monitor metabolic responses and oxidative stress in the pteridophyte species. Exogenous metals did not affect the metal content of the soil and had relatively little effect on the essential elements in leaves or rhizomes. The amounts of Cd and Ni were similar in treated leaves (7.2 µg Cd or 5.3 µg Ni/g DW in mature leaves compared with 0.4 µg Cd or 1.2 µg Ni/g DW in the respective control leaves), but Ni was more abundant in rhizomes (56.6 µg Ni or 3.4 µg Cd/g DW), resulting in a higher Cd translocation and bioaccumulation factor. The theoretical calculation revealed that ca. 4% of Cd and 5.5% of Ni from the applied solution per plant/pot was absorbed. Excess Cd induced stronger ROS production followed by changes in SOD and CAT activities, whereas nitric oxide (NO) stimulation was less intense, as detected by confocal microscopy. The hadrocentric vascular bundles in the petioles also showed higher ROS and NO signals under metal excess. This may be a sign of increased ROS formation, and high correlations were observed. Proteins and amino acids were stimulated by Cd or Ni application in individual organs, whereas phenols and flavonols were almost unaffected. The data suggest that even low levels of exogenous metals induce an oxidative imbalance, although no visible damage is observed, and that the responses of ferns to metals are similar to those of seed plants or algae.

• Klíčová slova
• antioxidant molecules, heavy metals, reactive oxygen species, soil pollution,
• MeSH
• Adiantum * metabolismus   MeSH
• kadmium metabolismus   MeSH
• kapradiny * metabolismus   MeSH
• látky znečišťující půdu * toxicita   chemie   MeSH
• rostliny metabolismus   MeSH
• těžké kovy * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kadmium MeSH
• látky znečišťující půdu * MeSH
• Nickel-56 MeSH Prohlížeč
• těžké kovy * MeSH

Indirect impact of humic acid (HA) on metal accumulation and toxicity (Cd, Ni, Pb, and Hg; 100 μM; 24 h of exposure) in Scenedesmus quadricauda was studied. Algae were pre-cultured on solid (10 and 100 mg HA/L) or in liquid media (1, 5, and 10 mg HA/L) over 30 days and then exposed to metals mentioned above. Accumulation of applied metals irrespective of pre-culture increased in the order Ni < Cd < Pb < Hg. Algae pre-cultured on solid HA-enriched media accumulated more Cd (+ 46% at 10 mg HA/L), Ni (+ 50 and + 81% at 10 and 100 mg HA/L, respectively), and Pb (+ 15% at 100 mg HA/L) but the impact on Hg amount was not detected. Potassium and calcium decreased in response to all metals (K strongly under Hg excess) and HA had negligible impact. Interestingly, fluorescence microscopy detection of reactive oxygen species/nitric oxide (ROS/NO) balance showed that HA pre-culture suppressed ROS signal and stimulated NO signal in response to Cd (indicating positive impact of HA) while ROS signal in Ni and Pb treatments rather increased but NO signal decreased as expected from elevated Ni and Pb accumulation. Hg had clearly the most toxic impact on the ROS/NO balance. Algae pre-cultured in liquid HA-enriched media showed significantly increased Ni accumulation only (+ 14% at a dose 10 mg HA/L). Present study for the first time showed that humic acid may indirectly affect accumulation of metals and that solid HA-enriched medium used for pre-culture is more suitable to increase accumulation of metals by algae.

• Klíčová slova
• Bioaccumulation, Fluorescence microscopy, Heavy metals, Oxidative stress,
• MeSH
• chemické látky znečišťující vodu toxicita   MeSH
• fluorescenční mikroskopie MeSH
• huminové látky analýza   MeSH
• mikrořasy účinky léků   MeSH
• oxidační stres MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• Scenedesmus účinky léků   MeSH
• testy akutní toxicity MeSH
• těžké kovy toxicita   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chemické látky znečišťující vodu MeSH
• huminové látky MeSH
• reaktivní formy kyslíku MeSH
• těžké kovy MeSH