Effect of Lead and Colchicine on Morphogenesis in Protonemata of the Moss Funaria hygrometrica

Protonemata of Funaria hygrometrica grown in artificial mediacontaining different lead concentrations grow more slowly thancontrols and show a disturbance of polar growth, changed arrangementof chloroplasts, alterations of nucleus and septa position.Morphological effects are dose-dependent. At the lowest leadconcentration (10^-6 M), only a delay in development was observed,but no cellular alterations, At 10^-5 M Pb nuclear migration,cellular shape, size and position of plastids, were alteredand a variety of aberrant forms were present. At 10^-4 M, besidesthese alterations, a drastic reduction of the protonemal system,high vacuolation and the growth of protonemal filaments fromleaves were evident. The highest concentration, (10^-3 M), causeddeath. Patterns of protonemal development and cellular arrangementin lead-treated samples showed similarities as well as differences,if compared to alterations induced by colchicine. Indirect immunofluorescencedemonstrated a correlation between lead concentration and alterationof cytoskeletal organization (alterations similar to those inducedby colchicine). Hypotheses are raised to account for effects of lead on microtubulestructure, arrangement and cytoplasm organization.Copyright1995, 1999 Academic Press Funaria hygrometrica, lead, protonemal development, cytomorphogenesis, microtubules