RESUMO
Macrocyclic lactone anthelmintics are widely used to control invertebrate pests in livestock, such as sheep. While anthelmintic effects on non-target animals, such as dung-dwelling insects, are well studied, effects on seed germination are largely unknown. Seeds can come into contact with anthelmintics either during passage through the gastro-intestinal tract of grazing animals or when anthelmintics are excreted with their dung into the environment, which may result in changed germination patterns. We used four commonly applied macrocyclic lactones to assess their effects on germination: moxidectin, ivermectin, abamectin and doramectin as pure substances; moxidectin and ivermectin also in formulated form. We tested these pharmaceuticals on 17 different temperate grassland species from five plant families. Seeds were exposed to three concentrations of macrocyclic lactones (0.1, 1.0 and 10.0 mg·l-1 ) under controlled conditions, and germination was assessed over a 6-week period. From these data, we calculated germination percentage, mean germination time and germination synchrony. Most of the tested species were significantly affected in germination percentage and/or mean germination time by at least one of the tested pharmaceuticals, with formulated moxidectin having the largest impact. In general, the effects found were species- and pharmaceutical-specific. While formulated substances generally reduced germination percentage and increased mean germination time, pure substances increased germination percentage. Synchrony showed less clear patterns in all pharmaceuticals. Although effect size and sign varied between species, our study shows that non-target effects of macrocyclic lactones commonly occur in terrestrial plants. This may impede successful seed exchange between habitats via sheep, and even translate into profound changes to grazed ecosystems.
Assuntos
Anti-Helmínticos , Lactonas , Animais , Ovinos , Lactonas/farmacologia , Ivermectina/farmacologia , Germinação , Pradaria , Ecossistema , Sementes , Anti-Helmínticos/farmacologia , Anti-Helmínticos/uso terapêutico , Plantas , Preparações Farmacêuticas , FezesAssuntos
Dióxido de Carbono/metabolismo , Fosfoenolpiruvato Carboxiquinase (GTP)/metabolismo , Fotossíntese , Plantas/metabolismo , Zea mays/metabolismo , Radioisótopos de Carbono , Escuridão , Ácidos Glicéricos/metabolismo , Cetoses/metabolismo , Luz , Nitrogênio , Compostos Organofosforados/metabolismo , Oxigênio , Pressão Parcial , Pentosefosfatos/metabolismo , Fosfoenolpiruvato/metabolismo , Plantas/enzimologia , Especificidade da Espécie , Fatores de Tempo , Zea mays/enzimologiaAssuntos
Alcanos/farmacologia , Cloroplastos/metabolismo , Fosforilação Oxidativa/efeitos dos fármacos , Fotossíntese , Adenosina Trifosfatases/antagonistas & inibidores , Adenosina Trifosfatases/metabolismo , Cálcio , Cloroplastos/enzimologia , Cloroplastos/efeitos da radiação , Depressão Química , Transporte de Elétrons/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Luz , Magnésio , Modelos Biológicos , NADP/metabolismo , Oxirredução , Fenazinas , Plantas/metabolismo , Prótons , Efeitos da Radiação , Estimulação Química , TripsinaRESUMO
Dark grown albescent corn seedlings are deficient in colored carotenoids but accumulate phytoene, phytofluene and an unidentified substance in the carotenol fraction. They bleach upon exposure to bright light and appear albino. Seedlings grown under low level incandescent light are normal in appearance and contain almost as much colored carotenoid as control seedlings. The existing leaf tissue of seedlings grown under low level light does not bleach upon exposure to bright light. The enhanced carotenoid synthesis and stabilization of plastids is not affected by brief illumination with red light but requires several hours of low level incandescent light.
