RESUMEN
This study aimed to examine the evidence of direct interaction among actin, myosin and phosphatidylinositol 3-kinase (PI3K) in the polarisation and formation of the tetraspore germ tube of Gelidium floridanum. After release, tetraspores were exposed to cytochalasin B, latrunculin B, LY294002 and BDM for a period of 6 h. In control samples, formation of the germ tube occurred after the experimental period, with cellulose formation and elongated chloroplasts moving through the tube region in the presence of F-actin. In the presence of cytochalasin B, an inhibitor of F-actin, latrunculin B, an inhibitor of G-actin, and BDM, a myosin inhibitor, tetraspores showed no formation of the germ tube or cellulose. Spherical-shaped chloroplasts were observed in the central region with a few F-actin filaments in the periphery of the cytoplasm. Tetraspores treated with LY294002, a PI3K inhibitor, showed no formation of the tube at the highest concentrations. Polarisation of cytoplasmic contents did not occur, only cellulose formation. It was concluded that F-actin directs the cell wall components and contributes to the maintenance of chloroplast shape and elongation during germ tube formation. PI3K plays a fundamental role in signalling for the asymmetric polarisation of F-actin. Thus, F-actin regulates the polarisation and germination processes of tetraspores of G. floridanum.
Asunto(s)
Citoesqueleto de Actina/metabolismo , Miosinas/metabolismo , Fosfatidilinositol 3-Quinasa/metabolismo , Rhodophyta/metabolismo , Compuestos Bicíclicos Heterocíclicos con Puentes/farmacología , Pared Celular/metabolismo , Cloroplastos/metabolismo , Cromonas/farmacología , Citocalasinas , Diacetil/análogos & derivados , Diacetil/farmacología , Morfolinas/farmacología , Inhibidores de las Quinasa Fosfoinosítidos-3 , Estructuras de las Plantas/crecimiento & desarrollo , Estructuras de las Plantas/metabolismo , Rhodophyta/efectos de los fármacos , Rhodophyta/crecimiento & desarrollo , Tiazolidinas/farmacologíaRESUMEN
The production of acid mine drainage of (AMD) is one of the main phenomena responsible for much of the degradation of water and soil resources. Organisms present at sites contaminated by AMD can have the potential to bioaccumulate heavy metals, stimulating their application in bioremediation processes. Ulothrix sp. LAFIC 010 was identified among the species of algae isolated from water contaminated by AMD in the region of Sideropólis (Brazil). The present study evaluated its tolerance and bioaccumulation potential related to zinc, manganese and nickel. Experiments were performed to see the effects of different concentrations of Zn, Mn and Ni (individually and in combination) on the physiological performance of the alga. The results showed that only the cultures submitted to concentrations above 0.55â¯mM Zn showed a decrease in growth rate and damage to physiological processes. There was no observed effect of Mn and Ni on Ulothrix sp. LAFIC 010 physiology, even with an 8-fold increase in concentrations of these metals in the medium. In cultures with combined metals, only the treatments with the highest concentrations of Zn presented reduced growth, regardless of the presence of other metals. Additionally, we observed that Mn and Ni did not decrease the toxic effect of Zn. Mn accumulation was indicated in the cell wall and Ni in the vacuole. Our results suggest that the distribution of this alga in contaminated medium is not affected by the concentration of Ni and Mn, at least under the pH that was evaluated. We conclude that Ulothrix sp. LAFIC 010 tolerates and grows under conditions with higher metal concentrations than previously reported for AMD.