Bisphenol A disrupts microtubules and induces multipolar spindles in dividing root tip cells of the gymnosperm Abies cephalonica

Abstract

The effects of bisphenol A (BPA), an endocrine chemical disruptor extensively used in the plastic and epoxy resin industry, on dividing root tip cells of the gymnosperm Abies cephalonica Loudon were investigated by confocal laser scanning microscopy after tubulin and endoplasmic reticulum immunolocalization and DNA staining. Microtubule arrays of all mitotic stages were disrupted within a few hours of treatment: preprophase bands exhibited asymmetric width; prometaphase, metaphase and anaphase spindles appeared sharply pointed, sigmoid or multipolar; phragmoplast microtubules were elongated and occasionally bended toward the daughter nuclei. Depending on the mitotic stage, the chromosomes appeared condensed at prophase, as a compact mass at metaphase and anaphase, unsegregated or bridged at telophase. Endoplasmic reticulum patterns were also affected, reflecting those of the respective microtubule arrays. Recovery of the microtubules after oryzalin treatment was more effective in a BPA solution than in water. It is concluded that the plant mitotic apparatus microtubules are very sensitive to BPA, the effect of which depends on the specific cell cycle stage. The formation of multipolar spindles is reminiscent of animal cells and is ascribed to the induction of multiple microtubule nucleation sites, deriving from the centrosomal properties of gymnosperms.

Keywords: Abies cephalonica; Bisphenol A; Centrosomal properties; Microtubules; Mitosis; Multipolar spindle.