Development of a rapid and effective method for preparing delicate dinoflagellates for scanning electron microscopy

Abstract

We developed a rapid and effective procedure for scanning electron microscopy of three delicate dinoflagellates, Karlodinium micrum, Akashiwo sanguinea and Heterocapsa niei. Good results were obtained when the specimens were fixed with a modified Párducz’s fixative (2% osmium tetroxide:saturated mercuric chloride=5:1 v/v) for 10 min, washed in 0.05 M sodium cacodylate trihydrate buffer for 2 min, dehydrated in a tert-butanol for 10 min and dried with hexamethyldisilazane in air for 3 min. All reagents were carefully used in a fume hood because reagents are very toxic. This method could be completed in 25 min. Compared with other preparative techniques, the present protocol has significant advantages for SEM observation by limiting distortion of delicate specimens and reducing the preparation time.