Localization of potential Ca2+ binding sites in lily pollen tubes and maize calyptra cells: Transmission electron microscopy, proton microprobe analysis and electron spectroscopic imaging

Abstract

The validity of a method for localization of potential Ca²⁺ binding sites was analyzed in pollen tubes ofLilium longiflorum and calyptra cells ofZea mays. The Ca²⁺-enriched fixation produced electron opaque deposits mainly on the plasma membrane, endoplasmic reticulum, and mitochondria, with details of localization differing somewhat between pollen tubes and maize calyptra cells. Proton microprobe analysis indicated a relative enrichment of Ca in the sections. The newly introduced technique of electron spectroscopic imaging confirmed the presence of Ca (and possibly P) in the induced electron opaque structures.