THE FUNCTIONAL CYTOLOGY OF BONAMIA SP (HAPLOSPORIDIA) INFECTING OYSTERS TIOSTREA-CHILENSIS - AN ULTRACYTOCHEMICAL STUDY

Bonamia sp., a serious pathogen of oysters Tiostrea chilensis, was stu died using the zinc iodide-osmium tetroxide technique (ZIO), the imida zole-osmium technique for lipids (IM), and reactivity for acid phospha tases [beta-glycerophosphatase (beta-GPase), cytidine monophosphatase at pH 5.0 (CMPase 5.0) and pH 2.7 (CMPase 2.7), thiamine pyrophosphata se (TPPase)], and beta-galactosidase to try and determine the function of cytoplasmic organelles. ZIO reacted with the nuclear membrane, Gol gi, endoplasmic reticulum (ER), cytoplasmic vesicles, and variably wit h putative phagosomes, the mitochondrial matrix, haplosporosomes and m ultivesicular bodies, but not lipoid bodies. IM strongly labelled lipo id bodies, and lipids in the nuclear membrane, ER except anastomosing ER (aER) and mitochondrial membranes and cristae, but was weak in aER and on haplosporosomes. beta-GPase occurred in the nuclear membrane, s ome elements of ER, Golgi and mitochondria, and in lipoid bodies. CMPa se 5.0 was variable in Golgi and ER, but was stronger at pH 2.7 and oc curred in the nuclear membrane. TPPase only occurred in a single Golgi cisterna, or very weakly in a few lipoid bodies. beta-galactosidase w as rarely seen, and only within Golgi. As there was considerable metab olism of unsaturated lipids and little hydrolytic enzyme content, it w as concluded that Bonamia sp. may synthesise lipids from triglycerides hydrolysed by haemocyte enzymes, reducing the need for parasite hydro lytic enzymes.