Ultrastructural detection of carbohydrates in the pellicle of Pneumocystis carinii

Abstract

The presence of carbohydrates in the pellicle of Pneumocystis carinii was demonstrated by methenamine silver (MS) and thiocarbohydrazide-silver proteinate (TCH-SP) staining techniques. An intense, positive reaction with MS was observed on both the electron-dense outer layer and the electron-lucent middle layer of the pellicle, whereas in the case of TCH-SP only the outer layer stained well. The middle layer did not stain as intensely with TCH-SP as with MS. This observation indicates that the pellicle of P. carinii contains carbohydrates but that the outer and middle layers differ in carbohydrate composition. The binding sites of concanavalin A (Con A) and Macura pomifera (MPA) lectins were elucidated on the pellicle of P. carinii using colloidal gold as a marker. In a preembedding staining method using Con A and MPA lectins, the adherence of gold particles was observed on the surface of all stages of the parasite. The homogeneous distribution of the gold particles indicates that the outer electron-dense layer contains both Con A- and MPA-specific carbohydrates. In postembedding staining with Con A, the adherence of gold particles was found on both the outer and middle layers, whereas in the case of MPA only the outer layer was labeled with gold particles. These results indicate that the electron-dense outer layer contains a considerable amount of carbohydrates specific for these lectins, whereas the electron-lucent middle layer seems to lack MPA-specific carbohydrates.

Golgi complex and lysosomes in rabbit derived Pneumocystis carinii

“…Using the ZIO method and serial thin sections of P carinii isolated from young rabbits, we were able to observe Golgi structures. The present results on the cell wall carbohydrate composition are in agreement with the observations reported on the rat-derived P carinii [28]. Indeed, while ConA labeled the outer-dense and the inner-lucent layers of the cyst cell wall, PA-TSC-SP only stained the inner layer.…”

“…Carbohydrate was detected in the cell wall of rat-derived P carinii [13,[26][27][28] but Golgi complex structures were not observed [25]. Using the ZIO method and serial thin sections of P carinii isolated from young rabbits, we were able to observe Golgi structures.…”

“…Carbohydrates were detected on the surface of P carinii [13,15,[26][27][28] obtained from lungs of artificially immuno-depressed rats. Using thiocarbohydrazide-silver proteinate (TCH-SP) or Concanavalin A (ConA), carbohydrates have been found on the external dense layer and on the middle layer of precystic and cystic wall [28]. The external dense layer of trophozoites was also labeled by ConA.…”

“…The external dense layer of trophozoites was also labeled by ConA. A labeling of the outer dense layer of all stages was observed using the lectin Macura pomifera (MPA) [28].…”

Autophagy Contributes to Leaf Starch Degradation

“…To confirm that the SSGLs observed under TEM were indeed starch components, we stained the sections using the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) staining method (Thiery, 1967), which has been widely used in histochemical localization of neutral polysaccharides in mammals, bacteria, fungi (Braña et al, 1980;Lo et al, 1987;Yoshikawa et al, 1988), and starch granules in plant leaves (Zeeman et al, 1998b). As expected, no silver grains were observed in the control sections stained with TCH-SP or PA-SP or SP (see Supplemental Figure 7 online).…”