Growth of the Pittsburgh pneumonia agent in animal cell cultures.

Pittsburgh pneumonia agent (Legionella micdadei) grew in monkey, chicken, and human cell cultures. Pittsburgh pneumonia agent grew predominantly in the cytoplasm, resulting in a nonfocal, mild cytopathic effect.

The ultrastructural morphologic features of Pittsburgh pneumonia agent.

The fine structure of "Pittsburgh Pneumonia Agent" (PPA) was studied in infected human lung, guinea pig omentum, yolk sac membrane, Vero cell culture, and after cultivation of the organism on buffered charcoal yeast extract agar. The organism is a prokaryotic cell with the general features of a gram-negative bacillus. PPA is ultrastructurally distinctive because of an unusually thick, electron-dense band present within the periplasmic space adjacent to the outer membrane of the cell wall. This band, presumably a mucopeptide (peptidoglycan) layer, was seen in about 95% of organisms in human lung but less frequently under certain conditions of laboratory infection or cultivation. Future studies are required to determine whether this ultrastructural dimorphism of PPA is related to variation in other properties of this bacterium, eg, gram-variability, acid-fastness, colony morphology, and virulence.

Schistosoma mansoni: topochemical features of intrasporocyst cercariae.

The carbohydrate rich filamentous coat investing the mature Schistosoma manosini cercaria affects important physiological and antigenic properties of the larval body surface. The origin of the filamentous coat and intrinsic topochemical properties of ccrcariae were investigated by fine structural and cytochemical examination of intrasporocyst larvae of various developmental stages. Staining results achieved with concanavalin A-peroxidase, bismuth subnitrate, silver protein, cationic colloidal iron, and polycationic ferritin indicate the presence of both neutral and acidic glycans at the external surface of the trilaminar tegumental plasmalemma, the latter saccharide moieties conferring upon this surface a superficial electronegative charge. The filamentous coat, apparent only on relatively well-developed larvae, is rich in neutral glycans, but fails to stain with cationic cytochemical reagents. Appearance of the surface coat occurs coincident with the differentiation of tegumentary cytons, the elaboration of carbohydrate-containing vesicles by Golgi complexes within these cell bodies, and the translocation of vesicles from sites of formation to the tegumental syncytium. It is likely that those saccharides, glycoproteins, and/or glycolipids present within the neutral filamentous coat, and those which constitute the acidic layer immediately superticial to the larval body surface, are intrinsic molecular constituents of the cercarial tegumental plasmalemma. Both the neutral filamentous coat and subjacent acidic layer may be regarded as distinct functional elements of the larval body surface glycocalyx. The molecular architecture of this membrane complex apparently reflects the specializations necessary for survival in fresh water followed by rapid adaptation to the serum environment of the mammalian host.