The intracellular location of lysosomal enzymes in developing Dictyostelium discoideum cells

Miscellaneous · Sun Jan 01 00:00:00 EST 1989

OSTI ID:5671234

Lenhard, J M

The author has found that developing Dictyostelium cells contain two distinct acid hydrolase-containing organelles. Vesicles from cells at different stages of development were separated using Percoll density gradients. The lower density vesicles (LDVs or lysosomes) were present in nourished and starved cells. The higher density vesicles (HDVs) arose during starvation-induced differentiation. HDVs lacked two prestalk cell-specific lysosomal enzymes which were contained in LDVs. Prespore cell-specific spore coat proteins were detected in HDVs by ELISA. ({sup 35}S)sulfate labeling revealed that HDVs contained newly made glycoproteins as well as glycoproteins found in preexisting LDVs. Pulse-chase experiments using ({sup 35}S)methionine revealed that {alpha}-mannosidase from pre-existing LDVs an newly made {alpha}-mannosidase had entered HDVs. These data suggest that prespore LDVs mature to become HDVs. He has obtained evidence that HDVs are identical to prespore vesicles. Prespore vesicles are specialized secretory organelles which arise during prespore cell differentiation and which secrete their contents during terminal differentiation. As prespore vesicles secreted their contents, there was a co-incidental increase in extracellular acid hydrolase activity and a decrease in HDV-associated enzyme activity. Electron micrographs revealed that prespore cells contained two acid phosphatase-staining organelles, one of which appeared to be identical to lysosomes from nourished cells and a second which had features similar to prespore vesicles. Ricin-gold affinity electron microscopy was used to label the mucopolysaccharide component of prespore vesicles and the spore coat. Immunoelectron microscopy revealed co-localization of {alpha}-mannosidase with ricin-gold in prespore vesicles and the spore coat.

• Research Organization: State Univ. of New York, Buffalo, NY (United States)
• OSTI ID: 5671234
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
HYDROLASES
BIOLOGICAL LOCALIZATION
MYXOMYCETES
CELL DIFFERENTIATION
ELECTROPHORESIS
FASTING
GLYCOPROTEINS
GOLGI COMPLEXES
LYSOSOMES
METHIONINE
SULFATES
SULFUR 35
TRACER TECHNIQUES
AMINO ACIDS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
CELL CONSTITUENTS
DAYS LIVING RADIOISOTOPES
DRUGS
ENZYMES
EVEN-ODD NUCLEI
FUNGI
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
LIPOTROPIC FACTORS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXYGEN COMPOUNDS
PLANTS
PROTEINS
RADIOISOTOPES
SULFUR COMPOUNDS
SULFUR ISOTOPES
550201* - Biochemistry- Tracer Techniques