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Ribonucleoprotein‐Containing Vesicles in Cysts of Naegleria gruberi *
Author(s) -
SCHUSTER FREDERICK L.,
SVIHLA GEORGE
Publication year - 1968
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1968.tb02206.x
Subject(s) - vesicle , acridine orange , cytoplasm , biology , organelle , biochemistry , ribonucleoprotein , staining , microbiology and biotechnology , chemistry , rna , apoptosis , genetics , membrane , gene
SYNOPSIS. Ultraviolet microscopy and electron microscope autoradiography were used to study ribonucleoprotein in cysts of Naegleria gruberi. The absorption maximum for cysts is at 265 nm with little detectable absorption occurring at 295 nm. Pre‐cystic trophozoites absorb less strongly than the cysts at 265 mm. Acridine orange staining indicated concentrations of ribose nucleic acid or ribonucleoprotein in the cytoplasm of young cysts. The dye stained discrete vesicles in the cytoplasm. Tritiated uridine and tritiated proline were used to follow changes in RN‐protein at encystment. Label was incorporated into vesicles filled with ribosome‐like particles. These are presumably the sites of acridine orange staining. Relatively little label was associated with the cyst cytoplasmic matrix; most of the silver grains lay over the nucleus and cytoplasmic organelles. The vesicles are believed to represent autophagosomal‐type vacuoles with the contents derived from breakdown of organelles such as mitochondria. The path of label into the vesicles is via lysis of labeled cytoplasmic organelles. The RN‐protein vesicles of Naegleria gruberi cysts are compared to the chromatoid bodies of Entamoeba invadens. It is concluded that, tho differences in detail are present, the role of the structures in the cysts is probably the same. They are a ready source of amino acids and ribosomes in a dedifferentiated or pool state to be used for synthetic reactions that accompany resumption of trophic existence.