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Ultrastructure of Symbiotic Bacteria in Normal and Antibiotic‐Treated Blastocrithidia culicis and Crithidia oncopelti *
Author(s) -
CHANG K.P.
Publication year - 1974
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.1550-7408.1974.tb03733.x
Subject(s) - nucleoid , biology , bacteria , ultrastructure , electron microscope , biophysics , microbiology and biotechnology , botany , biochemistry , genetics , escherichia coli , gene , physics , optics
SYNOPSIS. An electron microscope study of diplosomes in Blastocrithidia culicis and bipolar bodies in Crithidia oncopelti has shown that both entities appear to be intracellular symbiotes and have a similar fine structure. They are enclosed by 2 unit membranes which are separated by a large space of very low density. The outer membrane is derived probably from the host cell. The matrix of the symbiotes is composed of dense ribosome‐like particles and of areas of low density containing fine fibrillae. The particles are of the same size as ribosomes in bacteria and the fibrils have the characteristics of bacterial DNA. Thus, the lucid areas with fibrillae correspond to the nucleoids in bacteria. These observations suggest that the symbiotes are bacteria. The effect of chloramphenicol (CAP) and penicillin G (PCL) on these symbiotic bacteria was studied by culturing the host flagellates in media containing the antibiotics. The effect was analyzed at different intervals after the treatment by electron microscopy. After single treatment in the blood broth containing 0.08% (w/v) CAP, symbiotes appeared to have enlarged nucleoids, became deformed and eventually degenerated. In Grace's medium (supplemented with 10% fetal bovine serum) containing 0.6 or 2.4% (w/v) PCL, symbiotes of C. oncopelti remained unaltered, whereas some symbiotes of B. culicis became pleomorphic. Symbiotes of both species persisted after repeated transfers in PCL media and reverted to normal forms when transferred to PCL‐free media. Sensitivity of symbiotes to CAP provides further evidence of their bacterial nature. The effect of PCL on the symbiotes of B. culicis suggests the presence in their cell envelopes of mucopeptide, which probably provides rigidity for maintaining the bacterial shape of the symbiotes.