The stability of host nucleic acids in L cells infected with Chlamydia psittaci (strain meningopneumonitis) was studied. The L cells were prelabeled with either (32)P-orthophosphate, (3)H-uridine, or (3)H-thymidine. After infection, the redistribution of each label among the different fractions of host and parasite was quantitatively determined and compared. There were no signs of accelerated degradation of host nucleic acid as the consequence of meningopneumonitis infection. Comparison of the specific activities of the meningopneumonitis nucleic acids with that of the acid-soluble fraction of host cell cytoplasm suggested that the major source of precursors for parasite nucleic acid synthesis was the common cytoplasmic pool of the infected host cell.

Chlamydia↗

PubMed1968

Inhibition of thymidine kinase activity and deoxyribonucleic acid synthesis in L cells infected with the meningopneumonitis agent.

The activities of enzymes related to deoxyribonucleic acid (DNA) synthesis were studied in uninfected L cells and in L cells infected with Chlamydia psittaci (strain meningopneumonitis). The meningopneumonitis agent multiplied normally but failed to induce the synthesis of thymidine kinase in LM (TK(-)) cells which contain no thymidine kinase in the uninfected state. It was concluded that this microorganism has no thymidine kinase of its own and that it does not depend on the functioning of the host enzyme for synthesizing its DNA. Exposure of clone 5b L cells to the meningopneumonitis agent was followed by a decline in their thymidine kinase activity to nearly zero levels, whereas the levels of uridine kinase and thymidylate synthetase remained unchanged. Inhibition of thymidine kinase activity in L cells occurred soon after infection and required new protein synthesis by the meningopneumonitis agent. This inhibition occurred before inhibition of host DNA synthesis, but it was not an essential prelude to the latter inhibition. On the basis of this and previous investigations and in light of present knowledge of the mammalian cell cycle, it was postulated that the meningopneumonitis agent inhibits macromolecular synthesis in L cells by preventing the initiation of a new cell cycle.

Chlamydia↗

PubMed1967

A peculiar configuration of agranular reticulum (canaliculate lamellar body) in the rat pinealocyte.

A cytoplasmic structure exhibiting a peculiar configuration of agranular reticulum has been found in the rat pinealocyte, and has been designated a canaliculate lamellar body. It consists of a number of fenestrated, flat cisternae which are closely spaced. They bear some distant resemblance to the annulate lamellae previously reported in a variety of cell types. Profiles of stacks of lamellae in a plane of section always display two distinct aspects, the surface and the cross-sectional views of flat cisternae. A surface view shows the hexagonal arrangement of pores or fenestrations. The pores in successive lamellae are aligned precisely, one behind the other, so that clear, cylindrical channels are seen running perpendicular to the lamellae as indicated by transverse sections of the lamellar stacks. Large canaliculate lamellar bodies are composed of many extended series of lamellar stacks which pursue a tortuous course and cross one another. Occasionally the canaliculate lamellar body is located deep in a nuclear invagination, which reminds one of the so-called nuclear pellets (Kernkugeln) reported by light microscopy. The functional significance of the body is unknown.

Animals↗

PubMed1966

Patterns of response to sulfadiazine, D-cycloserine and D-alanine in members of the psittacosis group.

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Alanine↗

PubMed1965

Microcylinders within mitochondrial cristae in the rat pinealocyte.

A minute cylindrical structure with a dense core, designated as "microcylinder," has been observed within enlarged spaces of mitochondrial cristae in pinealocytes of some adult rats (osmium tetroxide fixed, methacrylate embedded). The microcylinders are 270 to 330 A in diameter and of indeterminate length. Their wall is found to be made up of slender filamentous subunits, probably 6 in number, and surrounds a central filament. The microcylinders are arranged parallel to one another, forming monolayered or, more frequently, multilayered aggregates. Their number within a crista varies considerably. Packets of microcylinders may be seen located in the outer mitochondrial chamber, but are never found in the mitochondrial matrix. They have been observed neither in other cell types of the pineal gland nor in neurons, ependymal, and glial cells of the nearby epithalamic tissue. The origin and nature of the microcylinders are unknown. Glycogen-like particles have been encountered, though very infrequently, accompanying bundles of microcylinders within mitochondrial cristae.

Animals↗