Autoradiography with the Agents of Psittacosis and Trachoma.

Starr, Theodore J.; Sharon, Nehama

doi:10.3181/00379727-113-28529

Cited by 13 publications

(9 citation statements)

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“…The demonstration by Hatch (10) that C. psittaci draws on the ribonucleotide pools of its L-cell host for precursors for ribonucleic acid synthesis supports the concept that chlamydiae owe their obligatory intracellular mode of reproduction, at least in part, to requirements for preformed energy intermediates. However, several investigators (4,14,19,22) have observed that exogenous thymidine fails to enter the DNA of chlamydiae although it readily enters the DNA of host cells, which suggests that not all phosphorylated products of host metabolism are available to the parasite. In extensive autoradiographic studies, Crocker From these values, the nanomoles of total thymidine incorporated into L-cell and C. psittaci DNA was calculated, assuming that the mole percentage of thymidine in both L cells and C. psittaci is 30.…”

Section: Discussionmentioning

confidence: 99%

Utilization of exogenous thymidine by Chlamydia psittaci growing in the thymidine kinase-containing and thymidine kinase-deficient L cells

Hatch¹

1976

J Bacteriol

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The incorporation of [3H]thymidine into the deoxyribonucleic acid (DNA) of Chlamydia psittaci (strain 6BC) growing in thymidine kinase (adenosine 5'-triphosphate-thymidine 5'-phosphotransferase, EC 2.7.1.21)-containing L cells, L(TK+), and thymidine kinase-deficient L cells, LM(TK-), was examined by autoradiography. Label was detected over C. psittaci inclusions in L(TK+) but not LM(TK-) cells. No evidence for a chlamydia-specific thymidine kinase activity in either L(TK+) or LM(TK-) cells was obtained. Entry of [3H]thymidine into the DNA of C. psittaci growing in L(TK+) cells was quantitated by measuring label in purified C. psittaci. It was 265 times less efficient than entry into infected host cell DNA. It is concluded that low levels of exogenous thymidine are incorporated into the DNA of C. psittaci and that this incorporation is dependent on a fully competent host thymidine kinase activity. Evidence also is presented that L cells possess at least two thymidine kinase activities, both of which are capable of supplying thymidylate precursors for nuclear DNA synthesis.

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Section: Discussionmentioning

confidence: 99%

Utilization of exogenous thymidine by Chlamydia psittaci growing in the thymidine kinase-containing and thymidine kinase-deficient L cells

Hatch¹

1976

J Bacteriol

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“…Although exogenously supplied thymidine serves as a precursor of DNA in many different kinds of cells, autoradiograms of infected cells showed that H3-thymidine did not significantly label the DNA of several different mem bers of the psittacosis group (23,38,97,113) . Thymidine also failed to re verse the growth inhibition of aminopterin on a psittacosis agent (101) .…”

Section: Mouldermentioning

confidence: 96%

The Relation of the Psittacosis Group (Chlamydiae) to Bacteria and Viruses

Moulder¹

1966

Annu. Rev. Microbiol.

115

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“…In this investigation, the activity of thymidine kinase and other enzymes related to DNA synthesis was studied in L cells infected with Chlamydia psittaci (strain meningopneumonitis). Thymidine kinase was singled out for intensive investigation, because it could be inferred from previous reports (2,34,47,53) of the failure of chlamydiae to incorporate exogenous thymidine I Present address: Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada. into their DNA that these microorganisms have no thymidine kinase of their own. Therefore, in view of the well-known relationship between thymidine kinase activity and DNA synthesis in mammalian cells (3,27,48), it appeared likely that the mechanism of inhibition of DNA synthesis in meningopneumonitis-infected L cells could be studied by use of the thymidine kinase activity of the L-cell host as an indicator.…”

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confidence: 99%

Inhibition of Thymidine Kinase Activity and Deoxyribonucleic Acid Synthesis in L Cells Infected with the Meningopneumonitis Agent

Lin

1968

J Bacteriol

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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.

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Autoradiography with the Agents of Psittacosis and Trachoma.

Cited by 13 publications

References 0 publications

Utilization of exogenous thymidine by Chlamydia psittaci growing in the thymidine kinase-containing and thymidine kinase-deficient L cells

Utilization of exogenous thymidine by Chlamydia psittaci growing in the thymidine kinase-containing and thymidine kinase-deficient L cells

The Relation of the Psittacosis Group (Chlamydiae) to Bacteria and Viruses

Inhibition of Thymidine Kinase Activity and Deoxyribonucleic Acid Synthesis in L Cells Infected with the Meningopneumonitis Agent

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