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Clones of Aedes albopictus cells resistant to methylmercaptopurine riboside
Author(s) -
Malinoski Frank J.,
Stollar Victor
Publication year - 1986
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/arch.940030307
Subject(s) - biology , riboside , biochemistry , adenosine kinase , guanosine , adenosine , adenosine deaminase
Abstract Four clones of A. albopictus cells resistant to 6‐methylmercaptopurine riboside (MMPR) (MMPR‐10, ‐11, ‐12, and ‐21) were isolated after mutagenesis of the parental LT C‐7 cells. As assayed by plating efficiencies these clones were from ten‐ to 20‐fold more resistant to MMPR than the LT C‐7 cells. Resistance was also demonstrated by the fact that concentrations of MMPR, which reduced the levels of ATP and GTP in LT C‐7 cells, had no such effect in the MMPR‐resistant cells. When de novo purine biosynthesis was measured by the incorporation of [14C]formate into ATP and GTP, MMPR had little effect on the MMPR‐10 cells (15% inhibition) but did depress synthesis considerably in the MMPR‐11 cells (80% inhibition) although not as severely as in the LT C‐7 cells (95% inhibition). Three of the resistant clones which were tested also showed considerable resistance to guanosine. Although the mechanism of resistance to MMPR in these cells is not clear it likely involves some alteration in one of the early enzymes involved in purine biosynthesis. Resistant as well as sensitive cells showed a new high‐performance liquid chromatography peak after treatment with MMPR suggesting that there was no defect in the uptake of MMPR. The conversion of labeled adenosine to AMP, ADP, and ATP in the resistant cells indicated that these cells were not deficient in adenosine kinase, another possible mechanism of resistance to MMPR. All clones showed a reduction in GTP following treatment with ribavirin; however, they varied considerably with respect to the amount of ribavirin triphosphate which they formed. In the case of the MMPR‐11 cells the amount of ribavirin triphosphate formed was markedly sensitive to cultural conditions. The fact that the various MMPR‐resistant cells responded differently to ribavirin, and that quantitative differences were also seen in their responses to MMPR (as measured by [14C]formate incorporation) and to guanosine, suggests that there are significant phenotypic differences among these resistant clones.