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THE tRNA METHYLASES DURING THYROXINE-INDUCED DIFFERENTIATION IN BULL FROG TADPOLES

1971; Bioscientifica; Volume: 49; Issue: 3 Linguagem: Inglês

10.1677/joe.0.0490547

1479-6805

David J. Pillinger, Ewa Borek, Woon Ki Paik,

Insect symbiosis and bacterial influences

The variegated, species-specific structures of the tRNA's and the species-specificity of the enzymes which achieve those modifications in the preformed macromolecule have prompted the suggestion that these modulations of structure, achieved at great cost in energy, serve as some recognition sites for regulatory mechanisms (Borek, 1963). The hypothesis has been tested in a variety of biological systems which are undergoing shifts in regulatory processes. The tRNA methylases are invariably constant in homogeneous biological systems. However, in organisms or tissues undergoing some process of differentiation there are profound alterations, both qualitative and quantitative, in these enzymes. Such systems examined formerly are: metamorphosing insects (Baliga, Srinivasan & Borek, 1965), embryonic and neonatal tissues (Kerr, 1970), a colonizing slime mold (Pillinger & Borek, 1969), tumour tissues (Borek, 1969) and the uterus after ovariectomy (Sharma & Borek, 1970). We now report studies of the enzymes during progressive stages of thyroxine-induced metamorphosis in the giant