Characterization and localization of cryptic satellite DNAs in barley (Hordeum vulgare).
Three satellites on the heavy side of the main band and two satellites on the light side were isolated in a pure from by preparative ultracentrifugation of H. vulgare DNA in Ag(+)/Cs2SO4 density gradients. The satellites were characterised in terms of their buoyant densities in CsCl and their thermal dissocation temperature in both native and reassociated forms to Cot 4. In CsCl gradients, heavy satellites formed a single peak whereas light satellites resolved into more than one component. Thermal transitions of some satellites indicated the presence of more than one molecular species. The multicomponent nature of thermal denaturation profiles was evident on differential analysis. Radioactive RNAs complementary to the three heavy satellites of H. vulgare were localised by in situ hybridization onto its nuclei and chromosomes. One heavy satellite (H3) was found to be distributed on all chromosomes, although one pair showed less hybridization compared to the others. The other satellite (H1) appeared to be present in a much lower amount on the chromosomes.
Department of Genetics, Research School of Biological Sciences, The Australian National University, 2601, Canberra, A.C.T., Australia.
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Chakrabarti
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Subrahmanyam