3H-uridine labelling patterns and chromosomal polymorphism inDrosophila subobscura: J and U chromosomes

The³H-uridine labelling patterns in J and U polytene chromosomes ofDrosophila subobscura were determined. The analysis was carried out in two developmental stages and in two strains proceeding from the same geographical origin whose genotypes were: J_st/J_st; U₁₊₂/U₁₊₂ and J₁/J₁; U₁₊₂₊₈/U₁₊₂₊₈ respectively. It was observed that the labelling pattern coincided very approximately with the puffing pattern in the same stages and chromosomal arrangements. Comparison of the³H-Uridine incorporation patterns between chromosomal arrangements showed light quantitative differences. These results are discussed in relation to the inversion effect.