Figure 2

FISH identification of autosomal parts of the S. c. walkeri and S. cynthia subsp. indet. neo-sex chromosomes on female pachytene chromosomes of three subspecies of S. cynthia. The Cy3-labelled orthologous probe of the B. mori XDH 1 gene (red signals, arrowheads) hybridized to an autosome bivalent, but not to the ‘U-shaped’ univalent of the Z chromosome in the female pachytene complement of S. c. ricini (a), whereas the XDH 1 orthologous probe mapped to autosomal parts of both the neo-W and neo-Z chromosomes in S. c. walkeri (b) and to autosomal parts of both the neo-W and Z1 chromosomes in S. cynthia subsp. indet. (c). The Cy3-labelled orthologous probe of the B. mori lysozyme gene (red signals, arrowhead) hybridized to the same autosomal segment of both the neo-W and neo-Z chromosomes in S. c. walkeri (d). GISH with Green-labelled female genomic probe (green signals) identified the original W-heterochromatin parts of the neo-W chromosome in S. c. walkeri (b, d) and S. cynthia subsp. indet. (c). Chromosomes were counterstained with DAPI (light blue). Bar represents 10 μm.