Evolutionary Dynamics of rDNA Clusters in Chromosomes of Five Clam Species Belonging to the Family Veneridae (Mollusca, Bivalvia)
Figure 1
Chromosomal location of 5S rDNA and major rDNA to mitotic chromosomes ((a), (c), (e), and (g)) and surface spread synaptonemal complexes ((b), (d), (f), and (h)) of Venerupis corrugata (VCO, (a) and (b)), Ruditapes philippinarum (RPH, (c) and (d)), Venus verrucosa (VVE, (e) and (f)), and Dosinia exoleta (DEX, (g) and (h)) counterstained with DAPI. Major rDNA signals (ITS; digoxigenin, Rhodamine, red) are intercalary to the long arms of a pair of metacentric chromosomes (bivalents) in Venerupis corrugata ((a) and (b)) but terminal to the short arms of a metacentric chromosome pair (bivalent) in Ruditapes philippinarum ((c) and (d)) and Dosinia exoleta ((g) and (h)) and a submetacentric chromosome pair (bivalent) in Venus verrucosa ((e) and (f)). 5S rDNA signals (5S; biotin, fluorescein, green) are subterminally located on the short arms of a subtelocentric chromosome pair (bivalent) in Venerupis corrugata ((a) and (b)), close to the centromere on the short arms of a metacentric chromosome pair (bivalent) in Venus verrucosa ((e) and (f)), intercalary to the long arms of submetacentric and subtelocentric chromosome pairs (bivalents) in Ruditapes philippinarum ((c) and (d)), terminal to the short arms, and centromeric on the long arms of two submetacentric chromosome pairs (bivalents) in Dosinia exoleta ((g) and (h)). Note that all signals are on different chromosome pairs (bivalents). Scale bars: 5 μm.
