Genome Res. 2006 Feb;16(2):297-303 doi:10.1101/gr.4156606

Shoguchi E, Kawashima T, Satou Y, Hamaguchi M, Sin-I T, Kohara Y, Putnam N, Rokhsar DS, Satoh N.

Chromosomal mapping of 170 BAC clones in the ascidian Ciona intestinalis.

The short arm of chromosome 4, 5 and 6 contains rDNA clusters.