Table 1 . Qualitative crossover data for the bb² set of crossover minichromosomes.

	Crossover minichromosome
Marker	m32	m29	m33	m30	m31	m25	m27	m28	m24
R2916	+	+
R2784	+	+
R2166	+	+	+	+	+	+	+
R2059	+	+	+	+	+	+	+	+	+
R1767	+	+
R1355	+	+
R0963	+	+	+	+	+
R0910	+	+	+	x	x	+
R0750	+	+
S3887	+	+	+	+	+	+	+	+	+
S3542	+	+	+	+	+	+	+
S3518	+	+	+	+	+	+	+	+	+
S3266	+	+
S3079	+	+	+	+	+	+	+	+
S3030	+	+	+	+	+	+	+	+	+
S2876	+	+	+	+	+	+	+	+	+
S2785	+	+	+	+	+	+	+	+	+

The presence of nine R2/1 and eight IGS markers was scored for the crossover minichromosome sets from bb², three Rex-magnified alleles (bb^M1, bb^M3, and bb^M4) and the Ybb⁻-magnified bb^M18 allele. The results for bb² are shown here, while the other four sets are in Table S1, Table S2, Table S3, and Table S4. The minichromosomes are listed from left to right on the basis of the number of markers carried; minichromosomes produced by more distal exchanges carry more markers than those produced by more proximal exchanges. One marker was absent in two lanes in which a new, slightly shorter, band was present (see text). +, marker present. x, marker with apparent molecular weight shift.