Fig. 8. The pds5^e6 mutation reduces the binding of cohesin to salivary gland chromosomes. The panels show double immunostaining of wild-type and homozygous pds5 mutant polytene chromosomes for Stromalin and Smc1. Chromosome morphology is altered in both mutants. The pds5^e3 chromosomes are slightly thicker and less extended, and the pds5^e6 chromosomes (arrows) are thinner. Chromosomes from both show banding and developmental puffs, indicating that they are transcribed. Immunostaining of chromosomes from size-matched mutants and wild type was performed at the same time with the same antibody dilution; digital micrographs were taken using identical exposures and were adjusted identically for reproduction. Examination of multiple nuclei from multiple glands showed that the staining intensity of the pds5^e3 mutant is indistinguishable from that of wild type, whereas the pds5^e6 mutants show strongly reduced staining, similar to background. Staining in pds5^e3 mutants appears somewhat less discrete than in wild type.