Plant polytene chromosomes

Cytolocalization of Ribosomal Cistrons in Plant Polytene Chromosomes

In both pIants and animals the mechanism of ribo-somal R N A synthesis is thought to be the same, yet genetic and biochemical evidence points to a dispersed origin along chromosomal D N A in plants (1, 2, 3) and a strict localization of genes coding for ribosomal R N A in the nucleolar organizer regions of chromosomes in animals (4, 5). A precise means of locahzing ribosomal cistrons has been m...

zeste protein on polytene chromosomes

Histone localization in polytene chromosomes by immunofluorescence

Polytene chromosomes of Chironomus thummi were treated with antisera elicited by purified calf thymus histone fractions, and the location of each histone type was visualized by the indirect immunofluorescence technique. Each of the antisera produced specific and distinct patterns of fluorescence, suggesting that it is possible to use the indirect immunofluorescence technique to study the in sit...

Polytene chromosomes in mouse trophoblast giant cells.

Mouse trophoblast giant cells undergo successive rounds of DNA replication resulting in amplification of the genome. It has been difficult to determine whether giant cell chromosomes are polyploid as in liver cells or polytene as in Dipteran salivary glands because the chromosomes do not condense. We have examined the pattern of hybridization of mouse giant cells with a variety of in situ chrom...

Locations of Z-DNA in polytene chromosomes

In polytene chromosomes of Drosophila hydei and D. melanogaster, Z-DNA was identified in varying distribution after different conditions for fixation were used. When salivary glands were fixed and squashed in 50% acetic acid alone, Z-DNA was found in the less dense DNA regions, such as interbands, some puffs, and a few of the less dense bands. Prefixation that combined ethanol and acetic acid e...