ELECTRON MICROSCOPE LOCALIZATION OF PROTEINS IN DROSOPHILA POLYTENE
CHROMOSOMES BY IMMUNOGOLD TECHNIQUE
V. F. Semeshin,1 * V. V. Shlonia,1 E. N. Andreyeva,1
H. Saumweber,2 I. F. Zhimulev 1
1 Institute of Cytology and Genetics, Siberian Branch of RAS, Novosibirsk 630090, Russia;
2 Humboldt University, Berlin, 10115, Germany;
* e-mail: shpakov@hormone.ief.spb.su
Using gold labeled antibodies, we developed and tested an immunoelectron microscope (IEM) method for detection
of protein localization in Drosophlla melanogaster polytene chromosomes. This method is based on procedures
widely used for indirect immunofluorescent (IF) staining of salivary gland polytene chromosome squashes. The
application of IEM was evaluated by using specific antibodies against proteins earlier localized in both
decondensed (interbands and puffs) and compact (bands) regions of polytene chromosomes. In all the experiments,
IEM and IF images for homologous chromosome regions were compared. When applied to regions of loose structures,
IEM enabled us to localize, with high precision, signals in fine bands, interbands and puffs. There was a good
correspondence between immunogold EM and IF data. However, there was no correspondence for dense bands: gold
particles were distributed at their boundaries, while the entire bands showed bright fluorescence. This
discrepancy probably resulted from a poor penetration of antibodies conjugated to gold particles in the tightly
packaged structures. From the results obtained it may by concluded that the IEM method is advantageous for studying
the fine protein topography of loose decompacted regions of polytene chromosomes. And this must be taken into
consideration when protein localization in polytene chromosomes is performed.
Key words: immunoelectron microscope, polytene chromosomes
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