Distribution of Polycomb during Drosophila spermatogenesis

The images and movies presented on this page are meant as an addendum to our article

Dietzel, S., H. Niemann, B. Brückner, C. Maurange and R. Paro (1999).
The nuclear distribution of Polycomb during Drosophila melanogaster development shown with a GFP fusion protein. Chromosoma , 108(2):83-94. ( Abstract)

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Larval testis

Projection of confocal sections through a fixed larval testis. The increasing compartmentalization of the Polycomb-GFP-signal during the growth period of spermatocytes can be seen from the apical tip (left) towards more mature stages (right). This image is another example for what is shown in the article in Fig. 5C. Please see article for details.
The image is composed of projections of two neighboring stacks which where overlaid electronically. The testis preparation was performed by Drs. D.-H. Lankenau and S. Lankenau, DKFZ Heidelberg. Thanks!

Adult testis: Spermatocytes

One confocal section showing spermatocyte nuclei in a fixed adult testis. Left: Polycomb-GFP fluorescence. Right: DIC-image. The hollow-sphere-signal in three of the nuclei in the fluorescent image clearly corresponds to the nucleolus identified in the DIC image. Not all nuclear Polycomb domains are in focus in this particular optical section..

Multi color confocal images

For the multi color preparations, the testis was fixed in buffered formaldehyde and stained for DNA (DAPI) and RNA (Propidiumiodide). Confocal images were recorded at Leica Lasertechnik , Heidelberg, Germany, where Dr. W. Knebel gave us access to his UV-Laser equipped Leica TCS NT. Thanks! Images were generated as Fig. 6 in the article mentioned above.

Overview over a region in the adult testis with several spermatocytes. Single confocal sections of DNA, Polycomb and RNA and the Overlay of the three. The very bright DNA signals on the right edge of the image (pink in the overlay) are the nuclei of testis wall cells.

Click here to enlarge this image.
(906x688 pixel, 654 Kbytes)

Consecutive confocal sections through two spermatocyte nuclei from the testis shown in the previous image. The distance between two sections is 2.1 µm. To facilitate the visualization of overlap between DNA and Polycomb, DNA was false colored in red (1st and 3rd row), Polycomb in green (2nd and 3rd row) and RNA in blue (4th row). Note the high overlap of DNA and Polycomb for the autosomes (arrowheads) and the limited overlap for the nucleolar X-chromosome. The identity of the nucleolus was confirmed by RNA-staining.


Confocal section of two mature spermatocytes with pronounced evaginations. Note the high overlap of DNA and Polycomb for the autosomes in the evaginations and the limited overlap for the nucleolar X-chromosome. In the lower nucleus the Polycomb domain of one autosome is nearly completely out of focus. In neighboring sections it is detectable in the upper left corner of that nucleus.
Quicktime movie showing a 3D rotation of these two nuclei. (very nice! 669 Kbytes.) Left: DNA stain (DAPI). Right: Polycomb - GFP signal. If the movie is not displayed automatically below, you can reload this page with 3 embedded Quicktime movies by clicking here . The combined size of the 3 is about 2.5 Mbytes. Or click here to download only this movie. This movie can also be downloaded from the Chromosoma Web site here .

Quicktime movie showing serial sections of another nucleus (608 Kbytes.)
Left: DNA stain (DAPI). Center: Polycomb - GFP signal. Right: RNA stain (Propidium Iodide). Note the dispersed DNA around the spherical Polycomb signal of the nucleolus (presumably the X-chromosome) and the more compact appearance of the 2 other DNA/Polycomb domains (presumably the bivalents of the autosomes).

If the movie is not displayed automatically below, you can reload this page with 3 embedded Quicktime movies by clicking here . The combined size of the 3 is about 2.5 Mbytes. Or Click here to download only this movie.

Quicktime movie showing a 3D rotation of this other nucleus. (1220 Kbytes)
Left: DNA stain (DAPI). Center: Polycomb - GFP signal. Right: RNA stain (Propidium Iodide). See above for description

Adult testis: Later Stages

Projection of confocal sections of spermatocytes at the onset of the meiotic division period in an unfixed adult testis. While the nucleolar Polycomb-GFP signal is still prominent, autosomal Pc signals could not be detected any more. Instead, a higher number of dot like signals than in previous stages was found in these nuclei.

Confocal section of onion stage spermatids in an unfixed adult testis. Only a weak fluorescent signal little above background remained (left). The onion pattern of the Nebenkern can be identified in the corresponding brightfield image (right).

Head of a mature spermatid bundle. Projection of fluorescence images (left) and on corresponding DIC section. No Polycomb signal can be detected.

Last Update: 12.09.2000
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