1022-7954/05/4110- © 2005 Pleiades Publishing, Inc.
Russian Journal of Genetics, Vol. 41, No. 10, 2005, pp. 1106–1112. Translated from Genetika, Vol. 41, No. 10, 2005, pp. 1350–1357.
Original Russian Text Copyright © 2005 by Anan’ina, Vedernikov, Wasserlauf, Karamysheva, Rubtsov, Stegnii.
Ovarian nurse cells in insects are an excellent model
for studying key cell processes in the interphase
nucleus: endoreplication, transcription, spatial reorga-
nization of the interphase chromatin and of the chromo-
somes in general. Nurse cells play an important role not
only in providing the oocyte with the products essential
for egg formation, but also in developing species-spe-
ciﬁc conformation of oocyte cytoplasm and nucleo-
plasm, i.e., for ooplasmatic segregation [1, 2].
Morphological investigation of ovarian nurse cells
Mg. has shown that chro-
mosome identiﬁcation and analysis of the spatial orga-
nization of the nucleus are possible only during a very
short time in the course of the oocyte development,
namely, at the stage of primary polytene chromosomes
Mg., further alteration of the
chromatin organization, from polytene chromosomes
to large reticular nuclei, is accompanied by intricate
chromatin transformations with a manifold increase in
ploidy (up to 4096 C) [4, 5]. It is known that the mate-
rial of individual chromosomes occupies spatially iso-
lated territories. This has been shown on interphase dip-
loid nuclei of many organisms [6–11]. It is also known
that polytene nurse cell chromosomes of the dipteran
species studied occupy deﬁnite positions in the nuclei
relative one another [3, 12, 13]. If some regularities in
chromosome localization are found in the nurse cell
nuclei with polytene chromosomes, are they preserved
upon the chromatin transition to the reticular state?
What happens during the manifold ploidy increase and
chromatin compaction–decompaction in the endomi-
totic cycle? In the present study, we attempted to
answer these questions, using chromosome-speciﬁc
DNA probes, which permit identiﬁcation of individual
chromosomes in the total bulk of the “dispersed” chro-
MATERIALS AND METHODS
The study was conducted using blue meat ﬂy
Mg., collected in a natural popu-
lation of the city of Almaty in 1998.
The procedures of obtaining lactoacetic orsein, air-
dried preparations and chromosome preparations for
microdissection followed the published protocols .
Microdissection was performed on an AXIOVERT 10
microscope equipped with micromanipulator IR (Zeiss,
Germany) and a mechanical positioner .
DNA libraries of chromosomes 3, 6 and a centro-
meric C-block of chromosome 2 were generated by col-
lecting eight copies of the corresponding chromosomes
and the chromosome 2 region by micromanipulation,
with subsequent ampliﬁcation of their DNA in poly-
merase chain reaction with a degenerate oligonucle-
otide primer (DOP-PCR). The DNA probes were con-
structed on the basis of DNA libraries [14–16].
Visualization of Chromosome Territories in Interphase Nuclei
of Ovarian Nurse Cells in
T. V. Anan’ina
, A. E. Vedernikov
, I. E. Wasserlauf
T. V. Karamysheva
, N. B. Rubtsov
, and V. N. Stegnii
Research Institute of Biology and Biophysics, Tomsk State University, Tomsk, 425616 Russia
fax: (3822) 42-56-16; @e-mail: email@example.com
Institute of Cytology and Genetics, Russian Academy of Sciences, Novosibirsk, 630090 Russia
fax: (3832) 33-12-78
Received December 16, 2004; in ﬁnal form, April 16, 2005
—Analysis of localization of chromosomes 2, 3, and 6 of
Mg. in ovarian
nurse cell nuclei with different chromatin structure has shown that the regions of DNA probe hybridization
reduced with increasing chromatin compaction. Hybridization of DNA probes of chromosomes 3 and 6 to sec-
ondary reticular nuclei demonstrated that chromosomes retain their territories in the nuclei when the chromatin
acquires a reticular structure. These results suggest regular organization of the chromosomal apparatus at all
stages of the endomitotic cycle, including the stage of highly polyploid reticular nuclei. FISH of DNA probe of
the chromosome 2 telomeric region to secondary reticular nuclei revealed a peripheral distribution of the signal.
Zones of more intensive DNA probe hybridization have been distinguished. These zones probably are the
regions of accumulation of telomeric and (or) centromeric chromosome regions.