1022-7954/05/4105- © 2005 Pleiades Publishing, Inc.
Russian Journal of Genetics, Vol. 41, No. 5, 2005, pp. 563–566. Translated from Genetika, Vol. 41, No. 5, 2005, pp. 697–701.
Original Russian Text Copyright © 2005 by Grishaeva, Dadashev, Bogdanov.
In all eukaryotic taxa, meiosis is accompanied by
the formation of the synaptonemal complex (SC), a
speciﬁc protein structure responsible for synapsis of
homologous chromosomes, recombination, and correct
segregation to the poles in the ﬁrst meiotic division .
The synaptonemal complex includes two lateral ele-
ments with attached chromatin and a central element
between them. It is believed that chromatin loops,
located close to each other in meiosis, are linked by
speciﬁc proteins near their bases. These proteins form
the chromosome axis and lateral elements in SC. The
density of the loops is a conservative index, approach-
ing 20 per one micrometer of the chromosome axis
[1, 2]. Short (300–3000 bp) speciﬁc DNA sequences
closely associated with SC (SCAR DNA) were experi-
mentally isolated and studied. Speciﬁc traits of these
sequences allow them to be classiﬁed as an individual
family [3–5]. However, these sequences are still too
scarce in the genome to ensure chromatin attachment to
the lateral SC elements according to the hypothesis of
the looplike organization of chromosomes in meiosis.
The objectives of this study were to develop a method
of search for speciﬁc meiotic DNA (meiDNA), per-
forming the function of attaching chromatin to SC; ﬁnd
these sequences in the human genome; and characterize
them. It is conjectured that chromatin loops are
attached to SC via DNA–protein interaction. As this
interaction must be the same along the chromosome,
we expected that the corresponding DNA repeats are
repetitive. Hamster SCAR DNA, isolated in earlier
studies [3, 4], consisted of unique sequences to the
extent of 80%. Nevertheless, it was enriched in certain
repeat classes (SINE/LINE and B1).
The human X and Y chromosomes have two very
short similar stretches: the so-called pseudoautosomal
regions, PAR1 and PAR2 . A nonrecombinating
region present only in men constitutes 95% of the Y
chromosome . Synapsis and recombination between
X and Y usually involve PAR1 on the short arms of the
chromosomes (2.6 Mb) to form a short synaptonemal
complex and then a single chiasma, sufﬁcient for cor-
rect chromosome segregation (Burgoyne
quoted in ). Thus, we expected that meiDNA would
be represented by multiple copies on all chromosomes
The sequences examined in the study were retrieved
from the following databases: GENBANK (www.ncbi.
nlm.nih.gov) and Human Genome Resources database
gous repeats were sought for with the NCBI BLAST
program (www.ncbi.nlm.nih.gov/BLAST) for the
human genome. The genome region in question was
broken into fragments (windows) 6 kb in length and
examined at a pitch of 5 kb. The search parameters were
as follows: Megablast Off, Expect = 10, Filter =
By Default, Descriptions = 10000, and Alignments = 0.
Several repeat classes were discovered. Their examina-
tion is described below in more detail. The statistical
evaluation of the data and plot construction were per-
formed with the STATISTICA software package, ver-
sion 6 (www.statsoft.com).
The NCBI Genome BLAST program searches for
sequences similar to a speciﬁed one and localizes them
on the chromosome. The method of search for meiDNA
was tested in several DNA families determining chro-
mosome structure. The sequences are described in
GENBANK as (1) DNA of Chinese hamster and rat
closely associated with SC (SCAR DNA) [3–5],
(2) murine DNA sequences associated with the nuclear
lamina (Lamina DNA) , (3) DNA sequences of the
core of the rosette-like structure of murine interphase
chromatin (CRLS DNA) , and (4) chick DNA
sequences associated with nuclear matrix (SAR/MAR
DNA)  (Table 1).
Some of these sequences are similar to one another
in size and copy number in the genome. They belong to
moderately repetitive sequences. The percentage of
Identification and Characterization
of Meiotic DNA
T. M. Grishaeva, S. Ya. Dadashev, and Yu. F. Bogdanov
Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow, 119991 Russia;
fax: (095)132-89-62; e-mail: firstname.lastname@example.org
Received June 21, 2004
—A method of
search for speciﬁc repetitive DNA sequences related to the synaptonemal
complex (meiDNA) in mammalian genomes was developed. A study of the distribution of these repeats over
chromosomes revealed their scarcity on the Y chromosome and a decrease in recombination frequency in
regions enriched in meiDNA. The results are discussed in context of the model of the looplike meiotic chromo-
some organization during the formation of the synaptonemal complex.
MODELS AND METHODS