[Localization of DNA sequences tightly associated with synaptonemal complex in compositional fractions of golden hamster]. / Lokalizatsiia posledovatel'nostei DNK, prochno assotsirovannykh s sinaptonemym kompleksom, v kompozitsionnykh fraktsiiakh zolotistogo khomiachka.

The synaptonemal complex isolated from the spermatocyte nuclei by exhaustive hydrolysis of the latter by DNase II contains tightly associated DNA sequences (SCAR DNA). Here we studied the compositional properties of a cloned family of SCAR DNA of golden hamster, namely we performed the localization of 27 SCAR DNA clones on compositionally fractionated genomic DNA from golden hamster. We observed that sequences of the SCAR DNA family are mainly localized in the GC-poor isochore families L1 and L2, that showed 63% hybridization signals. This means that 37% of signals is referred to the GC-rich isochores, indicating the presence of SCAR DNA overall the genome, even if each isochore family presents differences in density and sequence type. Moreover, the SCAR DNA sequences containing regions of homology with LINE/SINE repeats were observed in all the isochore families. The compositional localization of SCAR DNA is in agreement with the hypothesis that SC and SCAR DNA participate in the chromatin organization during the meiosis prophase I, which should result in the attachment of chromatin loops to lateral elements of SC along the whole length of the latter.

[Synaptonemal complex proteins: specific proteins of meiotic chromosomes]. / Belki sinaptonemnogo kompleksa--spetsificheskie belki meioticheskikh khromosom.

The review considers proteins of the synaptonemal complex (SC), a specific structure formed between homologous chromosomes in maturing germline cells during meiotic prophase I. The structure and functions are described for proteins that form ultrastructural SC elements in mammals, in yeast, and in higher plants. The roles of cohesions and of the SC proteins in meiotic sister-chromatid cohesion are considered. Though still scarce, data are summarized on the SC self-assembly and dissociation and on the molecular composition of SC-associated recombination nodules, which provide a compartment for meiotic recombination enzymes. The accumulating data on the SC molecular components and on their structure, properties, and interactions improve the understanding of the SC function.

[Features of the primary structure of DNA from the synaptonemal complex of the golden hamster]. / Osobennosti pervichnoi struktury DNK iz sinaptonemnogo kompleksa zolotistogo khomiachka.

DNA of golden hamster synaptonemal complex (SC) was cloned and partially sequenced. Computer analysis was performed to compare the SC DNA sequences for different families of eukaryotic genomic DNA. SC DNA is homologous to LINE family and in contrast to genomic DNA is enriched with alternative (GT/CA)n sequences and palindromes. By its ability to form potential hairpin loops, SC DNA is similar to nuclear matrix-associated regions of DNA (MARs) and differs considerably from DNA of microsatellite loci. It is noteworthy that SC DNA, which is supposed to be involved in meiotic recombination, and DNA of immunoglobulin genes, involved in somatic recombination, are both enriched with palindromes. The discovered peculiarities of the structure of hamster SC DNA allow us to join it with rat SC DNA into a special family of rodent genomic DNA sequences.