Karpova Oi

[Synaptonemal complex proteins: specific proteins of meiotic chromosomes].

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 cohesins 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.

Localization of DNA Sequences Tightly Associated with the Synaptonemal Complex in Compositional Fractions of the Golden Hamster Genome

Synaptonemal complex (SC) isolated from spermatocyte nuclei after their exhaustive hydrolysis by DNase II contains DNA sequences tightly associated with it (SCAR DNA). Here, the compositional properties of a cloned family of golden hamster SCAR DNA were studied. For this purpose, 27 SCAR DNA clones were hybridized with compositionally fractionated golden hamster genomic DNA. The sequences of the SCAR DNA family were mainly localized in the GC-poor isochore families L1 and L2, which accounted for 63% of hybridization signals. The remaining 37% of signals pertained to the GC-rich isochore families H1 and H2. Thus, SCAR DNA proved to be distributed throughout the genome, irrespective of differences in density and sequence type between isochore families. Moreover, the SCAR DNA sequences containing the regions of homology with LINE/SINE repeats were found in all the isochore families. The compositional localization of SCAR DNA is in agreement with the hypothesis that the SC and SCAR DNA participate in chromatin reorganization during meiosis prophase I, which should result in the attachment of chromatin loops to the lateral elements of SC throughout its length.