Earlier, polyclonal antibodies to Escherichia coli RecA protein were used to identify immunologically related proteins in meiotic spermatocytes of different eukaryotes. At least one such protein proved to be a component of the synaptonemal complex (SC) [1]. Subsequent experiments on localization of RecA-like antigens in SCs of spermatocytes were performed by indirect immunocytochemical methods and electron microscopy, which showed that RecA-like protein(s) at early leptotene are largely associated with chromatin. During SC formation (at leptotene and zygotene), they are found in both lateral elements and the central space of SC. In some cases, RecA-like proteins are associated with SC substructures that resemble recombination nodules. When spermatocytes enter late diplotene, Rec-A-like proteins cease to be detected in SC structures.
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