The sequential appearance of components of the synaptonemal complex during meiosis of the female rat

Abstract

This paper describes the light microscopy (LM) and electron microscopy (EM) localization of synaptonemal complex (SC) antigens in oocytes of rats. For this purpose, we used monoclonal antibodies (Mabs) that recognize components of 30 + 33, 125, and 190 kDa antigens of SCs of rat spermatocytes. The LM localization was performed by immunofluorescence and the EM localization by immunogold staining. The reaction of the Mabs with oocytes was similar to the reaction with spermatocytes, but weaker. The 30 + 33 kDa as well as the 190 kDa antigens could always be demonstrated if axial elements of the SC were present, irrespective of whether these were paired or unpaired. Thus, these antigens could be detected from leptotene--early zygotene until diplotene. The 190-kDa antigen appeared in a diffuse manner just before the appearance of the 30 + 33 kDa antigens. The 30 + 33 kDa antigens were not only detected in the axial elements of SCs but also in characteristic aggregates, which appeared in zygotene and persisted until after the SCs had disappeared. Such aggregates had rarely been observed in spermatocytes. The 125 kDa antigen was only present in the tripartite segments of SCs, at the inner edge of the lateral elements. Thus, the reaction of the Mab against the 125 kDa antigen was detectable in zygotene, pachytene, and very early diplotene. It appeared later than 30 + 33 kDa and 190 kDa antigens and it disappeared earlier. We found that several steps of the immunostaining procedure could cause variation in the intensity of the Mab reaction.

Localization of SCP2 and SCP3 protein molecules within synaptonemal complexes of the rat

“…The localization of SCP2 and SCP3 to the axial elements was confirmed ultrastructurally by immunogold labeling of agar filtrates and surface spreads of spermatocytes (Heyting et al , 1989Moens et al 1987;Offenberg et al 1991;Dobson et al 1994) and oocytes (Dietrich et al 1992a). However, the results were not unambiguous in all respects.…”

“…Surface spreads had been used in earlier experiments by us (Heyting et al , 1989Moens et al 1987;Offenberg et al 1991;Dietrich et al 1992a) and others (Dobson et al 1994); large numbers of cells can be analyzed relatively easily in these preparations, and the intensity of immunogold labeling is usually high. However, the risk of artifacts is also high for these preparations, because the spreading technique involves the use of DNase I and SDS .…”

“…The cDNA encoding the 190,000 M r component of rat SCs has recently been cloned and sequenced (Offenberg et al 1998); it encodes a 173 kDa protein, called SCP2, which has features of a protein that can bind to DNA, particularly to AT-rich sequences. In surface-spread preparations of spermatocytes and oocytes, SCP2 and SCP3 have both been localized to the axial elements, within and outside tripartite segments of SCs, from leptotene up to and including the diplotene stage of meiotic prophase (Heyting et al , 1989Moens et al 1987;Offenberg et al 1991;Dietrich et al 1992a).…”

Memory and DNA

“…The SC is chromosomal structure speci"c, up until now, for meiosis. It plays a major role in chromosome pairing and genetic recombination through crossing over during meiosis (Dietrich et al, 1992). Together with the results of Arnoldus et al (1989) of homologous chromosome pairing in brain tissue this observation makes the appearance of genetic recombination in neuron nuclei highly likely.…”

Primary Spermatocyte-Specific Cre Recombinase Activity in Transgenic Mice

“…It is present exclusively from the beginning of the zygotene up to the diplotene stage, in both male and female gonads (Heyting et al, 1989;Offenberg et al, 1991;Dietrich et al, 1992;Meuwissen et al, 1992;Moens et al, 1992;Dobson et al, 1994). Sequences within the 5 proximal 260 bp of mouse Sycp1 are sufficient to direct the expression of a lacZ transgene (Sycp1lacZ) in the testis, but are not active in the ovary (Sage et al, 1999).…”