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PubMed1988

[Karyotypes of cattle (Bos taurus) and horses (Equus caballus) on the basis of synaptonemal complexes].

The cytogenetic study performed has shown that karyotyping of meiotic cells can be based on the synaptonemal complexes (SC) of spreading pachytene spermatocytes of bull and of horse. The horse SC karyotype has not been previously described. A comparison of the relative length of SC with metaphase chromosomes of bull and horse somatic cells has revealed the correspondence of the chromosome length in pachytene of meiosis and metaphase, which is in agreement with the data on house mouse and Chinese hamster. The method of spreading pachytene cells may be of great practical importance in studies of the fertility disturbances in farm animals.

Animals↗

PubMed2002

Synaptonemal complex analysis in oocytes and spermatocytes of threespine stickleback Gasterosteus aculeatus (Teleostei, Gasterosteidae).

A surface-spreading synaptonemal complex (SC) technique was employed to analyze spermatocytes and oocytes of stickleback, Gasterosteus aculeatus, in order to visualize the process of chromosome synapsis. The mean SC length was 150 +/- 18 microm in three males and 143 +/- 12 microm in one female analyzed. A representative SC karyotype with 21 bivalents was also presented. Each SC had lateral elements of equal length. No bivalent displaying the atypical synaptic behaviour which is often associated with heteromorphic sex chromosomes was observed neither in males nor in the female analyzed.

Animals↗

PubMed1992

[Synaptonemal complexes of human spermatocytes and foetal oocytes observed by electron microscopy].

The electron microscopical studies on the synaptonemal complexes (SC) of Chinese spermatocytes and foetal oocytes have been made and used to construct SC karyotype with a modified surface micro-spreading technique. We also confirm the SC formation between the short arms of the X chromosome and Y chromosome as well as secondary association between the distal tips of Xq and Yq at pachytene. Moreover, attentions are paid to the morphology of the XY pairs and five pairing type of XY pairs. In our preparations, a rare triploid spermatocyte was observed and triple pairing was described. Some possible significances of the triple pairing of triploid spermatocyte in relation to the human chromosomal abnormalities have been supposed.

Female↗

PubMedDate not supplied

[Autoantibody formation against the antigens of the synaptonemal complex in the syngeneic immunization of male Mus musculus].

Male mice were immunized with the suspension of synaptonemal complexes (SC) isolated from mouse spermatocytes nuclei. The indirect immunofluorescent analysis showed the active binding of sera obtained from immunized mice to SC of mouse spermatocyte spreads. At early and mid-pachytene, SC can be clearly identified in 19 autosome bivalents and in sex chromosome bivalent. According to the electron microscopic analysis, all structural elements of SC bind antibodies. Metaphase chromosomes were not stained with the immune sera. Specificity of interaction between SC components and antibodies was confirmed in a series of control experiments. Analysis of sera obtained from mice after their syngeneic immunization with isolated SC fraction suggested that certain mouse SC components induce the formation of autoantibodies. This, in turn, suggests that these SC components are meiosis-specific.

Animals↗

PubMed1995

Synaptonemal complex analysis in a boar with tertiary, trisomy, product of a rcp(7;17)(q26;q11) translocation.

Synaptonemal complex analysis by electron microscopy showed a trivalent formed by pairing of chromosome 17(7) with chromosome pair 7 in two zygotene cells. In 89 pachytene cells (75.4%) the chromosome 17(7) occurred as a univalent with the axis being unpaired, in the shape of a ring (60.6%), a rod (38.2%) or self-paired (1 cell). Thirty-four (38.2%) of the univalents were paired or associated with the sex bivalent. Twenty-five (21.2%) of the 118 pachytene cells analysed demonstrated different types of trivalent pairing: the 17(7) chromosome paired with chromosome pair 7 in 24 cells and with pair 17 in one cell. Moreover, in 4 cells, chromosome 17(7) was paired with both pair 7 and pair 17, forming a pentavalent. Trivalent association with XY was observed in 4 cells. Nineteen bivalents plus a univalent (8 cells), and eighteen bivalents plus a trivalent (11 cells), were found during conventional meiotic investigation of diakinesis-metaphase I. Though the boar demonstrated a normal testicular histology, a qualitatively deviant semen picture was evident.

Animals↗

PubMed1998

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

SCP2 and SCP3 are major protein components of the lateral elements (LEs) of synaptonemal complexes (SCs) of the rat, with Mrs of 173, 000 and 30,000. We performed a detailed immunocytochemical comparison of the localization of SCP2 and SCP3 within SCs at the electron microscopic level. The ultrastructural localization of SCP2 and SCP3 was analyzed by immunogold labeling of two types of preparations, namely surface-spread spermatocytes and ultrathin sections of Lowicryl-embedded testicular tissue of the rat. For each of the antisera used, the distribution of immunogold label over SCs in surface-spread spermatocytes differed significantly from the distribution of label on sections. We attributed this difference to artifacts caused by the surface-spreading technique, and therefore we relied on sections for the precise localization of epitopes. On sections, the distribution of label obtained with two antisera against nonoverlapping, widely separated fragments of SCP2 did not differ significantly. There was a small but significant difference between the labeling pattern obtained with an anti-SCP3 serum and the pattern obtained with either of the two antisera against fragments of SCP2; although for all three antisera the peak of the immunogold label coincided with the center of the LE, the distributions of label obtained with the antisera against fragments of SCP2 were asymmetrical, with a shoulder at the inner side of the LE, whereas the distribution of label obtained with anti-SCP3 serum was symmetrical. Furthermore, we observed fuzzy connections between the LEs that were labeled by anti-SCP2 but not anti-SCP3 antibodies. It is possible that labeling of these fuzzy bridges caused the shoulder in the gold label distributions obtained with anti-SCP2 antibodies.

Animals↗

PubMedDate not supplied

[The production of spread synaptonemal complexes of meiocytes from animals and plants by a drying method].

A spreading technique was used to prepare synaptonemal complexes from animals (Bombyx mori and Mus musculus spermatocytes) and plants (Zea mays microsporocytes). Suspension of hypotonically treated cells was spread over plastic-coated slides and air-dried. Fixed and phosphotungsten acid-stained spread preparations were studied by phase-contrast and electron microscopes. The spreading-through-drying method is more efficient and thereby more preferable as compared to the classical hypophase spreading technique.

Animals↗

PubMed2000

Zip3 provides a link between recombination enzymes and synaptonemal complex proteins.

In budding yeast, absence of the meiosis-specific Zip3 protein (also known as Cst9) causes synaptonemal complex formation to be delayed and incomplete. The Zip3 protein colocalizes with Zip2 at discrete foci on meiotic chromosomes, corresponding to the sites where synapsis initiates. Observations suggest that Zip3 promotes synapsis by recruiting the Zip2 protein to chromosomes and/or stabilizing the association of Zip2 with chromosomes. Zip3 interacts with a number of gene products involved in meiotic recombination, including proteins that act at both early (Mre11, Rad51, and Rad57) and late (Msh4 and Msh5) steps in the exchange process. We speculate that Zip3 is a component of recombination nodules and serves to link the initiation of synapsis to meiotic recombination.

Adenosine Triphosphatases↗

PubMed1988

Sequential study of the synaptonemal complex in rat (Rattus norvegicus) oocytes by light and electron microscopy.

The progression of first meiotic prophase and synaptonemal complex (SC) formation in female rats, Rattus norvegicus S.D., is described through the analysis of the different stages of the first meiotic prophase, and confirms the high synchrony of the process in this species. Leptotene is a stage of very short duration and since pairing of the homologues begins very early, only a leptotene-zygotene stage can be distinguished. The progression of pairing during zygotene is asynchronous. The morphology of the SCs is similar to that described in other species. During diplotene and before disintegration of the lateral elements, desynapsis takes place. In some oocytes a double or even multiple nature of lateral elements was seen. Associations between SCs and nucleoli or nucleolar filaments are frequent. The presence of fragmented SCs can be interpreted as a technical artifact.

Animals↗

PubMed1989

Immunocytogenetics. III. Analysis of trivalent and multivalent configurations in mouse pachytene spermatocytes by human autoantibodies to synaptonemal complexes and kinetochores.

Mice heterozygous for one or more Robertsonian (Rb) translocation chromosomes have been used to analyze synaptonemal complex (SC) configurations and kinetochore arrangements in trivalents and multivalents. Rb heterozygosity without arm homologies leads to the formation of heteromorphic trivalents in meiosis I; alternating homology of the chromosome arms produces ringlike or chainlike multivalents. Immunofluorescence double-labeling with human antibodies to SCs and kinetochores was performed on surface-spread pachytene spermatocytes. Both Rb bivalents and Rb trivalents clearly showed that metacentrics possess only one centromere. In heteromorphic trivalent SCs, the nonhomologous kinetochores of the two acrocentrics were closely paired in a cis-configuration and juxtaposed opposite the kinetochore of the metacentric; the latter appeared to be an integral part of the longitudinal SC axis. Meiotic multivalents of interpopulation hybrids included up to 36 chromosome arms. In multivalent SCs, the kinetochores always lay together, with the SC arms arranged away from the central centromere cluster. The paracentromeric regions of the Rb chromosomes appeared to remain unsynapsed on both sides of the centromeres. The SC arms were often linked by end-to-end associations. Following desynapsis of the multivalent SC, the kinetochores of the Rb metacentrics showed a highly nonrandom topologic distribution within the nucleus, reminiscent of their arrangement during synapsis.

Animals↗

PubMed1994

The relationship between synaptonemal complex length and genome size in four vertebrate classes (Osteicthyes, Reptilia, Aves, Mammalia).

We investigated the relationship between synaptonemal complex (SC) length and genome size in 18 species of vertebrates from the classes Osteicthyes (bony fish), Reptilia (reptiles), Aves (birds), and Mammalia (mammals). When total SC length was plotted against genome size for all 18 vertebrate species, there did not appear to be a correlation between the two variables. However, when birds were excluded from the data and a linear regression analysis was performed, variation in genome size accounted for approximately 50% of the variation in total SC length (r2 = 0.47). Dividing the average total SC length for a species by its 4C DNA amount yields the species' SC/DNA ratio. SC/DNA ratios of birds were approximately twice as high as the SC/DNA ratios of reptiles and mammals. Bony fish showed intraclass divergence in SC/DNA ratios. The sunfish (Centrarchidae) had SC/DNA ratios almost as high as those of birds, while the remaining fish in the study had SC/DNA ratios similar to those of reptiles and mammals. These observations indicate that inter and intraclass divergence in the relationship between total SC length and genome size has occurred in the vertebrates. Coupled with evidence from the literature, our results also suggest that SC/DNA ratios are positively correlated with crossover frequency.

Animals↗

PubMed1991

Synaptonemal complex analysis in a human male carrier of a 4;6 translocation: heterosynapsis without previous homosynapsis.

Silver-stained synaptonemal complexes in surface-spread pachytene nuclei from a man, heterozygous for a reciprocal translocation, were analysed by electron microscopy. Contrary to the classically expected cross-shaped configuration, extensive non-homologous pairings were observed with asymmetrical association in the lateral elements of the non-homologous arms of the quadrivalents. A possible role of the heterosynapsis in reproductive failure is discussed.

Adult↗

PubMed1992

Microtubule-associated proteins during mouse spermatogenesis: localization of a protein immunologically related to brain MAP1B protein in the synaptonemal complex.

Monospecific polyclonal antibodies against MAP1A protein and an immunologically related brain MAP1B polypeptide were used to visualize mouse synaptonemal complexes (SCs) with immunofluorescence microscopy. Anti-MAP1A antibody recognized SCs uniformly. However, when anti-MAP1B antibody was used, a dashed pattern of staining was observed along the SCs in both autosomes and pachytene XY bivalents. After purification of SCs, immunoblots of the electrophoresed proteins revealed a polypeptide of 220 kDal, which was recognized by anti-MAP1B antibody, and two proteins of 180 kDal and 160 kDal, which were recognized by anti-MAP1A antibody. High-molecular-weight polypeptides immunologically related to microtubule-associated proteins were localized in the cell nucleus. The function of these nuclear proteins is unknown. The distribution of fluorescent signal corresponding to the 220-kDal protein during meiosis and spermiogenesis and its localization in the nuclear matrix suggest the participation of preexisting nucleoskeletal proteins in the molecular organization of the SC and its dynamics during meiotic prophase.

3T3 Cells↗

PubMed1997

The prevalence of a YY synaptonemal complex over XY synapsis in an XYY man with exclusive XYY spermatocytes.

An infertile XYY man was studied by synaptonemal complex analysis of microspread spermatocytes and by quantitation of germ cells in semithin sections. All the 74 spermatocytes micrographed have an XYY constitution, and the biopsy shows a homogeneous arrest of spermatogenesis at the spermatocyte/young spermatid stages. The overwhelming majority (86%) of spermatocytes showed a Y-Y bivalent plus a univalent X. The Y-Y bivalent is totally synapsed in 48% of the cells. In the remaining cells, the YY bivalent has an average synaptic segment covering 43% of its length that always includes Yp. Another 9% of the spermatocytes showed an XYY trivalent and 4% of the spermatocytes showed univalence of the three gonosomes. Progression through all the pachytene substages was observed in cells with the two main synaptic configurations, but a high level of germ cell death was observed at or immediately after the meiotic divisions. The prevalence of Y-Y synapsis arises from the longer homologous region and the higher speed of pairing between the two Y chromosomes. Germ cell death is probably related to the univalence of the X chromosome. Synaptic competition between three gonosomes seems to be similar to that found in triploid birds but is somewhat different from that of XYY mice.

Adult↗

PubMed1984

An acidic silver staining method for synaptonemal complexes under light microscopy.

A simple method is presented by which synaptonemal complexes (SCs) can be visualized under bright field microscopy. Staining was accomplished with a silver nitrate solution adjusted to pH 3-3.5 with formic acid, after an acidic fixation. This method is suitable for the demonstration of SCs, centromeres and NOR regions in both mammalian (Rattus norvegicus, 'Wistar') and orthopteran spermatocytes (Steropleurus martorelli complex). Results suggest that pretreatment with solutions of alkaline pH are not needed for demonstrating SCs, and that the silver impregnation may also operate when the proteinaceous lateral elements of the SC are subjected to low pH conditions. Differential staining of the X chromosome during meiosis in Orthoptera, and a core-like structure in the chromosomes during the more condensed stages of meiosis and mitosis can also be shown.

Animals↗

PubMed1997

Synaptonemal complex damage in mouse spermatocytes exposed to tequila and brandy.

We evaluated the capacity of tequila and brandy to induce synaptonemal complex (SC) breaks in mouse spermatocytes. The alcoholic beverages were 20% diluted in distilled water and administered daily by oral intubation for 21 days (1, 2, and 3 g/kg, six animals per group). A positive control group was administered cyclophosphamide (CP) (20 mg/kg), and another group of mice was treated with distilled water. The results indicated the following: (i) tequila induced a statistically significant increase in SC damage with 2 g/kg and 3 g/kg, and brandy was genotoxic only with 3 g/kg, (ii) CP induced almost a duplication of the total number of breaks produced by tequila or brandy; (iii) the average weight increase in the animals was 3.3 g, but the group treated with the highest dose of tequila showed a slight weight decrease; (iv) the weight of the testes did not show any significant difference among groups of animals; and (v) there were no significant differences between groups with respect to the frequency of pachytenes (mean number: 195 in 1000 cells).

Administration, Oral↗

PubMed2006

Mouse SYCP2 is required for synaptonemal complex assembly and chromosomal synapsis during male meiosis.

During meiosis, the arrangement of homologous chromosomes is tightly regulated by the synaptonemal complex (SC). Each SC consists of two axial/lateral elements (AEs/LEs), and numerous transverse filaments. SC protein 2 (SYCP2) and SYCP3 are integral components of AEs/LEs in mammals. We find that SYCP2 forms heterodimers with SYCP3 both in vitro and in vivo. An evolutionarily conserved coiled coil domain in SYCP2 is required for binding to SYCP3. We generated a mutant Sycp2 allele in mice that lacks the coiled coil domain. The fertility of homozygous Sycp2 mutant mice is sexually dimorphic; males are sterile because of a block in meiosis, whereas females are subfertile with sharply reduced litter size. Sycp2 mutant spermatocytes exhibit failure in the formation of AEs and chromosomal synapsis. Strikingly, the mutant SYCP2 protein localizes to axial chromosomal cores in both spermatocytes and fetal oocytes, but SYCP3 does not, demonstrating that SYCP2 is a primary determinant of AEs/LEs and, thus, is required for the incorporation of SYCP3 into SCs.

Animals↗

PubMed1992

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

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.

Animals↗