Original Article Cytogenet Genome Res 107:18–21 (2004) DOI: 10.1159/000079566 Characterization of all human male synaptonemal complexes by subtelomere multiplex-FISH M. Codina-Pascual, a J. Kraus, b M.R. Speicher, b M. Oliver-Bonet, a V. Murcia, a J. Sarquella, c J. Egozcue, a J. Navarro a and J. Benet a a Unitat Biologia, Facultat Medicina, Dept. Biologia CelWlular, Fisiologia i Immunologia, UAB, Bellaterra (Spain); b Institut für Humangenetik, Technische Universität, München and GSF-Gesellschaft für Umwelt und Gesundheit, Neuherberg (Germany); c Unitat de Reproduccio ´ Humana i Diagnòstic Genètic, Clı ´nica Girona, Girona (Spain) Supported by the Fondo Investigacio ´ n Sanitaria (Madrid) (project: PI020258), the Generalitat de Catalunya (project: 2001 SGR 00201) and the Deutsche For- schungsgemeinschaft (SP 460/4-1). MCP is recipient of a grant of the Generalitat de Catalunya (2001FI00468). Received 29 April 2004; revision accepted 26 May 2004. Request reprints from Montserrat Codina or Jordi Benet, Unitat Biologia Facultat Medicina, Dept. Biologia CelWlular Fisiologia i Immunologia, UAB, Bellaterra (Spain) telephone: +34 93 5811175; fax: +34 93 5811025 e-mail: Montserrat.Codina@uab.es, Jordi.Benet@uab.es ABC Fax + 41 61 306 12 34 E-mail karger@karger.ch www.karger.com © 2004 S. Karger AG, Basel 0301–0171/04/1072–0018$21.00/0 Accessible online at: www.karger.com/cgr Abstract. During meiotic prophase I, homologous chromo- somes synapse and recombine. Both events are of vital impor- tance for the success of meiosis. When homologous chromo- somes synapse, a proteinaceous structure called synaptonemal complex (SC) appears along the pairing axis and meiotic recombination takes place. The existence of immunolabeling techniques for SC proteins (SCP1, SCP2 and SCP3) and for DNA mismatch repair proteins present in late recombination nodules (MLH1) allow analyses of both synapsis and meiotic recombination in the gametocyte I. In situ hybridization meth- ods can be applied afterwards because chromatin is preserved during cell fixation for immunoanalysis. The combination of both methodologies allows the analysis of synapsis and the creation of recombination maps for each bivalent. In this work we apply the seven-fluorochrome subtelomere-specific multi- plex FISH assay (stM-FISH) to human male meiotic cells pre- viously labeled by immunofluorescence (SCP1, SCP3, MLH1, CENP) to assess its utility for human SC karyotyping. This FISH method consists of microdissected subtelomeric probes labeled combinatorially with seven different fluorochromes. Results prove its usefulness for the identification of all human SCs. Furthermore, by labeling subtelomeric regions this one- single-step method enables the characterization of interstitial and terminal SC fragments and SC delineation even if superpo- sition is present in pachytene spreads. Copyright © 2004 S. Karger AG, Basel During meiotic prophase I, when homologous chromo- somes pair, synapse and recombine, a proteinaceous structure called synaptonemal complex (SC) forms along the pairing axis. Synapsis and meiotic recombination are of vital importance for the success of meiosis. Synapsis failure or meiotic recombina- tion rate decrease were reported to cause partial or total meiotic arrest (Hultén et al., 1970; Egozcue et al., 2000). Several studies were carried out using silver nitrate or phosphotungstic acid to stain SC for its analysis by light and electron microscopy. These methods were applied indistinctly to gametocytes I of males (Hultén et al., 1974; Navarro et al., 1991) and of females (Gar- cia et al., 1987). In the last few years the appearance of immu- nolabeling techniques has renewed the interest for SC. Detec- tion of SC proteins (SCP1, SCP2 and SCP3) and of proteins present in late recombination nodules (MLH1) allow simulta- neous analyses of synapsis and meiotic recombination. Due to chromatin preservation during cell fixation, it is possible to combine the immunoassay with FISH techniques allowing the identification of single bivalents (Barlow and Hultén, 1996). Then, synapsis and meiotic recombination patterns can be evaluated for each specific pair of chromosomes (Barlow and Hultén, 1996; Lynn et al., 2002; Tease et al., 2002). Since 24-color karyotyping techniques were first described (Schröck et al., 1996; Speicher et al., 1996), a great number of different FISH-based multicolor technologies have been devel-