Progression of meiotic DNA replication is modulated by interchromosomal interaction proteins, negatively by Spo11p and positively by Rec8p

Spo11p is a key mediator of interhomolog interactions during meiosis. Delet ion of the SPO11 gene decreases the length of S phase by similar to 25%. Re c8p is a key coordinator of meiotic interhomolog and intersister interactio ns. Deletion of the REC8 gene increases S-phase length, by similar to 10% i n wild-type and similar to 30% in a spo11 Delta background. Thus, the progr ession of DNA replication is modulated by interchromosomal interaction prot eins. The spo11-Y135F DSB (double strand break) catalysis-defective mutant is normal for S-phase modulation and DSB-independent homolog pairing but is defective for later events, formation of DSBs, and synaptonemal complexes. Thus, earlier and later functions of Spell are defined. We propose that me iotic S-phase progression is linked directly to development of specific chr omosomal features required for meiotic interhomolog interactions and that t his feedback process is built upon a more fundamental mechanism, common to all cell types, by which S-phase progression is coupled to development of n ascent intersister connections and/or related aspects of chromosome morphog enesis. Roles for Rec8 and/or Spell in progression through. other stages of meiosis are also revealed.