Meiotic interference among MLH1 foci requires neither an intact axial element structure nor full synapsis.
During meiosis, homologous chromosomes (homologs) perform reciprocal exchanges (crossovers) at a high frequency. Crossovers display interference, i.e. their spacing is more even than would be expected if they were placed randomly along the chromosomes. Concomitantly with crossover formation, synaptonemal complexes (SCs) appear between homologs: each chromosome forms an axial structure, the axial element (AE); the AEs of homologs align, and numerous transverse filaments connect the AEs to form an SC. Both the AE and the SC have been implicated in the imposition of interference. We investigated whether intact AEs or SCs are required for crossover interference in the mouse, using a mutant lacking AE protein SYCP3, which displays structurally abnormal AEs and incomplete synapsis. We estimated the level of interference from the spacing of immunofluorescent MLH1 foci, which mark almost all crossover sites in the mouse, along the SCs. The levels of interference among MLH1 foci in wild-type and Sycp3(-/-) mice were comparable, implying that neither an intact AE structure nor full synapsis is required for wild-type levels of interference.
de Boer
Esther
E
Wageningen University, Molecular Genetics group, Arboretumlaan 4, 6703 BD Wageningen, The Netherlands.
Dietrich
Axel J J
AJ
Höög
Christer
C
Stam
Piet
P
Heyting
Christa
C
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics* / Q000502:physiology; D000818:Animals; D018797:Cell Cycle Proteins; D002503:Centromere / Q000235:genetics; D023902:Chromosome Pairing / Q000235:genetics* / Q000502:physiology; D003434:Crossing Over, Genetic / Q000235:genetics*; D004268:DNA-Binding Proteins; D005260:Female; D017404:In Situ Hybridization, Fluorescence; D008540:Meiosis / Q000235:genetics*; D051379:Mice; D018345:Mice, Knockout; D000070957:MutL Protein Homolog 1; D009687:Nuclear Proteins / Q000235:genetics* / Q000502:physiology; D009865:Oocytes / Q000378:metabolism; D013573:Synaptonemal Complex / Q000235:genetics* / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C501485:Mlh1 protein, mouse; D009687:Nuclear Proteins; C490062:Sycp3 protein, mouse; D000070957:MutL Protein Homolog 1