Two levels of interference in mouse meiotic recombination.
During meiosis, homologous chromosomes (homologs) undergo recombinational interactions, which can yield crossovers (COs) or noncrossovers. COs exhibit interference; they are more evenly spaced along the chromosomes than would be expected if they were placed randomly. The protein complexes involved in recombination can be visualized as immunofluorescent foci. We have analyzed the distribution of such foci along meiotic prophase chromosomes of the mouse to find out when interference is imposed and whether interference manifests itself at a constant level during meiosis. We observed strong interference among MLH1 foci, which mark CO positions in pachytene. Additionally, we detected substantial interference well before this point, in late zygotene, among MSH4 foci, and similarly, among replication protein A (RPA) foci. MSH4 foci and RPA foci both mark interhomolog recombinational interactions, most of which do not yield COs in the mouse. Furthermore, this zygotene interference did not depend on SYCP1, which is a transverse filament protein of mouse synaptonemal complexes. Interference is thus not specific to COs but may occur in other situations in which the spatial distribution of events has to be controlled. Differences between the distributions of MSH4/RPA foci and MLH1 foci along synaptonemal complexes might suggest that CO interference occurs in two successive steps.
de Boer
Esther
E
Molecular Genetics Group, Wageningen University and Research Centre, Arboretumlaan 4, 6703 BD Wageningen, The Netherlands.
Stam
Piet
P
Dietrich
Axel J J
AJ
Pastink
Albert
A
Heyting
Christa
C
D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics; D033481:Chromosomes, Mammalian / Q000235:genetics; D004247:DNA / Q000235:genetics; D004268:DNA-Binding Proteins; D005260:Female; D006657:Histones / Q000235:genetics; D008297:Male; D008540:Meiosis; D051379:Mice; D009687:Nuclear Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic / Q000235:genetics*; D051716:Replication Protein A / Q000235:genetics
D018797:Cell Cycle Proteins; D004247:DNA; D004268:DNA-Binding Proteins; D006657:Histones; D009687:Nuclear Proteins; D051716:Replication Protein A; C502328:Msh4 protein, mouse; C489754:Sycp1 protein, mouse; C475961:gamma-H2AX protein, mouse