Crossover Localisation Is Regulated by the Neddylation Posttranslational Regulatory Pathway
Figure 8
Synapsis is strongly perturbed in axr1, but HEI10 dynamics during early prophase are unchanged.
ZYP1 and HEI10 proteins were co-immunolocalised on lipsol-spread chromosomes from wild-type (A–D) and axr1 (N877989 allele, E–L) meiotic cells. The overlay of both signals is shown here (ZYP1 in red, HEI10 in green), but single channels can be found in Figures S7 and S8. In wild type as in axr1, ZYP1 appears on chromosomes as foci that quickly elongate, yielding a mixture of foci and short stretches (A, B, E, F, and I). Synapsis then progresses until complete synapsis is reached in wild type, defining the pachytene stage (C–D). In axr1, ZYP1 elongation can be detected, but full synapsis was never achieved (G, H, and K). In axr1, the ZYP1 signal is often uneven in thickness or forms dotted lines rather than a homogeneous and continuous signal (J and G). In addition, in some cases, only short and thick ZYP1 stretches were detected which could correspond to ZYP1 polycomplexes (L). During early zygotene, in wild type as in axr1, HEI10 forms numerous foci of variable sizes on chromatin (A, E, and I). Then, although synapsis progresses, combinations of large and small foci are observed, forming “strings of pearls” on ZYP1 stretches (B, F, and J, arrows). As meiosis progresses, a few bigger and brighter HEI10 foci can be observed in wild type (D) and in axr1 (G, H, K, and L), which generally co-exist with smaller and fainter HEI1O foci (C, D, G, H, and K). Whereas this latter HEI10 pattern is associated with complete synapsis in wild type (C–D), synapsis is only partial in axr1 (G, H, K, and L). Bar = 2 µm.