Phenotype Image Detail

Image

Caption

Alterations of meiotic DNA double-strand break (DSB) repair and inefficient homologous recombination in Lmna^tm1Rben/Lmna^tm1Rben (Lamin C2-/-) mice. Chromosome spread preparations were double-stained using anti-SYCP3 antibodies in combination with anti-gamma-H2AX (A,E), anti-RAD51 (B), anti-RPA (C) or anti-MLH1 (D,F) antibodies. (A-D) In males, mutant spermatocytes show incomplete repair of induced DSB as demonstrated by the increased persistence of gamma-H2AX (A'), RAD51 (B') and RPA (C') and they lack crossing over events indicated by the complete absence of MLH1 (D'). (E) In females, efficient DSB repair is also affected in Lmna^tm1Rben/Lmna^tm1Rben pachytene oocytes (17.5 dpf) as revealed by intensive gamma-H2AX staining surrounding incompletely synapsed chromatin (asterisk in E'). (F) In contrast to males, mutant females are able to recruit MLH1 onto chromosome axes in 19.5 dpf late-pachytene oocytes. However, the MLH1 foci number was lowered and a significant portion of cells lacked at least one obligate MLH1 focus indicating the absence of cross over recombination on the affected chromosomes (arrowheads in F' and F"). This phenomenon was likewise seen in oocytes with (asterisk in F") or without (F') obvious synaptic defects. Scale bars 10 um. (G) Quantification of pachytene oocytes with persistence of gamma-H2AX in wild-type and mutant littermates reveals inefficient DSB repair in mutant cells (Pearson's Chi² test p-value = 0.0323). (H) Whisker box plot showing the number of MLH1 foci per cell in late pachytene oocytes of mutant and control (Lamin C2+/+ and Lamin C2+/-) animals. Two pairs of littermates were analysed. Mutant oocytes show a significant reduction of MLH1 foci number, indicating a lowered rate of homologous recombination (median foci numbers: control, 29; mutant, 25.5; Mann-Whitney U-test p-value = 0.00025). (I) The number of late pachytene oocytes lacking one or more obligate MLH1 foci is significantly elevated in mutant animals compared to the controls (Lamin C2+/+ and Lamin C2+/-). As above, two pairs of littermates were analysed (Pearson's Chi² test p-value = 0.0005).

Copyright

This image is from Link J, PLoS Genet 2013;9(1):e1003261, and is displayed under the terms of the Creative Commons Attribution 4.0 International License. J:223056

Associated Alleles

Symbol	Name
Lmna^tm1Rben	lamin A; targeted mutation 1, Ricardo Benavente

Associated Genotypes

Allelic Composition	Genetic Background
Lmna^tm1Rben/Lmna^tm1Rben	involves: 129S1/Sv * 129X1/SvJ