Caenorhabditis elegans Ce-rdh-1/rad-51 functions after double-strand break formation of meiotic recombination.
During meiotic prophase 1, homologous recombination is accompanied by dynamic chromosomal changes. The Ce-rdh-1/rad-51 gene is the only bacterial recA-like gene in the nematode C. elegans genome. Upon depletion of Ce-rdh-1/rad-51 using the RNA interference method, abnormal 'kinked' chromosomes can be observed in mature oocytes at diakinesis, whereas synapsis between homologous chromosomes during the pachytene stage is normal. Following fertilization, Ce-rdh-1/rad-51-depleted embryos die early in embryogenesis, and their nuclei exhibit abnormal chromosome fragments and bridges. From epistasis analyses with Ce-spo-11 defective mutant and ionizing radiation, it is indicated that Ce-rdh-1/rad-51 functions after double-strand break (DSB) formation of meiotic recombination. Under the Ce-chk-2 defective condition, whose meiotic synapsis and meiotic recombination between homologous chromosomes are completely inhibited, the Ce-rdh-1/rad51 is normally expressed in the gonadal cells. Moreover, it seems that exogenous DSBs in the Ce-chk-2 defective nuclei at the pachytene stage can be repaired between sister chromatids in a Ce-rdh-1/rad-51-dependent manner. These results indicate that Ce-rdh-1/rad51 functions after both endogenous and exogenous DSB formation during meiosis, but not as 'pairing centers' for meiotic synapsis.
Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan.
Takako
T
Takanami
Akiyuki
A
Mori
Hideyuki
H
Takahashi
Saburo
S
Horiuchi
Atsushi
A
Higashitani
D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics*; D019457:Chromosome Breakage / Q000235:genetics*; D005456:Fluorescent Dyes; D017353:Gene Deletion; D015870:Gene Expression / Q000502:physiology; D006066:Gonads / Q000166:cytology; D017404:In Situ Hybridization, Fluorescence; D007211:Indoles; D008540:Meiosis / Q000235:genetics*; D034622:RNA Interference; D011995:Recombination, Genetic / Q000235:genetics*
D005456:Fluorescent Dyes; D007211:Indoles; C007293:DAPI