STRA8-deficient spermatocytes initiate, but fail to complete, meiosis and undergo premature chromosome condensation.
We analysed the phenotypic outcome of a Stra8-null mutation on male meiosis. Because the mutant spermatocytes (1) underwent premeiotic DNA replication, (2) displayed cytological features attesting initiation of recombination and of axial-element assembly, and (3) expressed Spo11 and numerous other meiotic genes, it was concluded that STRA8 is dispensable for meiotic initiation. The few mutant spermatocytes that progressed beyond leptonema showed a prolonged bouquet-stage configuration, asynapsis and heterosynapsis, suggesting function(s) of STRA8 in chromosome pairing. Most importantly, a large number of mutant leptotene spermatocytes underwent premature chromosome condensation, within 24 hours following the meiotic S phase. This phenomenon yielded aberrant metaphase-like cells with 40 univalent chromosomes, similar to normal mitotic metaphases. From these latter observations and from the wild-type pattern of Stra8 expression, we propose that, in preleptotene spermatocytes, STRA8 is involved in the process that leads to stable commitment to the meiotic cell cycle.
Mark
Manuel
M
Institut de Génétique et de Biologie Moléculaire et Cellulaire, INSERM U596, CNRS UMR7104, Illkirch, France. manuel.mark@igbmc.fr
Jacobs
Hugues
H
Oulad-Abdelghani
Mustapha
M
Dennefeld
Christine
C
Féret
Betty
B
Vernet
Nadège
N
Codreanu
Carmen-Alina
CA
Chambon
Pierre
P
Ghyselinck
Norbert B
NB
D048868:Adaptor Proteins, Signal Transducing; D000483:Alleles; D000818:Animals; D023902:Chromosome Pairing; D033481:Chromosomes, Mammalian / Q000378:metabolism*; D018390:Gene Targeting; D008297:Male; D008540:Meiosis; D049469:Meiotic Prophase I; D008677:Metaphase; D051379:Mice; D009154:Mutation / Q000235:genetics; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D016196:S Phase; D013090:Spermatocytes / Q000166:cytology* / Q000378:metabolism*; D013091:Spermatogenesis; D013573:Synaptonemal Complex / Q000378:metabolism; D013737:Testis / Q000166:cytology / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D011506:Proteins; C102019:Stra8 protein, mouse