A novel XXXX mei4 mutant that allows efficient synchronization of telomere dispersal and the first meiotic division.

@entity72684 @entity6739 @entity4523
The progression of meiosis is controlled by a number of gene-expression systems in the @entity6739 @entity6739 . A forkhead-type transcription factor Mei4 activates a number of genes essential for progression from the middle to late stages of meiosis, which include @entity4523 , meiosis II and sporulation. The mei4-deletion mutant (mei4/\) arrests after meiotic prophase and does not enter @entity4523 . To further analyse the Mei4 function, we isolated novel temperature-sensitive mei4 alleles. The two alleles isolated in the initial screen turned out to contain a substitution at N136 in the forkhead DNA-binding domain. Among site-directed mutants that carried a point mutation at this position, the mei4- @entity72684 mutant showed the most severe temperature sensitivity. The mei4- @entity72684 mutant arrested before @entity4523 at the restrictive temperature, as did the mei4/\ mutant. In @entity6739 , the telomeres are clustered at the spindle pole body (SPB) in meiotic prophase and disperse from it at the onset of @entity4523 . The mei4/\ mutant was found to arrest with its telomeres clustered at the SPB, demonstrating a role for Mei4 in telomere dispersion. The mei4- @entity72684 mutant also arrested with clustered telomeres at the restrictive temperature, and the clustering was synchronously resolved after a temperature down-shift, indicating that mei4- @entity72684 is a reversible allele. Hence, the mei4- @entity72684 mutant will be a unique tool to synchronize the meiotic cell cycle from @entity4523 onwards and may facilitate analyses of cellular activities occurring during @entity4523 .
