During meiotic prophase, chromosomes frequently adopt a bouquet-like a
rrangement, with their telomeres clustered close to the nuclear periph
ery(1-3). A dramatic example of this occurs in the fission yeast, Schi
zosaccharomyces pombe, where all telomeres aggregate adjacent to the s
pindle pole body (SPB)(4-7). Nuclei then undergo rapid traverses of th
e cell, known as 'horsetail' movement, which is led by the SPB draggin
g telomeres and chromosomes behind(4,6,7). This process may initiate o
r facilitate chromosome pairing before recombination and meiosis. With
the aim of identifying components involved in telomere structure and
function, we report here the isolation of S. pombe mutants defective i
n the ability to impose transcriptional silencing on genes placed near
telomeres(8). Two of these mutants, lot2-s17 and lot3-uv3, also displ
ay a dramatic lengthening of telomeric repeats. lot3-uv3 carries a mut
ation in Tazl (ref. 9), a telomere-binding protein containing a Myb-li
ke moth similar to two human telomere-binding proteins(10,11). Meiosis
is aberrant in these mutant yeast strains, and our analysis demonstra
tes a decreased association of telomeres with the SPB in meiotic proph
ase, This results in defective 'horsetail' movement, a significant red
uction in recombination, low spore viability and chromosome missegrega
tion through meiosis.