The Msd1–Wdr8–Pkl1 complex anchors microtubule minus ends to fission yeast spindle pole bodies

The minus ends of spindle microtubules are anchored to a microtubule-organizing center. The conserved Msd1/SSX2IP proteins are localized to the spindle pole body (SPB) and the centrosome in fission yeast and humans, respectively, and play a critical role in microtubule anchoring. In this paper, we show that fission yeast Msd1 forms a ternary complex with another conserved protein, Wdr8, and the minus end–directed Pkl1/kinesin-14. Individual deletion mutants displayed the identical spindle-protrusion phenotypes. Msd1 and Wdr8 were delivered by Pkl1 to mitotic SPBs, where Pkl1 was tethered through Msd1–Wdr8. The spindle-anchoring defect imposed by msd1/wdr8/pkl1 deletions was suppressed by a mutation of the plus end–directed Cut7/kinesin-5, which was shown to be mutual. Intriguingly, Pkl1 motor activity was not required for its anchoring role once targeted to the SPB. Therefore, spindle anchoring through Msd1–Wdr8–Pkl1 is crucial for balancing the Cut7/kinesin-5–mediated outward force at the SPB. Our analysis provides mechanistic insight into the spatiotemporal regulation of two opposing kinesins to ensure mitotic spindle bipolarity.     

Mapping of the interleukin 5 receptor gene to human Chromosome 3 p25–p26 and to mouse Chromosome 6 close to the Raf-1 locus with polymorphic tandem repeat sequences

Simple-sequence tandem repeat sequences in the 3 UTR of interleukin 5 (IL5)-receptor gene of human and mouse are polymorphic in their length among humans and different strains of mice. In 20 different human Epstein-Barr virus (EBV)-transformed cell lines, six alleles of IL5R could be distinguished. In the mouse, three different alleles are found. With the human-specific IL5R tandem repeat marker in human-rodent somatic cell hybrids, the IL5R gene was mapped to human Chromosome (Chr) 3 p25–p26. With the mouse-specific IL5R tandem repeat sequence in recombinant inbred strains of mice, the Il5r gene was mapped to the distal part of mouse Chr 6 close to the Raf-1 locus.     

The single DR β gene of the DRw8 haplotype is closely related to the DR β 3III gene encoding DRw52

In most individuals two HLA-DR genes are expressed from each chromosome. One of these genes encodes one of the classical DR specificities, while the other encodes either of the supertypic DRw52/DRw53 specificities. In addition to these genes usually one or two DR pseudogenes are present. In contrast, the DRw8 chromosomal region only contains a single DR gene. To determine the relationship of this single gene to the multiple DR genes of other DR specificities, comparisons of Southern genomic blots were carried out. In this analysis genomic clones for each individual DR chain locus were included. The DR w8 gene was indistinguishable from the DR III gene of DR3 cells (encoding DRw52), suggesting that it is closely related to the latter gene. The functional implications of this finding are discussed.     

Cloning and mapping of bovine ZFX gene to the long arm of the X-chromosome (Xq34) and homologous mapping of ZFY gene to the distal region of the short arm of the bovine (Yp13), ovine (Yp12–p13), and caprine (Yp12–p13) Y Chromosome

A part of mouse Zfy-2 sequence was synthesized and used to screen a genomic library of the spinous country-rat (Tokudaia osimensis spp., 2n = 45). An isolated clone had the C-terminal region of Zfy, which consisted of 1190 bp, encoded 336 amino acid residues, and harbored 11 out of 13 zinc finger motifs. With this as a probe, a bovine testis cDNA library was screened. Two ZFX clones were isolated and their sequences combined. The short sequence, lacking part of the 5′ upstream region, was amplified by PCR or RT-PCR, cloned, and sequenced. A full-length ZFX was constructed by combining these three sequences. The bovine ZFX consisted of 5328 bp and encoded 800 amino acid residues, which contained 13 zinc finger motifs. ZFX was used as a probe for fluorescence in situ hybridization and was mapped to Xq34, different from its previously reported site at Xq21-q231. A SINE (short interspersed nuclear element) sequence consisting of 188 bp was found close to the end of the 3′-untranslated region of ZFX. The SINE sequence hybridized to all bovine chromosomes. ZFY is highly homologous with ZFX and, as a result, ZFY could be mapped simultaneously. ZFY was mapped to the distal region of the short arm of the Y Chromosome (Chr) (Yp13), contradicting the previously reported position Yq1. Ovine and caprine ZFY were also mapped with bovine ZFX. Both were mapped to the distal region of the short arm of the Y Chr (Yp12-p13). Ovine ZFX was mapped to a region close to the centromere of the X Chr (Xq13). Received: 23 July 1997 / Accepted: 30 September 1997