afsS is a target of AfsR, a transcriptional factor with ATPase activity that globally controls secondary metabolism in Streptomyces coelicolor A3 (2) cally separable, and the two functions are modulated by phosphorylation on serine and threonine residues.Introduction afsR, encoding a 993-amino-acid protein, was cloned from Streptomyces coelicolor A3(2) as a gene that caused Streptomyces lividans to overproduce the pigmented antibiotics actinorhodin and undecylprodigiosin and A-factor (Horinouchi et al., 1983;Horinouchi and Beppu, 1984). The cloned gene 'awakened' transcription of the actinorhodin biosynthetic pathway in S. lividans, thus causing the host to produce actinorhodin (Horinouchi et al., 1989). The cloned gene had originally been thought to represent afsB, as it phenotypically complemented an afsB mutation (Horinouchi et al., 1983). Later, Stein and Cohen (1989) found by genetic analysis that the cloned DNA did not correspond to the afsB locus and renamed it afsR. It also induced overproduction of the calciumdependent antibiotic (CDA) (Horinouchi et al., 1989;. Disruption of the S. coelicolor A3(2) chromosomal afsR gene resulted in significant, but not complete, loss of pigment production. Floriano and Bibb (1996) also observed reduced production of actinorhodin, undecylprodigiosin and CDA in an afsR disruptant. We have thus called afsR a global regulatory gene for secondary metabolite formation.The N-terminal portion of AfsR shows similarity to ActII-ORF4 (Fernández-Moreno et al., 1991), RedD (Narva and Feitelson, 1990), DnrI (Stutzman-Engwall et al., 1992) and CcaR (Pérez-Llarena et al., 1997), all of which are pathway-specific transcriptional regulators that activate transcription of the genes in the respective gene clusters through DNA binding to specific nucleotide sequences (Wietzorrek and Bibb, 1997). In fact, ActII-ORF4 has been shown to recognize and bind specific regions in the actinorhodin biosynthetic gene cluster, thus activating the transcription of act genes (Arias et al., 1999). DnrI also binds promoter regions in the daunorubicin biosynthetic gene cluster and activates their transcription (Tang et al., 1996). However, afsR cannot substitute for the pathwayspecific regulators actII-ORF4 and redD, but may operate independently of these regulatory proteins to influence antibiotic production (Floriano and Bibb, 1996). AfsR was therefore thought to bind some specific DNA sequences

We report the long-term outcome of rotational acetabular osteotomy in 145 dysplastic hips of 131 patients after an average follow-up of 13 (10-23) years. The mean age at operation was 28 (11-52) years. The radiographic severity of osteoarthrosis before operation, according to the criteria of the Japanese Orthopaedic Association, was stage I (no degenerative change) in 63 hips, stage II (early degenerative stage) in 49, stage III (progressive stage) in 21 and stage IV (end stage) in 12. The clinical outcome based on the Merle d'Aubigné and Postel score was excellent or good for 90 (80%) of the 112 hips which had stage I or II osteoarthrosis preoperatively, and was excellent or good for only 9 of the 33 hips which had stage III or IV osteoarthrosis (p < 0.001, chi-square test). The radiographic severity of osteoarthrosis at the most recent review was stage I or II for 79 (70%) of the 112 hips which had stage I or II osteoarthrosis preoperatively. The long-term outcome of rotational acetabular osteotomy was satisfactory for a dysplastic hip with little, if any, osteoarthrosis, but was unsatisfactory for a hip with more advanced osteoarthrosis.

Aurora B kinase is an essential regulator of chromosome segregation with the action well characterized in eukaryotes. It is also implicated in cytokinesis, but the detailed mechanism remains less clear, partly due to the difficulty in separating the latter from the former function in a growing cell. A chemical genetic approach with an inhibitor of the enzyme added to a synchronized cell population at different stages of the cell cycle would probably solve this problem. In the deeply branched parasitic protozoan Trypanosoma brucei, an Aurora B homolog, TbAUK1, was found to control both chromosome segregation and cytokinetic initiation by evidence from RNAi and dominant negative mutation. To clearly separate these two functions, VX-680, an inhibitor of TbAUK1, was added to a synchronized T. brucei procyclic cell population at different cell cycle stages. The unique trans-localization pattern of the chromosomal passenger complex (CPC), consisting of TbAUK1 and two novel proteins TbCPC1 and TbCPC2, was monitored during mitosis and cytokinesis by following the migration of the proteins tagged with enhanced yellow fluorescence protein in live cells with time-lapse video microscopy. Inhibition of TbAUK1 function in S-phase, prophase or metaphase invariably arrests the cells in the metaphase, suggesting an action of TbAUK1 in promoting metaphase-anaphase transition. TbAUK1 inhibition in anaphase does not affect mitotic exit, but prevents trans-localization of the CPC from the spindle midzone to the anterior tip of the new flagellum attachment zone for cytokinetic initiation. The CPC in the midzone is dispersed back to the two segregated nuclei, while cytokinesis is inhibited. In and beyond telophase, TbAUK1 inhibition has no effect on the progression of cytokinesis or the subsequent G1, S and G2 phases until a new metaphase is attained. There are thus two clearly distinct points of TbAUK1 action in T. brucei: the metaphase-anaphase transition and cytokinetic initiation. This is the first time to our knowledge that the dual functions of an Aurora B homolog is dissected and separated into two clearly distinct time frames in a cell cycle.

Aurora B kinase plays essential roles in mitosis and cytokinesis in eukaryotes. In the procyclic form of Trypanosoma brucei, the Aurora B homolog TbAUK1 regulates mitosis and cytokinesis, phosphorylates the Tousled-like kinase TbTLK1, interacts with two mitotic kinesins TbKIN-A and TbKIN-B and forms a novel chromosomal passenger complex (CPC) with two novel proteins TbCPC1 and TbCPC2. Here we show with time-lapse video microscopy the time course of CPC trans-localization from the spindle midzone in late anaphase to the dorsal side of the cell where the anterior end of daughter cell is tethered, and followed by a glide toward the posterior end to divide the cell, representing a novel mode of cytokinesis in eukaryotes. The three subunits of CPC, TbKIN-B and TbTLK1 interact with one another suggesting a close association among the five proteins. An ablation of TbTLK1 inhibited the subsequent trans-localization of CPC and TbKIN-B, whereas a knockdown of CPC or TbKIN-B disrupted the spindle pole localization of TbTLK1 during mitosis. In the bloodstream form of T. brucei, the five proteins also play essential roles in chromosome segregation and cytokinesis and display subcellular localization patterns similar to that in the procyclic form. The CPC in bloodstream form also undergoes a trans-localization during cytokinesis similar to that in the procyclic form. All together, our results indicate that the five-protein complex CPC-TbTLK1-TbKIN-B plays key roles in regulating chromosome segregation in the early phase of mitosis and that the highly unusual mode of cytokinesis mediated by CPC occurs in both forms of trypanosomes.