The Drosophila centrosome-associated protein CP190 is essential for viability but not for cell division.

The Drosophila CP190 and CP60 proteins interact with each other and shuttle between the nucleus in interphase and the centrosome in mitosis. Both proteins can bind directly to microtubules in vitro, and have been shown to associate with a specific pattern of loci on salivary gland polytene chromosomes, but their functions are unknown. Here we show that reducing the level of CP190 or CP60 by >90% in tissue culture cells does not significantly interfere with centrosome or microtubule organisation, with cell division, or with cell viability. However, CP190 is an essential protein, as flies homozygous for mutations in the Cp190 gene die at late pupal stages of development. In larval brains of Cp190 mutants, mitosis is not radically perturbed, and a mutated form of CP190 (CP190DeltaM), that cannot bind to microtubules or associate with centrosomes, can rescue the lethality associated with mutations in the Cp190 gene. Thus, CP190 plays an essential role in flies that is independent of its association with centrosomes or microtubules.

Lighting up insulin action.

Understanding the mechanism of insulin action remains one of the most important challenges in modern medical biology. Recent advances in cell imaging techniques, increased processing power of computers and the internet, and the introduction of novel fluorescent reagents such as green fluorescent proteins (GFPs) have revolutionized our ability to scrutinize insulin action by time-lapse microscopy at the single-cell level. This article outlines some of the advances made in the authors' laboratory, with particular reference to imaging the movements of the insulin-sensitive glucose transporter, GLUT4, and the generation of phosphoinositide lipids.

The drosophila protein asp is involved in microtubule organization during spindle formation and cytokinesis.

Abnormal spindle (Asp) is a 220-kD microtubule-associated protein from Drosophila that has been suggested to be involved in microtubule nucleation from the centrosome. Here, we show that Asp is enriched at the poles of meiotic and mitotic spindles and localizes to the minus ends of central spindle microtubules. Localization to these structures is independent of a functional centrosome. Moreover, colchicine treatment disrupts Asp localization to the centrosome, indicating that Asp is not an integral centrosomal protein. In both meiotic and mitotic divisions of asp mutants, microtubule nucleation occurs from the centrosome, and gamma-tubulin localizes correctly. However, spindle pole focusing and organization are severely affected. By examining cells that carry mutations both in asp and in asterless, a gene required for centrosome function, we have determined the role of Asp in the absence of centrosomes. Phenotypic analysis of these double mutants shows that Asp is required for the aggregation of microtubules into focused spindle poles, reinforcing the conclusion that its function at the spindle poles is independent of any putative role in microtubule nucleation. Our data also suggest that Asp has a role in the formation of the central spindle. The inability of asp mutants to correctly organize the central spindle leads to disruption of the contractile ring machinery and failure in cytokinesis.

Centrosomes have a role in regulating the destruction of cyclin B in early Drosophila embryos.

We reported previously that the disappearance of cyclin B at the end of mitosis in early Drosophila embryos starts at centrosomes and spreads into the spindle [1]. Here, we used a novel mutation, centrosome fall off (cfo), to investigate whether centrosomes are required to initiate the disappearance of cyclin B from the spindle. In embryos laid by homozygous cfo mutant mothers, the centrosomes co-ordinately detached from the mitotic spindle during mitosis, and the centrosomeless spindles arrested at anaphase. Cyclin B levels decreased on the detached centrosomes, but not on the arrested centrosomeless spindles, presumably explaining why the spindles arrest in anaphase in these embryos. We found that the expression of a non-degradable cyclin B in embryos also caused an anaphase arrest, but most centrosomes remained attached to the arrested spindles, and non-degradable cyclin B levels remained high on both the centrosomes and spindles. These findings suggest that the disappearance of cyclin B from centrosomes and spindles is closely linked to its destruction, and that a connection between centrosomes and spindles is required for the proper destruction of the spindle-associated cyclin B in early Drosophila embryos. These results may have important implications for the mechanism of the spindle-assembly checkpoint, as they suggest that unattached kinetochores may arrest cells in mitosis, at least in part, by signalling to centrosomes to block the initiation of cyclin B destruction.

D-TACC: a novel centrosomal protein required for normal spindle function in the early Drosophila embryo.

We identify Drosophila TACC (D-TACC) as a novel protein that is concentrated at centrosomes and interacts with microtubules. We show that D-TACC is essential for normal spindle function in the early embryo; if D-TACC function is perturbed by mutation or antibody injection, the microtubules emanating from centrosomes in embryos are short and chromosomes often fail to segregate properly. The C-terminal region of D-TACC interacts, possibly indirectly, with microtubules, and can target a heterologous fusion protein to centrosomes and microtubules in embryos. This C-terminal region is related to the mammalian transforming, acidic, coiled-coil-containing (TACC) family of proteins. The function of the TACC proteins is unknown, but the genes encoding the known TACC proteins are all associated with genomic regions that are rearranged in certain cancers. We show that at least one of the mammalian TACC proteins appears to be associated with centrosomes and microtubules in human cells. We propose that this conserved C-terminal 'TACC domain' defines a new family of microtubule-interacting proteins.

Evidence-based well-baby care. Part 1: Overview of the next generation of the Rourke Baby Record.

PROBLEM BEING ADDRESSED: Well baby and child care in the primary care setting has not always been based on evidence that has been shown to be effective in preventing and detecting disease and injury. OBJECTIVE OF THE PROGRAM: To help physicians and nurses provide care that is more effective than a routine complete examination, the Rourke Baby Record has been revised to include evidence-based recommendations for preventive care for infants and young children. The revision incorporates the approach and recommendations of the Canadian Task Force on the Periodic Health Examination. The updated record is now called the Rourke Baby Record: Evidence-Based Infant/Child Health Maintenance Guide (Rourke Baby Record: EB). MAIN COMPONENTS OF PROGRAM: Part 1 of this two-part article briefly describes the background for development and presents an overview of the revised record. Part 2 discusses in detail the evidence that exists for maneuvers included in the education and advice section of the revised record. CONCLUSION: Using the Rourke Baby Record: EB and incorporating it into their office record systems as a working guide will help increase the effectiveness of the primary preventive care physicians provide to infants and young children.

Evidence-based well-baby care. Part 2: Education and advice section of the next generation of the Rourke Baby Record.

PROBLEM BEING ADDRESSED: Well baby and child care in the primary care setting has not always been based on evidence that has been shown to be effective in preventing and detecting disease and injury. OBJECTIVE OF THE PROGRAM: To help physicians and nurses provide care that is more effective than a routine complete examination, the Rourke Baby Record has been revised to include evidence-based recommendations for preventive care for infants and young children. The revision incorporates the approach and recommendations of the Canadian Task Force on the Periodic Health Examination. The updated record is now called the Rourke Baby Record: Evidence-Based Infant/Child Health Maintenance Guide (Rourke Baby Record: EB). MAIN COMPONENT OF PROGRAM: Part 2 of this two-part article discusses the maneuvers included in the education and advice section of the record. These maneuvers are discussed under the subheadings safety, behaviour, family coping, high-risk children, and other. CONCLUSION: Using the Rourke Baby Record: EB and incorporating it into their office record systems as a working guide will help increase the effectiveness of the primary preventive care physicians provide to infants and young children.

Assessment of cognitive and interpersonal skills in clinical problem-solving--a comparison between certification examination and formative evaluation.

The study describes an analysis of the relationship between formative evaluation of performance in the residency program in Family Medicine and performance in the oral components of the Certification Examination. Implications for the process of certification of clinical competence are discussed.

Using the psychiatrist: a different approach to consultation.

An innovative approach to behavioral problems in family practice is described. In addition to improving the type and degree of psychiatric input to patient care, this program includes an organized system of continuing education for the participating physicians and nurses. While this system was developed in a university setting, these guidelines should be applicable to private practice.