Polo-like kinases: a team that plays throughout mitosis

When the first mutant allele of the Drosophila genepolo was first characterized over 10 years ago, attention focused on the defects that centrosome behavior exhibited at various stages of development (Sunkel and Glover 1988). The subsequent realization that the serine-threonine kinase it encodes is highly conserved from yeasts to humans has provoked a flurry of investigation into the function of the enzyme. A role for the polo-like kinases (plks) in regulating centrosome behavior has been borne out in several organisms, and the enzymes have attracted further attention recently with the realization that they regulate multiple stages of mitotic progression. In this article we review the current status of our understanding of the functions of plks from the time of commitment to M phase in the activation of Cdc25, through the activation of the anaphase promoting complex (APC), to the regulation of late mitotic events essential for cytokinesis. We discuss how to reconcile the sometimes apparently disparate observations made upon plk function in different organisms

Efficiency of somatic cell count and california mastitis test in the diagnosis of subclinical mastitis in terrincha ewes

This study aimed to compare the efficiency of microbiological test with Californian Mastitis Test and somatic cell count in the diagnosis of Subclinical Mastitis (SM) in Terrincha sheep. Twenty-seven of a flock of about 200 Terrincha ewes (local breed) were studied for a period of 9 weeks (n > 497 samples). Milk samples were aseptically collected from each half udder once a week. At the same time, another sampled was collected from the bulk tank. After being transported to Lab under refrigeration all samples were immediately processed. The tests performed were the total microbial count (PCA), the Californian Mastitis Test (CMT) and the somatic cell count (SCC). After PCA testing, all samples exceeding 500 cfu/ml of milk (10-1 dilution) were considered positive to mastitis. The SCC was performed by a Fossmatic equipment at the Lactogal Lab. CMT was more accurate to predict Negative (87.1%) than Positive (43.1%) samples (Chi-square = 42.5; P≤0.001), meaning that 12.9% half udders were classified as negative being positive and 47.7% half udders were classified as positive being negative. PCA Negative and Positive samples were related to different SCC values (Negative: 277,048.9 ± 571,249.7 vs. Positive: 800,329.5 ± 1,444.970 somatic cells; P≤0.001), allowing to identify the real Positive (infected) half udders in complement to CMT

pavarotti encodes a kinesin-like protein required to organize the central spindle and contractile ring for cytokinesis

Mutations in the Drosophila gene pavarotti result in the formation of abnormally large cells in the embryonic nervous system. In mitotic cycle 16, cells of pav mutant embryos undergo normal anaphase but then develop an abnormal telophase spindle and fail to undertake cytokinesis. We show that the septin Peanut, actin, and the actin-associated protein Anillin, do not become correctly localized in pav mutants. pav encodes a kinesin-like protein, PAV–KLP, related to the mammalian MKLP-1. In cellularized embryos, the protein is localized to centrosomes early in mitosis, and to the midbody region of the spindle in late anaphase and telophase. We show that Polo kinase associates with PAV–KLP with which it shows an overlapping pattern of subcellular localization during the mitotic cycle and this distribution is disrupted in pavmutants. We suggest that PAV–KLP is required both to establish the structure of the telophase spindle to provide a framework for the assembly of the contractile ring, and to mobilize mitotic regulator proteins

pavarotti encodes a kinesin-like protein required to organize the central spindle and contractile ring for cytokinesis

Mutations in the Drosophila gene pavarotti result in the formation of abnormally large cells in the embryonic nervous system. In mitotic cycle 16, cells of pav mutant embryos undergo normal anaphase but then develop an abnormal telophase spindle and fail to undertake cytokinesis. We show that the septin Peanut, actin, and the actin-associated protein Anillin, do not become correctly localized in pav mutants. pav encodes a kinesin-like protein, PAV–KLP, related to the mammalian MKLP-1. In cellularized embryos, the protein is localized to centrosomes early in mitosis, and to the midbody region of the spindle in late anaphase and telophase. We show that Polo kinase associates with PAV–KLP with which it shows an overlapping pattern of subcellular localization during the mitotic cycle and this distribution is disrupted in pavmutants. We suggest that PAV–KLP is required both to establish the structure of the telophase spindle to provide a framework for the assembly of the contractile ring, and to mobilize mitotic regulator proteins

Polo-like kinases: a team that plays throughout mitosis

When the first mutant allele of the Drosophila genepolo was first characterized over 10 years ago, attention focused on the defects that centrosome behavior exhibited at various stages of development (Sunkel and Glover 1988). The subsequent realization that the serine-threonine kinase it encodes is highly conserved from yeasts to humans has provoked a flurry of investigation into the function of the enzyme. A role for the polo-like kinases (plks) in regulating centrosome behavior has been borne out in several organisms, and the enzymes have attracted further attention recently with the realization that they regulate multiple stages of mitotic progression. In this article we review the current status of our understanding of the functions of plks from the time of commitment to M phase in the activation of Cdc25, through the activation of the anaphase promoting complex (APC), to the regulation of late mitotic events essential for cytokinesis. We discuss how to reconcile the sometimes apparently disparate observations made upon plk function in different organisms

Co-silencing of human Bub3 and dynein highlights an antagonistic relationship in regulating kinetochore-microtubule attachments

We previously reported that the spindle assembly checkpoint protein Bub3 is involved in regulating kinetochore-microtubule (KT-MT) attachments. Also, Bub3 was reported to interact with the microtubule motor protein dynein. Here we examined how this interaction contributes to KT-MT attachments. Depletion of Bub3 or dynein induced misaligned chromosomes, consistent with their role in KT-MT attachments. Unexpectedly, co-silencing of both proteins partially suppressed the misalignment phenotype and restored chromosome congression. Consistent with these observations, KT-MT attachments in co-depleted cells were stable, able to drive chromosome congression, and produce inter-and intra-kinetochore stretch, indicating they are functional. We suggest that a mutual antagonism exists between Bub3 and dynein to ensure optimal KT-MT attachments. (C) 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.CESPU [02-GCQF-CICS-2011N]; FCT - Fundacao para a Ciencia e a Tecnologia [CEQUIMED-PEst-OE/SAU/UI4040/2014]; FCT [SFRH/BD/90744/2012]info:eu-repo/semantics/publishedVersio

Latin American critical thought. Theory and practice

The resurgence of LATin AmericAn criTicAL thought in the late 1990s and the early twenty-first century has brought about some discoveries that distinguish it from the sociological production of the world. it is a scientific framework that has taken on the features of a new social scientific paradigm. A growing number of authors have aligned themselves with this perspective, with visions that include critical read- ings geared to contributing to transformative social change, in a Latin American context. Thus, we ask ourselves: What are the characteristics that distinguish Latin American critical thought and give it its identity? What are its germinal features and what are its unresolved matters? A distinguishing feature of this thought is its belonging to social sciences, particularly sociology and its traditions of critical theory, whose roots, as gramsci said, do not come from fundamentalist op- position but rather from the acquisition of scientific certainty on the basis of critical analysis (...

Dynein-dependent transport of spindle assembly checkpoint proteins off kinetochores toward spindle poles

A predominant mechanism of spindle assembly checkpoint (SAC) silencing is dynein-mediated transport of certain kinetochore proteins along microtubules. There are still conflicting data as to which SAC proteins are dynein cargoes. Using two ATP reduction assays, we found that the core SAC proteins Mad1, Mad2, Bub1, BubR1, and Bub3 redistributed from attached kinetochores to spindle poles, in a dynein-dependent manner. This redistribution still occurred in metaphase-arrested cells, at a time when the SAC should be satisfied and silenced. Unexpectedly, we found that a pool of Hec1 and Mis12 also relocalizes to spindle poles, suggesting KMN components as additional dynein cargoes. The potential significance of these results for SAC silencing is discussed. (C) 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.CESPU [02-GCQF-CICS-2011N]; national Portuguese funding through FCT - Fundacao para a Ciencia e a Tecnologia FCT [POCTI/BIA/PRO/60337/2004, PTDC/SAU-OBD/105234/2008]; FCT [PEst-OE/ EQB/LA0023/2013, SFRH/BD/90744/2012]; [EXPL/BEX-BCM/1104/2013