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1.
Inorg Chem ; 59(18): 12983-12987, 2020 Sep 21.
Artículo en Inglés | MEDLINE | ID: mdl-32897061

RESUMEN

Two air-stable, isostructural, mononuclear six-coordinate manganese(II) and cobalt(II) oxamate complexes, [M(4-HOpa)2(H2O)2] [4-HOpa = N-4-hydroxyphenyloxamate; M= Mn2+ (1) or Co2+ (2)], exhibit field-induced slow magnetic relaxation. A bottleneck process is observed throughout the temperature range of 2-20 K for 1, while for 2, it dominates only at low temperatures (2-4 K). Additionally, the Raman process [n = 6.9(2)] is responsible for an increase in the relaxation time at higher temperatures to 2.

2.
Am J Clin Oncol ; 47(4): 177-184, 2024 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-38200688

RESUMEN

OBJECTIVES: This study evaluated real-world treatment patterns of approved bone-targeting agents (BTAs) with various mechanisms of action-pamidronate, zoledronic acid, and denosumab-for the prevention of skeletal-related events in patients with bone metastases (BM) from solid tumors. METHODS: Adult patients with BM secondary to solid tumors between January 1, 2014, and December 31, 2018, were identified from the Flatiron Health Oncology Services Comprehensive Electronic Records database and categorized by BTA use and therapy type. Time from diagnosis to initiation, persistence (mean time on treatment), and compliance (≥12 administrations/year) with BTA with up to 4 years of follow-up were examined. RESULTS: This study included 27,268 patients with BM (breast cancer, 32.7%; lung cancer, 16.5%; prostate cancer, 17.2%; and other solid tumors, 33.6%); of these, 41.4% initiated denosumab after BM diagnosis; 21.3%, zoledronic acid; 0.6%, pamidronate; and 36.7% had no treatment record. Mean (SD) time to initiation for denosumab or zoledronic acid was 68.6 (157.0) days (denosumab, 70.3 (160.4) days; zoledronic acid, 65.2 [150.2] days). Mean persistence and compliance (first year of treatment) were significantly higher for denosumab than for zoledronic acid (22.0 vs. 14.9 mo [ P <0.0001] and 42.3% vs. 34.8% [ P <0.0001], respectively). Treatment compliance was the highest in patients with breast cancer (denosumab, 48.2%; zoledronic acid, 39.1%). CONCLUSION: Real-world BTA treatment patterns in the United States suggest that over one-third of patients with BM secondary to solid tumors remain untreated and less than 50% of the patients received ≥12 administrations/year of BTA therapy.


Asunto(s)
Conservadores de la Densidad Ósea , Neoplasias Óseas , Neoplasias de la Mama , Masculino , Humanos , Estados Unidos , Ácido Zoledrónico/uso terapéutico , Denosumab/uso terapéutico , Conservadores de la Densidad Ósea/uso terapéutico , Pamidronato/uso terapéutico , Registros Electrónicos de Salud , Neoplasias Óseas/tratamiento farmacológico , Neoplasias Óseas/secundario , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/patología , Difosfonatos/uso terapéutico
3.
BMC Immunol ; 14: 22, 2013 May 14.
Artículo en Inglés | MEDLINE | ID: mdl-23668673

RESUMEN

BACKGROUND: Infection with parasite protozoa is a long-term health issue in tropical and subtropical regions throughout the world. The Toll-like receptor (TLR) signaling pathway is one of the first-responding defense systems against Leishmania. The aim of this study was to investigate the expression of TLR2 and TLR9 in jejunum and colon and its correlation with CD11c, CD11b, and CD14 receptors used as markers for dendritic cells and macrophages. METHODS: Twenty four dogs infected with Leishmania infantum were used in this study. Cytometry was carried out in lamina propria cells from jejunum and colon using markers for TLR2, TLR9, CD11b, CD11c and CD14. RESULTS: Cellular inflammatory exudate was diffuse in the mucosa and submucosa, predominately comprising mononuclear cells: plasma cells, macrophages, and lymphocytes. Despite the parasite load, microscopy showed no erosion was evident in the epithelial mucosa layers. The colon harbored more parasites than the jejunum. Flow cytometry revealed higher frequency of TLR2+ and CD11c+ dendritic cells in the colon than in the jejunum. Conversely, TLR9-expressing cells were more frequent in jejunum. Moreover, frequency of macrophages (CD11b+ and CD14+) expressing simultaneity TLR9 were lower in the colon than in jejunum, while CD11c+ cells predominated in the colon. Despite of the negative ELISA serum results, IL-10 and TNF-α were higher in jejunum than colon of infected animals. However, IL-4 was higher in colon than jejunum of infected animals. A higher expression these cytokines were demonstrated in infected dogs compared to uninfected dogs. CONCLUSIONS: There was no correlation between clinical signs and pathological changes and immunological and parasitological findings in the gastrointestinal tract in canine visceral leishmaniasis. However, jejunum showed a lower parasite load with increased frequency and expression of CD11b, TLR9, CD14/CD11b/TLR9 receptors and IL-10 and TNF-α cytokines. Conversely, the colon showed a higher parasite load along with increased frequency and expression of TLR2, CD11c receptors, and IL-4 cytokine. Thus, Leishmania infantum is able to interfere in jejunum increased expression of TLR2, TLR9, CD11b, CD14, CD14/CD11b/TLR9 receptors, IL-10, and TNF-α; and in colon increased expression of CD11c, TLR2, TLR9, CD11b, CD14 e, CD14/CD11b/TLR9 receptors, IL-10, and TNF-α.


Asunto(s)
Colon/metabolismo , Enfermedades de los Perros/inmunología , Enfermedades de los Perros/parasitología , Yeyuno/metabolismo , Leishmania infantum/inmunología , Leishmaniasis Visceral/veterinaria , Receptor Toll-Like 2/metabolismo , Receptor Toll-Like 9/metabolismo , Animales , Antígenos CD/metabolismo , Brasil , Colon/inmunología , Colon/parasitología , Colon/patología , Citocinas/metabolismo , Enfermedades de los Perros/metabolismo , Enfermedades de los Perros/patología , Perros , Fluorescencia , Yeyuno/inmunología , Yeyuno/parasitología , Yeyuno/patología , Leishmania infantum/fisiología , Leishmaniasis Visceral/inmunología , Leishmaniasis Visceral/parasitología , Leishmaniasis Visceral/patología , Células Mieloides/metabolismo , Parásitos
4.
Dev Biol ; 344(1): 224-32, 2010 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-20457146

RESUMEN

The Drosophila eggshell is a specialised extracellular matrix (ECM) that surrounds and protects the oocyte and the embryo until its eclosion. In addition, the vitelline membrane, the innermost layer of the eggshell, holds the local determinant required to activate the Torso RTK pathway, which establishes the embryonic terminal regions. Here we report the identification and characterisation of closca, a gene encoding a new member of a group of proteins that act non-redundantly in vitelline membrane biogenesis and in Torso signalling. We also show that the Nasrat protein, another member of this group, is incorporated into the vitelline membrane, thereby indicating that the eggshell is a shared ECM that receives contributions from both follicle cells and the germline. This observation also provides a new scenario that accounts for the long known contribution of germline products to vitelline membrane biogenesis and to the follicle cell-dependent activation of the Torso receptor.


Asunto(s)
Proteínas de Drosophila/fisiología , Drosophila melanogaster/embriología , Regulación del Desarrollo de la Expresión Génica , Membrana Vitelina/embriología , Alelos , Animales , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Matriz Extracelular/metabolismo , Femenino , Células Germinativas , Proteínas de la Membrana/metabolismo , Modelos Biológicos , Mutación , Proteínas Tirosina Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-raf , Proteínas Tirosina Quinasas Receptoras/metabolismo , Análisis de Secuencia de ADN , Membrana Vitelina/metabolismo
5.
J Med Econ ; 24(1): 983-992, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34325606

RESUMEN

AIM: Skeletal-related events (SREs) are major bone complications that frequently occur in patients with solid tumors (ST) and bone metastases, and in patients with multiple myeloma (MM). SREs include pathological fracture, spinal cord compression, radiation to bone, and surgery to bone. Limited data are available regarding the burden of SREs in Latin America. We built an economic model to quantify the current and future economic burden of SREs among adults in four Latin American countries: Argentina, Brazil, Colombia, and Mexico. METHODS: A comprehensive literature review with a systematic search strategy was conducted to parameterize the economic burden of illness (BOI) model. Economic analyses were conducted using a prevalence-based model. Aggregate SRE costs obtained from country-specific sources were used. We also included patient productivity losses. Costs were expressed in 2020 USD for the total annual burden, annual burden per 1,000 at risk, and projected five-year burden. RESULTS: The estimated total number of SREs was 251,503 in 2020, amounting to a total annual cost of USD 1.4 billion. The total projected five-year cost was USD 6.9 billion. Annual costs were highest in Brazil (USD 779.1 million), followed by Mexico (USD 281.8 million), Argentina (USD 174.6 million), and Colombia (USD 120.1 million). The average financial burden per 1,000 at risk was greatest in Brazil (USD 3.6 million), followed by Mexico (USD 3.4 million), Colombia (USD 2.9 million), and Argentina (USD 2.7 million). CONCLUSION: Despite recommendations by medical societies for the use of bone-targeted agents in patients with solid tumors and bone metastasis or with multiple myeloma and bone lesions, a large proportion of patients at risk of experiencing SREs are not treated. Early detection of bone metastases and SREs and the use of the most effective preventative treatments are needed to decrease the clinical and economic burden of SREs in Latin America.


Asunto(s)
Costos de la Atención en Salud , Adulto , Argentina , Brasil/epidemiología , Colombia/epidemiología , Humanos , América Latina/epidemiología , México/epidemiología
6.
Dev Biol ; 323(2): 197-206, 2008 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-18801358

RESUMEN

During mitosis different types of cells can have differential requirements for chromosome segregation. We isolated two new alleles of the separation anxiety gene (san). san was previously described in both Drosophila and in humans to be required for centromeric sister chromatid cohesion (Hou et al., 2007; Williams et al., 2003). Our work confirms and expands the observation that san is required in vivo for normal mitosis of different types of somatic cells. In addition, we suggest that san is also important for the correct resolution of chromosomes, implying a more general function of this acetyltransferase. Surprisingly, during oogenesis we cannot detect mitotic defects in germ line cells mutant for san. We hypothesize the female germ line stem cells have differential requirements for mitotic sister chromatid cohesion.


Asunto(s)
Acetiltransferasas/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citología , Drosophila melanogaster/enzimología , Células Germinativas/citología , Células Germinativas/enzimología , Mitosis , Alelos , Animales , Blastodermo/citología , Blastodermo/enzimología , Segregación Cromosómica , Cromosomas/enzimología , Drosophila melanogaster/embriología , Drosophila melanogaster/genética , Genes de Insecto , Larva/citología , Larva/enzimología , Neuronas/citología , Neuronas/enzimología , Oogénesis , Intercambio de Cromátides Hermanas , Cigoto/citología , Cigoto/enzimología
7.
Genetics ; 176(4): 1967-77, 2007 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-17507684

RESUMEN

Meiotic checkpoints monitor chromosome status to ensure correct homologous recombination, genomic integrity, and chromosome segregation. In Drosophila, the persistent presence of double-strand DNA breaks (DSB) activates the ATR/Mei-41 checkpoint, delays progression through meiosis, and causes defects in DNA condensation of the oocyte nucleus, the karyosome. Checkpoint activation has also been linked to decreased levels of the TGFalpha-like molecule Gurken, which controls normal eggshell patterning. We used this easy-to-score eggshell phenotype in a germ-line mosaic screen in Drosophila to identify new genes affecting meiotic progression, DNA condensation, and Gurken signaling. One hundred eighteen new ventralizing mutants on the second chromosome fell into 17 complementation groups. Here we describe the analysis of 8 complementation groups, including Kinesin heavy chain, the SR protein kinase cuaba, the cohesin-related gene dPds5/cohiba, and the Tudor-domain gene montecristo. Our findings challenge the hypothesis that checkpoint activation upon persistent DSBs is exclusively mediated by ATR/Mei-41 kinase and instead reveal a more complex network of interactions that link DSB formation, checkpoint activation, meiotic delay, DNA condensation, and Gurken protein synthesis.


Asunto(s)
Polaridad Celular/genética , Drosophila/citología , Drosophila/genética , Genes de Insecto , Meiosis/genética , Oocitos/citología , Animales , Secuencia de Bases , Cruzamientos Genéticos , Roturas del ADN de Doble Cadena , Cartilla de ADN/genética , Drosophila/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Femenino , Prueba de Complementación Genética , Masculino , Modelos Genéticos , Mutación , Oocitos/metabolismo , Polimorfismo de Nucleótido Simple , Factor de Crecimiento Transformador alfa/genética , Factor de Crecimiento Transformador alfa/metabolismo
8.
Biomed Pharmacother ; 107: 1530-1539, 2018 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-30257371

RESUMEN

Visceral Leishmaniasis is a chronic and lethal, parasitic disease. In the later infection stages, it is known that expressive hematological disorders can be observed, including changes in the frequency and phenotype of certain leukocytes. There is a lack of good prognostic indicators to characterize the on-goin clinical status of the patient. In this study, we have analyzed the frequency of monocyte subpopulations in mice infected with Leishmania major (L. major). Our results show a significant correlation between increased blood monocyte frequency and lesion development in both BALB/c and in the C57BL/6 mice infected with L. major. In BALB/c mice we observed a significant correlation between the frequency of GR1+ monocytes and lesion size. Furthermore, treatment of infected BALB/c mice with Anfotericin B, to resolve lesions, resulted in a lower frequency of GR1+ monocytes compared to untreated infected BALB/c mice. C57BL/6 infected mice, which normally resolve infections, show decreased numbers of monocytes during the healing phase of infection. The results indicate that disease severity can be predicted by analyzing monocyte frequency. Thus, we propose that the frequency of monocytes, can be used to define the severity of the disease as well as the success of the treatment in experimental leishmaniasis.


Asunto(s)
Anfotericina B/farmacología , Leishmania major/aislamiento & purificación , Leishmaniasis Visceral/parasitología , Monocitos/parasitología , Animales , Antiprotozoarios/farmacología , Biomarcadores , Modelos Animales de Enfermedad , Femenino , Leishmania major/efectos de los fármacos , Leishmaniasis Visceral/tratamiento farmacológico , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Monocitos/metabolismo , Índice de Severidad de la Enfermedad
9.
Genetics ; 165(4): 1889-900, 2003 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-14704174

RESUMEN

To identify genes involved in the process of germ-cell formation in Drosophila, a maternal-effect screen using the FLP/FRT-ovoD method was performed on chromosome 3R. In addition to expected mutations in the germ-cell determinant oskar and in other genes known to be involved in the process, several novel mutations caused defects in germ-cell formation. Mutations in any of three genes [l(3)malignant brain tumor, shackleton, and out of sync] affect the synchronous mitotic divisions and nuclear migration of the early embryo. The defects in nuclear migration or mitotic synchrony result in a reduction in germ-cell formation. Mutations in another gene identified in this screen, bebra, do not cause mitotic defects, but appear to act upstream of the localization of oskar. Analysis of our mutants demonstrates that two unique and independent processes must occur to form germ cells-germ-plasm formation and nuclear division/migration.


Asunto(s)
Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Genes de Insecto/fisiología , Células Germinativas/citología , Proteínas de Neoplasias/fisiología , Animales , Animales Modificados Genéticamente , División Celular/genética , Movimiento Celular/genética , Núcleo Celular/metabolismo , Proteínas Cromosómicas no Histona , Femenino , Prueba de Complementación Genética , Masculino , Mitosis , Mutación/genética , Transporte de Proteínas , Proteínas Represoras , Temperatura , Transgenes , Proteínas Supresoras de Tumor
10.
PLoS One ; 7(12): e52649, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-23300733

RESUMEN

Organs develop distinctive morphologies to fulfill their unique functions. We used Drosophila embryonic gonads as a model to study how two different cell lineages, primordial germ cells (PGCs) and somatic gonadal precursors (SGPs), combine to form one organ. We developed a membrane GFP marker to image SGP behaviors live. These studies show that a combination of SGP cell shape changes and inward movement of anterior and posterior SGPs leads to the compaction of the spherical gonad. This process is disrupted in mutants of the actin regulator, enabled (ena). We show that Ena coordinates these cell shape changes and the inward movement of the SGPs, and Ena affects the intracellular localization of DE-cadherin (DE-cad). Mathematical simulation based on these observations suggests that changes in DE-cad localization can generate the forces needed to compact an elongated structure into a sphere. We propose that Ena regulates force balance in the SGPs by sequestering DE-cad, leading to the morphogenetic movement required for gonad compaction.


Asunto(s)
Proteínas de Unión al ADN/metabolismo , Drosophila melanogaster/embriología , Gónadas/embriología , Organogénesis , Animales , Cadherinas/metabolismo , Forma de la Célula , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/fisiología , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citología , Femenino , Células Germinativas/fisiología , Gónadas/citología , Modelos Biológicos , Morfogénesis , Transporte de Proteínas , Células Madre/fisiología , Imagen de Lapso de Tiempo
11.
Arq. bras. neurocir ; 33(3): 266-272, set. 2014. ilus, tab
Artículo en Portugués | LILACS | ID: lil-756184

RESUMEN

Objetivo: Relatar uma série de casos de doença moyamoya/síndrome de moyamoya (DMM/SMM) tratados por revascularização cerebral no período de 2001 a 2013. Método: Estudo retrospectivo de 12 pacientes portadores de DMM/SMM submetidos à revascularização cerebral. Resultados: Trêspacientes foram operados por meio de by-pass de alto fluxo, três com by-pass de baixo fluxo e seis por revascularização indireta (encefaloarteriossinangiose associada à galeossinangiose). Realizamosdurante o seguimento: análise da ocorrência de novos acidentes vasculares cerebrais (AVC), avaliação funcional (utilizando a Escala de Rankin Modificada) e das complicações cirúrgicas. O tempo de acompanhamento para o grupo de by-pass de alto fluxo foi de quatro a dez anos, para o grupo de baixo fluxo e revascularização indireta de três meses a três anos. Nenhum paciente apresentou outro AVC no hemisfério operado tampouco piora funcional. As taxas de morbimortalidade e de infecção foram nulas. Conclusão: A revascularização cerebral foi efetiva, prevenindo a ocorrência de novos AVC e evitando piora funcional.


Objective: To report a case series of moyamoya disease/moyamoya syndrome (DMM/SMM) treated by cerebral revascularization in the period 2001-2013. Method: Retrospective study of twelve patients with DMM/SMM submitted to cerebral revascularization. Results: Three patients were operated through high-flow by-pass, three with low flow by-pass and six with indirect revascularization (encephaloarterio-sinangiosis associated with galeo-sinangiosis). Analyzed during follow-up: the occurrence of new strokes, functional assessment (using the modified Rankin scale) and surgical complications. The follow up to the group of high-flow by-pass was 4-10 years for the group of low flow and indirect revascularization of three months to three years. No patient had another cerebrovascular accident (CVA) in the hemisphere operated nor functional worsening. Rates of morbidity and mortality and infection were nil. Conclusion: Cerebral revascularization was effective, preventing the occurrence of new strokesand preventing functional deterioration.


Asunto(s)
Revascularización Cerebral/métodos , Accidente Cerebrovascular/prevención & control , Estado Funcional , Enfermedad de Moyamoya/cirugía , Enfermedad de Moyamoya/diagnóstico , Angiografía/métodos , Registros Médicos , Estudios Retrospectivos , Interpretación Estadística de Datos , Estudio Observacional
12.
J Cell Biol ; 183(1): 157-68, 2008 Oct 06.
Artículo en Inglés | MEDLINE | ID: mdl-18824569

RESUMEN

Despite significant progress in identifying the guidance pathways that control cell migration, how a cell starts to move within an intact organism, acquires motility, and loses contact with its neighbors is poorly understood. We show that activation of the G protein-coupled receptor (GPCR) trapped in endoderm 1 (Tre1) directs the redistribution of the G protein Gbeta as well as adherens junction proteins and Rho guanosine triphosphatase from the cell periphery to the lagging tail of germ cells at the onset of Drosophila melanogaster germ cell migration. Subsequently, Tre1 activity triggers germ cell dispersal and orients them toward the midgut for directed transepithelial migration. A transition toward invasive migration is also a prerequisite for metastasis formation, which often correlates with down-regulation of adhesion proteins. We show that uniform down-regulation of E-cadherin causes germ cell dispersal but is not sufficient for transepithelial migration in the absence of Tre1. Our findings therefore suggest a new mechanism for GPCR function that links cell polarity, modulation of cell adhesion, and invasion.


Asunto(s)
Cadherinas/fisiología , Movimiento Celular/fisiología , Proteínas de Drosophila/fisiología , Drosophila melanogaster/fisiología , Células Germinativas/citología , Receptores Acoplados a Proteínas G/fisiología , Animales , Cadherinas/genética , Cadherinas/metabolismo , Adhesión Celular/fisiología , Polaridad Celular/fisiología , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriología , Drosophila melanogaster/genética , Embrión no Mamífero/citología , Embrión no Mamífero/metabolismo , Embrión no Mamífero/ultraestructura , Epitelio/embriología , Epitelio/metabolismo , Epitelio/ultraestructura , Femenino , Células Germinativas/metabolismo , Proteínas de Unión al GTP Heterotriméricas/genética , Proteínas de Unión al GTP Heterotriméricas/metabolismo , Proteínas de Transporte de Membrana/genética , Proteínas de Transporte de Membrana/metabolismo , Microscopía Electrónica , Mutación , Subunidades de Proteína/genética , Subunidades de Proteína/metabolismo , Receptores Acoplados a Proteínas G/genética , Transducción de Señal/fisiología , Factor de Crecimiento Transformador beta/genética , Factor de Crecimiento Transformador beta/metabolismo
13.
Biosci. j. (Online) ; 26(5): 675-682, Sept.- Oct. 2010.
Artículo en Portugués | LILACS | ID: biblio-911420

RESUMEN

Com o objetivo de avaliar o comportamento de dezessete linhagens de soja em diferentes regiões de Estado do Tocantins (Central e Sul) foram conduzidos dois ensaios no ano agrícola 2007/08, sendo um na Área Experimental da Universidade Federal do Tocantins - UFT no município de Palmas-TO e outro na Área Experimental da Universidade Federal do Tocantins - UFT no município de Gurupi-TO. O delineamento experimental foi de blocos ao acaso com 34 tratamentos e três repetições, instalados em um esquema fatorial 17 X 2, constituído por dezessete cultivares de soja (CD 219RR, M-SOY 8585RR, M-S0Y 8787RR, M-SOY 8925RR, M-SOY 9056RR, P98R31, P98R62, P98R91, P98Y51, P99R01, TMG103RR, TMG106RR, TMG108RR, TMG115RR, TMG117RR, TMG121RR e BRSMG Valiosa) e duas localidades (Gurupi e Palmas). Foram avaliadas as características: altura de vagem; número de dias para o florescimento; número de dias para a maturação; altura das plantas e produção de grãos. Houve efeito significativo da interação local x cultivar para todas as características, exceto para número de dias para o florescimento. Os cultivares BRSMG Valiosa, M-SOY 8585 RR e TMG 106 RR alcançaram as maiores médias de produção.


Asunto(s)
Glycine max , Agricultura
14.
J Cell Sci ; 116(Pt 5): 929-41, 2003 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-12571290

RESUMEN

The weak spindle integrity checkpoint in Drosophila spermatocytes has revealed a novel function of the gamma-tubulin ring complex (gammaTuRC) in maintaining spindle bipolarity throughout meiosis. Bipolar and bi-astral spindles could form in Drosophila mutants for dd4, the gene encoding the 91 kDa subunit of gammaTuRC. However, these spindles collapsed around metaphase and began to elongate as if attempting anaphase B. The microtubules of the collapsing spindle folded back on themselves, their putative plus ends forming the focused apexes of biconical figures. Cells with such spindles were unable to undergo cytokinesis. A second type of spindle, monopolar hemi-spindles, also formed as a result of either spindle collapse at an earlier stage or failure of centrosome separation. Multiple centrosome-like bodies at the foci of hemi-spindles nucleated robust asters of microtubules in the absence of detectable gamma-tubulin. Time-lapse imaging revealed these to be intermediates that developed into cones, structures that also had putative plus ends of microtubules focused at their tips. Unlike biconical figures, however, cones seemed to contain a central spindle-like structure at their apexes and undergo cytokinesis. We conclude that spermatocytes do not need astral microtubules nucleated by opposite poles to intersect in order to form a central spindle and a cleavage furrow.


Asunto(s)
Proteínas de Drosophila , Proteínas de Microtúbulos/metabolismo , Espermatocitos/metabolismo , Huso Acromático/metabolismo , Tubulina (Proteína)/metabolismo , Animales , División Celular/genética , División Celular/fisiología , Centrosoma/metabolismo , Drosophila/genética , Drosophila/metabolismo , Proteínas de Homeodominio/metabolismo , Masculino , Microscopía Confocal , Proteínas de Microtúbulos/genética , Proteínas Asociadas a Microtúbulos/metabolismo , Microtúbulos/metabolismo , Mutación , Proteínas Nucleares/metabolismo , Espermatocitos/citología , Tubulina (Proteína)/genética
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