Chromosome Segregation Is Biased by Kinetochore Size

Chromosome missegregation during mitosis or meiosis is a hallmark of cancer and the main cause of prenatal death in humans. The gain or loss of specific chromosomes is thought to be random, with cell viability being essentially determined by selection. Several established pathways including centrosome amplification, sister-chromatid cohesion defects, or a compromised spindle assembly checkpoint can lead to chromosome missegregation. However, how specific intrinsic features of the kinetochore—the critical chromosomal interface with spindle microtubules—impact chromosome segregation remains poorly understood. Here we used the unique cytological attributes of female Indian muntjac, the mammal with the lowest known chromosome number (2n = 6), to characterize and track individual chromosomes with distinct kinetochore size throughout mitosis. We show that centromere and kinetochore functional layers scale proportionally with centromere size. Measurement of intra-kinetochore distances, serial-section electron microscopy, and RNAi against key kinetochore proteins confirmed a standard structural and functional organization of the Indian muntjac kinetochores and revealed that microtubule binding capacity scales with kinetochore size. Surprisingly, we found that chromosome segregation in this species is not random. Chromosomes with larger kinetochores bi-oriented more efficiently and showed a 2-fold bias to congress to the equator in a motor-independent manner. Despite robust correction mechanisms during unperturbed mitosis, chromosomes with larger kinetochores were also strongly biased to establish erroneous merotelic attachments and missegregate during anaphase. This bias was impervious to the experimental attenuation of polar ejection forces on chromosome arms by RNAi against the chromokinesin Kif4a. Thus, kinetochore size is an important determinant of chromosome segregation fidelity

Métodos de cálculo de taxa lotação em pastagens com suplementação.

A taxa de lotação é a relação entre o número de unidades animais (UA) e a área por eles ocupada. O uso da unidade animal no cálculo da taxa de lotação tem a finalidade de padronizar o efeito das diferentes categorias animais sobre o pasto. O fornecimento de suplementação alimentar provoca distorções no cálculo da taxa de lotação. O objetivo desse trabalho foi determinar uma alternativa de cálculo de taxa de lotação para animais a pasto recebendo suplementação alimentar. A taxa de lotacão foi calculada assumindo que 1 UA corresponde a 1 animal de 454 e que 1 UA corresponde a um animal consumindo 12kg MS/dia. O consumo de forragem foi estimado pelo Corne" Net Carbohydrate and Protein System (CNCPS 3.0). Em todos os períodos, a taxa de lotação calculada a partir do peso vivo dos anímais foi mais elevada que aquela calculada com base na estimativa do consumo de matéria seca, com variações de 0,6 a 11,8 unidades de taxa de lotação. Para vacas em lactação sob pastejo, o concentrado pode representar mais de 50% do consumo total de matéria seca. Concluiu-se que o cálculo da taxa de lotação com base no peso vivo dos animais não é adequado quando os animais recebem suplementação alimentar. O cálculo da taxa de lotação a partir da estimativa do consumo de matéria seca de forragem é uma alternativa viável, porém os modelos de simulação que estimatimam consumo de matéria seca dos animais precisam ser aprimorados e validados para condições tropicais

Comparação da taxa de lotação em piquetes de Panicum maximum cv. Tazania irrigado e sequeiro com suplementação.

O presente trabalho teve como objetivo comparar a taxa de lotação em pastagem de Panicum maximum " cv. Tanzânia, irrigada e em sequeiro, de acordo com o consumo de forragem de vacas em lactação, da raça holandesa preta e branca, suplementadas com concentrado de acordo com suas produções, predicto pelo programa de Cornell 3.0

A conjugate for the Bargmann representation

In the Bargmann representation of quantum mechanics, physical states are mapped into entire functions of a complex variable z*, whereas the creation and annihilation operators $\hat{a}^\dagger$ and $\hat{a}$ play the role of multiplication and differentiation with respect to z*, respectively. In this paper we propose an alternative representation of quantum states, conjugate to the Bargmann representation, where the roles of $\hat{a}^\dagger$ and $\hat{a}$ are reversed, much like the roles of the position and momentum operators in their respective representations. We derive expressions for the inner product that maintain the usual notion of distance between states in the Hilbert space. Applications to simple systems and to the calculation of semiclassical propagators are presented.Comment: 15 page

A rapid and simple method for determination of 5-hydroxytryptophan in dietary supplements by capillary electrophoresis

A rapid and simple capillary electrophoresis (CE) method was developed to determine 5-hydroxytryptophan (5-HTP) in samples of commercial dietary supplements. The optimized background electrolyte (BGE) was composed by 20 mmol L-1 sodium phosphate (pH 10) and 0.2 mmol L-1 cetyltrimethylammonium bromide (CTAB) for electroosmotic flow inversion. The limits of detection (LOD) and quantification (LOQ) for 5-HTP were 3.1 and 10.1 µmol L-1, respectively. The analytical curve demonstrated linearity over a concentration range of 0-500 µmol L-1 with a correlation coefficient (R2) of 0.9995. The intraday instrumental precision (repeatability) as relative standard deviation (RSD) in terms of peak area and migration time of the 5-HTP were 2.2 and 1.9% (n = 8), respectively. The CE method was applied to the analysis of four different samples of commercial dietary supplements and the RSD (n = 3) for the determinations ranged from 2 to 3%. The accuracy of the method was evaluated comparing the measured 5-HTP concentrations to those obtained by a high performance liquid chromatography (HPLC) method. The relative error ranged from 0 to 5.9% (n = 3) and no significant differences between the concentrations were observed at a confidence level of 95%254783787Neste trabalho é apresentado o desenvolvimento de um método rápido e simples, empregando eletroforese capilar, para determinação de 5-hidroxitriptofano (5-HTP) em amostras de suplementos alimentares. O eletrólito de corrida utilizado foi constituído por 20 mmol L-1 de fosfato de sódio (pH 10) e 0,2 mmol L-1 de brometo de cetiltrimetilamônio (CTAB), empregado como inversor de fluxo eletrosmótico. Foram obtidos limites de detecção e quantificação de 3,1 e 10,1 µmol L-1, respectivamente. A curva analítica obtida, para concentrações do analito entre 0-500 µmol L-1, apresentou linearidade com coeficiente de correlação linear (R2) de 0,9995. A precisão instrumental intra-dia (repetibilidade), expressa em desvio padrão relativo (RSD), para a área de pico e tempo de migração do 5-HTP foram de 2,2 e 1,9% (n = 8), respectivamente. O método eletroforético foi empregado na análise de quatro diferentes amostras comerciais de suplementos alimentares e o RSD (n = 3) para as determinações variaram de 2 a 3%. A exatidão do método foi avaliada pela comparação das concentrações de 5-HTP obtidas pelo método proposto e por cromatografia líquida de alta eficiência (HPLC). Os erros relativos variaram entre 0 e 5,9% e não foram observadas diferenças significativas entre as concentrações, ao nível de 95% de confianç

Efeito da irrigação sobre a taxa de lotação em pastagens de capim-tânzania utilizadas para produção de leite em São Carlos, SP.

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Quality of Life and characterization of patients with atopic dermatitis in Portugal - QUADEP study

OBJECTIVES: To investigate the quality of life (QoL) and to characterize patients with atopic dermatitis (AD) in Portugal. METHODS: This was a cross-sectional study, including patients with AD and other eczemas. Skindex-29, Skindex-teen and Childhood Atopic Dermatitis Impact Scale (CADIS) were the instruments used to assess QoL in adults, teenagers, and children respectively. Complementarily, the SF-12 was used and disease severity was evaluated through Patient-Oriented SCORAD (PO-SCORAD). Odds Ratio (OR) were performed to measure associations with QoL. SPSS statistics 95% confidence intervals and values of p<0.05 were considered statistically significant. RESULTS: 162 participants were included, aging 0.5-74 years. We found that 37.3% of AD patients consider their disease as disabling and more than half of AD patients feel stigmatized by society. The mean Skindex score for AD was 39.68, and 44% patients presented a severe QoL impact. "Symptoms" was the most affected category in adults. Moderate to severe AD patients were 87% of the sample. Regarding the factors that most influenced worse QoL in AD, with increasing age, the Skindex score is likely to increase (OR: 1.03 [95%CI 1.00-1.06]). "Consider having disability" was also associated, OR: 6.72 (95%CI 2.56-17.63). With increasing affected body area and edema, the QoL worsens (OR: 1.07 [95%CI 1.03-1.11] and OR: 2.04 [95%CI 1.23-3.40], respectively). CONCLUSIONS: This is the first study with QoL data about AD patients in Portugal, revealing an expected negative impact. More awareness-raising activities are needed to increase literacy, decrease the stigma, and consequently to address some impacted factors in AD patients' QoL.info:eu-repo/semantics/publishedVersio

Raman excitation spectroscopy of carbon nanotubes: effects of pressure medium and pressure

Raman excitation and emission spectra for the radial breathing mode (RBM) are reported, together with a preliminary analysis. From the position of the peaks on the two-dimensional plot of excitation resonance energy against Raman shift, the chiral indices (m, n) for each peak are identified. Peaks shift from their positions in air when different pressure media are added - water, hexane, sulphuric acid - and when the nanotubes are unbundled in water with surfactant and sonication. The shift is about 2 - 3 cm-1 in RBM frequency, but unexpectedly large in resonance energy, being spread over up to 100meV for a given peak. This contrasts with the effect of pressure. The shift of the peaks of semiconducting nanotubes in water under pressure is orthogonal to the shift from air to water. This permits the separation of the effects of the pressure medium and the pressure, and will enable the true pressure coefficients of the RBM and the other Raman peaks for each (m, n) to be established unambiguously.Comment: 6 pages, 3 Figures, Proceedings of EHPRG 2011 (Paris