2,377 research outputs found

    Chromosome passenger complexes control anaphase duration and spindle elongation via a kinesin-5 brake

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    Chromosome passenger complexes and bipolar kinesins act together to coordinate spindle elongation, spindle breakdown, and mitotic exit

    A novel role for the CBF3 kinetochore–scaffold complex in regulating septin dynamics and cytokinesis

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    In budding yeast, the kinetochore scaffold complex centromere binding factor 3 (CBF3) is required to form kinetochores on centromere DNA and to allow proper chromosome segregation. We have previously shown that SKP1 and SGT1 balance the assembly and turnover of CBF3 complexes, a cycle that we suggest is independent of its role in chromosome segregation (Rodrigo-Brenni, M.C., S. Thomas, D.C. Bouck, and K.B. Kaplan. 2004. Mol. Biol. Cell. 15:3366–3378). We provide evidence that this cycle contributes to a second, kinetochore-independent function of CBF3. In this study, we show that inhibiting the assembly of CBF3 causes disorganized septins and defects in cell polarity that give rise to cytokinesis failures. Specifically, we show that septin ring separation and disassembly is delayed in anaphase, suggesting that CBF3 regulates septin dynamics. Only mutations that affect the CBF3 cycle, and not mutants in outer kinetochore subunits, cause defects in septins. These results demonstrate a novel role for CBF3 in regulating cytokinesis, a role that is reminiscent of passenger proteins. Consistent with this possibility, we find that CBF3 interacts with Bir1p, the homologue of the passenger protein Survivin. Mutants in Bir1p similarly affect septin organization, leading us to propose that CBF3 and Bir1p act as passenger proteins to coordinate chromosome segregation with cytokinesis

    The effect of vertical prism induced stress on the accommodation and vergence ranges

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    This paper presents a study of the effect a vertical imbalance has on the lateral vergence and accommodation ranges as measured in standard clinical testing. The clinical tests included lateral duction ranges at 6 meters and 40 centimeters, the positive relative accommodation (PRA), and the negative relative accommodation (NRA). Nineteen subjects considered visually normal were tested once with two prism diopters of induced vertical imbalance, and once under normal conditions. An ANOV A was performed on the means of thirteen clinical tests . The F-test and probability values are also presented . Results indicate that the findings of the tests with the vertical prism in place were not different from the findings with no pr ism in place

    Genetic Progress From 50 Years of Smooth Bromegrass Breeding

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    Since its introduction from Eurasia, smooth bromegrass (Bromus inermis Leyss.) has become an important cool-season forage grass in North America. The objective of this study was to document breeding progress in smooth bromegrass between 1942 and 1995 in North America. Thirty cultivars or experimental populations were tested at up to seven sites in the eastern and central USA, with a range of soil types and climates. There have been small genetic changes in forage yield, brown leafspot resistance [caused by Pyrenophora bromi (Died) Drechs.], in vitro dry matter digestibility (IVDMD), and neutral detergent fiber (NDF) concentration. Brown leafspot resistance increased gradually, averaging 0.21 units decade(-1). Mean forage yield did not change for cultivars developed after 1942, but was 0.54 Mg ha(-1) (7.2%) higher for the post-1942 group than in \u27Lincoln\u27, a direct representative of smooth bromegrass introduced into North America. Selection for increased IVDMD led to an average increase in IVDMD of 9 g kg(-1) (1.4%), an increase in forage yield of 0.33 Mg ha(-1) (5.0%), and a decrease in NDF of -8 g kg(-1) (-1.2%) in the post-1942 group. The slow rate of progress for smooth bromegrass forage yield is due to its complex polypoid inheritance, emphasis on traits other than forage yield, and relatively little concentrated attention from public and private breeders

    Latitudinal and Longitudinal Adaptation of Smooth Bromegrass Populations

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    Breeding progress has been slow in smooth bromegrass (Bromus inermis Leyss) since its introduction to North America. Much of the variability among cultivars appears to have arisen by natural selection and adaptive responses. The objective of this study was to determine if smooth bromegrass cultivars differ in latitudinal or longitudinal adaptation, as measured by forage yield, and if that variability relates to their breeding or selection history. The target region was defined as the Great Plains to the East Coast of the USA, from 38 to 47 degrees N latitude. Twenty-nine cultivars and experimental populations were evaluated for forage yield at up to seven locations ranging from central to eastern USA. Populations were classified according to pooled population main effect and population x location interaction effect (G + GL deviations). Cluster analysis resulted in eight clusters that explained 90% of the variation among G + GL deviations. One cluster consisted of populations average in adaptation, four clusters consisted of populations that were largely unadapted across the entire region, and three clusters consisted of populations that were specifically adapted to the entire region or a large part thereof. Much of the grouping and adaptation characteristics could be explained by similar pedigrees, selection history, and selection location. However, the phenotypic similarity of some superior, but divergent-pedigree populations suggested that alleles for high and stable forage yield in smooth bromegrass probably exist in numerous germplasm sources. Despite a history of little to no gains in forage yield, these results suggest unrealized potential for future improvement of forage yield of smooth bromegrass across a broad geographic region

    The renewable energy and energy efficiency potential of Waitakere City : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Technology in Energy Management at Massey University

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    Electricity restrictions and blackouts have occurred in Waitakere City in the past and are likely to occur again in the future unless the city can become more self reliant by meeting, at least in part, the increasing energy requirements for what is one of the fastest growing cities in New Zealand. In this study the potentials for energy conservation, energy efficiency and renewable energy resources have been broadly quantified and assessed using desktop analysis of publicly available data for stationary final use energy systems (i.e. excluding transportation) within the geographical area of Waitakere City and adjoining waters. It was found that energy efficiency and energy conservation measures can consistently and predictably achieve overall energy savings and reduce daily and seasonal peak demand. The best renewable energy resource potential exists with solar and geothermal for heating applications and wave, offshore and inshore wind and tidal currents for electricity generation. There is very limited potential for hydro and bioenergy systems beyond what already exists. PV solar and land based wind power generation are currently only feasible for limited off-grid applications. This scoping study confirms the achievability of the vision expressed in Waitakere City Council's "Long Term Council Community Plan" (LTCCP) that by 2020 " Waitakere City will be an energy cell, not an energy sink. Air quality supports good health". A range of flagship projects have been identified to progress the achievement of this vision. Waitakere City Council can use this report as part of the development of a comprehensive energy management plan

    High-resolution Near-Infrared Images and Models of the Circumstellar Disk in HH 30

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    We present Hubble Space Telescope (HST) Near-Infrared Camera and Multi-object Spectrometer (NICMOS) observations of the reflection nebulosity associated with the T Tauri star HH 30. The images show the scattered light pattern characteristic of a highly inclined, optically thick disk with a prominent dustlane whose width decreases with increasing wavelength. The reflected nebulosity exhibits a lateral asymmetry in the upper lobe on the opposite side to that reported in previously published Wide Field Planetary Camera 2 (WFPC2) images. The radiation transfer model which most closely reproduces the data has a flared accretion disk with dust grains larger than standard interstellar medium grains by a factor of approximately 2.1. A single hotspot on the stellar surface provides the necessary asymmetry to fit the images and is consistent with previous modeling of the light curve and images. Photometric analysis results in an estimated extinction of Av>~80; however, since the photometry measures only scattered light rather than direct stellar flux, this a lower limit. The radiative transfer models require an extinction of Av = 7,900.Comment: Accepted for publication in Ap.

    Dose-response of myofibrillar protein synthesis to ingested whey protein during energy restriction in overweight postmenopausal women: a randomized, controlled trial

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    BackgroundDiet-induced weight loss is associated with a decline in lean body mass, as mediated by an impaired response of muscle protein synthesis (MPS). The dose-response of MPS to ingested protein, with or without resistance exercise, is well characterized during energy balance but limited data exist under conditions of energy restriction in clinical populations.ObjectiveTo determine the dose-response of MPS to ingested whey protein following short-term diet-induced energy restriction in overweight, postmenopausal, women at rest and postexercise.DesignForty middle-aged (58.6±0.4 y), overweight (BMI: 28.6±0.4), postmenopausal women were randomly assigned to 1 of 4 groups: Three groups underwent 5 d of energy restriction (∼800 kcal/d). On day 6, participants performed a unilateral leg resistance exercise bout before ingesting either a bolus of 15g (ERW15, n = 10), 35g (ERW35, n = 10) or 60g (ERW60, n = 10) of whey protein. The fourth group (n = 10) ingested a 35g whey protein bolus after 5 d of an energy balanced diet (EBW35, n = 10). Myofibrillar fractional synthetic rate (FSR) was calculated under basal, fed (FED) and postexercise (FED-EX) conditions by combining an L-[ring-13C6] phenylalanine tracer infusion with the collection of bilateral muscle biopsies.ResultsMyofibrillar FSR was greater in ERW35 (0.043±0.003%/h, P = 0.013) and ERW60 (0.042±0.003%/h, P = 0.026) than ERW15 (0.032 ± 0.003%/h), with no differences between ERW35 and ERW60 (P = 1.000). Myofibrillar FSR was greater in FED (0.044 ± 0.003%/h, P < 0.001) and FED-EX (0.048 ± 0.003%/h, P < 0.001) than BASAL (0.027 ± 0.003%/h), but no differences were detected between FED and FED-EX (P = 0.732) conditions. No differences in myofibrillar FSR were observed between EBW35 (0.042 ± 0.003%/h) and ERW35 (0.043 ± 0.003%/h, P = 0.744).ConclusionA 35 g dose of whey protein, ingested with or without resistance exercise, is sufficient to stimulate a maximal acute response of MPS following short-term energy restriction in overweight, postmenopausal women, and thus may provide a per serving protein recommendation to mitigate muscle loss during a weight loss program.Trial registryclinicaltrials.gov (ID: NCT03326284)

    Towards More Precise Survey Photometry for PanSTARRS and LSST: Measuring Directly the Optical Transmission Spectrum of the Atmosphere

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    Motivated by the recognition that variation in the optical transmission of the atmosphere is probably the main limitation to the precision of ground-based CCD measurements of celestial fluxes, we review the physical processes that attenuate the passage of light through the Earth's atmosphere. The next generation of astronomical surveys, such as PanSTARRS and LSST, will greatly benefit from dedicated apparatus to obtain atmospheric transmission data that can be associated with each survey image. We review and compare various approaches to this measurement problem, including photometry, spectroscopy, and LIDAR. In conjunction with careful measurements of instrumental throughput, atmospheric transmission measurements should allow next-generation imaging surveys to produce photometry of unprecedented precision. Our primary concerns are the real-time determination of aerosol scattering and absorption by water along the line of sight, both of which can vary over the course of a night's observations.Comment: 41 pages, 14 figures. Accepted PAS

    Efficient GRASP+VND and GRASP+VNS metaheuristics for the traveling repairman problem

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    The traveling repairman problem is a customer-centric routing problem, in which the total waiting time of the customers is minimized, rather than the total travel time of a vehicle. To date, research on this problem has focused on exact algorithms and approximation methods. This paper presents the first metaheuristic approach for the traveling repairman problem
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