Extensive regulation of metabolism and growth during the cell division cycle

Yeast cells grown in culture can spontaneously synchronize their respiration, metabolism, gene expression and cell division. Such metabolic oscillations in synchronized cultures reflect single-cell oscillations, but the relationship between the oscillations in single cells and synchronized cultures is poorly understood. To understand this relationship and the coordination between metabolism and cell division, we collected and analyzed DNA-content, gene-expression and physiological data, at hundreds of time-points, from cultures metabolically-synchronized at different growth rates, carbon sources and biomass densities. The data enabled us to extend and generalize an ensemble-average-over-phases (EAP) model that connects the population-average gene-expression of asynchronous cultures to the gene-expression dynamics in the single-cells comprising the cultures. The extended model explains the carbon-source specific growth-rate responses of hundreds of genes. Our data demonstrate that for a given growth rate, the frequency of metabolic cycling in synchronized cultures increases with the biomass density. This observation underscores the difference between metabolic cycling in synchronized cultures and in single cells and suggests entraining of the single-cell cycle by a quorum-sensing mechanism. Constant levels of residual glucose during the metabolic cycling of synchronized cultures indicate that storage carbohydrates are required to fuel not only the G1/S transition of the division cycle but also the metabolic cycle. Despite the large variation in profiled conditions and in the time-scale of their dynamics, most genes preserve invariant dynamics of coordination with each other and with the rate of oxygen consumption. Similarly, the G1/S transition always occurs at the beginning, middle or end of the high oxygen consumption phases, analogous to observations in human and drosophila cells.Comment: 34 pages, 7 figure

Semiclosed-circuit atmosphere control in a portable recompression chamber

A small portable recompression chamber is described that can be used both to treat a diver for decompression sickness or to transport him to a larger chamber complex. The device can be operated in either open circuit or semiclosed circuit atmospheres, permits two way conversation between patient and attendant, and uses an air injector for circulation of the chamber atmosphere

Iron and Manganese in Potable Water

In the presentation of this thesis the subject matter has been divided into three sections. The first to be a comparison of the different methods for the determination of Manganese in water with special reference to accuracy and availability for routine work. The second to be devoted to the occurrence of Iron and Manganese in waters, the characteristics of such waters, and a survey of the State of Kansas to obtain some information as to the localities where such waters were to be found. The third and last section to be a review of American and European practices and experience with Iron and Manganese waters, and the methods of removal when the waters are to be used as public supplies or for industrial purposes

L'imposition des dividendes de source française : est-il fiscalement plus avantageux de résider en France ou au Luxembourg lorsque l'on perçoit des dividendes français ?

Quelle est la résidence fiscale la plus avantageuse pour un associé qui perçoit des dividendes de source française ? Cet article compare les contextes français et uxembourgeois en posant plusieurs hypothèses sur la situation personnelle des associés, personnes physiques ou morales. Un modèle théorique d'imposition est élaboré et appliqué à quatre cas pratiques. Il met en évidence que la charge fiscale des associés est souvent plus légère au Luxembourg qu'en France.imposition ; dividendes ; résidence fiscale ; personne physique ; personne morale

The Daughterless N-terminus directly mediates synergistic interactions with Notch transcription complexes via the SPS+A DNA transcription code

BACKGROUND: Cell-specific expression of a subset of Enhancer of split (E(spl)-C) genes in proneural clusters is mediated by synergistic interactions between bHLH A (basic Helix-Loop-Helix Activator) and Notch-signalling transcription complex (NTC) proteins. For a some of these E(spl)-C genes, such as m8, these synergistic interactions are programmed by an "SPS+A" transcription code in the cis-regulatory regions. However, the molecular mechanisms underlying this synergistic interaction between NTCs and proneural bHLH A proteins are not fully understood. FINDINGS: Using cell transcription assays, we show that the N-terminal region of the Daughterless (Da) bHLH A protein is critical for synergistic interactions with NTCs that activate the E(spl)-C m8 promoter. These assays also show that this interaction is dependent on the specific inverted repeat architecture of Suppressor of Hairless (Su(H)) binding sites in the SPS+A transcription code. Using protein-protein interaction assays, we show that two distinct regions within the Da N-terminus make a direct physical interaction with the NTC protein Su(H). Deletion of these interaction domains in Da creates a dominant negative protein that eliminates NTC-bHLH A transcriptional synergy on the m8 promoter. In addition, over-expression of this dominant negative Da protein disrupts Notch-mediated lateral inhibition during mechanosensory bristle neurogenesis in vivo. CONCLUSION: These findings indicate that direct physical interactions between Da-N and Su(H) are critical for the transcriptional synergy between NTC and bHLH A proteins on the m8 promoter. Our results also indicate that the orientation of the Su(H) binding sites in the SPS+A transcription code are critical for programming the interaction between Da-N and Su(H) proteins. Together, these findings provide insight into the molecular mechanisms by which the NTC synergistically interacts with bHLH A proteins to mediate Notch target gene expression in proneural clusters

Are preschoolers expected to learn difficult science constructs? A content analysis of U.S. standards

In the current paper, we report on the recommendations for preschool science put forward in the educational standards of U.S. states. Our focus was specifically on whether educational standards recommend abstract science constructs—constructs that are difficult to learn. In Study 1, we focused on science constructs related to inquiry (i.e., activities geared towards the generation of scientific knowledge). And in Study 2, we focused on science constructs related to facts (i.e., established scientific knowledge). In each study, we developed a coding scheme to distinguish between concrete and abstract constructs and then determined the relative prevalence of each. Our findings show that preschoolers are indeed expected to learn abstract science constructs. At the same time, educational standards varied considerably across U.S. states. Implications for the field of early science learning are discussed

Natural Language Processing (NLP) tools for the analysis of incident and accident reports

International audienceThe human factor field is expected to evolve due to the development of Natural Language Processing tools which allow for new approaches to handle natural language data. In the current project, we use NLP methods to facilitate experience feedback in the field of civil aviation safety. In this paper, we present how NLP methods based on the extraction of textual information from the Air France ASR can contribute to (i) the improvement of the reliability of the coding, facilitating the coding itself, (ii) the analysis of reports regardless of the categorization in order to expand the analysis perimeter and to avoid the inherent limitations of the codification

Measuring differential gene expression by short read sequencing: quantitative comparison to 2-channel gene expression microarrays

<p>Abstract</p> <p>Background</p> <p>High-throughput cDNA synthesis and sequencing of poly(A)-enriched RNA is rapidly emerging as a technology competing to replace microarrays as a quantitative platform for measuring gene expression.</p> <p>Results</p> <p>Consequently, we compared full length cDNA sequencing to 2-channel gene expression microarrays in the context of measuring differential gene expression. Because of its comparable cost to a gene expression microarray, our study focused on the data obtainable from a single lane of an Illumina 1 G sequencer. We compared sequencing data to a highly replicated microarray experiment profiling two divergent strains of <it>S. cerevisiae</it>.</p> <p>Conclusion</p> <p>Using a large number of quantitative PCR (qPCR) assays, more than previous studies, we found that neither technology is decisively better at measuring differential gene expression. Further, we report sequencing results from a diploid hybrid of two strains of <it>S. cerevisiae </it>that indicate full length cDNA sequencing can discover heterozygosity and measure quantitative allele-specific expression simultaneously.</p

Diverse conditions support near-zero growth in yeast: Implications for the study of cell lifespan

Baker’s yeast has a finite lifespan and ages in two ways: a mother cell can only divide so many times (its replicative lifespan), and a non-dividing cell can only live so long (its chronological lifespan). Wild and laboratory yeast strains exhibit natural variation for each type of lifespan, and the genetic basis for this variation has been generalized to other eukaryotes, including met-azoans. To date, yeast chronological lifespan has chiefly been studied in relation to the rate and mode of functional decline among non-dividing cells in nutrient-depleted batch culture. However, this culture method does not accurately capture two major classes of long-lived metazoan cells: cells that are terminally differentiated and metabolically active for periods that approximate animal lifespan (e.g. cardiac myocytes), and cells that are pluripotent and metabolically quiescent (e.g. stem cells). Here, we consider alternative ways of cultivating Saccharomyces cerevisiae so that these different metabolic states can be explored in non-dividing cells: (i) yeast cultured as giant colonies on semi-solid agar, (ii) yeast cultured in retentostats and provided sufficient nutrients to meet minimal energy requirements, and (iii) yeast encapsulated in a semisolid matrix and fed ad libitum in bioreactors. We review the physiology of yeast cultured under each of these conditions, and explore their potential to provide unique insights into determinants of chronological lifespan in the cells of higher eukaryotes