The CDK-Activating Kinase (CAK) Csk1 Is Required for Normal Levels of Homologous Recombination and Resistance to DNA Damage in Fission Yeast

BACKGROUND: Cyclin-dependent kinases (CDKs) perform essential roles in cell division and gene expression in all eukaryotes. The requirement for an upstream CDK-activating kinase (CAK) is also universally conserved, but the fission yeast Schizosaccharomyces pombe appears to be unique in having two CAKs with both overlapping and specialized functions that can be dissected genetically. The Mcs6 complex--orthologous to metazoan Cdk7/cyclin H/Mat1--activates the cell-cycle CDK, Cdk1, but its non-redundant essential function appears to be in regulation of gene expression, as part of transcription factor TFIIH. The other CAK is Csk1, an ortholog of budding yeast Cak1, which activates all three essential CDKs in S. pombe--Cdk1, Mcs6 and Cdk9, the catalytic subunit of positive transcription elongation factor b (P-TEFb)--but is not itself essential. METHODOLOGY/PRINCIPAL FINDINGS: Cells lacking csk1(+) are viable but hypersensitive to agents that damage DNA or block replication. Csk1 is required for normal levels of homologous recombination (HR), and interacts genetically with components of the HR pathway. Tests of damage sensitivity in csk1, mcs6 and cdk9 mutants indicate that Csk1 acts pleiotropically, through Cdk9 and at least one other target (but not through Mcs6) to preserve genomic integrity. CONCLUSIONS/SIGNIFICANCE: The two CAKs in fission yeast, which differ with respect to their substrate range and preferences for monomeric CDKs versus CDK/cyclin complexes as substrates, also support different functions of the CDK network in vivo. Csk1 plays a non-redundant role in safeguarding genomic integrity. We propose that specialized activation pathways dependent on different CAKs might insulate CDK functions important in DNA damage responses from those capable of triggering mitosis

EPS à l’école primaire : un état des pratiques d’enseignement

International audienc

EPS à l’école primaire : Un état des pratiques d’enseignement

International audienc

Passive Vector Geoacoustic Inversion in Coastal Areas Using a sequential Unscented Kalman Filter Passive vector geoacoustic inversion in coastal areas using a sequential unscented Kalman filter

Abstract-An unscented Kalman filter (UKF) for geoacoustic inversion using scalar and vector sound fields created by a passing ship is discussed in this paper. The continuous sound field emitted by a ship of opportunity is processed by the sequential filtering technique to estimate slowly changing environmental properties along the source range. The inversion problem is solved by the UKF with a random-walk parameter model, which is expected to perform well when dealing with highly nonlinear problems. Synthetic geoacoustic inversions are performed using multi-frequency pressure, vertical particle velocity and waveguide impedance (a ratio between pressure and vertical particle velocity) data for the geoacoustic model of a mud environment offshore at the mouth of the Amazon river in Brazil (CANOGA 12). For the preliminary tests, the sound source is composed of a flat spectrum. Numerical results demonstrate that the sequential filtering technique is capable of estimating the evolution of environmental properties along the source range. In practice, ship data have complex time-varying spectral characteristics that can greatly limit the accuracy of broadband or multi-frequency passive applications. Since the vertical waveguide impedance is independent of the source spectral level, it is preferred for environmental characterization by the sound field generated from a ship of opportunity. Because of this independence property, the vertical waveguide impedance is expected to yield a more reliable inversion than that of pressure or vertical particle velocity field

: Heat management strategies and high level sports performance: Psychophysiological insights and applied recommendations

International audienceObjectives: This article sheds light on the different heat stress management strategies, common or innovative, in order to analyze those that would be the most suitable and effective for athletes who have to compete in humid and/or hot environments.News: The Paris summer Olympics Games in 2024 will take place from July 26th to September 8th with a high risk for athletes to practice their sport at high temperatures, thereby imposing physiological (cardiovascular, ventilatory, thermoregulatory, etc.) and psychological (early mental fatigue, decreased motivation, discomfort, etc.) which can have a major negative impact on their performance.Prospects and projects: To perform in a hot environment, it is now recommended to use strategies, in particular active acclimatization which promotes physiological but also psychological adaptations. Similarly, fluid management and cooling techniques have potentially beneficial effects on physiological factors but their psychological consequences are still poorly understood and need to be investigated. Finally, mental strategies (goal setting, mental imagery, positive self-talk, music, etc.) or cognitive training in the heat can limit poor performance in this condition. The effects of combining physical and mental techniques, as well as innovative strategies such as cold suggestion, are also being investigated.Conclusion: For each strategies presented, the scientific work has enabled the development of practical recommendations for athletes, coaches and mental trainers in order to allow them to physiologically and psychologically anticipate the effects of high relative humidity and/or high temperature.ObjectifsCet article apporte un éclairage sur les différentes stratégies de gestion de la chaleur, usuelles ou innovantes, afin d’analyser celles qui seraient les plus adaptées et les plus efficaces chez des athlètes devant participer à des compétitions dans des environnements humides et/ou chauds.ActualitésLes Jeux olympiques de Paris en 2024 se dérouleront du 26 juillet au 8 septembre avec un risque élevé pour les athlètes de pratiquer leur sport à des températures élevées, imposant de fait des contraintes physiologiques (cardiovasculaires, ventilatoires, thermorégulatoires, etc.) et psychologiques (fatigue mentale précoce, baisse de motivation, inconfort, etc.) pouvant ainsi largement impacter négativement leur performance.Perspectives et projetsPour « performer » en environnement chaud, il est aujourd’hui recommandé d’avoir recours à des stratégies, notamment une acclimatation active qui favorise des adaptations physiologiques mais aussi psychologiques. De même, les techniques de gestion de fluides et de refroidissement « physiques » ont des effets potentiellement bénéfiques sur des facteurs physiologiques mais leurs conséquences psychologiques sont encore peu connues et doivent être investiguées. Enfin, des stratégies mentales (fixation d’objectifs, imagerie mentale, dialogue interne positif, musique, etc.) ou entraînements cognitifs en environnement chaud peuvent limiter les contre-performances dans ces conditions. Les effets de la combinaison de techniques physiques et mentales, ainsi que des stratégies innovantes comme la suggestion au froid, sont également en cours d’investigation.ConclusionPour chacune des stratégies présentées, les travaux scientifiques ont permis l’élaboration de recommandations pratiques à l’intention des athlètes, des entraîneurs et des préparateurs mentaux, afin de leur permettre d’anticiper physiologiquement et psychologiquement les effets d’une hygrométrie et ou d’une température élevée

Range-resolving shallow water acoustic tomography by ensemble Kalman filtering

info:eu-repo/semantics/publishe

Inversion for time-evolving sound-speed field in a shallow ocean by ensemble Kalman filtering

info:eu-repo/semantics/publishe

Passive Vector Geoacoustic Inversion in Coastal Areas Using a sequential Unscented Kalman Filter

An unscented Kalman filter (UKF) for geoacoustic inversion using scalar and vector sound fields created by a passing ship is discussed in this paper. The continuous sound field emitted by a ship of opportunity is processed by the sequential filtering technique to estimate slowly changing environmental properties along the source range. The inversion problem is solved by the UKF with a random-walk parameter model, which is expected to perform well when dealing with highly nonlinear problems. Synthetic geoacoustic inversions are performed using multi-frequency pressure, vertical particle velocity and waveguide impedance (a ratio between pressure and vertical particle velocity) data for the geoacoustic model of a mud environment offshore at the mouth of the Amazon river in Brazil (CANOGA 12). For the preliminary tests, the sound source is composed of a flat spectrum. Numerical results demonstrate that the sequential filtering technique is capable of estimating the evolution of environmental properties along the source range. In practice, ship data have complex time-varying spectral characteristics that can greatly limit the accuracy of broadband or multi-frequency passive applications. Since the vertical waveguide impedance is independent of the source spectral level, it is preferred for environmental characterization by the sound field generated from a ship of opportunity. Because of this independence property, the vertical waveguide impedance is expected to yield a more reliable inversion than that of pressure or vertical particle velocity field

Measurement of low-frequency tissue response of the seagrass Posidonia oceanica

A one-dimensional acoustic resonator technique was used to study leaves of the Mediterranean seagrass species Posidonia oceanica collected from Crete and Sicily. The leaf blades were finely divided, mixed with artificial seawater, and degassed to create a suspension of tissue independent of leaf structure and free bubbles or internal voids. The low-frequency (1 to 8 kHz) bulk modulus of the leaf tissue was inferred from the acoustic measurements and independent density measurements. The measured density of the seagrass tissue was 960 ± 20 kg/m3 which agrees with previously published values. The inferred bulk modulus was 2.1 GPa with 90% confidence limits 1.0-5.0 GPa.SCOPUS: ar.jinfo:eu-repo/semantics/publishe