Role of CDK9 in skeletal muscle

Cdk9 is a member of cyclin-dependent kinases and it is expressed in human and murine tissue with high levels in terminally differentiated cells. The elevated levels of Cdk9 and its regulatory subunits in terminally differentiated cells, together with the fact that it is implicated in the regulation of transcriptional elongation via phosphorylation of CTD of RNA polII, distinguishes Cdk9 from the other cdks. Cyclin partners of CDK9 are cyclin T1, T2a, T2b and K, with a formation of a complex, called p-TEF-B. In Hela cells about 80% of cellular P-TEFb is composed of cyclin T1 and the cyclin –dependent kinase 9 (CDK9), and about 20% of cellular CDK9 is complexed to other cyclins, such as cyclin T2a, T2b and with cyclin K. It was demonstrated that CdK9 complexed with CyT2a plays a role in the activation of myogenic program and Cdk9-CyT2a activity is not down-regulated in myotube formation, but its activation contributes to the transcriptional activity MyoD-mediated during myogenic program. The formation of a multimeric complex, containing cdk9/cyclin T2a and MyoD is present in muscle cells during the activation of the differentiation program and the N-terminal region of Cdk9 directly interacts with the b-HLH region of MyoD, allowing the formation of a complex also containing cyclin T2a. Recently a 55 kDa protein called CDK9-55 has been identified. This isoform presents 117 additional amminoacids residues at the N-terminal portion of Cdk9-42 and it conserves all molecular features of 42 isoform, indeed it associates with CycT phosphorylates CTD of RNA polII. Cdk9-55 is significantly upregulated in cells induced to differentiate, either in C2C12 cells or in satellite isolated cells, and it was demonstrated that there is a clear induction of cdk9-55 expression in injured skeletal muscles. Analysis in vivo on limbs at different times of development demostrated a different correlation between two CDK9 isoforms: CDK9-55 is involved during foetal myogenesis, whereas the CDK9-42 is expressed during embrional myogenesis. Study in vitro demonstrated that CDK9-55 is the isoform more expressed during differentiation both embrional and fetal myoblasts. A new antibody, p-CDK9, permitted us to define CDK9-55 as the active isoform during the differentiation. CDK9-55 is also the isoform more expressed during the re-innervation process. The analysis of different cyclins that complex with different members of kinase proteins showed that in vivo only cyclin K and D3 are involved during foetal myogenesis, suggesting their interaction with CDK9-55, whereas Cyclin T1, T2, L and H are implicated during primary myogenesis, in concomitance with CDK9-42 expression. Study in vitro demonstrated that only cyclin T2 is involved during the differentiation process for embrional and fetal myoblasts. Between inhibitory post transcriptional regulator mechanism of CDK9 there is the interaction with 7SKsnRNA and HEXIM1, our studies, on C2C12 cells, by RIP assay demonstrated that CDK9 isn’t associated with 7SKsnRNA/Hexim1 during differentiative phase, supporting that in differentiation CDK9 is active

Yield, fruit quality, bud fertility and starch reserves of the wood as a function of leaf removal in Vitis vinifera-Evidence of compensation and stress recovering

Einfluß unterschiedlicher Entblätterung auf Ertrag, Traubenqualität, Knospenfruchtbarkeit und Stärkegehalt des Holzes von Vitis vinifera sowie Kompensations- und ErholungsvermögenAn Ertragsreben wurde der Einfluß des Entfernens von Hauptblättern oder Geiztrieben auf Gesamtblattfläche, Traubenertrag und -qualität sowie Stärkegehalt des Holzes studiert. Die Bedeutung von Haupt- und Geizblättern sowie des Zeitpunktes der Entblätterung auf dss Verrieseln wurde untersucht. Ziel der Studie war, Kompensationsmechanismen und -limiten der Rebe unter Streßbedingungen kennenzulernen, wie sie durch eine Entblätterung verursacht werden. Ferner sollte die Erholung der Pflanze nach längerer Streßeinwirkung erforscht werden.Wurden die Hauptblätter entfernt (L = nur Geizblätter}, so bildeten die Pflanzen mehr Geiztriebe mit einer größeren Anzahl Blätter. Dies führte nach dem ersten Streßjahr zu einer ungefähr gleichen Gesamtblattfläche wie bei den Kontrollpflanzen. Nach einem weiteren Streßjahr jedoch hatten die L-Pflanzen zwar weiterhin mehr Geizblätter, allerdings von geringerer Größe. Hieraus resultierte eine im Vergleich zur Kontrolle verringerte Gesamtblattfläche. Pflanzen nur mit Hauptblättern (M) kompensierten das Fehlen der Geiztriebe mit verzögerter Blattalterung und späterem Blattfall. Auch hier ergab sich nach dem zweiten Streßjahr eine geringere Blattgröße. Der Traubenertrag der L-Pflanzen wurde im 1. Jahr durch die Blattentfernung kaum negativ beeinflußt, aber im 2. Jahr war er 50 % niedriger als in der Kontrolle. Bei den M-Pflanzen ergab sich in beiden Jahren kein verringerter Ertrag. Der Zuckergehalt der Trauben war in den L-Pflanzen im 1. Streßjahr leicht erhöht, nicht aber im 2. Jahr. Diese Reben hatten während beider Jahre eine bessere Beerenfarbe.Die Blattfläche vom Zeitpunkt der Blüte bis 2-3 Wochen danach ist für den Traubenertrag entscheidend. Eine Entblätterung zu diesem Zeitpunkt verursachte nicht nur ein Verrieseln, sondern im folgenden Jahr zusätzlich eine reduzierte Knospenfruchtbarkeit. Die Zuckereinlagerung in den Trauben hängt von der assimilierenden Blattfläche während der Reifeperiode ab. Der Stärkegehalt im Holz war nach 2 Streßjahren erheblich reduziert. Es ergaben sich schwach positive Korrelationen zwischen Zuckergehalt des Mostes und Stärkegehalt des Holzes.Die Zuckereinlagerung in die Traube und das Auffüllen der Stärkereserven im Holz ging bereits in der auf eine Streßbehandlung folgenden Saison normal vonstatten. Ein normaler Ertrag war l Jahr nach einem längeren Entblätterungsstreß jedoch noch nicht möglich, da die Bildung der Infloreszenzen bekanntlich während dieser Zeit (in unserem Fall die Streßperiode) einsetzt. Erst im 2. Jahr kam es zu einer vollständigen Erholung der Pflanze

What is new about the Culicoides identification freeware?

In the framework of Medreonet workpackage on "Regional surveillance of vectors", a Culicoides identification key based on morphology is proposed. This key will help to identify the different Culicoides species, including those of the Palaearctic region. The tool will be available in a freeware version and in a web version. At time of writing, the key was not yet available but a first draft version was to be presented soon after to Culicoides taxonomists so as to improve it. Currently, females of 85 species including 9 morphological variations are included in a database of 63 descriptors codified in 172 states. These descriptors and states of descriptors were discussed and validated by the participants of the last taxonomic meeting in Strasbourg, France, in March 2009. (Texte intégral

Influence of partial defoliation on gas exchange parameters and chlorophyll content of field-grown grapevines - Mechanisms and limitations of the compensation capacity

In order to study the compensation mechanisms related to leaf removal, gas exchange response to defoliation as well as chlorophyll content were investigated in field-grown Pinot noir grapevines. Mature 16 years old bearing plants and 2 years old fruitless potted plants were compared. Defoliation treatments were performed 1 week after full bloom. Besides topping, three levels of main leaf removal (3, 6 or all 12 main leaves retained) were combined with two levels of laterals (all retained or all removed). The single leaf measurements (on the 11th main leaf from the base) were carried out from treatment time to fruit maturity

Influence of the twospotted spider mite, Tetranychus urticae, on the gas exchange of Pinot noir grapevine leaves

The effect of feeding damage by the twospotted spider mite (Tetranychus urticae KOCH; Acari: Tetranychidae) on the gas exchange of grapevine leaves (Vitis vinifera L.; cv. Pinot noir) was investigated. In addition, the influence of some pesticides was studied. A significant reduction of the net CO2 assimilation, transpiration as well as stomatal and mesophyll conductance with increasing mite feeding damage were observed. At 6000 mite-days per leaf the 3rd and 9th main leaves (from the base) showed an average reduction in net CO2 assimilation of 52.2 % and 48.4 %, respectively, while the 6th leaf showed a reduction of only 21.3 %. The response of grapevine photosynthesis to mite feeding seems to depend not only on mite density and duration of feeding, but also on the phenological stage of the plant. In fact, at veraison the vines showed increased tolerance to mite feeding compared with other phenological stages. At mite infestation levels of 6000 mite-days, leaves infested with T. urticae showed, as compared to uninjured leaves, an average reduction in transpiration rate of 14.4 % to 40.8 %, depending on the leaf position. The acaricides Tetradifon and Fenbutatin-oxide and the fungicide Folpet combined with Penconazol showed no effect on the gas exchange parameters

Spatio-temporal patterns of earthworm abundance suggest time-limited food availability for a subalpine bird species

Changes in food availability may act as a major mechanism by which global change impacts populations of birds, especially in seasonal environments at high elevations or latitudes. Systematic sampling of invertebrates, which constitute the diet of many bird species during the breeding season, is however largely missing in mountain ecosystems and is overall very rare for soil-dwelling species or stages. Here, we repeatedly sampled earthworms (Lumbricidae), the staple prey of the Ring Ouzel Turdus torquatus, over a whole breeding season in a study area in the Swiss Alps. Our main goal was to finely characterise spatio-temporal patterns of food availability for this declining bird species, in relation to elevation, habitat type and snowmelt stage. In 24 sampling plots, we extracted two soil cores every week for 6–10 weeks and hand-sorted soil invertebrates separately for two 5-cm soil layers. We then analysed the abundance of earthworms in those two layers in relation to various environmental parameters. We show that within our study area, edaphic and topographical parameters are poor predictors of the mean abundance of earthworms over the breeding season. Ground vegetation cover and soil moisture, however, are suitable predictors for the number of earthworms within the soil profile at each sampling time, i.e., of their availability for Ring Ouzels. Moreover, we provide evidence for a clear seasonal peak in earthworm availability, which was more pronounced in open grasslands compared to forested areas and happened later in the season where snow lingered. This study, by improving our understanding of the factors driving food availability for a mountain bird species, provides insights into how shifts in land-use and climate might lead to altered predator-prey interactions

ICT management in Latin America educational institutions. Between policies and innovation

[EN] The use of Information and Communication Technologies (ICT) in educational contexts has focused its greatest efforts on the acquisition and use of technology. This makes necessary a conceptual and methodological redesign of its use, one that integrates all the members of the organization and generate permanent changes in the culture of the organization (Salinas, 2005). The management of educational institutions is crucial to normalize experiences and provide references that can be integrated into environmental conditions. Despite this, educational management has been relegated to the studies of innovation in education supported by technology, with little systematized information in this regard (Sunkel, Trucco, & Espejo, 2013). The present work uses bibliographic techniques to analyze the trends that have been followed in Latin America in terms of educational management for the adoption of ICT. The influence of public policy on the promotion of these programs is observed, as well as the need for a theoretical methodological support for the development of an integral management model, in which the technology component does not constitute a parallel item.Avitia Carlos, P.; Rodríguez Tapia, B.; Candolfi Arballo, N. (2020). ICT management in Latin America educational institutions. Between policies and innovation. Editorial Universitat Politècnica de València. 111-119. https://doi.org/10.4995/INN2019.2019.10108OCS11111