Les Pseudoperisphinctinae (Ammonitina, Perisphinctidae) de l'horizon à Leckenbyi (Callovien supérieur, zone à Athleta) de Montreuil-Bellay (Maine-et-Loire, France) et description d'une nouvelle espèce, Choffatia isabellae.

International audienceDans la région de Montreuil-Bellay (Maine-et-Loire), de nombreuses coupes ont été réalisées au passage Callovien moyen-Callovien supérieur. Le premier banc attribué au Callovien supérieur a été daté de l'horizon à Leckenbyi. Il a fourni une très importante faune ammonitique (N=3125), dans laquelle les Perisphinctidae représentent 51% de l'effectif. À côté de formes plus ou moins bien connues comme Pseudopeltoceras leckenbyi (Bean), Orionoides pseudorion (Waagen), Subgrossouvria famulum (Bean) et S. crassa Gérard et Contaut, on trouve une espèce qui n'a jamais été ni décrite ni figurée : cette espèce fait l'objet du présent article. Choffatia isabellae n. sp. se distingue sans aucune ambiguité des Perisphinctidae contemporains par : 1) un long stade juvénile lisse, 2) une costulation habituellement ténue, 3) l'absence de formations paraboliques et 4) la très grande fréquence des constrictions. Comme cette espèce est inconnue dans les faunes de l'extrême sommet du Callovien moyen, nous pensons qu'elle a colonisé, avec beaucoup d'autres espèces, dont Peltoceras marysae Bonnot et alii, via la marge sud de la Téthys, la plate-forme nord-ouest européenne à la faveur de l'intervalle transgressif qui débute à l'extrême base du Callovien supérieur. Apparue brutalement à la base de l'horizon à Leckenbyi, cette nouvelle espèce possède son acmé dans la partie médiane de l'horizon, où elle peut représenter la moitié des Perisphinctidae, avant de devenir rare dans la partie supérieure de l'horizon, puis très rare dans l'horizon à Athleta

Evaluating the spatial and temporal variations of the performance of CAMS Radiation Service and HelioClim-3 databases of surface irradiation in Germany

International audienceSatellite-derived databases of the surface solar irradiance (SSI) have become an essential source of information for various applications in solar energy. Assessing the accuracy of these data by comparison with reference in-situ measurements is therefore ever gaining in importance. Several authors have reported that performances of a given database differ from one site to another depending on the geographical region, topography, orography, climate, viewing angle from the satellite.. . A good understanding of the spatial and temporal variation of the SSI estimation error is key to allow end-user to have an appropriate level of expectation on the accuracy of this data. This knowledge can also be very important for the further developments of the algorithms. The present work contributes to this objective by extending the validation works carried out in the last years for numerous regions (Europe, Brazil, Egypt, Arabic Peninsula, Morocco and The Netherlands) to Germany. We consider two databases: the CAMS Radiation Service version 3 (abbreviated as CAMS-Rad) and the HelioClim-3 version 5 (abbreviated as HC3v5) that are widely used by academics and practitioners. The present communication focuses on several stations located in Germany operated by the Deutscher Wetterdienst (DWD). They are spread over the country, thus allowing the study of the spatial consistency of the performance of each database. Measurements of 10 min means of global irradiance made by pyranometers (CM11 and CM21) and SCAPP set publicly available by the DWD for the period 2010-2018 (9 years) have been used for the validation. Measurements were quality-checked using the method described by Roesch et al. (2011). Satellite-derived SSI estimates were collected from the SoDa web site (www.soda-pro.com) for the same locations and same instants of measurements for both databases. CAMS-Rad uses the Heliosat-4 method with different inputs: the clear-sky radiation is evaluated using Copernicus Atmosphere Monitoring Service (CAMS) information on the aerosol, ozone and water vapour contained in the atmosphere, the cloud attenuation is considered using cloud optical properties retrieved every 15 min from Meteosat imagery using APPOLO. The second database is the HelioClim-3v5 that is derived from Meteosat images using the Heliosat-2 method, McClear and CAMS products. For each database, standard error metrics are computed at each station. A particular attention is paid in the presentation of the validation results to evaluate the effects of different parameters such as e.g. the solar elevation and the clearness index on the error. A focus of this work is laid on the consistency of the errors with space and time

Untangling methodological and scale considerations in growth and productivity trend estimates of Canada’s forests

In view of the economic, social and ecological importance of Canada's forest ecosystems, there is a growing interest in studying the response of these ecosystems to climate change. Accurate knowledge regarding growth trajectories is needed for both policy makers and forest managers to ensure sustainability of the forest resource. However, results of previous analyses regarding the sign and magnitude of trends have often diverged. The main objective of this paper was to analyse the current state of scientific knowledge on growth and productivity trends in Canada's forests and provide some explanatory elements for contrasting observations. The three methods that are commonly used for assessments of tree growth and forest productivity (i.e. forest inventory data, tree-ring records, and satellite observations) have different underlying physiological assumptions and operate on different spatiotemporal scales, which complicates direct comparisons of trend values between studies. Within our systematic review of 44 peer-reviewed studies, half identified increasing trends for tree growth or forest productivity, while the other half showed negative trends. Biases and uncertainties associated with the three methods may explain some of the observed discrepancies. Given the complexity of interactions and feedbacks between ecosystem processes at different scales, researchers should consider the different approaches as complementary, rather than contradictory. Here, we propose the integration of these different approaches into a single framework that capitalizes on their respective advantages while limiting associated biases. Harmonization of sampling protocols and improvement of data processing and analyses would allow for more consistent trend estimations, thereby providing greater insight into climate-change related trends in forest growth and productivity. Similarly, a more open data-sharing culture should speed-up progress in this field of research

Pseudoperisphinctinae (Ammonitina, Perisphinctidae) from the Leckenbyi horizon (Upper Callovian, Athleta zone) of Montreuil-Bellay (Maine-et-Loire, France) and description of a new species, Choffatia isabellae

Many outcrops exposing the Mid-Callovian/Upper Callovian boundary have been found near Montreuil-Bellay (Maine-et-Loire). The lowermost bed of the Upper Callovian has been dated as the Leckenbyi horizon. It contains an abundant ammonite fauna (3125 specimens), in which Perisphinctidae make up just over half of the specimens. In company with reasonably well-known species such as Pseudopeltoceras leckenbyi (BEAN), Orionoides pseudorion (WAAGEN), Subgrossouvria famulum (BEAN) and S. crassa GÉRARD et CONTAUT, occurs a species, previously unknown, which is described in this article. Choffatia isabellae n. sp. differs markedly from contemporary Perisphinctidae, for it is distinguished by : 1) a long, smooth juvenile stage, 2) weakly developed ribbing, 3) the absence of parabolic ornamentation and 4) a high frequency of constrictions. As this species is unknown in the fauna of the uppermost Middle Callovian, along with many other species, including Peltoceras marysae BONNOT et alii, it must have colonised the northwestern part of the European platform via the southern margin of the Tethys during the transgressive interval which started at the beginning of the Late Callovian. This new species appears abruptly at the base of the Leckenbyi horizon, reaches its acme in the middle of the horizon, where it probably represents half of the Perisphinctidae, before becoming rare in the upper part of the horizon, then very rare in the Athleta horizon.Dans la région de Montreuil-Bellay (Maine-et-Loire), de nombreuses coupes ont été réalisées au passage Callovien moyen-Callovien supérieur. Le premier banc attribué au Callovien supérieur a été daté de l'horizon à Leckenbyi. Il a fourni une très importante faune ammonitique (N=3125), dans laquelle les Perisphinctidae représentent 51% de l'effectif. À côté de formes plus ou moins bien connues comme Pseudopeltoceras leckenbyi (BEAN), Orionoides pseudorion (WAAGEN), Subgrossouvria famulum (BEAN) et S. crassa GÉRARD et CONTAUT, on trouve une espèce qui n'a jamais été ni décrite ni figurée : cette espèce fait l'objet du présent article. Choffatia isabellae n. sp. se distingue sans aucune ambiguité des Perisphinctidae contemporains par : 1) un long stade juvénile lisse, 2) une costulation habituellement ténue, 3) l'absence de formations paraboliques et 4) la très grande fréquence des constrictions. Comme cette espèce est inconnue dans les faunes de l'extrême sommet du Callovien moyen, nous pensons qu'elle a colonisé, avec beaucoup d'autres espèces, dont Peltoceras marysae BONNOT et alii, via la marge sud de la Téthys, la plate-forme nord-ouest européenne à la faveur de l'intervalle transgressif qui débute à l'extrême base du Callovien supérieur. Apparue brutalement à la base de l'horizon à Leckenbyi, cette nouvelle espèce possède son acmé dans la partie médiane de l'horizon, où elle peut représenter la moitié des Perisphinctidae, avant de devenir rare dans la partie supérieure de l'horizon, puis très rare dans l'horizon à Athleta

Perspectives sur le statut des équipements électroniques à Montréal = Perspectives on the Status of Electronic Equipment in Montreal

"The [...] anthology responds to the ever-increasing amount of electronic equipment that is perceived as obsolete, valueless or disposable. Contributors from diverse disciplines including ecology, waste management, technology activism and contemporary art bring their expertise to bear on the consumption, use, obsolescence, disposal and repair and re-use of electronic equipment. Perspectives’ hybrid approach to these topics will be of interest to both general and specialized readers negotiating the cultural, environmental and social impacts of contemporary technology. Essays, projects and resource materials highlight approaches and practices that question consumption patterns and propose alternative approaches to using technology. Case studies and local contexts from Montreal Quebec are related to issues and initiatives across industrialized societies." -- Publisher's website

HIV-1 Integrase-Targeted Short Peptides Derived from a Viral Protein R Sequence

HIV-1 integrase (IN) inhibitors represent a new class of highly effective anti-AIDS therapeutics. Current FDA-approved IN strand transfer inhibitors (INSTIs) share a common mechanism of action that involves chelation of catalytic divalent metal ions. However, the emergence of IN mutants having reduced sensitivity to these inhibitors underlies efforts to derive agents that antagonize IN function by alternate mechanisms. Integrase along with the 96-residue multifunctional accessory protein, viral protein R (Vpr), are both components of the HIV-1 pre-integration complex (PIC). Coordinated interactions within the PIC are important for viral replication. Herein, we report a 7-mer peptide based on the shortened Vpr (69–75) sequence containing a biotin group and a photo-reactive benzoylphenylalanyl residue, and which exhibits low micromolar IN inhibitory potency. Photo-crosslinking experiments have indicated that the peptide directly binds IN. The peptide does not interfere with IN-DNA interactions or induce higher-order, aberrant IN multimerization, suggesting a mode of action for the peptide that is distinct from clinically used INSTIs and developmental allosteric IN inhibitors. This compact Vpr-derived peptide may serve as a valuable pharmacological tool to identify a potential new pharmacologic site

Covalent binding of the natural antimicrobial peptide indolicidin to DNA abasic sites

Indolicidin is a host defense tridecapeptide that inhibits the catalytic activity of HIV-1 integrase in vitro. Here we have elucidated its mechanism of integrase inhibition. Using crosslinking and mass spectrometric footprinting approaches, we found that indolicidin interferes with formation of the catalytic integrase-DNA complex by directly binding DNA. Further characterization revealed that the peptide forms covalent links with abasic sites. Indolicidin crosslinks single- or double-stranded DNAs and various positions of the viral cDNA with comparable efficiency. Using truncated and chemically modified peptides, we show that abasic site crosslinking is independent of the PWWP motif but involves the indolicidin unique lysine residue and the N- and C- terminal NH(2) groups. Because indolicidin can also inhibit topoisomerase I, we believe that multiple actions at the level of DNA might be a common property of antimicrobial peptides

4-Pregnen-21-ol-3,20-dione-21-(4-bromobenzenesulfonate) (NSC 88915) and related novel steroid derivatives as tyrosyl-DNA phosphodiesterase (Tdp1) inhibitors

Tyrosyl-DNA phosphodiesterase 1 (Tdp1) is an enzyme that catalyzes the hydrolysis of 3'-phosphotyrosyl bonds. Such linkages form in vivo when topoisomerase I (Top1) processes DNA. For this reason, Tdp1 has been implicated in the repair of irreversible Top1-DNA covalent complexes. Tdp1 inhibitors have been regarded as potential therapeutics in combination with Top1 inhibitors, such as the camptothecin derivatives, topotecan and irinotecan, which are used to treat human cancers. Using a novel high-throughput screening assay, we have identified the C21-substituted progesterone derivative, NSC 88915 (1), as a potential Tdp1 inhibitor. Secondary screening and cross-reactivity studies with related DNA processing enzymes confirmed that compound 1 possesses specific Tdp1 inhibitory activity. Deconstruction of compound 1 into discrete functional groups reveals that both components are required for inhibition of Tdp1 activity. Moreover, the synthesis of analogues of compound 1 has provided insight into the structural requirements for the inhibition of Tdp1. Surface plasmon resonance shows that compound 1 binds to Tdp1, whereas an inactive analogue fails to interact with the enzyme. Based on molecular docking and mechanistic studies, we propose that these compounds are competitive inhibitors, which mimics the oligonucleotide-peptide Tdp1 substrate. These steroid derivatives represent a novel chemotype and provide a new scaffold for developing small molecule inhibitors of Tdp1