Search results for "CLO"

Astrochronology of the Valanginian Stage from reference sections (Vocontian Basin, France) and palaeoenvironmental implications for the Weissert Even…

2013

12 pages; International audience; High-resolution gamma-ray measurements performed on five biostratigraphically well-dated reference sections from the Vocontian Basin (south-eastern France) are used to develop a new astrochronology of the Valanginian Stage and its subdivisions (i.e. ammonite and calcareous nannofossil zones and subzones). Spectral analyses show a pervasive dominance of 405-kyr eccentricity cycles with the expression of 100-kyr eccentricity, obliquity and precession. Previous rough estimates of Valanginian Stage duration ranged from 3.9 to 6.5 myr but were generally based on less reliable or indirect methods. This study provides a precise duration of 5.08 myr, tuning the ser…

A large temnospondyl humerus from the Rhaetian (Late Triassic) of Bonenburg (Westphalia, Germany) and its implications for temnospondyl extinction

2018

Temnospondyls are a group of basal tetrapods that existed from the Early Carboniferous to the Early Cretaceous. They were characteristic members of Permian and Triassic continental faunas around the globe. Only one clade, the Brachyopoidea (Brachyopidae and Chigutisauridae), is found as relics in the Jurassic of eastern Asia and the Cretaceous of Australia. The other Late Triassic clades, such as Plagiosauridae, Metoposauridae, and Cyclotsauridae, are generally believed to have gone extinct gradually before the end of the Triassic and putative Rhaetian records are stratigraphically poorly constrained. Temnospondyl humeri all show a similar morphological pattern, being stout, short, with wid…

High-resolution clay mineralogy as a proxy for orbital tuning: example of the Hauterivian-Barremian transition in the Betic Cordillera (SE Spain).

2012

11 pages; International audience; The response of clay mineral assemblages to potential orbital forcing is tested in Mesozoic hemipelagic marl- limestone rhythmites of the Río Argos section (Betic Cordillera, Southeastern Spain). Along the section, marls are pervasively enriched in kaolinite and illite, whereas limestones are enriched in smectite-rich illite/smectite mixed-layers, suggesting that marl-limestone alternations are produced by cyclic high-frequency fluctuations of continental runoff. Spectral analyses show that clay mineral assemblages evolve accordingly to precession, obliquity and eccentricity cycles. Durations of ammonite zones are assessed at 535 kyr for the Late Hauterivia…

The Valanginian isotope event: a complex suite of palaeoenvironmental perturbations.

2011

17 pages; International audience; The Valanginian records a severe crisis of carbonate systems, both on platforms and in the pelagic realm. This crisis is roughly concomitant with the Weissert Event, characterized by a positive δ13C excursion of about 2‰in marine carbonates. However, it is unclear if the response of these two carbonate systems to the global perturbations is contemporaneous, or if they react differently. For this purpose, accumulation rates of pelagic carbonates produced by nannofossils and of platform-derived carbonates have been quantified in a hemipelagic environment (the Vocontian Basin, SE France) that has the potential to record the reaction of both shallow-water and p…

Carbon-isotope records of the Early Jurassic (Toarcian) Oceanix Anixic Event from the Valdorbia (Umbria-Marche Apennines) and Monte Mangart (Julian A…

2009

The Toarcian oceanic anoxic event (ca 183 Ma) coincides with a global perturbation marked by enhanced organic carbon burial and a general decrease in calcium carbonate production, probably triggered by changes in the composition of marine plankton and elevated carbon dioxide levels in the atmosphere. This study is based on high-resolution sampling of two stratigraphic successions, located in Valdorbia (Umbria-Marche Apennines) and Monte Mangart (Julian Alps), Italy, which represent expressions of the Toarcian oceanic anoxic event in deep-water pelagic sediments. These successions are characterized by the occurrence of black shales showing relatively low total organic carbon concentrations (…

Modelling circulation in an ice-covered lake

2010

In deep ice-covered lakes with temperatures below 4 °C the heat flux from the bottom sediment results in a horizontal density gradient and a consequent flow along the bottom slope. Measurements in Lake Paajarvi, Finland, show a stable temperature field where a heat gain through the bottom and a heat loss through the ice nearly balance each other. The circulation is thermal with low velocities (less than 1.5 cm s -1 ). We used the 3D hydrodynamic Princeton Ocean Model as a tool to simulate the water circulation and the temperature distribution under the ice. The model forcing was based on field temperature measurements. The model simulations suggest that in midwinter the velocity field of th…

Diversity of Fish Scales in Late Triassic deposits of Krasiejów (SW Poland)

2018

Abstract. Taxonomy of extinct fishes is mostly based on the shapes of their bodies, teeth and skeletons and sometimes the coverage of the body. Analysis of modern fishes shows that sometimes even single-scale morphology can also be used as a taxonomic tool. In spite of the fact that variation in scales character in one species can be broad, some specific features distinguish species of the same genus. Analysis of the fossilized scales of fishes found in the Late Triassic deposits of Krasiejow (SW Poland) shows that the microstructure of the external surface of scales can also be considered as a taxonomic tool in the fossil record. Description of the ornamentation pattern of several scales o…

A Lack of Attribution: Closing the Citation Gap Through a Reform of Citation and Indexing Practices

2012

Highly efficient construction of infectious viroid-derived clones

2019

[Background] Viroid research generally relies on infectious cDNA clones that consist of dimers of the entire viroid sequence. At present, those dimers are generated by self-ligation of monomeric cDNA, a strategy that presents several disadvantages: (i) low efficiency, (ii) it is a non-oriented reaction requiring tedious screenings and (iii) additional steps are required for cloning into a binary vector for agroinfiltration or for in vitro RNA production.

Recombinant laccase from Pediococcus acidilactici CECT 5930 with ability to degrade tyramine

2017

Biogenic amines degradation by bacterial laccases is little known, so we have cloned and heterologously expressed, in E. coli, a new laccase from Pediococcus acidilactici CECT 5930 (Lpa5930), a lactic acid bacterium commonly found in foods able to degrade tyramine. The recombinant enzyme has been characterized by physical and biochemical assays. Here we report the optimization of expression and purification procedures of this laccase. DNA encoding sequence of laccase from P. acidilactici was amplified by PCR and cloned into the expression plasmid pET28a for induction by isopropyl-β-D-thiogalactoipyranoside. Protein expression was performed in E. coli BL21(DE3) harboring pGro7 plasmid expres…