Search results for "ACC"

Sr isotope variations in the Upper Triassic succession at Pizzo Mondello, Sicily: Constraints on the timing of the Cimmerian Orogeny

2018

Abstract The Late Triassic Cimmerian Orogeny was a result of the final closure of the Palaeotethys Ocean and the accretion of Gondwana-derived (Cimmerian) continents to southern Eurasia. Determining the timing of the Cimmerian Orogeny is crucial to our understanding of the large-scale climate changes driven by the uplift of the Cimmerian Mountains. Here we present stratigraphic variations in 87Sr/86Sr values of Upper Triassic pelagic limestone from the Pizzo Mondello section, Sicily, Italy, that constrain the timing of uplift of the Cimmerian Mountains. The 87Sr/86Sr values remain relatively constant in the lower part of the section, decreasing slightly in the Tuvalian (upper Carnian) and L…

Taphonomic processes inconsistent with indigenous Mesolithic acculturation during the transition to the Neolithic in the Western Mediterranean

2018

Abstract We applied taphonomic analysis combined with geostatistical approaches to investigate the hypothesis that Cocina cave (Eastern Iberia) represents an acculturation context for the appearance of Neolithic Cardial pottery. In the 1970s, Fortea suggested that this important site was a prime example of acculturation because of the presence of early Neolithic pottery in late Mesolithic contexts. Since that time Cocina cave has been heralded as an example of indigenous hunter-gatherers incorporating Neolithic cultural elements into their lifeways. We analyzed the area excavated by Fortea in the 1970s by digitizing archaeological records and testing the spatial distribution of artifacts us…

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…

Higher sensitivity towards light stress and ocean acidification in an Arctic sea-ice-associated diatom compared to a pelagic diatom.

2020

Thalassiosira hyalina and Nitzschia frigida are important members of Arctic pelagic and sympagic (sea-ice-associated) diatom communities. We investigated the effects of light stress (shift from 20 to 380 µmol photons m-2  s-1 , resembling upwelling or ice break-up) under contemporary and future pCO2 (400 vs 1000 µatm). The responses in growth, elemental composition, pigmentation and photophysiology were followed over 120 h and are discussed together with underlying gene expression patterns. Stress response and subsequent re-acclimation were efficiently facilitated by T. hyalina, which showed only moderate changes in photophysiology and elemental composition, and thrived under high light aft…

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

2012

Cuticular hydrocarbon profiles differ between ant body parts: implications for communication and our understanding of CHC diffusion.

2020

Abstract Insect cuticular hydrocarbons (CHCs) serve as communication signals and protect against desiccation. They form complex blends of up to 150 different compounds. Due to differences in molecular packing, CHC classes differ in melting point. Communication is especially important in social insects like ants, which use CHCs to communicate within the colony and to recognize nestmates. Nestmate recognition models often assume a homogenous colony odor, where CHCs are collected, mixed, and redistributed in the postpharyngeal gland (PPG). Via diffusion, recognition cues should evenly spread over the body surface. Hence, CHC composition should be similar across body parts and in the PPG. To te…

Effects of acclimation time and epigenetic mechanisms on growth of Neurospora in fluctuating environments

2017

AbstractReaction norms or tolerance curves have often been used to predict how organisms deal with fluctuating environments. A potential drawback is that reaction norms measured in different constant environments may not capture all aspects of organismal responses to fluctuating environments. We examined growth of the filamentous fungusNeurospora crassain fluctuating temperatures and tested if growth in fluctuating temperatures can be explained simply by growth in different constant temperatures or if more complex models are needed. In addition, as previous studies on fluctuating environments have revealed that past temperatures that organisms have experienced can affect their response to c…

Ecological genomics of adaptation to unpredictability in experimental rotifer populations

2019

AbstractElucidating the genetic basis of phenotypic variation in response to different environments is key to understanding how populations evolve. Facultatively sexual rotifers can develop adaptive responses to fluctuating environments. In a previous evolution experiment, diapause-related traits changed rapidly in response to two selective regimes (predictable vs unpredictable) in laboratory populations of the rotifer Brachionus plicatilis. Here, we investigate the genomic basis of adaptation to environmental unpredictability in these experimental populations. We identified and genotyped genome-wide polymorphisms in 169 clones from both selective regimes after seven cycles of selection usi…

Variation in the immune state of Gammarus pulex (Crustacea, Amphipoda) according to temperature: are extreme temperatures a stress?

2017

9 pages; International audience; Temperature is known to impact host-parasite interactions in various ways. Such effects are often regarded as the consequence of the increased metabolism of parasites with increasing temperature. However, the effect of temperature on hosts' immune system could also be a determinant. Here we assessed the influence of temperature on the immunocompetence of the crustacean amphipod Gammarus pulex. Amphipods play a key ecological role in freshwater ecosystems that can be altered by several parasites. We investigated the consequences of three weeks of acclimatization at four temperatures (from 9 °C to 17 °C) on different immunological parameters. Temperature influ…

Evaluation of the Ability of Polyphenol Extracts of Cocoa and Red Grape to Promote the Antioxidant Response in Yeast Using a Rapid Multiwell Assay

2017

Saccharomyces cerevisiae has been used as a model organism to study the capacity of cocoa and red grape extracts to trigger an antioxidant response. A methodology adapted to microtiter plates has been developed to monitor yeast growth after culture preincubation with food ingredients and exposure to oxidative stress by hydrogen peroxide and menadione. This methodology proved effective in measuring the ability of cocoa and red grape extracts to promote an antioxidant response in yeast, and also the prospect of conducting dose-response studies. Additionally, the method has proven useful to perform studies with mutant strains lacking genes that may be related to the mechanism of action underly…