Search results for " Cell"
showing 10 items of 14074 documents
Selection for Robustness in Mutagenized RNA Viruses
2007
Mutational robustness is defined as the constancy of a phenotype in the face of deleterious mutations. Whether robustness can be directly favored by natural selection remains controversial. Theory and in silico experiments predict that, at high mutation rates, slow-replicating genotypes can potentially outcompete faster counterparts if they benefit from a higher robustness. Here, we experimentally validate this hypothesis, dubbed the ‘‘survival of the flattest,’’ using two populations of the vesicular stomatitis RNA virus. Characterization of fitness distributions and genetic variability indicated that one population showed a higher replication rate, whereas the other was more robust to mut…
The Spodoptera exigua ABCC2 Acts as a Cry1A Receptor Independently of its Nucleotide Binding Domain II
2019
ABC proteins are primary-active transporters that require the binding and hydrolysis of ATP to transport substrates across the membrane. Since the first report of an ABCC2 transporter as receptor of Cry1A toxins, the number of ABC transporters known to be involved in the mode of action of Cry toxins has increased. In Spodoptera exigua, a mutation in the SeABCC2 gene is described as genetically linked to resistance to the Bt-product XentariTM. This mutation affects an intracellular domain involved in ATP binding, but not the extracellular loops. We analyzed whether this mutation affects the role of the SeABCC2 as a functional receptor to Cry1A toxins. The results show that Sf21 cells express…
Introducing anatomical techniques to subfossil wood
2018
Abstract Successful cross-dating of subfossil wood, ideally in combination with precise information on germination and dieback, requires the accurate detection of tree-ring width (TRW) boundaries along continuous measurement tracks from pith to bark. However, wood decay and the mechanical deformation of cells often challenge the dendrochronological analysis and subsequent paleoclimatic and environmental interpretations. Here, we show that wood anatomical techniques can improve the assessment of heavily degraded and/or deformed material. We apply state-of-the-art sample preparation, thin sectioning and double-staining to a unique collection of Late Glacial pines that were growing ∼13,000 yea…
Phytochemical profiles, phototoxic and antioxidant properties of eleven Hypericum species - A comparative study
2018
Hypericum is one out of the nine genera belonging to the botanical family Clusiaceae Lindl (syn. Hypericaceae Juss.; APG III, 2009). The genus contains 484 species spread worldwide, one of which, Hypericum perforatum, is largely used in folk medicine. The aim of this study was to evaluate the chemical composition, along with the antioxidant and phototoxic activity, of 11 Hypericum species grown in Sicily (H. perforatum L., H. aegypticum L., H. androsaemum L., H. calycinum L., H. hircinum L., H. hirsutum L., H. montanum L., H. patulum Thunb., H. perfoliatum L., H. pubescens Boiss., H. tetrapterum Fr.). Samples of flowering tops collected from these Hypericum species were extracted and analys…
Collateral sensitivity of natural products in drug-resistant cancer cells
2018
Cancer chemotherapy is frequently hampered by drug resistance. Concepts to combine anticancer drugs with different modes of action to avoid the development of resistance did not provide the expected success in the past, because tumors can be simultaneously non-responsive to many drugs (e.g. the multidrug resistance phenotype). However, tumors may be specifically hypersensitive to other drugs - a phenomenon also termed collateral sensitivity. This seems to be a general biological mechanism, since it also occurs in drug-resistant Escherichia coli and Saccharomyces cerevisiae. Here, we give a timely and comprehensive overview on hypersensitivity in resistant cancer cells towards natural produc…
Fatty acid hydroperoxide lyase of green bell pepper: cloning in Yarrowia lipolytica and biogenesis of volatile aldehydes
2004
Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Fatty acid hydroperoxide lyase (HPO lyase) is a cytochrome P450 acting on fatty acid hydroperoxides in many organisms. The expression of green bell pepper HPO lyase in the yeast Yarrowia lipolytica is described for the first time. HPO lyase activity from yeast extract and whole yeast cells is measured and aldehydes production from yeast extract and whole yeast cells is compared. 1200 U/L reaction medium were obtained after 96 h of culture on olive oil rich me…
ABP1 Mediates Auxin Inhibition of Clathrin-Dependent Endocytosis in Arabidopsis
2010
SummarySpatial distribution of the plant hormone auxin regulates multiple aspects of plant development. These self-regulating auxin gradients are established by the action of PIN auxin transporters, whose activity is regulated by their constitutive cycling between the plasma membrane and endosomes. Here, we show that auxin signaling by the auxin receptor AUXIN-BINDING PROTEIN 1 (ABP1) inhibits the clathrin-mediated internalization of PIN proteins. ABP1 acts as a positive factor in clathrin recruitment to the plasma membrane, thereby promoting endocytosis. Auxin binding to ABP1 interferes with this action and leads to the inhibition of clathrin-mediated endocytosis. Our study demonstrates th…
The tiny eukaryote Ostreococcus provides genomic insights into the paradox of plankton speciation
2007
The smallest known eukaryotes, at ≈1-μm diameter, are Ostreococcus tauri and related species of marine phytoplankton. The genome of Ostreococcus lucimarinus has been completed and compared with that of O. tauri . This comparison reveals surprising differences across orthologous chromosomes in the two species from highly syntenic chromosomes in most cases to chromosomes with almost no similarity. Species divergence in these phytoplankton is occurring through multiple mechanisms acting differently on different chromosomes and likely including acquisition of new genes through horizontal gene transfer. We speculate that this latter process may be involved in altering the cell-surface character…
III. Biochemistry of S-layers
1997
During evolution prokaryotes have developed different envelope structures exterior to the cell wall proper. Among these surface components are regularly arranged S-layers and capsules. The structural characterization and the detailed chemical analysis of these surface molecules is a prerequisite to understand their biosynthesis and functional role(s) at the molecular level. Of particular interest are the glycosylated S-layer proteins which belong to the first prokaryotic glycoproteins ever described. Their characterization was performed on strains belonging to the thermophilic Bacillaceae and included structural studies and experiments to learn about the pathways for the glycan biosynthesis…
The combined action of 9 lipoxygenase and galactolipase is sufficient to bring about programmed cell death during tobacco hypersensitive response
2005
International audience; Oxylipins, derived from fatty acid hydroperoxides (FAHs), are thought to play different roles during plant pathogen interactions. During hypersensitive response (HR) some of them serve as signals necessary for defence gene activation whereas others could contribute to pathogen killing or could participate in the execution of plant programmed cell death (PCD) associated with this resistance. In order to address the role of these compounds in the latter process, we have closely observed lipid peroxidation, the first step of this metabolic pathway, under different situations which led either to accelerated or inhibited HR cell death. The oxidative process has been studi…