Search results for "wall"
showing 10 items of 970 documents
GIPC: Glycosyl Inositol Phospho Ceramides, the major sphingolipids on earth
2016
What are the most abundant sphingolipids on earth? The answer is Glycosyl Inositol Phosphoryl Ceramides (GIPCs) present in fungi and the green lineage. In this review, we discuss the putative role of plant GIPCs in the lipid bilayer asymmetry, in the lateral organization of membrane rafts and in the very long chain fatty acid inter-leaflet coupling of lipids in the plant plasma membrane (PM). A special focus on the structural similarities -and putative functions- of GIPCs is discussed by comparison with animal gangliosides, structural homologs of plant GIPCs.
Through the eye of a lizard: hue discrimination in a lizard with ventral polymorphic coloration.
2017
Colour polymorphisms are thought to be maintained by complex evolutionary processes some of which require that the colours of the alternative morphs function as chromatic signals to conspecifics. Unfortunately, a key aspect of this hypothesis has rarely been studied: whether the study species perceives its own colour variation as discrete rather than continuous. The European common wall lizard (Podarcis muralis) presents a striking colour polymorphism: the ventral surface of adults of both sexes may be coloured orange, white, yellow, or with a mosaic of scales combining two colours (orange-white, orange-yellow). Here we use a discrimination learning paradigm to test if P. muralis is capable…
Untangling the hidden intrathalline microalgal diversity inParmotrema pseudotinctorum:Trebouxia crespoanasp. nov.
2018
AbstractIntrathalline phycobiont diversity was investigated in a rosette-forming lichen,Parmotrema pseudotinctorum, using a combination of Sanger sequencing, 454-pyrosequencing, conventional light and confocal microscopy, and transmission electron microscopy. A total of 39 thalli sampled in five Canary Island populations were investigated. Three novel lineages of lichen phycobionts were detected, all being inferred within theTrebouxiaclade G. The most abundant phycobiont lineage, occurring in all lichen populations investigated, is described here asTrebouxia crespoanasp. nov. This species produces spherical to pyriform cells possessing a crenulate chloroplast with lobes elongated at their e…
Calcium—Nutrient and Messenger
2019
Calcium is an essential element needed for growth and development of plants under both non-stressed and stress conditions. It thereby fulfills a dual function, being not only an important factor for cell wall and membrane stability, but also serving as a second messenger in many developmental and physiological processes, including the response of plants to biotic stress. The perception of non-self hereby induces an influx of calcium ions (Ca2+) into the cytosol, which is decoded into downstream responses ultimately leading to defense. Maintaining intracellular Ca2+ homeostasis is crucial for the ability to generate this signal. This review will describe the current knowledge of the mechanis…
SEXUAL SELECTION WHEN FERTILIZATION IS NOT GUARANTEED
2005
Much of the theory of sexual selection assumes that females do not generally experience difficulties getting their eggs fertilized, yet sperm limitation is occasionally documented. How often does male limitation form a selection for female traits that improve their mating rate? The question is difficult to test, because if such traits evolve to be efficient, sperm limitation will no longer appear to be a problem to females. Here, we suggest that changes in choosiness between populations, and in particular between virgin and mated females, offer an efficient way to test this hypothesis. We model the "wallflower effect," that is, changes in female preferences due to time and mortality costs o…
Geographical variation in egg mass and egg content in a passerine bird
2011
Reproductive, phenotypic and life-history traits in many animal and plant taxa show geographic variation, indicating spatial variation in selection regimes. Maternal deposition to avian eggs, such as hormones, antibodies and antioxidants, critically affect development of the offspring, with long-lasting effects on the phenotype and fitness. Little is however known about large-scale geographical patterns of variation in maternal deposition to eggs. We studied geographical variation in egg components of a passerine bird, the pied flycatcher (Ficedula hypoleuca), by collecting samples from 16 populations and measuring egg and yolk mass, albumen lysozyme activity, yolk immunoglobulins, yolk and…
Stimulation of Defense Reactions in Medicago truncatula by Antagonistic Lipopeptides from Paenibacillus sp. Strain B2
2010
ABSTRACT With the aim of obtaining new strategies to control plant diseases, we investigated the ability of antagonistic lipopolypeptides (paenimyxin) from Paenibacillus sp. strain B2 to elicit hydrogen peroxide (H 2 O 2 ) production and several defense-related genes in the model legume Medicago truncatula . For this purpose, M. truncatula cell suspensions were used and a pathosystem between M. truncatula and Fusarium acuminatum was established. In M. truncatula cell cultures, the induction of H 2 O 2 reached a maximum 20 min after elicitation with paenimyxin, whereas concentrations higher than 20 μM inhibited H 2 O 2 induction and this was correlated with a lethal effect. In plant roots in…
Expression of xyloglucan endotransglucosylase/hydrolase (XTH) genes and XET activity in ethylene treated apple and tomato fruits.
2013
[EN] Xyloglucan endotransglucosylase/hydrolase (XTHs: EC 2.4.1.207 and/or EC 3.2.1.151), a xyloglucan modifying enzyme, has been proposed to have a role during tomato and apple fruit ripening by loosening the cell wall. Since the ripening of climacteric fruits is controlled by endogenous ethylene biosynthesis, we wanted to study whether XET activity was ethylene-regulated, and if so, which specific genes encoding ripening-regulated XTH genes were indeed ethylene-regulated. XET specific activity in tomato and apple fruits was significantly increased by the ethylene treatment, as compared with the control fruits, suggesting an increase in the XTH gene expression induced by ethylene. The 25 Sl…
Ultrastructural and cell wall modifications during infection of Eucalyptus viminalis roots by a pathogenic Fusarium oxysporum strain
2004
Fusarium species are soil-borne fungal pathogens that produce a variety of disease symptoms when attacking crop plants. The mode of root colonization of Eucalyptus viminalis seedlings by a pathogenic F. oxyporum strain (Foeu1) at the ultrastructural level and changes in cell wall pectin during host pathogen interactions are described. Root systems of E. viminalis plants were inoculated with F. oxysporum in an in vitro model system. Hyphae of F. oxysporum adhered to the outer epidermal cell walls through fibrillar material, and after penetration they spread into the internal tissues. They developed intercellularly and intracellularly in the root cortex and invaded vascular tissues. Papillae …
No exception to the rule: Candidatus Portiera aleyrodidarum cell wall revisited
2014
International audience; Many insect endosymbionts described so far are gram-negative bacteria. Primary endosymbionts are obligatory bacteria usually harboured by insects inside vacuoles in specialized cells called bacteriocytes. This combination produces a typical three-membrane system with one membrane derived from the insect vacuole and the other two from the bacterial gram-negative cell envelope, composed by the cell wall (the outer membrane plus the periplasmic space) and the plasma membrane (the inner membrane). For the last 21 years, the primary endosymbiont of whiteflies 'Candidatus Portiera aleyrodidarum' was considered an exception to this rule. Previous works stated that only two …