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Maternal effects and environmental filtering shape seed fungal communities in oak trees
No full textTrees, as foundation species, play a pivotal role in the species interaction networks that constitute forest Ecosystems. From the seed stage, they interact with microbial communities that affect their growth, health and fitness. Despite their eco-evolutionary importance, the processes shaping seed microbial communities in natural forests have received little attention.
To unravel these processes, we analyzed the microbial communities of seeds collected in populations of sessile oak (Quercus petraea) growing along elevation gradients. We focused on the fungal communities as this group includes seed pathogens. Ecological processes shaping the communities were quantified using joint species distribution models.
Fungi were present in all seed tissues, including the embryo. Fungal communities differed significantly among oak populations along the elevation gradients, and among mother trees within the same population. These maternal effects remained significant after seed fall, despite colonization by fungal species on the ground. Associations between tree pathogens and their antagonists were detected in the seeds.
Our results demonstrate that both maternal effects and environmental filtering shape seed microbial communities of sessile oak. They provide a starting point for future research aimed at identifying the seed extended phenotypic traits that influence seed dispersal and germination, and seedling survival and growth across environments
Agroforestry for ruminants in Northern Europe: recent studies to address challenges expressed by stakeholders
No full textA first insight into the effect of Lotilaner on GABA-gated channels from the european tick Ixodes ricinus
No full textTicks are strict blood-feeding arthropods (Acari), which represent a major health issue for wild or domesticated animals and humans, due to their potential to transmit disease agents. Control of ticks is increasingly difficult due to the development of drug-resistant parasites. Ligand-gated ion channels of the tick central nervous system are the primary targets of acaricides. Among those receptors, the γ-aminobutyric acid-gated chloride ion channels (GABACls) are the main synaptic inhibitory receptors. Lotilaner is a recently developed parasiticide from the isoxazoline chemical class that was shown to be a non-competitive antagonist of GABACls from the livestock tick Rhipicephalus microplus. In the present study, we characterized the GABACls from the European tick species Ixodes ricinus.
We extracted RNAs from Ixodes ricinus nymphs. Taking advantage of the phylogenetic closeness of I. ricinus and R. microplus in the Arthropoda phylum, we identified the I. ricinus GABACl subunit homologue. The cDNA encoding the Iri- GABACl was cloned and the corresponding in vitro synthesized cRNAs were micro-injected into Xenopus laevis oocytes to investigate its pharmacological properties. Functional expression and two-electrode voltage clamp studies demonstrated that the GABACl subunit formed a homomeric receptor gated by GABA. Importantly, the insecticides like lotilaner, fipronil and picrotoxin efficiently blocked the GABA currents as previously observed for the R. microplus GABACl. Surprisingly, I. ricinus GABACl was not sensitive to the pesticide dieldrin, suggesting a potential naturally existing resistance mechanism involving alternative exons.
Here we report the functional characterization of the first GABACl of I. ricinus demonstrating that it is an important molecular target for lotilaner. Transcriptomic analysis of I. ricinus are in progress to identify new acaricidal targets
Anatomical and hormonal description of rootlet primordium development along white lupin cluster root.
No full textCluster root (CR) is one of the most spectacular plant developmental adaptations to hostile environment. It can be found in a few species from a dozen botanical families, including white lupin (Lupinus albus) in the Fabaceae family. These amazing structures are produced in phosphate-deprived conditions and are made of hundreds of short roots also known as rootlets. White lupin is the only crop bearing CRs and is considered as the model species for CR studies. However, little information is available on CRs atypical development, including the molecular events that trigger their formation. To provide insights on CR formation, we performed an anatomical and cellular description of rootlet development in white lupin. Starting with a classic histological approach, we described rootlet primordium development and defined 8 developmental stages from rootlet initiation to their emergence. Due to the major role of hormones in the developmental program of root system, we next focussed on auxin-related mechanisms. We observed the establishment of an auxin maximum through rootlet development in transgenic roots expressing the DR5:GUS auxin reporter. Expression analysis of the main auxin related genes (TIR, ARF, AUX/IAA…) during a detailed time course revealed specific expression associated with the formation of the rootlet primordium. We showed that LaTIR1b [TRANSPORT INHIBITOR RESPONSE 1b] is expressed during rootlet primordium formation and that LaARF5 [AUXIN RESPONSE FACTOR 5] is expressed in the vasculature but absent in the primordium itself. Altogether, our results describe the very early cellular events leading to CR formation and reveal some of the auxin-related mechanisms
The unique features of proteins depicting the chicken amniotic fluid
No full textIn many amniotes, the amniotic fluid is depicted as a dynamic milieu that participates in the protection of the embryo (cushioning, hydration, and immunity). However, in birds, the protein profile of the amniotic fluid remains unexplored, even though its proteomic signature is predicted to differ compared with that of humans. In fact, unlike humans, chicken amniotic fluid does not collect excretory products and its protein composition strikingly changes at mid-development because of the massive inflow of egg white proteins, which are thereafter swallowed by the embryo to support its growth. Using GeLC-MS/MS and shotgun strategies, we identified 91 nonredundant proteins delineating the chicken amniotic fluid proteome at day 11 of development, before egg white transfer. These proteins were essentially associated with the metabolism of nutrients, immune response and developmental processes. Forty-eight proteins were common to both chicken and human amniotic fluids, including serum albumin, apolipoprotein A1 and alpha-fetoprotein. We further investigated the effective role of chicken amniotic fluid in innate defense and revealed that it exhibits significant antibacterial activity at day 11 of development. This antibacterial potential is drastically enhanced after egg white transfer, presumably due to lysozyme, avian beta-defensin 11, vitelline membrane outer layer protein 1, and beta-microseminoprotein-like as the most likely antibacterial candidates. Interestingly, several proteins recovered in the chicken amniotic fluid prior and after egg white transfer are uniquely found in birds (ovalbumin and related proteins X and Y, avian beta-defensin 11) or oviparous species (vitellogenins 1 and 2, riboflavin-binding protein). This study provides an integrative overview of the chicken amniotic fluid proteome and opens stimulating perspectives in deciphering the role of avian egg-specific proteins in embryonic development, including innate immunity. These proteins may constitute valuable biomarkers for poultry production to detect hazardous situations (stress, infection, etc.), that may negatively affect the development of the chicken embryo
A nutrient cocktail prevents lipid metabolism alterations induced by 20 days of daily steps reduction and fructose overfeeding: Result from a randomized study
No full textCONTEXT: Physical inactivity and sedentary behaviours are independent risks factors for numerous diseases.
OBJECTIVE: We examined the capacity of a nutrient cocktail composed of polyphenols, omega-3 fatty acids, vitamin E and selenium to prevent the expected metabolic alterations induced physical activity and sedentary behaviors. DESIGN/SETTING/PARTICIPANTS: Twenty healthy trained men (averaging∼14,000 steps/d and engaged in sports) were randomly divided into a control group (no supplementation) and a cocktail group for a 20-day free-living intervention during which they stopped exercise and decreased their daily steps to averaging∼3000. During the last 10 days metabolic changes were further triggered by fructose overfeeding. On days 0, 10 and 20 body composition (DXA), blood chemistry, glucose tolerance (OGTT) and substrate oxidation (indirect calorimetry) were measured. Glucose tolerance included 1% fructose labelled with (U-13C) fructose to assess liver de novo lipogenesis. Histological changes and related cellular markers were assessed from muscle biopsies collected on days 0 and 20. RESULTS: While the cocktail did not prevent the decrease in insulin sensitivity and its muscular correlates induced by the intervention, it fully prevented the hypertriglyceridemia, the drop in fasting HDL and total fat oxidation, and the increase in de novo lipogenesis. The cocktail further prevented the decrease in type-IIa muscle fiber cross-sectional area and was associated with lower protein ubiquitination content. The circulating anti-oxidant capacity was improved by the cocktail following the OGTT. CONCLUSION: A cocktail of nutrient compounds from dietary origin protects against the alterations in lipid metabolism induced by physical inactivity and fructose overfeeding
Dynamics of structural barriers and innate immune components during incubation of the avian egg : critical interplay between autonomous embryonic development and maternal anticipation
No full textThe integrated innate immune features of the calcareous egg and its contents are a critical underpinning of the remarkable evolutionary success of the Aves clade. Beginning at the time of laying, the initial protective structures of the egg, i.e., the biomineralized eggshell, egg-white antimicrobial peptides, and vitelline membrane, are rapidly and dramatically altered during embryonic development. The embryo-generated extra-embryonic tissues (chorioallantoic/amniotic membranes, yolk sac, and associated chambers) are all critical to counteract degradation of primary egg defenses during development. With a focus on the chick embryo (Gallus gallus domesticus), this review describes the progressive transformation of egg innate immunity by embryo-generated structures and mechanisms over the 21-day course of egg incubation, and also discusses the critical interplay between autonomous development and maternal anticipation
Mitigating the Impact of Cellulose Particles on the Performance of Biopolyester-Based Composites by Gas-Phase Esterification
No full textMaterials that are both biodegradable and bio-sourced are becoming serious candidates for substituting traditional petro-sourced plastics that accumulate in natural systems. New biocomposites have been produced by melt extrusion, using bacterial polyester (poly(3-hydroxybutyrate-co-3-hydroxyvalerate)) as a matrix and cellulose particles as fillers. In this study, gas-phase esterified cellulose particles, with palmitoyl chloride, were used to improve filler-matrix compatibility and reduce moisture sensitivity. Structural analysis demonstrated that intrinsic properties of the polymer matrix (crystallinity, and molecular weight) were not more significantly affected by the incorporation of cellulose, either virgin or grafted. Only a little decrease in matrix thermal stability was noticed, this being limited by cellulose grafting. Gas-phase esterification of cellulose improved the filler’s dispersion state and filler/matrix interfacial adhesion, as shown by SEM cross-section observations, and limiting the degradation of tensile properties (stress and strain at break). Water vapor permeability, moisture, and liquid water uptake of biocomposites were increased compared to the neat matrix. The increase in thermodynamic parameters was limited in the case of grafted cellulose, principally ascribed to their increased hydrophobicity. However, no significant effect of grafting was noticed regarding diffusion parameters
Increasing Ascorbic Acid Content and Salinity Tolerance of Cherry Tomato Plants by Suppressed Expression of the Ascorbate Oxidase Gene
No full textAscorbic acid is considered to be one of the most important antioxidants in plants and plays a vital role in the adaptation of plants to unfavorable conditions. In the present study, an ascorbate oxidase gene (Solyc04g054690) was over-expressed in cherry tomato cv. West Virginia 106 lines and compared with previously studied RNAi silenced ascorbate oxidase lines. Two lines with lower ascorbate oxidase activity (AO−15 and AO−42), two lines with elevated activity (AO+14 and AO+16), and the non-transgenic line (WVa106) were grown and irrigated with 75 mM and 150 mM NaCl in 2015 and 2016. Growth, yield, and chemical composition of the lines under salinity stress were evaluated. Lines with lower ascorbate oxidase activity resulted in higher plant growth parameters (plant height, leaf number, flower, and cluster number in 2015 and stem diameter and flower number in 2016), and improved fruit quality (firmness in 2016 and soluble solid content in 2015) and total yield per plant under salinity stress over both years. In addition, we show that ascorbic acid, lycopene, and carotene contents of fruits were higher in lines with lower ascorbate oxidase activity compared to lines with elevated activity and the non-transgenic line under conditions of moderate and high salinity in both years