Cognitive impact of multidomain intervention and omega 3 according to blood Aβ42/40 ratio: A subgroup analysis from the randomized MAPT trial

BACKGROUND: In MAPT (Multidomain Alzheimer Preventive Trial), a cognitive effect of multidomain intervention (MI) was showed in non-demented subjects with positive amyloid PET. However, screening eligible patients for multidomain intervention by PET is difficult to generalize in real-world settings. METHODS: MAPT study was a 3-year, randomized, placebo-controlled trial followed by a 2-year observational and optional extension. All participants were non-demented and randomly assigned (1:1:1:1) to the MI plus omega 3, MI plus placebo, omega 3 alone, or placebo alone group. The objectives were to assess the cognitive effect of MAPT interventions (omega 3 supplementation, MI, combined intervention) in non-demented subjects according to amyloid blood status at 12, 36, and 60 months. In this subgroup analysis (n = 483), amyloid status was defined by plasma Aβ42/40 ratio (cutoff ≤ 0.0107). The primary outcome measure was the change in cognitive composite score after a 1, 3, and 5-year clinical follow-up. RESULTS: The intention-to-treat (ITT) population included 483 subjects (161 positive and 322 negative amyloid participants based on plasma Aβ42/40 ratio). In the positive amyloid ITT population, we showed a positive effect of MI plus omega 3 on the change in composite cognitive score in 12 (raw p = .0350, 0.01917, 95% CI = [0.0136 to 0.3699]) and 36 months (raw p = .0357, 0.2818, 95% CI = [0.0190 to 0.5446]). After correction of multiple comparisons and adjustments, these differences were not significant (adjusted p = .1144 and .0690). In the per-protocol positive amyloid group (n = 154), we observed a significant difference between the combined intervention and placebo groups at 12 (p = .0313, 0.2424, 0.0571 to 0.4276) and 36 months (p = .0195, 0.3747, 0.1055 to 0.6439) persisting after adjustment. In the ITT and per-protocol analyses, no cognitive effect was observed in the positive and negative amyloid group at 60-month visit. CONCLUSIONS: These findings suggest a benefit of MI plus omega 3 in positive blood amyloid subjects. This promising trend needs to be confirmed before using blood biomarkers for screening in preventive trials. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01513252

A bloodâ based nutritional risk index explains cognitive enhancement and decline in the multidomain Alzheimer prevention trial

IntroductionMultinutrient approaches may produce more robust effects on brain health through interactive qualities. We hypothesized that a bloodâ based nutritional risk index (NRI) including three biomarkers of diet quality can explain cognitive trajectories in the multidomain Alzheimer prevention trial (MAPT) over 3â years.MethodsThe NRI included erythrocyte nâ 3 polyunsaturated fatty acids (nâ 3 PUFA 22:6nâ 3 and 20:5nâ 3), serum 25â hydroxyvitamin D, and plasma homocysteine. The NRI scores reflect the number of nutritional risk factors (0â 3). The primary outcome in MAPT was a cognitive composite Z score within each participant that was fit with linear mixedâ effects models.ResultsEighty percent had at lease one nutritional risk factor for cognitive decline (NRI â ¥1: 573 of 712). Participants presenting without nutritional risk factors (NRI=0) exhibited cognitive enhancement (β = 0.03 standard units [SU]/y), whereas each NRI point increase corresponded to an incremental acceleration in rates of cognitive decline (NRIâ 1: β = â 0.04 SU/y, P = .03; NRIâ 2: β = â 0.08 SU/y, P < .0001; and NRIâ 3: β = â 0.11 SU/y, P = .0008).DiscussionIdentifying and addressing these wellâ established nutritional risk factors may reduce ageâ related cognitive decline in older adults; an observation that warrants further study.Highlightsâ ¢Multiâ nutrient approaches may produce more robust effects through interactive propertiesâ ¢Nutritional risk index can objectively quantify nutritionâ related cognitive changesâ ¢Optimum nutritional status associated with cognitive enhancement over 3â yearsâ ¢Suboptimum nutritional status associated with cognitive decline over 3â yearsâ ¢Optimizing this nutritional risk index may promote cognitive health in older adultsPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152935/1/trc2jtrci201911004.pd

Plant Nutrient Resource Use Strategies Shape Active Rhizosphere Microbiota Through Root Exudation

Plant strategies for soil nutrient uptake have the potential to strongly influence plant–microbiota interactions, due to the competition between plants and microorganisms for soil nutrient acquisition and/or conservation. In the present study, we investigate whether these plant strategies could influence rhizosphere microbial activities via root exudation, and contribute to the microbiota diversification of active bacterial communities colonizing the root-adhering soil (RAS) and inhabiting the root tissues. We applied a DNA-based stable isotope probing (DNA-SIP) approach to six grass species distributed along a gradient of plant nutrient resource strategies, from conservative species, characterized by low nitrogen (N) uptake, a long lifespans and low root exudation level, to exploitative species, characterized by high rates of photosynthesis, rapid rates of N uptake and high root exudation level. We analyzed their (i) associated microbiota composition involved in root exudate assimilation and soil organic matter (SOM) degradation by 16S-rRNA-based metabarcoding. (ii) We determine the impact of root exudation level on microbial activities (denitrification and respiration) by gas chromatography. Measurement of microbial activities revealed an increase in denitrification and respiration activities for microbial communities colonizing the RAS of exploitative species. This increase of microbial activities results probably from a higher exudation rate and more diverse metabolites by exploitative plant species. Furthermore, our results demonstrate that plant nutrient resource strategies have a role in shaping active microbiota. We present evidence demonstrating that plant nutrient use strategies shape active microbiota involved in root exudate assimilation and SOM degradation via root exudation

A new era for understanding amyloid structures and disease

The aggregation of proteins into amyloid fibrils and their deposition into plaques and intracellular inclusions is the hallmark of amyloid disease. The accumulation and deposition of amyloid fibrils, collectively known as amyloidosis, is associated with many pathological conditions that can be associated with ageing, such as Alzheimer disease, Parkinson disease, type II diabetes and dialysis-related amyloidosis. However, elucidation of the atomic structure of amyloid fibrils formed from their intact protein precursors and how fibril formation relates to disease has remained elusive. Recent advances in structural biology techniques, including cryo-electron microscopy and solid-state NMR spectroscopy, have finally broken this impasse. The first near-atomic-resolution structures of amyloid fibrils formed in vitro, seeded from plaque material and analysed directly ex vivo are now available. The results reveal cross-β structures that are far more intricate than anticipated. Here, we describe these structures, highlighting their similarities and differences, and the basis for their toxicity. We discuss how amyloid structure may affect the ability of fibrils to spread to different sites in the cell and between organisms in a prion-like manner, along with their roles in disease. These molecular insights will aid in understanding the development and spread of amyloid diseases and are inspiring new strategies for therapeutic intervention

The effect of plant nutrient resource strategies on the investment into exudation, and the consequences on active rhizospheric microbiote

L'exsudation racinaire est connue pour avoir une influence sur le fonctionnement des communautés microbiennes, en particulier celles impliquées dans le cycle de l'azote (Haichar et al, 2012). Elle est liée à la physiologie de la plante, cette dernière pouvant être évaluée via les traits fonctionnels végétaux, permettant une classification des plantes en fonction de leur performance dans leur environnement. Ainsi, nous pouvons distinguer d'une part les espèces exploitatrices, avec une efficience de la photosynthèse élevée et une acquisition rapide de l'azote dans les sols, et d'autre part les plantes conservatrices, possédant des caractéristiques contraires (Aerts & Chapin, 1999) et des plantes intermédiaires dont les caractéristiques sont intermediaires.L'objectif de ces travaux de thèse est de déterminer l'influence de la stratégie de gestion des ressources de 6 poacées, réparties le long d'un gradient de stratégie de gestion des ressources, allant de stratégies conservatrices (Sesleria caerulea et Festuca paniculata), intermédiaires (Antoxanthum odoratum, Bromus erectus) à des stratégies exploitatrices (Dactylis glomerata et Trisetum flavescens), sur la diversité et le fonctionnement des communautés totales et dénitrifiantes. I) Dans un premier temps nous avons étudié le lien entre la stratégie de gestion de ressources des plantes et la quantité d'exsudats racinaires dans le sol adhérent aux racines (SAR). Nous avons ensuite déterminé l'influence de la quantité d'exsudats racinaire sur les activités microbiennes potentielles des communautés microbiennes du SAR (respiration et dénitrification potentielles), puis par une approche ADN-SIP (Stable Isotope Probing) couplée à du séquençage haut-débit, l'influence de l'exsudation racinaire sur la structure et la diversité des communautés bactérienne colonisant le SAR et le système racinaire. II) Dans un second temps, nous avons étudié le lien entre la stratégie de gestion des ressources des plantes et la nature des exsudats racinaires libérés au niveau du SAR et présents dans les extraits racinaires en analysant les profils des métabolites primaires chez Festuca paniculata, Bromus erectus et Dactylis glomerata, représentant respectivement des stratégies de gestion des ressources conservative, intermédiaire et exploitatriceRoot exudation is known to influence microbial communities functioning, in particular those involve in nitrogen cycle. (Haichar et al, 2012). It’s linked to plant physiology, which can be evaluated with functional traits, allowing a plant distribution in function of their performance in their environment. Thus, we can distinguish competitive species, with higher photosynthetic capacity and rapid rates of N acquisition, conservative species with the opposite characteristics (Aerts & Chapin, 1999) and intermediate plants, with intermediate characteristics.The objective of this work is to determinate the influence of nutrient management strategiy of 6 poaceae, along a strategies gradient from conservative strategy (Sesleria caerulea and Festuca paniculata), intermediate (Antoxanthum odoratum and Bromus erectus) to competitive strategy (Dactylis glomerata and Trisetum flavescens), on diversity and functioning of total and denitrifying communities.I) Firstly, we studied the link between the plant nutrient management strategy and the root exudates quantity in the root adhering soil (RAS). Then, we determined the influence of the rate of root exudation on potential microbial activities (respiration and denitrification), and with a DNA-SIP (Stable Isotope Probing) approach coupled to high-throughput sequencing, the influence of root exudation on the bacterial structure and diversity of communities colonizing the RAS and the root system. II) Secondly, we studied the link between the plant nutrient management strategy and the nature of molecules exuded in RAS and present in root extracts by analyzing primary metabolites profile to Festuca paniculata, Bromus erectus and Dactylis glomerata, respectively a conservative, an intermediate and a competitive plant. Then, we determined the influence of primary metabolites profile of each plant on semi-real denitrification of communities colonizing RAS of plants. III) Finally, an mRNA-SIP approach is in progress to determine the influence of exuded metabolites on active bacterial communities functioning and the expression of genes involved in denitrification process in RAS and root system. Our results show an influence of the nutrient management strategy on the rate of carbon exudation, the competitive plants exuding more than conservatives ones

Impact of fishing gears and fishing intensities on maerl beds: An experimental approach

WOS:00058828650000

Root exudation rate as functional trait involved in plant nutrient-use strategy classification

International audienc

Plant host habitat and root exudates shape fungal diversity

The rhizospheric microbiome is clearly affected by plant species and certain of their functional traits. These functional traits allow plants to adapt to their environmental conditions by acquiring or conserving nutrients, thus defining different ecological resource-use plant strategies. In the present study, we investigated whether plants with one of the two nutrient-use strategies (conservative versus exploitative) could influence fungal communities involved in soil organic matter degradation and root exudate assimilation, as well as those colonizing root tissues. We applied a DNA-based, stable-isotope probing (DNA-SIP) approach to four grass species distributed along a gradient of plant nutrient resource strategies, ranging from conservative to exploitative species, and analyzed their associated mycobiota composition using a fungal internal transcribed spacer (ITS) and Glomeromycotina 18S rRNA gene metabarcoding approach. Our results demonstrated that fungal taxa associated with exploitative and conservative plants could be separated into two general categories according to their location: generalists, which are broadly distributed among plants from each strategy and represent the core mycobiota of soil organic matter degraders, root exudate consumers in the root-adhering soil, and root colonizers; and specialists, which are locally abundant in one species and more specifically involved in soil organic matter degradation or root exudate assimilation on the root-adhering soil and the root tissues. Interestingly, for arbuscular mycorrhizal fungi analysis, all plant roots were mainly colonized by Glomus species, whereas an increased diversity of Glomeromycotina genera was observed for the exploitative plant species Dactylis glomerata

Stable isotope probing of carbon flow in the plant holobiont

Microbial communities associated with a plant host, constituting a holobiont, affect the physiology and growth of the plant via metabolites that are mainly derived from their photosynthates. The structure and function of active microbial communities that assimilate root exudates can be tracked by using stable isotope probing (SIP) approaches. This article reviews results from ongoing SIP research in plant microbe interactions, with a specific focus on investigating the fate of fresh and recalcitrant carbon in the rhizosphere with C-13 enriched-root exudates, in addition to identifying key players in carbon cycling. Finally, we discuss new SIP applications that have the potential to identify novel enzymes implicated in rhizoremediation or plant genes dedicated to root exudation by combining SIP approaches and genome wide associations studies

Influence of soil properties on the toxicity of TiO₂ nanoparticles on carbon mineralization and bacterial abundance

Information regarding the impact of low concentration of engineered nanoparticles on soil microbial communities is currently limited and the importance of soil characteristics is often neglected in ecological risk assessment. To evaluate the impact of TiO2 nanoparticles (NPs) on soil microbial communities (measured on bacterial abundance and carbon mineralization activity), 6 agricultural soils exhibiting contrasted textures and organic matter contents were exposed for 90 days to a low environmentally relevant concentration or to an accidental spiking of TiO2-NPs (1 and 500mgkg(-1) dry soil, respectively) in microcosms. In most soils, TiO2-NPs did not impact the activity and abundance of microbial communities, except in the silty-clay soil (high OM) where C-mineralization was significantly lowered, even with the low NPs concentration. Our results suggest that TiO2-NPs toxicity does not depend on soil texture but likely on pH and OM content. We characterized TiO2-NPs aggregation and zeta potential in soil solutions, in order to explain the difference of TiO2-NPs effects on soil C-mineralization. Zeta potential and aggregation of TiO2-NPs in the silty-clay (high OM) soil solution lead to a lower stability of TiO2-NP-aggregates than in the other soils. Further experiments would be necessary to evaluate the relationship between TiO2-NPs stability and toxicity in the soil