Biology subjects

Nicolas, S.

Publications and source records attributed to Nicolas, S..

6 recordsLinked to original sources

bioRxiv2026

A major chromosome 4 region modulates early vigor under chilling through brassinosteroid signaling associated genes in maize

AbstractEarly sowing is a key strategy to improve maize productivity and resilience under climate change, but it exposes plants to prolonged chilling stress that can severely compromise seedling establishment. While previous genetic studies have focused on germination or very early stages, tolerance to long-term chilling during the autotrophic transition remains poorly characterized. Here, we combined genome-wide association studies (GWAS) and transcriptome analysis on QTL near-isogenic lines (NILs) to dissect the genetic architecture of early vigor under chilling in maize. We identified a major genomic region on chromosome 4 (LD_COL4), harboring two QTLs within a 2.7 Mb interval, that were consistently associated with early vigor under long-term chilling conditions. Transcriptomic analysis of contrasted NILs revealed a cluster of differentially expressed genes co-localizing with LD_COL4, pointing to two strong candidate genes, Zm00001d048582, an ortholog of the Arabidopsis OPS gene that regulates the brassinosteroid (BR) signaling pathway upstream of the key transcription factors BES1 and BZR1, and Zm00001d048612, a brassinosteroid-signaling kinase (BSK). Multiple orthologs of BES1/BZR1 modulators were differentially expressed between genotypes under chilling, supporting the involvment of brassinosteroid signaling in this response. These findings highlight both genes as promising targets for marker-assisted breeding and gene editing to improve maize adaptation to early sowing.

plant biology↗

bioRxiv2024

A cafeteria diet blunts effects of exercise on adult hippocampal neurogenesis but not neurogenesis-dependent behaviours in adult male rats

Animal studies have shown that a cafeteria (CAF) diet (high in saturated fat and sugar), is associated with memory impairments and increased anxiety, while exercise can enhance antidepressant-like effects and cognitive function. The mechanisms underlying the effects of a CAF diet, exercise, or their convergence on memory, mood and anxiety are not fully understood, but alterations in adult hippocampal neurogenesis (AHN), gut microbial metabolites, or plasma metabolic hormones may play a role. Therefore, this study investigated whether a 7.5-week voluntary running exercise intervention in young adult male rats could alter the effects of a concurrent CAF diet on depression-like, anxiety-like and cognitive behaviours and AHN, and determined associated changes in metabolic hormones and gut microbial metabolites. We found that exercise produced a mild anxiolytic effect, regardless of diet, and increased PYY, a hormone previously shown to reduce anxiety-like behaviour. CAF diet induced differential abundance of caecal metabolites, and exercise attenuated CAF diet-induced decreases in certain metabolites implicated in cognitive function or depression-like behaviour. Although exercise exerted antidepressant-like effects in the FST, induced subtle improvements in spatial learning strategy, and increased plasma metabolic hormones previously implicated in depression-like behaviour in CAF diet-fed animals, CAF diet blunted exercise-induced increases in plasma GLP-1 and AHN, suggesting that exercise should be accompanied by a healthy diet to increase AHN. Together, these findings highlight the importance of exercise and healthy diet for hippocampal health and provide insight into potential metabolite and hormone-mediated mechanisms underlying the effects of CAF diet and exercise on brain and behaviour. Key points- Diets high in saturated fat and sugar are associated with memory impairments and increased anxiety while exercise can exert antidepressant-like effects and enhance cognitive function, but the biological underpinnings of these effects and whether exercise can negate effects of such diets remain to be elucidated. - We found that running exercise modestly reduced anxiety in rats fed either a healthy or a cafeteria-style diet and increased a hormone (peptide YY) previously shown to decrease anxiety. - Running exercise exerted antidepressant-like effects in cafeteria diet-fed rats and attenuated cafeteria diet-induced decreases in gut metabolites previously implicated in cognition or depression-like behaviour. - Cafeteria diet blunted exercise-induced production of new neurons in the hippocampus, a brain region important in mood and memory. - These data highlight the importance of combining exercise with a healthy diet for hippocampal health, while identifying potential targets for intervention or dietary supplementation to prevent a cafeteria diet blunting beneficial effects of exercise

neuroscience↗

bioRxiv2024

High-dimensional multi-omics measured in controlled conditions are useful for maize platform and field trait predictions

The effects of climate change in the form of drought, heat stress, and irregular seasonal changes threaten global crop production. The ability of multi-omics data, such as transcripts and proteins, to reflect a plants response to such climatic factors can be capitalized in prediction models to maximize crop improvement. Implementing multi-omics characterization in routine field evaluations is challenging due to high costs. It is, however, possible to do it on reference genotypes in controlled conditions. Using omics measured on a platform, we tested different multi-omics-based prediction approaches, with and without pedo-climatic data, using a high dimensional linear mixed model (MegaLMM) to predict genotypes for platform traits and agronomic field traits in a hybrid panel of 244 maize Dent lines crossed to a Flint tester. We considered two prediction scenarios: in the first one, new hybrids are predicted (CV1), and in the second one, partially observed hybrids are predicted (CV2). For both scenarios, all hybrids were characterized for omics on the platform. We observed that omics can predict both additive and non-additive genetic effects for the platform traits, resulting in much higher predictive abilities than GBLUP. This highlights their efficiency in capturing regulation processes in relation to the growth conditions. For the field traits, we observed that only the additive components of omics were useful and only slightly improved predictive abilities for predicting new hybrids (CV1, model MegaGAO) and for predicting partially observed hybrids (CV2, model GAOxW-BLUP) in comparison to GBLUP. We conclude that measuring the omics in the fields would be of considerable interest for predicting productivity, if the omics costs were to drop significantly. Our study confirms the potential of omics to predict additive and non-additive genetic effects, resulting in a potentially high increase in predictive abilities compared to standard genomic prediction models. Key MessageTranscriptomics and proteomics information collected on a platform can predict additive and non-additive effects for platform traits and additive effects for field traits.

genetics↗

bioRxiv2023

Large genetic variability of maize leaf palatability to european corn borer : metabolic insights

Maize is the most-produced cereal in the world, but its production faces constraints such as parasitic attacks from stemborers. We evaluated the resistance of a core-collection of 18 maize lines by measuring their palatability to European Corn Borer (ECB) larvae fed on maize leaf discs. Using an original consumption test device that takes into account the variability of larvae behaviour, we were able to phenotype the resistance of the 18 maize lines. We matched consumption data to existing enzymatic and metabolomic data that characterized the maize core-collection and identified some metabolites such as caffeoyl-lquinate, trocopherol, digalactosylglycerol and tyrosine that are positively or negatively correlated with the palatability to ECB larvae. Altogether, our results confirm the metabolic complexity involved in the establishment of plant defenses. Metabolic changes associated to leaf palatability mostly concern membrane and cell wall composition. Some of them, pointing-out to the phenylpropanoids pathway, were observed independently of plant developmental pace and plant earliness.

genetics↗

bioRxiv2022

Faecal microbiota transplantation from Alzheimer's participants induces impairments in neurogenesis and cognitive behaviours in rats

The gut microbiome is emerging as an important susceptibility factor in Alzheimers disease (AD) possibly due to the increased prevalence of pro-inflammatory genera in gut microbiota of AD participants. Microbiota-mediated changes in cognition and adult hippocampal neurogenesis (AHN), an important process for memory which is altered in AD, position the microbiota-gut-brain axis as a key regulator of AD. However, it is unknown whether gut microbiota alterations are the cause or consequence of AD symptoms. We transplanted faecal microbiota from AD participants and age-matched controls into microbiota-depleted naive adult rats and found impairments in AHN and associated memory tasks, which correlated with clinical cognitive scores. Discrete changes in the rat caecal and hippocampal metabolome were evident. Serum from AD participants also decreased neurogenesis in vitro and correlated with cognitive scores and pro-inflammatory genera. Our results reveal that the cognitive symptoms in AD may be due to alterations in gut microbiota, and that impaired neurogenesis may be a mechanistic link between altered gut microbiota and cognitive impairment in AD. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=191 SRC="FIGDIR/small/515189v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@143263forg.highwire.dtl.DTLVardef@1842a23org.highwire.dtl.DTLVardef@1ea8aaborg.highwire.dtl.DTLVardef@135e5a3_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2020

Computer modeling of whole-cell voltage-clamp analyses to delineate guidelines for good practice of manual and automated patch-clamp

The patch-clamp technique has contributed to major advances in the characterization of ion channels. The recent development of high throughput patch-clamp provides a new momentum to the field. However, whole-cell voltage-clamp technique presents certain limits that need to be considered for robust data generation. One major caveat is that current amplitude profoundly impacts the precision of the analyzed characteristics of the ion current under study. For voltagegated channels, the higher the current amplitude is, the less precise the characteristics of voltagedependence are. Similarly, in ion channel pharmacology, the characteristics of dose-response curves are hindered by high current amplitudes. In addition, the recent development of high throughput patch-clamp technique is often associated with the generation of stable cell lines demonstrating high current amplitudes. It is therefore critical to set the limits for current amplitude recordings to avoid inaccuracy in the characterization of channel properties or drug actions, such limits being different from one channel to another. In the present study, we use kinetic models of a voltage-gated sodium channel and a voltage-gated potassium channel to edict simple guidelines for good practice of whole-cell voltage-clamp recordings.

biophysics↗