Biology subjects

Louis, F.

Publications and source records attributed to Louis, F..

7 recordsLinked to original sources

bioRxiv2026

From Light to Acetate: How Trophic Conditions Shape Growth and Cell Cycle Progression in Chlamydomonas reinhardtii

The unicellular green alga Chlamydomonas reinhardtii provides a tractable model for investigating how carbon availability influences metabolic organization and cell-cycle control in photosynthetic eukaryotes. Its capacity for autotrophic (light, CO), mixotrophic (light, CO, acetate), and heterotrophic (acetate, dark) growth enables systematic analysis of trophic-state-dependent regulation. We performed comparative transcriptomic analyses of strain 21gr grown under these three regimes at 30 {degrees}C. Mixotrophy resulted in the highest biomass accumulation and was associated with earlier cell-cycle commitment compared with autotrophy, whereas heterotrophy displayed delayed commitment and reduced growth. Transcriptomic profiling revealed coordinated upregulation of central carbon metabolic pathways under mixotrophy, including photorespiration, glycolysis, the oxidative pentose phosphate pathway, and tricarboxylic acid cycle functions, consistent with enhanced carbon flux and biosynthetic capacity. In contrast, heterotrophy preferentially induced acetate assimilation and glyoxylate cycle genes and was accompanied by elevated expression of cell-cycle regulators, including the CDK-inhibitory kinase WEE1. Together, these findings indicate that trophic mode modulates the coupling between carbon metabolism and cell-cycle progression, with mixotrophy supporting integrated metabolic and proliferative activity, whereas heterotrophy is associated with delayed cell-cycle timing and transcriptional signatures of metabolic adjustment.

plant biology↗

bioRxiv2025

Meat the Fat: From High Lipid Content to Nutritional Enhancement to Reconstruct Wagyu Fat with Tunable Rheology and Organoleptic Fidelity for Cultivated Meat

Cultivated meat holds promise as a sustainable and ethical alternative to conventional meat, but reproducing the rich flavor, texture, and lipid composition of premium beef, such as Wagyu, remains a major hurdle. In this study, we redefine bovine adipogenesis by systematically optimizing edible biomaterials, fatty acid delivery systems, and culture conditions to engineer high-fat cultivated tissues with authentic sensory properties. Among various candidates, 1% alginate emerged as the optimal scaffold, providing mechanical softness compatible with adipogenic differentiation and mimicking the rheological properties of native fat. Supplementation with oleic acid complexed to edible albumins, especially whey protein (WP), significantly enhanced lipid accumulation and monounsaturated fatty acid content, particularly oleic acid, which reached up to 80.6% of total fatty acids. Engineered fat tissues displayed soft, spreadable textures and organoleptic characteristics consistent with high-quality beef fat. Fatty acid profiling revealed a bovine-like omega-6 signature, dominated by linoleic, arachidonic, and dihomo-{gamma}-linolenic acids, alongside detectable omega-3 subtypes including alpha-linolenic acid and trace levels of EPA and DHA. This composition not only validates the physiological relevance of the engineered fat, but also highlights its potential to deliver bioactive lipids rarely found in terrestrial animal products. Additionally, the WP-oleic acid system supported robust adipogenesis even under lower serum conditions. These findings establish a food-grade, tunable platform for producing physiologically and nutritionally enhanced fat tissues, advancing the realism, functionality, and health potential of next-generation cultivated meat.

bioengineering↗

bioRxiv2025

Cultivated Beef Meat Has the Potential to Maintain Original Characteristics of Beef Meat with Customizable Features

Cultivated meat (CM) is currently attracting much attention because of its promise to become a solution to issues of environmental sustainability, animal welfare, and decarbonization. While the fabrication process and materials are still the main focus, it is not yet clear what the characteristics of the constructed CMs are and how they take on the original characteristics of beef meat. In this study, the biological, physicochemical and sensory characteristics of three types of beef (Wagyu, Crossbreed and Holstein) meat were systematically analyzed and compared to muscle and fat fibers constructed by three-dimensional printing using satellite and adipose-derived stem cells isolated from these beef meats. The different characteristics of each beef meat were largely taken on by the CM fibers composed of bSC and bADSC of each meat. In addition, some differing properties from those of the respective beef meat were observed in CM fibers such as one of the omega-3 fatty acids, docosahexaenoic acid (DHA; Wagyu fat fibers showed the highest amount). Furthermore, we also found the important possibility to increase the composition of oleic acid to over 80% in monounsaturated fatty acid (Wagyu has around 50% oleic acid). This study revealed the importance of using cells isolated from each beef meat to provide CM that closely resemble the original texture and taste of each meat, and further the possibility of more carefully arranging their properties.

bioengineering↗

bioRxiv2024

The evolutionary history and functional specialization of microRNA genes in Arabidopsis halleri and A. lyrata

MicroRNAs (miRNAs) are a class of small non-coding RNAs that play important regulatory roles in plant genomes. While some miRNA genes are deeply conserved, the majority appear to be species-specific, raising the question of how they emerge and integrate into cellular regulatory networks. To better understand this, we first performed a detailed annotation of miRNA genes in the closely related plants Arabidopsis halleri and A. lyrata and evaluated their phylogenetic conservation across 87 plant species. We then characterized the process by which newly emerged miRNA genes progressively acquire the properties of "canonical" miRNA genes, in terms of size and stability of the hairpin precursor, loading of their cleavage products into Argonaute proteins, and potential to regulate downstream target genes. Nucleotide polymorphism was lower in the mature miRNA sequence than in the other parts of the hairpin (stem, terminal loop), and the regions of coding sequences targeted by miRNAs also had reduced diversity as compared to their neighboring regions along the genes. These patterns were less pronounced for recently emerged than for evolutionarily conserved miRNA genes, suggesting a weaker selective constraint on the most recent miRNA genes. Our results illustrate the rapid birth-and-death of miRNA genes in plant genomes, and provide a detailed picture of the evolutionary processes by which a small fraction of them eventually integrate into "core" biological processes.

evolutionary biology↗

bioRxiv2023

Astrocytes control cocaine-induced synaptic plasticity and reward through the matricellular protein hevin

Drug addiction involves profound modifications of neuronal plasticity in the nucleus accumbens, which may engage various cell types. Here, we report prominent effects of cocaine on calcium signals in astrocytes characterized by in vivo fiber photometry. Astrocyte calcium signals in the nucleus accumbens are sufficient and necessary for the acquisition of cocaine seeking behavior. We identify the astrocyte-secreted matricellular protein hevin as an effector of the action of cocaine and calcium signals on reward and neuronal plasticity.

neuroscience↗

bioRxiv2023

Organic cation transporter 2 contributes to SSRI antidepressant efficacy by controlling tryptophan availability in the brain

Selective serotonin reuptake inhibitors (SSRI) are common first-line treatments for major depression. However, a significant number of depressed patients do not respond adequately to these pharmacological treatments. In the present preclinical study, we demonstrate that organic cation transporter 2 (OCT2), an atypical monoamine transporter, contributes to the effects of SSRI by regulating the routing of the essential amino acid tryptophan to the brain. Contrarily to wild-type mice, OCT2-invalidated mice failed to respond to prolonged fluoxetine treatment in a chronic depression model induced by corticosterone exposure recapitulating core symptoms of depression, i.e., anhedonia, social withdrawal, anxiety, and memory impairment. After corticosterone and fluoxetine treatment, the levels of tryptophan and its metabolites serotonin and kynurenine were decreased in the brain of OCT2 mutant mice compared to wild-type mice and reciprocally tryptophan and kynurenine levels were increased in mutants plasma. OCT2 was detected by immunofluorescence in several structures at the blood-cerebrospinal fluid (CSF) or brain-CSF interface. Tryptophan supplementation during fluoxetine treatment increased brain concentrations of tryptophan in wild-type and OCT2 mutant mice, yet more efficiently in WT than in mutants, while discretely increasing 5-HT concentrations. Importantly, tryptophan supplementation improved the sensitivity to fluoxetine treatment of OCT2 mutant mice, impacting chiefly anhedonia and short-term memory. Western blot analysis showed that glycogen synthase kinase-3{beta} (GSK3{beta}) and mammalian/mechanistic target of rapamycin (mTOR) intracellular signaling was impaired in OCT2 mutant mice brain after corticosterone and fluoxetine treatment and, conversely, tryptophan supplementation recruited selectively the mTOR protein complex 2. This study provides the first evidence of the physiological relevance of OCT2-mediated tryptophan transport, and its biological consequences on serotonin homeostasis in the brain and SSRI efficacy.

neuroscience↗

bioRxiv2020

Injectable prevascularized mature adipose tissues (iPAT) to achieve long-term survival in soft tissues regeneration

Soft tissue regeneration remains a challenge in reconstructive surgery. Current autologous fat implantations lead to high fat absorption ratios, while artificial implants can be associated with lymphoma occurrence. To overcome these limitations, our aim was to reproduce adipose tissue vasculature structure before implantation. Here, we developed injectable prevascularized adipose tissues (iPAT), using physiological collagen microfibers (CMF) mixed with human mature adipocytes, adipose-derived stem cells (ADSC) and human umbilical vein endothelial cells (HUVEC). Following murine subcutaneous implantation, higher cell survival (84{+/-}6% viability) and volume maintenance were shown after 3 months for the iPAT (up to twice heavier than the non-prevascularized balls). This higher survival can be explained by the greater amount of blood vessels (up to 1.6 folds increase), with balanced host anastomosis (51{+/-}1% of human/mouse lumens), also involving infiltration by the lymphatic and neural vasculature networks. These iPAT tissues allowed non-invasive soft tissue reconstruction for long-term outcomes, and the ability to cryopreserve them with maintained viability and functionality also enables a later reinjection usually required before reaching the final patient desired graft volume.

bioengineering↗