Biology subjects

Legrand, M.

Publications and source records attributed to Legrand, M..

8 recordsLinked to original sources

bioRxiv2026

Risk management strategies in social grooming among Tonkean and rhesus macaques

Group-living individuals interact constantly, maintaining cohesion, stability, and security within their social groups. However, these interactions can entail risks that individuals must manage to optimize their social navigation through complex social groups, such as those of non-human primates. Here, we investigated how macaques manage risk during social grooming by analysing its somatic modalities, including body orientation and body site being groomed. We compared two macaque species with contrasting social styles: the more despotic rhesus macaque and the more tolerant Tonkean macaque. Using dyadic analyses including species, kinship, age difference, rank difference, and male presence as predictors, we found marked species differences in grooming patterns. Tonkean macaques engaged more frequently in face-to-face grooming and less in face-to-back grooming compared to rhesus macaques. They also groomed body sites associated with high eye-contact probability, such as the head, neck, and chest, more often than rhesus macaques. Kin dyads groomed these body sites more often, particularly in rhesus macaques. These findings suggest that avoiding body sites associated with potential eye-contact may constitute a risk management strategy during grooming. Overall, our results reveal a previously overlooked dimension of primate social cognition that may shape dyadic relationships and social network structure.

animal behavior and cognition↗

bioRxiv2026

In vivo real-time elastography with unmodified commercial endoscopes using noise-correlation-inspired method and laser speckle imaging

AO_SCPLOWBSTRACTC_SCPLOWEarly tumor detection is critical for improving patient survival and recovery. Clinically, tissue palpation is routinely used to identify regions of abnormal stiffness, a hallmark of many pathological conditions. However, palpation is restricted to anatomically accessible sites and remains highly operator dependent. Here, we introduce a method for real-time quantitative stiffness mapping using an unmodified commercial endoscope, with the goal of enhancing diagnostic capabilities and restoring mechanical feedback during endoscopic procedures. Our approach combines shear wave elastography with speckle imaging and an innovative synchronization strategy that enables the measurement of shear wave propagation using an unmodified commercial endoscope. The resulting wave fields are analyzed with the noise-correlation-inspired (NCI) method[1], providing pixel-wise estimates of shear wave velocity and, consequently, quantitative maps of local tissue stiffness. The method demonstrated robust performance in both benchtop and endoscopic configurations. Validation was achieved on polymer phantoms as well as on ex vivo and in vivo biological tissues, highlighting its potential for minimally invasive biomechanical imaging and real-time tissue characterization.

biophysics↗

bioRxiv2023

Metabolic reprogramming during Candida albicans planktonic-biofilm transition is modulated by the ZCF15 and ZCF26 paralogs

Candida albicans is a commensal of the human microbiota that can form biofilms on implanted medical devices. These biofilms are tolerant to antifungals and to the host immune system. To identify novel genes modulating C. albicans biofilm formation, we performed a large-scale screen with 2454 C. albicans doxycycline-dependent overexpression strains and identified 16 genes whose overexpression significantly hampered biofilm formation. Among those, overexpression of the ZCF15 and ZCF26 paralogs that encode transcription factors and have orthologs only in biofilm-forming species of the Candida clade, caused impaired biofilm formation both in vitro and in vivo. Interestingly, overexpression of ZCF15 specifically impeded biofilm formation without any defect in hyphal growth. Transcript profiling, transcription factor binding, and phenotypic microarray analyses conducted upon overexpression of ZCF15 and ZCF26 demonstrated their direct role in reprogramming cellular metabolism by regulating glycolytic cycle and tricarboxylic acid cycle genes. Taken together, this study has identified a new set of biofilm regulators, including ZCF15 and ZCF26, that appear to control biofilm development through their specific role in metabolic remodeling.

microbiology↗

bioRxiv2021

A phylogenetically-restricted essential cell cycle progression factor in the human pathogen Candida albicans

Chromosomal instability in fungal pathogens caused by cell division errors is associated with antifungal drug resistance. To identify mechanisms underlying such instability and to uncover new potential antifungal targets, we conducted an overexpression screen monitoring chromosomal stability in the human fungal pathogen Candida albicans. Analysis of ~1000 genes uncovered six chromosomal stability (CSA) genes, five of which are related to cell division genes in other organisms. The sixth gene, CSA6, is selectively present in the CUG-Ser clade species that includes C. albicans and other human fungal pathogens. The protein encoded by CSA6 localizes to the spindle pole bodies, is required for exit from mitosis, and induces a checkpoint-dependent metaphase arrest upon overexpression. Together, Csa6 defines an essential CUG-Ser fungal clade-specific cell cycle progression factor, highlighting the existence of phylogenetically-restricted cell division genes which may serve as potential unique therapeutic targets. TeaserCsa6 is essential for mitotic progression and mitotic exit in the human fungal pathogen Candida albicans.

cell biology↗

bioRxiv2019

Efficacy of chronic ultrasound neurostimulation on behaviors and distributed brain metabolism in depressive-like mice

Major depression is one of the main factors contributing to the Global Burden of Disease. Current treatment strategies (e.g., antidepressants and neurostimulation techniques) of major depression show some limitations including inaccuracy and invasiveness. Ultrasound neurostimulation (USNS) has been recently introduced as a physical non-invasive method for brain tissue stimulation and has gained increasing interest. In this study, we sought to evaluate the efficacy of transcranial USNS in an unpredictable chronic mild stress (UCMS) mouse model. The results show that transcranial USNS of the infralimbic cortex reduced anxiety-related behaviors as well as some, but not all, depression-related parameters. [18F]-FDG microPET imaging and brain metabolomic analyses showed that USNS triggered the activation of targeted brain region in addition to brain areas at a distance from the targeted zone, alleviating anxiety and depression-related behaviors induced by the UCMS regimen. Transcranial ultrasound neurostimulation show therapeutic potential in some aspects of major depression.

neuroscience↗

bioRxiv2018

Endogenous retroviruses transcriptional modulation after severe infection, trauma and burn.

Although human endogenous retroviruses (HERVs) expression is a growing subject of interest, no study focused before on specific endogenous retroviruses loci activation in severely injured patients. Yet, HERV reactivation is observed in immunity compromised settings like some cancers and auto-immune diseases. Our objective was to assess the transcriptional modulation of HERVs in burn, trauma and septic shock patients. We analyzed HERV transcriptome with microarray data from whole blood samples of a burn cohort (n=30), a trauma cohort (n=105) and 2 septic shock cohorts (n=28, n=51), and healthy volunteers (HV, n=60). We described expression of the 337 probesets targeting HERV from U133 plus 2.0 microarray in each dataset and then we compared HERVs transcriptional modulation of patients compared to healthy volunteers. Although all 4 cohorts contained very severe patients, the majority of the 337 HERVs was not expressed (around 74% in mean). Each cohort had differentially expressed probesets in patients compared to HV (from 19 to 46). Strikingly, 5 HERVs were in common in all types of severely injured patients, with 4 being up-modulated in patients. We highlighted co-expressed profiles between HERV and nearby gene as well as autonomous HERV expression. We suggest an inflammatory-specific HERV transcriptional response, and importantly, we introduce that the HERVs close to immunity-related genes might have a role on its expression.

immunology↗

bioRxiv2018

Generating genomic platforms to study Candida albicans pathogenesis

The advent of the genomic era has made elucidating gene function at large scale a pressing challenge. ORFeome collections, whereby almost all ORFs of a given species are cloned and can be subsequently leveraged in multiple functional genomic approaches, represent valuable resources towards this endeavor. Here we provide novel, genome-scale tools for the study of Candida albicans, a commensal yeast that is also responsible for frequent superficial and disseminated infections in humans. We have generated an ORFeome collection composed of 5,102 ORFs cloned in a Gateway donor vector, representing 83% of the currently annotated coding sequences of C. albicans. Sequencing data of the cloned ORFs are available in the CandidaOrfDB database at http://candidaorfeome.eu. We also engineered 49 expression vectors with a choice of promoters, tags, and selection markers and demonstrated their applicability to the study of target ORFs transferred from the C. albicans ORFeome. In addition, the use of the ORFeome in the detection of protein-protein interaction was demonstrated. Mating-compatible strains as well as Gateway-compatible two-hybrid vectors were engineered, validated and used in a proof of concept experiment. These unique and valuable resources should greatly facilitate future functional studies in C. albicans and the elucidation of mechanisms that underlie its pathogenicity.

genomics↗

bioRxiv2017

Outbreak of invasive wound mucormycosis in a burn unit due to multiple strains of Mucor circinelloides f. circinelloides resolved by whole genome sequencing

Mucorales are ubiquitous environmental molds responsible for mucormycosis in diabetic, immunocompromised, and severely burned patients. Small outbreaks of invasive wound mucormycosis (IWM) have already been reported in burn units without extensive microbiological investigations. We faced an outbreak of IWM in our center and investigated the clinical isolates with whole genome sequencing (WGS) analysis.\n\nWe analyzed M. circinelloides isolates from patients in our burn unit (BU1) together with non-outbreak isolates from burn unit 2 (BU2, Paris area) and from France over a two-year period (2013-2015). For each isolate, WGS and a de novo genome assembly was performed from read data extracted from the aligned contig sequences of the reference genome (1006PhL).\n\nA total of 21 isolates were sequenced including 14 isolates from six BU1 patients. Phylogenetic classification showed that the clinical isolates clustered in four highly divergent clades. Clade1 contained at least one of the strains from the six epidemiologically-linked BU1 patients. The clinical isolates seemed specific to each patient. Two patients were infected with more than two strains from different clades suggesting that an environmental reservoir of clonally unrelated isolates was the source of contamination. Only two patients shared one strain in BU1, suggesting direct transmission or contamination with the same environmental source.\n\nWGS coupled with precise epidemiological data and analysis of several isolates per patients revealed in our study a complex situation with both potential cross-transmission and multiple contaminations with a heterogeneous pool of strains from a cryptic environmental reservoir.\n\nImportanceInvasive wound mucormycosis (IWM) is a severe infection due to the environmental molds belonging to the order Mucorales. Severely burned patients are particularly at risk for IWM. Here, we used Whole Genome Sequencing (WGS) analysis to resolve an outbreak of IWM due to Mucor circinelloides that occurred in our hospital (BU1). We sequenced 21 clinical isolates, including 14 from BU1 and 7 unrelated isolates, and compared them to the reference genome (1006PhL). This analysis revealed that the outbreak was mainly due to multiple strains that seemed patient-specific, suggesting that the patients were more likely infected from a pool of diverse strains from the environment rather than from direct transmission between the patients. This study revealed the complexity of a Mucorales outbreak in the settings of IWM in burn patients, which has been highlighted based on whole genome sequencing and careful sampling.

microbiology↗