Biology subjects

Mondin, M.

Publications and source records attributed to Mondin, M..

9 recordsLinked to original sources

bioRxiv2026

Adaptive-optics lattice light-sheet microscopy enables correlative single-molecule imaging of endogenous proteins in native environments

Resolving molecular organization and dynamics in native environments remains challenging, as single-molecule imaging requires high sensitivity and spatiotemporal resolution while preserving 3D cellular context. Here, we present ALPINE (Adaptive-optics Lattice light-sheet microscopy for endogenous Protein Imaging in Native Environments), a modular framework for quantitative single-molecule imaging into complex biological samples. ALPINE combines adaptive-optics lattice light-sheet microscopy, programmable PSF shaping and acquisition stabilization, an engineered cell-specific labelling toolkit for endogenous cell-surface proteins and analysis pipelines assigning molecular localizations and trajectories to 3D cellular compartments. Labelling endogenous AMPA receptors in intact brain tissue, we demonstrate aberration-corrected 3D single-molecule localization and nanoscale organization within neuronal compartments. Importantly, fast optical sectioning of lattice light-sheet illumination further enables 3D single-molecule tracking in live tissue and quantification of molecular dynamics within native cellular environment. Together, ALPINE provides a modular approach to investigate how endogenous molecules are organized and dynamically regulated in complex biological systems, with components adaptable to diverse biological questions and imaging modalities.

neuroscience↗

bioRxiv2026

Dishevelled2 Condensates control Axon Initial Segment (AIS) assembly and function through MTCL1-Dependent microtubule recruitment.

In the epithelium, Planar Cell Polarity (PCP) signaling coordinates cellular organization along the plane of the tissue, perpendicular to the apicobasal axis. In neurons, polarity is instead expressed through the structural and molecular asymmetry that separates the axon from the somatodendritic compartment. Core PCP proteins are essential for neuronal development and function, and have been linked to neurodevelopmental disorders, including autism spectrum disorders and epilepsy. However, their precise roles in the establishment of neuronal polarity remain incompletely understood. Here, we identify Dishevelled2 (Dvl2), a central PCP signaling scaffold, as a novel component of the axon initial segment (AIS), the proximal axonal domain that maintains neuronal polarity and initiates action potentials. We show that Dvl2 defines, both in vivo and in cultured hippocampal neurons, a proximal subdomain positioned upstream of the major AIS marker Ankyrin-G (Ank-G) and is closely associated with microtubule bundles. Dvl2 is already detected during early axon specification, suggesting that it participates in the initial organization of the proximal axon. Functional depletion of Dvl proteins disrupts AIS architecture, reduces the accumulation of Ankyrin-G and other core AIS components, and impairs the organization of AIS microtubule bundles. These structural defects translate into altered neuronal excitability, with a reduced AIS-dependent component of the action potential. Mechanistically, we identify MTCL1 as a microtubule-associated partner that recruits Dvl2 from biomolecular condensate assemblies onto microtubules. This recruitment requires the DIX and PDZ domains of Dvl2. Notably, selective intracellular binders targeting the Dvl2 PDZ domain perturb Dvl2 condensate organization and compromise AIS formation. Together, our data identify Dvl2 as an organizer of the proximal AIS and reveal a Dvl2-MTCL1-dependent mechanism coupling condensate scaffolding, microtubule organization, and neuronal excitability.

neuroscience↗

bioRxiv2026

KNOB K180 CONSTITUTIVE HETEROCHROMATIN OF MAIZE EXHIBIT TISSUE-SPECIFIC CHROMATIN SENSTITIVE PROFILES DISTINCT FROM OTHER TYPES OF HETEROCHROMATINS

BackgroundMaize knobs are regions of constitutive heterochromatin that are readily identified in both meiotic and somatic chromosomes. These structures have been characterized as stable throughout the cell cycle, exhibiting late replication during the S-phase, and are composed of two specific families of highly repetitive DNA sequences: K180 and TR-1. Although widely used as cytogenetic markers due to their variability in number and chromosomal position across inbred lines, hybrids, and landraces, little is known about their chromatin structure and dynamics. In this study, we analyzed chromatin accessibility of knobs using DNS-seq data across four maize tissues representing distinct developmental stages. ResultsOur results reveal that K180 knobs exhibit tissue-specific variation in chromatin accessibility, transitioning between open and closed states during development. In contrast, the TR-1 knob of chromosome 4 remained consistently inaccessible across all tissues analyzed. A knob composed of both K180, and TR-1 further supported this observation, with only the K180 region showing dynamic accessibility. To validate these findings, we also analyzed other repetitive regions such as centromeres, which showed a uniformly closed chromatin structure similar to TR-1. These results suggest a unique developmental modulation of chromatin accessibility associated with K180 repeats. While the chromatin accessibility of knobs does not reach the levels observed at Transcription Start Sites (TSS), the comparison among different classes of repetitive DNA within maize constitutive heterochromatin provides compelling evidence for sequence-specific and tissue-specific chromatin dynamics. ConclusionsOur findings uncover a previously unrecognized property of maize knobs and establish a reference for future studies on chromatin organization and epigenetic regulation of repetitive DNA in plant genomes.

genetics↗

bioRxiv2026

βII and βIII spectrin paralogues define robustness and specialization of the neuronal membrane periodic skeleton

Neuron connectivity and signal processing rely on a complex, dynamic morphology regulated by the cytoskeleton. The membrane-associated periodic skeleton (MPS), a 190-nm periodic actin-spectrin lattice, is a conserved feature of neurons. Here, we show that the dendritic MPS is built from a dual {beta}-spectrin system in which {beta}II- and {beta}III-spectrins are co-expressed and interleaved at the nanoscale in shafts and spine necks. 3D MINFLUX nanoscopy suggests that these paralogues form both homotypic ({beta}II- or {beta}III-only) and heterotypic ({beta}II/{beta}III) tetramers with an approximately 100-nm radial periodicity. Either paralogue alone is sufficient to maintain lattice architecture, whereas their combined loss disrupts MPS integrity. Using targeted mutagenesis, we show that actin binding is required to stabilize both paralogues within the MPS, whereas {beta}III-spectrin additionally depends on phosphoinositide interactions. Our findings reveal that, unlike the axonal MPS, the dendritic MPS is a composite scaffold in which structural redundancy coexists with paralogue-specific regulatory mechanisms, with potential consequences for synaptic function.

neuroscience↗

bioRxiv2026

Functional Redundancy of ZmSWEET6a/b in Mediating Sugar Transport and Redox Homeostasis for Maize Primexine Formation

Male gametophyte development in maize requires precise coordination of carbohydrate allocation, yet the molecular mechanisms linking sugar transport to early pollen wall formation remain poorly understood. Although sugar transporters, particularly SWEET family members, are known to regulate male fertility in Arabidopsis and rice, their roles in maize microsporogenesis--especially in primexine assembly and redox homeostasis--have not been functionally characterized. Here, we identify two anther-specific Clade II SWEET genes, ZmSWEET6a and ZmSWEET6b, encoding redundant plasma membrane hexose transporters. Loss of both genes leads to complete male sterility, accompanied by disrupted deposition of primexine polysaccharides (pectin and xylan), premature accumulation of reactive oxygen species (ROS), and ectopic programmed cell death (PCD) in the tapetum. We demonstrate that ZmSWEET6a/b-mediated hexose transport is essential for maintaining sugar homeostasis and redox balance during early microsporogenesis. These findings establish a direct mechanistic link between sugar transport, ROS signaling, and pollen wall development in maize, providing new insights into the integration of metabolic and developmental pathways during plant reproduction.

developmental biology↗

bioRxiv2025

GENETIC, MORPHOLOGICAL, AND PHYTOCHEMICAL DIFFERENTIATION OF CARNAVAL - A NEW HOP CULTIVAR ADAPTED TO TROPICAL ENVIRONMENT

AO_SCPLOWBSTRACTC_SCPLOWThe global hops market generates approximately US$8 billion annually, primarily driven by beer production, the worlds most consumed beverage. Despite this global demand, hop cultivation remains concentrated in temperate regions. Brazil, the third-largest beer consumer, imports over 99% of its hops. This study aimed to technically validate a new tropicalized hop cultivar, "Carnaval," developed over six years of breeding and genetic improvement to adapt the crop to Brazilian conditions. A comparative analysis was conducted between Carnaval and two commercial varieties, Comet and Cascade, evaluating morphological traits, production potential, phytochemical composition via GC-MS, and genotyping using 10,541 SNP markers obtained through dd-GBS on the Illumina(R) NextSeq 1000/2000 platform. Carnaval exhibited clear genotypic and phenotypic distinctiveness, with notable differences in cone, leaf, and branch morphology, as well as in alpha (14.0%) and beta (6.9%) acid content and essential oil concentration (0.61%), comprising over 35 components--mainly myrcene, -humulene, selinene, and caryophyllene. Productivity reached 478 kg/ha, comparable to commercial cultivars. Genetic analyses revealed high diversity (HS = 0.35), and population structure showed Carnaval grouping with its female parent Zeus but with distinct genomic characteristics. These findings confirm Carnavals unique identity and its adaptation to tropical conditions, making it a promising alternative for domestic hop production in Brazil.

plant biology↗

bioRxiv2024

A minor impact of VGLUT1 expression level on quantal size revealed through the characterization of VGLUT1mEos2 knock-down new mouse model

Synaptic vesicles (SVs) are small organelles secreting neurotransmitters at synapses. By fusing a photoactivated fluorescent protein to VGLUT1, we generated a VGLUT1mEos2 knock-in mouse. VGLUT1mEos2 knock-in mice are viable and healthy, but exhibit a severe reduction in VGLUT1 expression levels. Using VGLUT1mEos2 expressing neurons, we established paradigms to trace individual SV mobility at the single-molecule level or via massive photoconversion. Hippocampal neurons with significantly diminished VGLUT1 expression maintain unaltered miniature glutamate release characteristics in terms of quantal size and frequency. We demonstrate that VGLUT1 expression level are not correlated in a linear fashion with the vesicular glutamate content. In conclusion, the VGLUT1mEos2 mouse line serves as a powerful tool for exploring SV mobility properties and elucidating the contributions of VGLUT1 to excitatory neurotransmission and cognitive processes.

neuroscience↗

bioRxiv2021

A heterochromatic knob reducing the flowering time in maize

Maize flowering time is an important agronomic trait, which has been associated with variations in the genome size and heterochromatic knobs content. We integrated three steps to show this association. Firstly, we selected inbred lines varying for heterochromatic knob composition at specific sites in the homozygous state. Then, we produced homozygous and heterozygous hybrids for knobs. Second, we measured the genome size and flowering time for all materials. Knob composition did not affect the genome size and flowering time. Finally, we developed an association study and identified a knob marker on chromosome 9 showing the strongest association with flowering time. Indeed, modelling allele substitution and dominance effects could offer only one heterochromatic knob locus that could affect flowering time, making it earlier rather than the knob composition.

genetics↗

bioRxiv2021

Bacillus sp. RZ2MS9, a tropical PGPR, colonizes maize endophytically and alters the plant's production of volatile organic compounds both independently and when co-inoculated with Azospirillum brasilense Ab-V5

Bacillus spp. are among the most efficient known plant growth-promoting rhizobacteria (PGPR). The PGPR Bacillus sp. strain RZ2MS9 is a multi-trait maize growth promoter previously isolated from guarana plants cultivated in the Amazon rainforest. However, there are several aspects of its interaction with the host that need further investigation. To achieve effective performance of microbial inoculants in crop production, it is necessary to monitor the plants colonization by a PGPR and to assess the potential synergy among beneficial strains. Here, we obtained a stable mutant of RZ2MS9 labelled with green fluorescent protein (RZ2MS9-GFP). We verified that the insertion of the plasmid did not affect either bacterial growth nor its ability to promote maize growth in vitro. Using fluorescent microscopy and qPCR, we demonstrated that RZ2MS9-GFP successfully colonizes maizes roots and leaves endophytically. Subsequently, we evaluated whether RZ2MS9 has a synergistic effect on plant growth promotion when co-inoculated with Azospirillum brasilense Ab-V5, a commercial inoculant for maize. The two strains combined enhanced maizes roots and shoots dry weight by 50.8% and 79.6%, respectively, when compared to the non-inoculated control. In addition, we used co-inoculation experiments in glass chambers to analyze the plants Volatile Organic Compounds (VOCs) production during the maize-RZ2MS9 and maize-RZ2MS9-Ab-V5 interaction. We found that the single and co-inoculation altered maizes VOCs emission profile, with an increase in the production of indoles in the co-inoculation. Collectively, these results increase our knowledge about the interaction between the tropical PGPR Bacillus sp. RZ2MS9 and maize, and provide a new possibility of combined application with the commercial inoculant A. brasilense Ab-V5. ImportanceBacillus sp. RZ2MS9 is a PGPR, previously isolated from guarana plants cultivated in the Brazilian Amazon, which successfully promotes the growth of maize and soybean plants. To improve our knowledge about the interaction between this very promising PGPR and maize, we labelled RZ2MS9 with gfp and monitored its maize colonization. The transformation did not affect either RZ2MS9 growth nor its ability to promote maize growth in vitro. We demonstrated that RZ2MS9 colonizes endophytically maizes roots and leaves. We also verified that the co-inoculation of RZ2MS9 and Azospirillum brasilense Ab-V5, a known commercial maize inoculant enhanced maizes roots and shoots growth. Moreover, the co-inoculation altered the maizes volatile organic compounds, increasing the production of indoles, that is related with decreased upon the reduction of fertilization. Certainly, our research contributed with better Bacillus sp. RZ2MS9 - maize interaction understanding and also provided new information concerning RZ2MS9 activity when applied with A. brasilense Ab-V5.

molecular biology↗