Biology subjects

Vincent, R.

Publications and source records attributed to Vincent, R..

4 recordsLinked to original sources

bioRxiv2025

DAF-18/PTEN prevents oocyte wastage in spermless C. elegans hermaphrodites by blocking spermatheca neck dilation through RHO-1/RhoA disinhibition

Loss of the Phosphatase and TENsin homolog PTEN drives cancer in humans. In C. elegans hermaphrodites that lack sperm, the PTEN ortholog DAF-18 is required for oocyte quiescence and their proximal accumulation, along with the concomitant homeostatic downregulation of germline stem cell proliferation. As such, spermless daf-18(o) mutants undergo full-scale oogenesis and ovulation in a futile manner, wasting all produced oocytes. When oocyte laying is prevented in these mutants, oocytes hyperaccumulate to form differentiated benign tumors. Here, we show that daf-18 expression in the spermatheca neck myoepithelium is sufficient to induce oocyte arrest and homeostatic downregulation of germline stem cell proliferation in spermless hermaphrodites, altogether prohibiting tumorigenesis. We demonstrate that DAF-18 promotes spermatheca neck contractility through limiting PIP3 levels and AKT activity, preventing the latter from inactivating RHO-1/RhoA by direct phosphorylation at a conserved site. Loss of PTEN may therefore promote benign tumorigenesis in humans through similar cell non-autonomous effects.

genetics↗

bioRxiv2024

Designing a simple and efficient phage biocontainment system using the amber suppressor

Multidrug-resistant infections are becoming increasingly prevalent worldwide. One of the fastest emerging alternative and adjuvant therapies being proposed is phage therapy. Naturally-isolated phages are used in the vast majority of phage therapy treatments today. Engineered phages are being developed to enhance the effectiveness of phage therapy, but concerns over their potential escape remains a salient issue. To address this problem, we designed a biocontained phage system based on conditional replication using amber stop codon suppression. This system can be easily installed on any natural phage with a known genome sequence. To test the system, we mutated the start codons of three essential capsid genes in the phage {phi}X174 to the amber stop codon (TAG). These phages were able to efficiently infect host cells expressing the amber initiator tRNA, which suppresses the amber stop codon and initiates translation at TAG stop codons. The amber phage mutants were also able to successfully infect host cells and reduce their population on solid agar and liquid culture but could not produce infectious particles in the absence of the amber initiator tRNA or complementing capsid gene. We did not detect any growth-inhibiting effects on E. coli strains known to lack a receptor for {phi}X174, and we show that engineered phages have a limited propensity for reversion. The approach outlined here may be useful to control engineered phage replication in both the lab and clinic.

microbiology↗

bioRxiv2020

Artificial scaffolds that mimic the plant extracellular environment for the culture and attachment of plant cells

Plant growth and development involves an intricate program of cell division and cell expansion to generate different cell types, tissue patterns and organ shapes. Plant cells are stuck together by their cell walls and the spatial context of cells within tissues plays a critical role in cell fate specification and morphogenesis. An in vitro model system to study plant development and its regulation by various extrinsic and intrinsic factors requires the ability to mimic the physical interactions between cells and their environment. Here, we present a set of artificial scaffolds to which cultured tobacco BY-2 cells adhere without causing morphological abnormalities. These scaffolds mimic native plant cell walls in terms of their fibrous nature, charge, hydrophobicity and piezoelectricity. We found that the extent of plant cell adhesion was essentially insensitive to the stiffness, fiber dimension, and fiber orientation of the scaffolds, but was affected by the piezoelectric properties of scaffolds where adhesion increased on piezoelectric materials. We also found that the plant cell wall polysaccharide, pectin, is largely responsible for adhesion to scaffolds, analogous to pectin-mediated adhesion of plant cells in tissues. Together, this work establishes biomimetic scaffolds that realistically emulate the plant tissue environment and provide the capability to develop microfluidic devices to study how cell-cell and cell-matrix interactions affect plant developmental pathways.

cell biology↗

bioRxiv2018

Rapid identification of an Arabidopsis NLR gene conferring susceptibility to Sclerotinia sclerotiorum using time-resolved automated phenotyping

The broad host range necrotrophic fungus Sclerotinia sclerotiorum is a devastating pathogen of many oil and vegetable crops. Plant genes conferring complete resistance against S. sclerotiorum have not been reported. Instead, plant populations challenged by S. sclerotiorum exhibit a continuum of partial resistance designated as quantitative disease resistance (QDR). Because of their complex interplay and their small phenotypic effect, the functional characterization of QDR genes remains limited. How broad host range necrotrophic fungi manipulate plant programmed cell death is for instance largely unknown. Here, we designed a time-resolved automated disease phenotyping pipeline and assessed the kinetics of disease symptoms caused by seven S. sclerotiorum isolates on six A. thaliana natural accessions with unprecedented resolution. We hypothesized that large effect polymorphisms common to the most resistant A. thaliana accessions, but absent from the most susceptible ones, would point towards disease susceptibility genes. This identified highly divergent alleles of the nucleotide-binding site leucine-rich repeat gene LAZ5 in the resistant accessions Rubenzhnoe and Lip-0. Two LAZ5-deficient mutant lines in the Col-0 genetic background showed enhanced QDR to S. sclerotiorum, whereas plants mutated in the closely related CSA1 gene responded like the wild type. These findings illustrate the value of time-resolved image-based phenotyping for unravelling the genetic bases of complex traits such as QDR. Our results suggest that S. sclerotiorum manipulates plant sphingolipid pathways guarded by LAZ5 to trigger programmed cell death and cause disease.

plant biology↗