Biology subjects

Skinner, D. J.

Publications and source records attributed to Skinner, D. J..

4 recordsLinked to original sources

bioRxiv2025

Diploid gametes in maize by mutation of A-Type cyclins: a step towards apomeiosis and synthetic apomixis.

Hybrid crops are agriculturally desirable due to heterosis but are costly or difficult to produce. Synthetic apomixis, clonal reproduction through seed, offers the ability to fix hybrid vigor. Two components are needed to achieve this goal: the formation of diploid gametes identical to the maternal parent through apomeiosis, and the induction of embryogenesis in the egg cell without fertilization, known as parthenogenesis. In maize, parthenogenesis was achieved by egg cell expression of the transcription factor ZmBABY BOOM 1 but a viable apomeiosis strategy has not been reported. In the MiMe (Mitosis instead of Meiosis) system, in addition to mutants that skip recombination and sister chromatid adhesion, mutation of genes involved in cell cycle control during meiosis is needed to skip the second division and ensure diploid gametes. In this report we describe the effect of mutation of maize A-type cyclin genes with similarity to Arabidopsis TARDY ASYNCHRONOUS MEIOSIS (TAM). In double mutant plants, we find that diploid gametes are formed with high efficiency and that the progeny are tetraploid. These genes provide a viable route towards creating synthetic apomixis in maize.

plant biology↗

bioRxiv2022

The Arabidopsis INNER NO OUTER (INO) gene acts exclusively and quantitatively in regulation of ovule outer integument development

The INNER NO OUTER (INO) gene is essential for formation of the outer integument of ovules in Arabidopsis thaliana. Initially described lesions in INO were missense mutations resulting in aberrant mRNA splicing. To determine the null mutant phenotype we used CRISPR to induce frame-shift mutations and found, in confirmation of results on another recently identified frame-shift mutation (Vijayan et al., 2021), that such mutants have a phenotype identical to the most severe splicing mutant (ino-1), with effects specific to outer integument development. We show that the altered protein of an ino mRNA splicing mutant with a less severe phenotype (ino-4) does not have INO activity, and the mutant is partial because it produces a small amount of correctly spliced INO mRNA. Screening for suppressors of ino-4 in a fast-neutron mutagenized population identified a genetic duplication of the ino-4 gene leading to an increase in the amount of this mRNA. The increased expression led to a decrease in the severity of the mutant effects, indicating that the amount of INO activity quantitatively regulates outer integument growth. The results further confirm that the role of INO in Arabidopsis development is specific to the outer integument of ovules where it quantitatively affects the growth of this structure.

plant biology↗

bioRxiv2021

Multispecies phase diagram reveals biophysical principles of bacterial biofilm architectures

Bacterial biofilms are among the most abundant multicellular structures on Earth and play essential roles in a wide range of ecological, medical, and industrial processes. However, general principles that govern the emergence of biofilm architecture across different species remain unknown. Here, we combine experiments, simulations and statistical analysis to identify shared biophysical mechanisms that determine biofilm architecture development at the single-cell level, for the species Vibrio cholerae, Escherichia coli, Salmonella enterica, and Pseudomonas aeruginosa. Our data-driven analysis reveals that despite the many molecular differences between these species, the biofilm architecture differences can be described by only two control parameters: cellular aspect ratio and cell density. Further experiments using single-species mutants for which the cell aspect ratio and the cell density are systematically varied, and mechanistic simulations, show that tuning these two control parameters reproduces biofilm architectures of different species. Altogether, our results show that early-stage biofilm architecture is determined by mechanical cell-cell interactions which are conserved across different species and, therefore, provide a unifying understanding of biofilm architecture development.

microbiology↗

bioRxiv2019

Flow-induced symmetry breaking in growing bacterial biofilms

Bacterial biofilms represent a major form of microbial life on Earth and serve as a model active nematic system, in which activity results from growth of the rod-shaped bacterial cells. In their natural environments, ranging from human organs to industrial pipelines, biofilms have evolved to grow robustly under significant fluid shear. Despite intense practical and theoretical interest, it is unclear how strong fluid flow alters the local and global architectures of biofilms. Here, we combine highly time-resolved single-cell live imaging with 3D multi-scale modeling to investigate the mechanisms by which flow affects the dynamics of all individual cells in growing biofilms. Our experiments and cell-based simulations reveal three quantitatively different growth phases in strong external flow, and the transitions between them. In the initial stages of biofilm development, flow induces a downstream gradient in cell orientation, causing asymmetrical droplet-like biofilm shapes. In the later developmental stages, when the majority of cells are sheltered from the flow by the surrounding extracellular matrix, buckling-induced cell verticalization in the biofilm core restores radially symmetric biofilm growth, in agreement with predictions of a 3D continuum model.

biophysics↗