Biology subjects

Mulvey, H.

Publications and source records attributed to Mulvey, H..

4 recordsLinked to original sources

bioRxiv2026

RHO GTPase of Plants contributes to robust establishment of cellular asymmetry during development from a single cell

A fundamental question in developmental biology is how highly complex, yet reproducible multicellular body plans form from a single cell. The multicellular haploid body of the land plant Marchantia polymorpha develops from a single isolated cell - the spore - that divides asymmetrically. This produces a small terminally differentiating basal cell, and a large proliferative apical cell that gives rise to the multicellular sporeling body. The genetic basis for the establishment of asymmetry, first within the spore, and later within the sporeling body has remained virtually unknown. Here, we show that the plant specific RHO-type GTPase - RHO OF PLANTS (ROP) - polarises to the spore basal pole to ensure spore division is highly and reproducibly asymmetric. We demonstrate this highly asymmetric division is necessary to specify the terminal differentiation of the basal cell. Furthermore, we show that ROP-mediated polarised outgrowth is required to establish asymmetry within the sporeling body derived from the apical cell. Our discovery highlights how ROP function confers developmental robustness and contributes to the establishment of asymmetry during plant development from a single isolated cell.

plant biology↗

bioRxiv2023

ROP GTPase regulates polarised cell growth and cell division orientation during tissue development and organogenesis in Marchantia polymorpha

Cell polarity - broadly defined as the asymmetric distribution of cellular activities and or subcellular components within a cell - determines the geometry of cell growth and division during development. RHO GTPase proteins regulate the establishment of cell polarity and are conserved among eukaryotes. RHO Of Plant (ROP) proteins are a subgroup of RHO GTPases that are required for cellular morphogenesis in plants. However, how ROP proteins modulate the geometry of cell growth and division during the morphogenesis of plant tissues and organs is not well understood. To investigate how ROP proteins function during tissue development and organogenesis, we characterised the function of the single copy ROP gene of the liverwort Marchantia polymorpha. M. polymorpha develops morphologically complex three-dimensional tissues and organs exemplified by air chambers and gemmae, respectively. Mprop loss of function mutants form defective air chambers and gemmae, indicating ROP function is required for tissue development and organogenesis. During air chamber and gemma development in wild-type, the MpROP protein is enriched to sites of polarised growth at the cell surface and accumulates at the expanding cell plate of dividing cells. Consistent with these observations, polarised cell growth is lost, and cell divisions are misoriented in Mprop mutants. We propose that ROP regulates both polarised cell growth and cell division orientation in a coordinated manner to orchestrate tissue development and organogenesis in land plants.

plant biology↗

bioRxiv2022

Systematic analysis of YFP gene traps reveals common discordance between mRNA and protein across the nervous system

While post-transcriptional control is thought to be required at the periphery of neurons and glia, its extent is unclear. Here, we investigate systematically the spatial distribution and expression of mRNA at single molecule sensitivity and their corresponding proteins of 200 YFP trap protein trap lines across the intact Drosophila nervous system. 98% of the genes studied showed discordance between the distribution of mRNA and the proteins they encode in at least one region of the nervous system. These data suggest that post-transcriptional regulation is very common, helping to explain the complexity of the nervous system. We also discovered that 68.5% of these genes have transcripts present at the periphery of neurons, with 9.5% at the glial periphery. Peripheral transcripts include many potential new regulators of neurons, glia and their interactions. Our approach is applicable to most genes and tissues and includes powerful novel data annotation and visualisation tools for post-transcriptional regulation. Brief outlineA novel high resolution and sensitive approach to systematically co-visualise the distribution of mRNAs and proteins in the intact nervous system reveals that post-transcriptional regulation of gene expression is very common. The rich data landscape is provided as a browsable resource (link), using Zegami, a cloud-based data exploration platform (link). Our solution provides a paradigm for the characterisation of post-transcriptional regulation of most genes and model systems. HighlightsO_LI196/200 (98%) Drosophila genes show discordant RNA and protein expression in at least one nervous system region C_LIO_LI137/200 (68.5%) mRNAs are present in at least one synaptic compartment C_LIO_LINovel localised mRNA and protein discovered in periphery of glial processes C_LIO_LINew paradigm for analysis of post-transcriptional regulation and data exploration C_LI

cell biology↗

bioRxiv2018

A single cis-element that controls cell-type specific expression in Arabidopsis

C4 photosynthesis evolved repeatedly from the ancestral C3 state, improving photosynthetic efficiency by ∼50%. In most C4 lineages photosynthesis is compartmented between mesophyll and bundle sheath cells but how gene expression is restricted to these cell types is poorly understood. Using the C3 model Arabidopsis thaliana we identified cis-elements and transcription factors driving expression in bundle sheath strands. Upstream of the bundle sheath preferentially expressed MYB76 gene we identified a region necessary and sufficient for expression containing two cis-elements associated with the MYC and MYB families of transcription factors. MYB76 expression is reduced in mutant alleles for each. Moreover, down-regulated genes shared by both mutants are preferentially expressed in the bundle sheath. Our findings are broadly relevant for understanding the spatial patterning of gene expression, provide specific insights into mechanisms associated with evolution of C4 photosynthesis and identify a short tuneable sequence for manipulating gene expression in the bundle sheath.Competing Interest StatementThe authors have declared no competing interest.View Full Text

plant biology↗