Biology subjects

Lloyd, J.

Publications and source records attributed to Lloyd, J..

5 recordsLinked to original sources

bioRxiv2026

Characterization of a cofilin mutant with high actin bundling activity in living cells

Cofilin is a key regulator of actin dynamics that, along with a myriad of other actin-binding proteins, controls the balance of F- and G-actin in numerous cell types. While prior structural studies of the cofilin-actin binding interface have delineated many critical interactions between cofilin and actin, the roles of some residues within the cofilin-actin binding interface remain poorly defined. In this study, we investigate the role of cofilin S119 in the cofilin-actin interaction. Despite its unique position within the cofilin-actin interface and its putative role as a phosphorylation site, relatively little direct evidence exists to define whether it plays an important role in cofilin-actin dynamics. Using site-directed mutagenesis, we demonstrate that mutation of S119 to aromatic amino acids (W, F, Y) results in cofilins with strong actin bundling activity in living cells. This activity can be countered by the incorporation of mutants that disfavor actin rod forming activity (R21Q). Mutation of S119 to phospho-mimic (E) and non-phosphorylated (A) residues either strongly inhibits (E) or modestly increases (A) actin bundling activity. Expression of the S119W mutant in neurons reveals its impacts on spine length and size, while FRAP studies show that its mobile fraction is intermediate between that of LifeAct and WT cofilin. Finally, it is shown that the strong actin bundling phenotype associated with S119W inhibits the progression of optogenetically induced apoptosis.

cell biology↗

bioRxiv2025

Isolation of a novel plant growth-promoting Dyella sp. from a Danish natural soil

Environmental soils are natural reservoirs of unexplored microbes, including potentially beneficial microbes to improve plant performance. Here, we isolated 75 bacterial strains from surface-sterilized roots of Arabidopsis thaliana (Arabidopsis) grown in a natural soil derived from an alder swamp. Culture-dependent isolation of individual strains from the roots followed by monoassociation-based screening identified seven bacteria that promoted Arabidopsis seedling weight. Of those, we identified a new species from the Dyella genus which increased biomass of tomato and Arabidopsis seedlings in agar as well as the shoot biomass of Arabidopsis grown in both the alder swamp soil and potting soil. Dyella sp. A4 specifically promoted the elongation of lateral roots without affecting lateral root number and primary root elongation. The new Dyella sp. A4 expands the toolbox of biostimulants for plant growth promotion via modulating root architecture.

plant biology↗

bioRxiv2023

Murine uterine gland branching is necessary for gland function in implantation

Uterine glands are branched, tubular structures whose secretions are essential for pregnancy success. It is known that pre-implantation glandular expression of leukemia inhibitory factor (LIF) is crucial for embryo implantation, however contribution of uterine gland structure to gland secretions such as LIF is not known. Here we use mice deficient in estrogen receptor 1 (ESR1) signaling to uncover the role of ESR1 signaling in gland branching and the role of a branched structure in LIF secretion and embryo implantation. We observed that deletion of ESR1 in neonatal uterine epithelium, stroma and muscle using the progesterone receptor PgrCre causes a block in uterine gland development at the gland bud stage. Embryonic epithelial deletion of ESR1 using a mullerian duct Cre line - Pax2Cre, displays gland bud elongation but a failure in gland branching. Surprisingly, adult uterine epithelial deletion of ESR1 using the lactoferrin-Cre (LtfCre) displays normally branched uterine glands. Intriguingly, unbranched glands from Pax2Cre Esr1flox/flox uteri fail to express glandular pre-implantation Lif, preventing implantation chamber formation and embryo alignment along the uterine mesometrial-antimesometrial axis. In contrast, branched glands from LtfCre Esr1flox/flox uteri display reduced expression of glandular Lif resulting in delayed implantation chamber formation and embryo-uterine axes alignment but deliver a normal number of pups. Finally, pre-pubertal unbranched glands in control mice express Lif in the luminal epithelium but fail to express Lif in the glandular epithelium even in the presence of estrogen. These data strongly suggest that branched glands are necessary for pre-implantation glandular Lif expression for implantation success. Our study is the first to identify a relationship between the branched structure and secretory function of uterine glands and provides a framework for understanding how uterine gland structure-function contributes to pregnancy success.

developmental biology↗

bioRxiv2022

CRISPRi-based circuits for genetic computation in plants

Synthetic gene circuits can enable new cellular behaviours by integrating multiple input signals into customisable genetic programs. However, gene circuit development in plants has been limited by a lack of orthogonal and modular parts required for their construction. Here, we present a tool-kit of reversible CRISPRi-based gene circuits for use in plants. First, we created a range of engineered repressible promoters of different strengths and used them as integrators for the construction of NOT and NOR gates in Arabidopsis cells. Next, we determined the optimal processing system to express sgRNAs from RNA Pol II promoters to introduce NOR gate programmability and interface it with host regulatory sequences. Finally, we connected multiple NOR gates together in layered arrangements to create OR, NIMPLY, and AND logic functions. Our CRISPRi circuits are orthogonal, compact, reversible, programmable, and modular, providing a new platform for sophisticated and deliberate spatio-temporal control of gene expression in plants.

synthetic biology↗

bioRxiv2018

Predicting cell-cycle expressed genes identifies canonical and non-canonical regulators of time-specific expression in Saccharomyces cerevisiae

The collection all TFs, target genes and their interactions in an organism form a gene regulatory network (GRN), which underly complex patterns of transcription even in unicellular species. However, identifying which interactions regulate expression in a specific temporal context remains a challenging task. With multiple experimental and computational approaches to characterize GRNs, we predicted general and phase-specific cell-cycle expression in Saccharomyces cerevisiae using four regulatory data sets: chromatin immunoprecipitation (ChIP), TF deletion data (Deletion), protein binding microarrays (PBMs), and position weight matrices (PWMs). Our results indicate that the source of regulatory interaction information significantly impacts our ability to predict cell-cycle expression where the best model was constructed by combining selected TF features from ChIP and Deletion data as well as TF-TF interaction features in the form of feed-forward loops. The TFs that were the best predictors of cell-cycle expression were enriched for known cell-cycle regulators but also include regulators not implicated in cell-cycle regulation previously. In addition, ChIP and Deletion datasets led to the identification different subsets of TFs important for predicting cell-cycle expression. Finally, analysis of important TF-TF interaction features suggests that the GRN regulating cell cycle expression is highly interconnected and clustered around four groups of genes, two of which represent known cell-cycle regulatory complexes, while the other two contain TFs that are not known cell-cycle regulators (Ste12-Tex1 and Rap1-Hap1-Msn4), but are nonetheless important to regulating the timing of expression. Thus, not only do our models accurately reflect what is known about the regulation of the S. cerevisiae cell cycle, they can be used to discover regulatory factors which play a role in controlling expression during the cell cycle as well as other contexts with discrete temporal patterns of expression.

genetics↗