Biology subjects

Murray, M. J.

Publications and source records attributed to Murray, M. J..

3 recordsLinked to original sources

bioRxiv2024

Regenerative clustering of Enteroblasts in the Drosophila midgut revealed by a morphometric analysis

Enteroblasts (EBs) are the cells responsible for the maintenance of the epithelium that lines the adult midgut in Drosophila. In response to cell death and damage, EBs undergo a Mesenchymal-Epithelial-Transition (MET) as they incorporate into the epithelium and differentiate into enterocytes (ECs). The morphogenetic mechanisms driving this MET process are not well understood. To improve phenotypic analysis of EBs, we established an analysis pipeline that uses machine learning segmentation to produce a reliable and automated quantification of cellular morphology and spatial distributions. EB morphology and fate is visualised using the Repressible Dual Differential stability cell Marker (ReDDM) approach. We show that wildtype EB cells exhibit a bimodal distribution pattern in which midguts fall into two categories: "quiescent" guts, in which EBs are evenly spaced out and newly formed ECs are uncommon, and "regenerative" guts, in which EBs are clustered and new ECs are prevalent. Using this system we first show that RNAi knockdown of Septate Junction proteins disrupts normal EB morphology and spatial distribution. With time-lapse imaging, we have also established that EBs are motile in nature, and when artificial tissue damage was introduced, exhibited increased cytoplasmic movements, and formed distinct clusters. We then demonstrate the utility of our pipeline in a small candidate screen for genes that might mediate EB clustering. Based on our results, we propose a working model that links the dynamic behaviour of EBs with midgut regeneration.

developmental biology↗

bioRxiv2022

Clonal diversification and histogenesis of malignant germ cell tumours

Germ cell tumours (GCTs) are a collection of benign and malignant neoplasms derived from primordial germ cells. They are uniquely able to recapitulate embryonic and extraembryonic tissues, which carries prognostic and therapeutic significance. The developmental pathways underpinning GCT initiation and histogenesis are incompletely understood. Here, we studied the relationship of histogenesis and clonal diversification in GCTs by analysing the genome and transcriptome of 547 microdissected histological units. We found that the extensive diversification of tissues and genetic subclones were not correlated. However, we identified unifying features including the retention of fetal developmental transcripts across tissues, expression changes on chromosome 12p, and a conserved somatic evolutionary sequence of whole genome duplication followed by clonal diversification. Whilst this pattern was preserved across all GCTs, the developmental timing of the duplication varied between prepubertal and postpubertal cases. In addition, tumours of younger children exhibited distinct substitution signatures, including a novel one, which may lend themselves as potential biomarkers for risk stratification. Our findings portray the extensive diversification of GCT tissues and genetic subclones as randomly distributed, whilst identifying overarching tissue and tumour transcriptional and genomic features.

cancer biology↗

bioRxiv2021

Characterisation of B.1.1.7 and Pangolin coronavirus spike provides insights on the evolutionary trajectory of SARS-CoV-2

The recent emergence of SARS-CoV-2 variants with increased transmission, pathogenesis and immune resistance has jeopardised the global response to the COVID-19 pandemic. Determining the fundamental biology of viral variants and understanding their evolutionary trajectories will guide current mitigation measures, future genetic surveillance and vaccination strategies. Here we examine virus entry by the B.1.1.7 lineage, commonly referred to as the UK/Kent variant. Pseudovirus infection of model cell lines demonstrate that B.1.1.7 entry is enhanced relative to the Wuhan-Hu-1 reference strain, particularly under low expression of receptor ACE2. Moreover, the entry characteristics of B.1.1.7 were distinct from that of its predecessor strain containing the D614G mutation. These data suggest evolutionary tuning of spike protein function. Additionally, we found that amino acid deletions within the N-terminal domain (NTD) of spike were important for efficient entry by B.1.1.7. The NTD is a hotspot of diversity across sarbecoviruses, therefore, we further investigated this region by examining the entry of closely related CoVs. Surprisingly, Pangolin CoV spike entry was 50-100 fold enhanced relative to SARS-CoV-2; suggesting there may be evolutionary pathways by which SARS-CoV-2 may further optimise entry. Swapping the NTD between Pangolin CoV and SARS-CoV-2 demonstrates that changes in this region alone have the capacity to enhance virus entry. Thus, the NTD plays a hitherto unrecognised role in modulating spike activity, warranting further investigation and surveillance of NTD mutations.

microbiology↗