Biology subjects

Alibhai, D.

Publications and source records attributed to Alibhai, D..

3 recordsLinked to original sources

bioRxiv2021

Platelet generation from circulating megakaryocytes is triggered in the lung vasculature

Platelets, small hemostatic blood cells, are derived from megakaryocytes, although the generation process is not clear. Only small numbers of platelets have been produced in systems outside the body, where bone marrow and lung are proposed as sites of platelet generation. Here we show that perfusion of megakaryocytes ex vivo through the mouse lung vasculature generates very large numbers of platelets, up to 3,000 per megakaryocyte. Despite their large size, megakaryocytes were able repeatedly to passage through the lung vasculature, leading to enucleation and fragmentation to generate platelets intravascularly. Using the ex vivo lung and a novel in vitro microfluidic chamber we determined the contributions of oxygenation, ventilation and endothelial cell health to platelet generation, and showed a critical role for the actin regulator TPM4. One-Sentence SummaryMegakaryocytes form platelets intravascularly in the lung, dependent upon oxygenation, endothelium and megakaryocyte TPM4

physiology↗

bioRxiv2021

Green Fluorescent Carbon Dots as Targeting Probes for LED-Dependent Bacterial Killing

The emergence of antimicrobial resistance represents a significant health and economic challenge worldwide. The slow pace of antibacterial discovery necessitates strategies for optimal use of existing agents, including effective diagnostics able to drive informed prescribing; and development of alternative therapeutic strategies that go beyond traditional small-molecule approaches. Thus, the development of novel probes able to target bacteria for detection and killing, and that can pave the way to effective theranostic strategies, is of great importance. Here we demonstrate that metal-free green-emitting fluorescent carbon dots (FCDs) synthesized from glucosamine HCl and m-phenylenediamine, and featuring 2,5-deoxyfructosazine on a robust amorphous core, can label both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa) bacterial pathogens within 10 minutes of exposure. Moreover, effective killing of Gram-positive and -negative bacteria can be induced by combining FCD treatment with irradiation by LED light in the visible range. Cell-based, electron microscopy and Tandem Mass Tag (TMT) proteomic experiments indicate that FCD administration in combination with LED exposure gives rise to local heating, ROS production, and membrane- and DNA-damage, suggesting multiple routes to FCD-mediated bacterial killing. Our data identify FCDs as materials that combine facile synthesis from low-cost precursors with labelling and light-dependent killing of clinically important bacterial species, and that thus warrant further exploration as the potential bases for novel theranostics.

microbiology↗

bioRxiv2017

Streamlined histone-based fluorescence lifetime imaging microscopy reveals ATM regulation of chromatin compaction

Changes in chromatin compaction are crucial during genomic responses. Thus, methods that enable such measurements are instrumental for investigating genome function. Here, we address this challenge by developing, validating, and streamlining histone-based fluorescence lifetime imaging microscopy (FLIM) that robustly detects chromatin compaction states in fixed and live cells; in 2D and 3D. We present quality-controlled and detailed method that is simpler and faster than previous approches, and uses FLIMfit open-source software. We demonstrate the versatility of our method through its combination with immunofluorescence and its implementation in immortalised cells and primary neurons. Owing to these developments, we applied this method to elucidate the function of the DNA damage response kinase, ATM, in regulating chromatin organisation after genotoxic-stress. We unravelled a role for ATM in regulating chromatin compaction independently of DNA damage. Collectively, we present an adaptable chromatin FLIM method for examining chromatin structure in cells, and establish its broader utility.

cell biology↗