Biology subjects

Mackenzie, A.

Publications and source records attributed to Mackenzie, A..

5 recordsLinked to original sources

bioRxiv2025

Spatio-molecular analysis of primate subthalamus defines anatomical domains relevant to Parkinson disease and neuropsychiatry

The subthalamic nucleus (STN) is a deep brain stimulation (DBS) treatment target for several disorders of vastly different symptoms, including Parkinsons disease (PD) and obsessive compulsive disorder (OCD). The STN is located in close proximity to the superolateral branch of the medial forebrain bundle (slMFB), a recent DBS target for treatment-resistant depression. Despite clinical application, spatio-molecular understanding of the STN and slMFB has remained elusive. To help solving this, transcriptome data generated in mice was here implemented in comparative analysis with macaque and human. Fluorescent in situ hybridization (FISH) analysis was performed on multiple serial brain sections covering the whole STN area in mice and macaque. Selected markers were further analysed in human sections and in whole mouse brains to allow spatial 3D analysis by light-sheet microscopy. Contrary to available brain atlases, we can now show that the hypothalamic structure known as the para-STN, a critical hub for interoception and emotional regulation, aligns with the STN, and is partly embedded within the MFB. Thus, para-STN occupies considerable space around several major DBS sites. Spatio-molecular data expose STN, MFB and para-STN as highly heterogeneous, including gradients of serotonin receptor subtype 2C (HTR2C). Molecularly reinforced anatomical maps of STN, para-STN, and MFB reveal unexpected details, and may inform spatial precision in neuromodulation strategies while also providing openings for molecular drug discovery.

neuroscience↗

bioRxiv2024

Urban wastewater contains a functional human antibody repertoire of mucosal origin

Wastewater-based surveillance of human disease offers timely insights to public health, helping to mitigate infectious disease outbreaks and decrease downstream morbidity and mortality. These systems rely on nucleic acid amplification tests for monitoring disease trends, while antibody-based seroprevalence surveys gauge community immunity. However, serological surveys are resource-intensive and subject to potentially long lead times and sampling bias. We identified and characterized a human antibody repertoire, predominantly secretory IgA, isolated from a central wastewater treatment plant and building-scale wastewater collection points. These antibodies partition to the solids fraction and retain immunoaffinity for SARS-CoV-2 and Influenza A virus antigens. This stable pool could enable real-time tracking of correlates of vaccination, infection, and immunity, aiding in establishing population-level thresholds for immune protection and assessing the efficacy of future vaccine campaigns, particularly those that are designed to induce humoral mucosal immunity.

immunology↗

bioRxiv2023

Near infrared-light treatment alters mitochondrial homeostasis to induce senescence in breast cancer cells

The application of near infrared (NIR)-light to living systems has been suggested as a potential method to enhance tissue repair, decrease inflammation, and possibly mitigate cancer therapy-associated side effects. In this study, we examined the effect of exposing three cell lines: breast cancer (MCF7), non-cancer breast cells (MCF10A), and lung fibroblasts (IMR-90), to 734 nm NIR-light for 20 minutes per day for six days, and measuring changes in cellular senescence. Positive senescent populations were induced using doxorubicin. Flow cytometry was used to assess relative levels of senescence together with mitochondria-related variables. Exposure to NIR-light significantly increased the level of senescence in MCF7 cells (13.5%; P<0.01), with no observable effects on MCF10A or IMR-90 cell lines. NIR-induced senescence was associated with significant changes in mitochondria homeostasis, including raised ROS level (36.0%; P<0.05) and mitochondrial membrane potential (14.9%; P<0.05), with no changes in mitochondrial Ca2+. These results suggest that NIR-light exposure can significantly arrest the proliferation of breast cancer cells via inducing senescence, while leaving non-cancerous cell lines unaffected.

cell biology↗

bioRxiv2021

Identification and correction of phase switches with Hi-C data in the Nanopore and HiFi chromosome-scale assemblies of the dikaryotic leaf rust fungus Puccinia triticina

BackgroundMost animals and plants have more than one set of chromosomes and package these haplotypes into a single nucleus within each cell. In contrast, many fungal species carry multiple haploid nuclei per cell. Rust fungi are such species with two nuclei (karyons) that contain a full set of haploid chromosomes each. The physical separation of haplotypes in dikaryons means that, unlike in diploids, Hi-C chromatin contacts between haplotypes are false positive signals. ResultsWe generate the first chromosome-scale, fully-phased assembly for the dikaryotic leaf rust fungus Puccinia triticina and compare Nanopore MinION and PacBio HiFi sequence-based assemblies. We show that false positive Hi-C contacts between haplotypes are predominantly caused by phase switches rather than by collapsed regions or Hi-C read mis-mappings. We introduce a method for phasing of dikaryotic genomes into the two haplotypes using Hi-C contact graphs, including a phase switch correction step. In the HiFi assembly, relatively few phase switches occur, and these are predominantly located at haplotig boundaries and can be readily corrected. In contrast, phase switches are widespread throughout the Nanopore assembly. We show that haploid genome read coverage of 30-40 times using HiFi sequencing is required for phasing of the leaf rust genome (~0.7% heterozygosity) and that HiFi sequencing resolves genomic regions with low heterozygosity that are otherwise collapsed in the Nanopore assembly. ConclusionsThis first Hi-C based phasing pipeline for dikaryons and comparison of long-read sequencing technologies will inform future genome assembly and haplotype phasing projects in other non-haploid organisms.

genomics↗

bioRxiv2016

Towards new cholera prophylactics and treatment: Crystal structures of bacterial enterotoxins in complex with GM1 mimics

Cholera is a life-threatening disease in many countries, and new drugs are clearly needed. C-glycosidic antagonists may serve such a purpose. Atomic resolution crystal structures of these compounds in complexes with the cholera toxin give unprecedented atomic details of the molecular interactions, and show how the inhibitors efficiently block the GM1 binding site. These molecules are well suited for development into low-cost prophylactic drugs, due to their relatively easy syntheses and their resistance to glycolytic enzymes. One of the compounds links two toxin B-pentamers in the crystal structure, which may yield improved inhibition through the formation of toxin aggregates. These structures can spark the improved design of GM1 mimics, either alone or as multivalent inhibitors connecting multiple GM1-binding sites. Future developments may further include compounds that link the primary and secondary binding sites. Serving as decoys, receptor mimics may lessen symptoms while avoiding the use of antibiotics.

biochemistry↗