Biology subjects

Lowman, M.

Publications and source records attributed to Lowman, M..

4 recordsLinked to original sources

bioRxiv2026

Evolution of new cerebellar nuclei by excitatory progenitor diversification in the early rhombic lip

The cerebellar nuclei, the output regions of the cerebellum, have evolved via repeated duplication of a conserved cell type set to produce different numbers of nuclei across species. Here, we investigate the mechanism underlying this process using developmental single-cell and spatial transcriptomics time courses in mouse and chicken. We show that new nuclei formation is governed by excitatory neurons born from nucleus-specific progenitors in the early and late rhombic lip (RL), with inhibitory neurons incorporating into established nuclear territories. Evolutionarily newer canonical cerebellar nuclei with increasingly higher-order functions are produced by diversification of the early RL, where nuclear identity and spatial organization are established in part by co-option of border formation programs in conserved progenitor cell types. In contrast, the late RL generates the higher-order subnuclei of the medial nucleus and forms a non-canonical olivocerebellar circuit. Together, our findings suggest that new brain regions can evolve through developmental diversification of excitatory progenitors and spatial segregation of conserved sister cell types with generic inhibitory neurons filling in after.

neuroscience↗

bioRxiv2026

Generation and validation of an Acan-Cre mouse line to selectively label Class-B excitatory neurons of the cerebellar nuclei

The cerebellar nuclei form the main output structures of the cerebellum and are composed of a deeply conserved set of cell types. Two excitatory cell classes, Class-A and -B, are present in each cerebellar nucleus and mediate all excitatory output of the cerebellum. To provide genetic access to these cell types, here we identified Acan as a marker gene for Class-B cells and generated a knock-in Acan-P2A-Cre mouse line. We demonstrate that this Acan-Cre line selectively labels Class-B neurons in the cerebellar nuclei and validate its use in viral projection tracing. This new mouse line provides a valuable genetic tool to study cerebellar nuclei organization and function.

neuroscience↗

bioRxiv2023

Pathogenesis of Breakthrough Infections with SARS-CoV-2 Variants in Syrian Hamsters

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19, has evolved into multiple variants. Animal models are important to understand variant pathogenesis, particularly for those with mutations that have significant phenotypic or epidemiological effects. Here, cohorts of naive or previously infected Syrian hamsters (Mesocricetus auratus) were infected with variants to investigate viral pathogenesis and disease protection. Naive hamsters infected with SARS-CoV-2 variants had consistent clinical outcomes, tissue viral titers, and pathology, while hamsters that recovered from initial infection and were reinfected demonstrated less severe clinical disease and lung pathology than their naive counterparts. Males had more frequent clinical signs than females in most variant groups, but few sex variations in tissue viral titers and lung pathology were observed. These findings support the use of Syrian hamsters as a SARS-CoV-2 model and highlight the importance of considering sex differences when using this species. ImportanceWith the continued circulation and emergence of new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, understanding differences between the initial and a subsequent reinfection on disease pathogenesis is critical and highly relevant. This study characterizes Syrian hamsters as an animal model to study reinfection with SARS-CoV-2. Previous infection reduced the disease severity of reinfection with different SARS-CoV-2 variants.

microbiology↗

bioRxiv2021

A bacterial extracellular vesicle-based intranasal vaccine against SARS-CoV-2

Several vaccines have been introduced to combat the coronavirus infectious disease-2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Current SARS-CoV-2 vaccines include mRNA-containing lipid nanoparticles or adenoviral vectors that encode the SARS-CoV-2 Spike (S) protein of SARS-CoV-2, inactivated virus, or protein subunits. Despite growing success in worldwide vaccination efforts, additional capabilities may be needed in the future to address issues such as stability and storage requirements, need for vaccine boosters, desirability of different routes of administration, and emergence of SARS-CoV-2 variants such as the Delta variant. Here, we present a novel, well-characterized SARS-CoV-2 vaccine candidate based on extracellular vesicles (EVs) of Salmonella typhimurium that are decorated with the mammalian cell culture-derived Spike receptor-binding domain (RBD). RBD-conjugated outer membrane vesicles (RBD-OMVs) were used to immunize the golden Syrian hamster (Mesocricetus auratus) model of COVID-19. Intranasal immunization resulted in high titers of blood anti-RBD IgG as well as detectable mucosal responses. Neutralizing antibody activity against wild-type and Delta variants was evident in all vaccinated subjects. Upon challenge with live virus, hamsters immunized with RBD-OMV, but not animals immunized with unconjugated OMVs or a vehicle control, avoided body mass loss, had lower virus titers in bronchoalveolar lavage fluid, and experienced less severe lung pathology. Our results emphasize the value and versatility of OMV-based vaccine approaches.

immunology↗