Biology subjects

Smith, M. C.

Publications and source records attributed to Smith, M. C..

5 recordsLinked to original sources

bioRxiv2026

Mite Genome Miniaturization: Assembly of the biological control agent Floracarus perrepae reveals dynamic genome evolution in eriophyoid mites

The eriophyoid mites (Acari: Eriophyoidea) represent an extreme case of genome streamlining, with genomes averaging just 32Mb, among the smallest of all animals. This clade of mites is highly diverse with more than 4000 species. Their morphologies are specialized for feeding on their host plants, including a simplified worm-like body plan with just two pairs of legs and modified mouth parts that can induce the formation of galls or plant deformities during feeding. Their generally strong host affinities make eriophyoid mites appealing for use as biological control agents, although their short generation times and small genomes could facilitate rapid evolution and impact their efficacy in management programs. Here, we sequenced the genome of the biological control mite Floracarus perrepae, producing a highly contiguous genome totalling just 23.1 Mb, among the smallest of all animals. We also assembled another non-eriophyid mite genome from accidental DNA bycatch (69.4Mb). We placed this new genomic resource in a phylogenetic context to reveal that mites have highly dynamic genome evolution, with a significant trend in genome downsizing in the eriophyoids. Our results suggest that this streamlining is associated with non-genic elements such as the suppression or excision of retrotransposons and purging of introns. As new sequencing techniques become available, novel genomic resources for tiny organisms such as F. perrepae will be more readily accessible, facilitating both fundamental genome evolutionary biology and applied sciences such as biological control programs which use eriophyoid mites for the management of invasive species.

evolutionary biology↗

bioRxiv2025

Near chromosome-level genome assembly of Neomusotima conspurcatalis gives insights into the evolution of moth genome architecture and fern-insect interactions

Plant-insect interactions are the foundation of ecosystems globally, yet we are still determining the underlying mechanisms through which these relationships evolve. The co-evolution between insects and their host plants should shape the genomes of both partners, and genes involved in interaction specificity should show unique genomic signatures (e.g., rapid evolution, gene family expansions). Biological control programs are an excellent system for disentangling the genomics and molecular biology of the establishment of an insect and its host plant specificity. Fern-insect relationships are among the most poorly understood, and ferns have long been thought to have few interactions with insects, although recent evidence suggests that these relationships are under-sampled and studied. Here, we present a near-chromosome genome assembly of the crambid moth Neomusotima conspurcatalis, a biological control agent employed in the management of the invasive vining fern Lygodium microphyllum. We use this novel genomic resource to explore the evolution of genome architecture across the Crambidae, revealing highly conserved genome structure across this family of moths. We also examine gene family evolution across the phylogeny and identify expansions in odorant receptor gene families that may be involved in the highly specific interaction of N. conspurcatalis with L. microphyllum. This work highlights the utility of genomics in biological control, and the utility of biological control in informing fundamental understanding of plant-insect interactions. SummaryPlant-insect interactions form the basis of ecological communities and can be highly specific through long lasting co-evolution. Classical biological control provides excellent opportunities to investigate how insect and host genomes are shaped by co-evolutionary processes. We sequenced the genome of Neomusotima conspurcatalis, a biological control moth used to manage the invasive fern Lygodium microphyllum. We analyzed how the structure of the genome has evolved over time relative to other crambid moths and how expansions in gene families involved in odorant reception may be involved in co-evolution with its host. This work provides insight into herbivore interactions in seed-free vascular plants.

evolutionary biology↗

bioRxiv2025

Brain-wide mapping reveals temporal and sexually dimorphic opioid actions

While the molecular and cellular effects of opioids have been extensively studied, the precise mechanisms by which these drugs target specific brain regions over time remain unclear. Similarly, despite well-documented sex differences in opioid responses, the anatomical basis for this sexual dimorphism is not well characterized. To address these questions, we developed an automated, scalable, and unbiased approach for whole-brain anatomical mapping of the neuronal activity marker c-Fos in response to acute morphine exposure. Using ribbon scanning confocal microscopy, we imaged whole cleared brains from male and female wild-type mice at 1 hour and 4 hours post-morphine administration. Our whole-brain analysis of c-Fos expression revealed distinct patterns of morphine-induced regional brain activation across time and sex. Notably, we observed a greater number of structures with significant activity differences at 4 hours compared to 1 hour. In male mice, significant changes were primarily localized to regions within the dopamine system, whereas in female mice, they were concentrated in cortical regions. By combining high-throughput imaging with whole-brain expression analysis, particularly in the context of opioid actions, our approach provides a more comprehensive understanding of how drugs of abuse affect the brain.

neuroscience↗

bioRxiv2023

Sexually dimorphic mechanisms of VGLUT-mediated protection from dopaminergic neurodegeneration

Parkinsons disease (PD) targets some dopamine (DA) neurons more than others. Sex differences offer insights, with females more protected from DA neurodegeneration. The mammalian vesicular glutamate transporter VGLUT2 and Drosophila ortholog dVGLUT have been implicated as modulators of DA neuron resilience. However, the mechanisms by which VGLUT2/dVGLUT protects DA neurons remain unknown. We discovered DA neuron dVGLUT knockdown increased mitochondrial reactive oxygen species in a sexually dimorphic manner in response to depolarization or paraquat-induced stress, males being especially affected. DA neuron dVGLUT also reduced ATP biosynthetic burden during depolarization. RNA sequencing of VGLUT+ DA neurons in mice and flies identified candidate genes that we functionally screened to further dissect VGLUT-mediated DA neuron resilience across PD models. We discovered transcription factors modulating dVGLUT-dependent DA neuroprotection and identified dj-1{beta} as a regulator of sex-specific DA neuron dVGLUT expression. Overall, VGLUT protects DA neurons from PD-associated degeneration by maintaining mitochondrial health.

neuroscience↗

bioRxiv2021

Deletion of Fibroblast growth factor 9 globally and in skeletal muscle results in enlarged tuberosities at sites of deltoid tendon attachments

The growth of most bony tuberosities, like the deltoid tuberosity (DT), rely on the transmission of muscle forces at the tendon-bone attachment during skeletal growth. Tuberosities distribute muscle forces and provide mechanical leverage at attachment sites for joint stability and mobility. The genetic factors that regulate tuberosity growth remain largely unknown. In mouse embryos with global deletion of fibroblast growth factor 9 (Fgf9), the DT size is notably enlarged. In this study, we explored the tissue-specific regulation of DT size using both global and targeted deletion of Fgf9. We showed that cell hypertrophy and mineralization dynamics of the DT, as well as transcriptional signatures from skeletal muscle but not bone, were influenced by the global loss of Fgf9. Loss of Fgf9 during embryonic growth led to increased chondrocyte hypertrophy and reduced cell proliferation at the DT attachment site. This endured hypertrophy and limited proliferation may explain the abnormal mineralization patterns and locally dysregulated expression of markers of endochondral development in Fgf9null attachments. We then showed that targeted deletion of Fgf9 in skeletal muscle leads to postnatal enlargement of the DT. Taken together, we discovered that Fgf9 may play an influential role in muscle-bone crosstalk during embryonic and postnatal development.

developmental biology↗