Biology subjects

Harvey, A.

Publications and source records attributed to Harvey, A..

5 recordsLinked to original sources

bioRxiv2025

Spatially precise neuron formation via hydrogel mediated modulation of the host astrocyte response

The regenerative capacity of the central nervous system after injury or disease is limited. Advancements in genetic and epigenetic reprogramming of non-neuronal cells into induced neurons presents a promising strategy for neuronal replacement and circuit reconstruction yet is hindered by suboptimal reprogramming efficacy. Here, we have achieved high astrocyte-to-neuron reprogramming efficacy through the ectopic expression of a SOX2 transcription factor using adeno-associated viral vectors. We subsequently designed a hybrid composite biomaterial to act as an implantable reprogramming workshop that perform sequential operations. Once injected, this bespoke system forms a tissue mimetic hydrogel encouraging the ingress of astrocytes to act as our raw material. We demonstrate that the system localized and enhanced the spatially confined delivery of reprogramming factors, entrapping astrocytes to then pass through an intermediate neuroblast state to robustly yield mature neurons. Sustained delivery of valproic acid within the system further promoted neuronal maturation. Overall, using design rules informed by requirements of the reprogramming strategy, we have designed a smart delivery system optimized for both the target tissue and reprogramming factors in a minimally invasive manner to enhance neural repair. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=163 HEIGHT=200 SRC="FIGDIR/small/695501v1_ufig1.gif" ALT="Figure 1"> View larger version (65K): org.highwire.dtl.DTLVardef@397e41org.highwire.dtl.DTLVardef@90047forg.highwire.dtl.DTLVardef@1175831org.highwire.dtl.DTLVardef@19f30eb_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2024

Validating Atlantic salmon (Salmo Salar) scale reading by genetic parent assignment and PIT-tagging

Understanding changes in abundance and survival in Atlantic salmon populations requires knowledge of growth rates and age. Salmon are typically aged through scale reading, but such estimates are rarely validated against age-verified fish from the wild. Here, we present a unique dataset of scales from 254 PIT-tagged Atlantic salmon with known sea-age. In addition, the freshwater age is known for 81 of these fish, through genetic parent-offspring identification. This dataset was used to estimate precision and bias in age readings and back-calculated length, as estimated by three independent experienced salmon scale readers. Overall, readers had an accuracy of 97.1% for sea-age and 71.7% for freshwater-age. For sea-age, scale reading was less accurate for salmon that had spent 2 or more years at sea than for salmon that had spent 1 year at sea. Freshwater age did however not affect scale reading accuracy. None of the scale readers erroneously misclassified freshwater-or sea-age with more than one year, and there was no significant pattern of misclassified ages to be under-or overestimate by the scale readers. Back-calculated smolt length was significantly different to length when measured as a smolt prior to seaward migration: it was shorter than the measured body-length for small smolts and longer for large smolts. This unique dataset, including the age-validated images of all scales, is now made openly available providing an important resource for training and testing salmon scale readers globally.

ecology↗

bioRxiv2022

A Clinically Useful and Biologically Informative Genomic Classifier for Papillary Thyroid Cancer

Clinical management of papillary thyroid cancer depends on estimations of prognosis. Standard care, which relies on prognostication based on clinicopathologic features, is inaccurate. We applied a machine learning algorithm (HighLifeR) to 502 cases annotated by The Cancer Genome Atlas Project to derive an accurate molecular prognostic classifier. Unsupervised analysis of the 82 genes that were most closely associated with recurrence after surgery enabled identification of three unique molecular subtypes. One subtype had a high recurrence rate, an immunosuppressed microenvironment, and enrichment of the EZH2-HOTAIR pathway. Two other unique molecular subtypes with a lower rate of recurrence were identified, including one subtype with a paucity of BRAFV600E mutations and a high rate of RAS mutations. The genomic risk classifier, in addition to tumor size and lymph node status, enabled effective prognostication that outperformed the American Thyroid Association clinical risk stratification. The genomic classifier we derived can potentially be applied preoperatively to direct clinical decision-making. Distinct biological features of molecular subtypes also have implications regarding sensitivity to radioactive iodine, EZH2 inhibitors, and immune checkpoint inhibitors.

cancer biology↗

bioRxiv2020

Investigating expression of a human optimized cas9 transgene in Neurospora crassa

The CRISPR-associated Cas9 enzyme is used in molecular biology to engineer the genomes of a wide range of organisms. While Cas9 can be injected or transfected into a target cell to achieve the desired goal, there are situations where stable expression of Cas9 within a target organism is preferable. Here, we show that the model filamentous fungus Neurospora crassa is recalcitrant to heterologous expression of a human-optimized version of Streptococcus pyogenes cas9. Furthermore, partial optimization of cas9 by synonymous codon exchange failed to improve its expression in the fungus. Finally, we show that transgene expression can be detected when cas9Hs sequences are placed in the 3 UTR regions of transgene-derived mRNAs, but not when the same sequences are in the translated part of the transgene-derived mRNA. This finding suggests that the primary obstacle to high cas9Hs expression levels in N. crassa is translational in nature.

molecular biology↗

bioRxiv2019

Comprehensive identification of HSP70/HSC70 Chaperone Clients in Human Cells

The HSP70 family of chaperones are the front-line of protection from stress-induced misfolding and aggregation of polypeptides in most organisms and are responsible for promoting the stability, folding, and degradation of clients to maintain cellular protein homeostasis. Here we demonstrate quantitative identification of HSP70 and HSC70 clients using an ubiquitin-mediated proximity tagging strategy and show that, despite their high degree of similarity, these enzymes have largely non-overlapping specificities. Both proteins show a preference for association with newly synthesized polypeptides but each responds differently to changes in the stoichiometry of proteins in obligate multi-subunit complexes. In addition, expression of an ALS-associated SOD1 mutant protein induces changes in HSP70 and HSC70 client association and aggregation toward polypeptides with predicted disorder, indicating that there are global effects from a single misfolded protein that extend to many clients within chaperone networks. Together these findings show that the ubiquitin-mediated UBAIT fusion system can efficiently isolate the complex interactome of HSP chaperone family proteins under normal and stress conditions.

molecular biology↗