Biology subjects

Heaney, J.

Publications and source records attributed to Heaney, J..

3 recordsLinked to original sources

bioRxiv2020

Musashi regulates follicle stem cell maintenance and epithelial niche homeostasis in the Drosophila ovary

The Drosophila ovary is regenerated from germline and somatic stem cell populations that have provided fundamental conceptual understanding on how adult stem cells are regulated within their niches. Recent ovarian transcriptomic studies have failed to identify mRNAs that are specific to follicle stem cells (FSCs), suggesting that their fate may be regulated post-transcriptionally. We have identified that the RNA-binding protein, Musashi (Msi) is required for maintaining the stem cell state of FSCs. Loss of msi function results in stem cell loss, not due to cell death, but mutant FSCs upregulate Lamin C, indicating a change in differentiation state. In msi mutant ovaries, Lamin C upregulation was also observed in posterior escort cells and mutant somatic cells within regions 2/3 were dysfunctional, as evidenced by the presence of germline cyst collisions and fused egg chambers. The msi locus produces two classes of mRNAs (long and short). We show that FSC maintenance and escort cell function specifically requires the long transcripts, thus providing the first evidence of isoform-specific regulation in a population of Drosophila epithelial cells. We further demonstrate that although male germline stem cells have previously been shown to require Msi function to prevent differentiation this is not the case for female germline stem cells, indicating that these similar stem cell types have different requirements for Msi, in addition to the differential use of Msi isoforms between soma and germline.

developmental biology↗

bioRxiv2020

Real-time colorimetric LAMP methodology for quantitative nucleic acids detection at the point-of-care

Loop-mediated isothermal amplification is known for its high sensitivity, specificity and tolerance to inhibiting-substances. We developed a device for performing real-time colorimetric LAMP combining the accuracy of lab-based quantitative molecular diagnosis with the simplicity of point-of-care testing. This handheld device employs a single reaction-pot for amplification and a mini-camera for detection. Competitive features are the rapid analysis (<30min), quantification over 9 log-units, crude sample-compatibility (saliva, tissue, swabs), low detection limit (<5copies/reaction), smartphone-operation and fast prototyping (3D-printing). The devices clinical utility is demonstrated in cancer-mutations and COVID-19 testing. Excellent performance includes: detection of 0.01% of BRAF-V600E-to-wild-type molecules; 97% sensitivity to SARS-CoV-2 RNA detection (89 samples); 83% (Ct<34), 98% (Ct<30) and 100% (Ct<25) to 163 nasopharyngeal-swabs; 100% specificity in all cases. The device high technology-readiness-level makes it a suitable platform for performing any colorimetric LAMP assay; moreover, its simple and inexpensive fabrication holds promise for fast deployment and application in global diagnostics.

bioengineering↗

bioRxiv2020

Pre-existing and de novo humoral immunity to SARS-CoV-2 in humans

Several related human coronaviruses (HCoVs) are endemic in the human population, causing mild respiratory infections1. Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the etiologic agent of Coronavirus disease 2019 (COVID-19), is a recent zoonotic infection that has quickly reached pandemic proportions2,3. Zoonotic introduction of novel coronaviruses is thought to occur in the absence of pre-existing immunity in the target human population. Using diverse assays for detection of antibodies reactive with the SARS-CoV-2 spike (S) glycoprotein, we demonstrate the presence of pre-existing humoral immunity in uninfected and unexposed humans to the new coronavirus. SARS-CoV-2 S-reactive antibodies were readily detectable by a sensitive flow cytometry-based method in SARS-CoV-2-uninfected individuals and were particularly prevalent in children and adolescents. These were predominantly of the IgG class and targeted the S2 subunit. In contrast, SARS-CoV-2 infection induced higher titres of SARS-CoV-2 S-reactive IgG antibodies, targeting both the S1 and S2 subunits, as well as concomitant IgM and IgA antibodies, lasting throughout the observation period of 6 weeks since symptoms onset. SARS-CoV-2-uninfected donor sera also variably reacted with SARS-CoV-2 S and nucleoprotein (N), but not with the S1 subunit or the receptor binding domain (RBD) of S on standard enzyme immunoassays. Notably, SARS-CoV-2-uninfected donor sera exhibited specific neutralising activity against SARS-CoV-2 and SARS-CoV-2 S pseudotypes, according to levels of SARS-CoV-2 S-binding IgG and with efficiencies comparable to those of COVID-19 patient sera. Distinguishing pre-existing and de novo antibody responses to SARS-CoV-2 will be critical for our understanding of susceptibility to and the natural course of SARS-CoV-2 infection.

immunology↗