Biology subjects

Luna, J.

Publications and source records attributed to Luna, J..

3 recordsLinked to original sources

bioRxiv2026

Hog1/p38 and ZAKα drive Shwachman-Diamond syndrome and provide targets to improve cell growth

Shwachman-Diamond syndrome (SDS) is a ribosomopathy characterized by neutropenia, pancreatic insufficiency, skeletal defects, and predisposition to leukemia. Most cases result from biallelic SBDS mutations that impairing 80S ribosome and polysome assembly. In yeast lacking SDO1 (the SBDS ortholog), growth slows dramatically and the p38 ortholog Hog1 signaling is elevated by multiple types of stress. SBDS-deficient HeLa cells exhibited reduced proliferation and slowed cell cycling. The p38 kinase was constitutively activated in SBDS mutants and SDS patient-derived blood cells. Because ZAK detects ribosome dysfunction, its activation links ribosomal defects to stress kinase pathways in SDS. Suppressing p38 or its upstream activator ZAK restored cell growth and reduced stress signaling. These findings reveal an evolutionarily conserved-independent mechanism via p38 drives SDS pathophysiology and identifies stress kinases as potential therapeutic targets for ribosomal dysfunction.

cell biology↗

bioRxiv2025

Single-molecule FRET with a minimalistic 3D-printed setup and dyes in the blue-green spectral region

Forster Resonance Energy Transfer (FRET) is a powerful technique for the detection and characterization of biomolecular interactions and conformational changes with sub-nanometer spatial resolution and a temporal resolution down to the timescale of fluorescence. While the technique is widely adopted in structural biology and biophysics, the evolution of single-molecule FRET has led to experimental setups with sophisticated optical layouts, multi-laser excitation schemes and time-resolved detection electronics. We here present an accessible alternative towards single-molecule FRET based on Brick-MIC, a recently introduced 3D-printed micro-spectroscopy platform. The FRET-Brick uses continuous-wave excitation at 488 nm with a minimal set of opto-mechanical components and photomultiplier detectors (PMTs). With this we were able to significantly reduce the setup complexity retaining single-molecule sensitivity with dyes matching the sensitivity of PMTs. To maximize the photon output of Alexa488, ATTO488 (donors), Alexa555, ATTO542 and Cy3B (acceptors), we introduce ferrocene-derivatives as photostabilizers that increase both dye brightness and remove dark-states. We benchmark the performance of the FRET-Brick with fluorophore-labelled oligonucleotide reference structures also in comparison to accessible volume simulations, and by detecting conformational changes in bacterial substrate binding proteins. Our work demonstrates that qualitative and quantitative smFRET measurements are possible with the minimalistic and cost-effective FRET-Brick.

biophysics↗

bioRxiv2025

Characterization of a dominant SmNac-like gene as a candidate for photosensitivity in the fruit peel of eggplant

Anthocyanins in the fruit peel of photosensitive eggplants exhibit a different distribution pattern compared to the photo-insensitive ones. The latter exhibits a uniform anthocyanin content, whereas photosensitive eggplants lack anthocyanin accumulation in areas not exposed to light, such as under the calyx, or have lower concentrations in less-exposed areas. In the current research work, genetic analysis of F1 and F2 populations revealed that the photo-insensitive phenotype in eggplants follows an autosomal dominant inheritance with a 3:1 ratio, indicating that the photosensitive trait is regulated by a single dominant gene. To locate and narrow down the genomic region underlying photosensitivity, a segregating F2 population was used for bulked segregant analysis sequencing (BSA-seq) and compared with previous QTLs identified in previous developed eggplants populations (ILs and MAGIC population). The accumulation of QTLs at the end of chromosome 10 postulate that chromose region as a hot spot for anthocyanin related traits. In our population all the QTLs considered overlap between the genomic region 84,1-87,9 Mb. Moreover, no DNA mutations in the progenitors of the eggplant accessions used were found. A RNA-seq analysis of bagged photosensitive and photo- insensitive eggplants was performed, as a result we identified the SmNAC1-like protein gene as a promising gene to be involved in fruit photosensitivity trait. In the photo-insensitive accession (IVIA- 371) SmNAC1-like protein was depply repressed compare to the photosensitive accession (ASI-S-1). No consistent mutations in the coding sequences (CDS) of SmNac-like protein locus among all the different eggplants accessions used were found, suggesting that other layer of regulation maybe acting in our eggplant accessions. These findings provide new insight into the regulation of the molecular mechanisms of anthocyanin biosynthesis in eggplant as point out for the first time the possible role of NAC transcription factors in the anthocyanin biosynthesis in eggplant.

plant biology↗