pH variations enable guanine crystal formation within iridosomes
Abstract
Many animals produce vivid colors by reflecting and amplifying light with stacked guanine crystals within membrane-bound organelles called iridosomes. While the presence of guanine crystals in iridosomes is well documented, the mechanisms facilitating the accumulation of water-insoluble guanine and driving its crystallization remain unclear. Here we used cryo-electron microscopy, live-cell pH imaging, pharmacological perturbations and spectroscopy to study iridosome maturation in zebrafish. Cryo-electron and synchrotron-based soft X-ray microscopies revealed that amorphous guanine initially accumulates in early-stage iridosomes in its protonated state. Live-cell imaging with a pH sensor demonstrated that early iridosomes are acidic, with pH gradually neutralizing during development. Inhibiting V-ATPase disrupted this acidification and significantly reduced crystal formation, indicating its role in pH regulation. Our findings reveal insights into the molecular mechanisms facilitating guanine formation within iridosomes, emphasizing the pivotal role of pH alternations in the precise formation of biogenic crystals. Many animals display brilliant colors thanks to the precise formation of guanine crystals within specialized organelles. Here, the authors demonstrate that dynamic pH shifts orchestrate this process: an initially acidic lumen stabilizes amorphous, protonated guanine and subsequent alkalinization triggers its crystallization.
Read the paper
Related studies
- The Prediction of the In Vitro Release Curves for PLGA-Based Drug Delivery Systems with Neural Networks
- Promising Ursolic Acid as a Novel Antituberculosis Agent: Current Progress and Challenges
- Proof of principle concept for the analysis and functional prediction of rare genetic variants in the CYP2C19 and CYP2D6 genes
- Fabrication, characterization, and docking studies of furosemide-loaded nanosponges using the emulsion solvent diffusion method
- The Effect of Concomitant Administration of Proton Pump Inhibitors on the Pharmacokinetics of CDK4/6 Inhibitors in Rats: Implications for the Evaluation of Hepatic and Transporter-Mediated Drug–Drug Interactions
- Mining the Metabolic Capacity of Clostridium sporogenes Aided by Machine Learning
Go deeper in Evidence Hub
Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.