Biology subjects

Andres, P.

Publications and source records attributed to Andres, P..

3 recordsLinked to original sources

bioRxiv2026

Mafb-lineage activation of a short polyalanine (+5) PHOX2B mutation produces severe respiratory dysfunction with preserved postnatal weight gain among survivors in a mouse model of congenital central hypoventilation syndrome

Rationale: Congenital central hypoventilation syndrome (CCHS) is most commonly caused by polyalanine repeat mutations in PHOX2B. The in vivo consequences of the short five-alanine expansion and the contribution of specific hindbrain lineages to the resulting respiratory phenotype remain poorly understood. Objectives: To characterize the neonatal phenotype caused by the Phox2b25Ala/+ mutation and determine the contribution of the MafB lineage associated with the r5-r6 hindbrain territory. Methods: We generated a conditional Phox2b25Ala allele and studied mice with constitutive or MafB-lineage activation. Neonatal survival, growth, gastric milk content, ventilation, and hypercapnic responses were assessed in vivo. Respiratory-network activity and responses to extracellular acidification were recorded in E18.5 isolated brainstem-spinal cord preparations, and retrotrapezoid nucleus (RTN) development was examined histologically. Measurements and Main Results: Constitutive Phox2b25Ala/+ pups exhibited high neonatal mortality, markedly impaired weight gain, reduced gastric milk scores, hypoventilation, increased apnea time, and blunted ventilatory responses to CO2. Embryonic preparations showed a slower respiratory rhythm, an impaired response to acidification, and severe RTN dysgenesis. Activation of the mutant allele in the MafB lineage was also associated with severe respiratory dysfunction, RTN dysgenesis, and early neonatal mortality. In contrast, postnatal weight gain was preserved among surviving MafB-lineage mutants, and the reduction in gastric milk scores was significantly attenuated compared with constitutive mutants. Conclusions: A short PHOX2B polyalanine expansion reproduces major respiratory features of CCHS in mice. Activating the mutant allele in the MafB lineage is sufficient to cause severe respiratory dysfunction and neonatal mortality, whereas postnatal weight gain is preserved among survivors.

neuroscience↗

bioRxiv2026

Development of a Multidose Irradiation Protocol for Clonogenic Assays in Cell Culture Plates

PurposeIn vitro experimental radiobiology is a fundamental tool for understanding the cellular and molecular mechanisms involved in the response to ionizing radiation. Conventional experimental designs require separate irradiations to achieve different absorbed doses, thereby introducing experimental variability between irradiation sessions due to inter-session variability in both culture conditions and irradiation geometry. Here, we developed a multidose irradiation system for multiwell cell culture plates that enables the simultaneous delivery of three distinct dose levels within a single plate, thereby reducing resource consumption and operating time MethodsThe system was designed using a clinical linear accelerator delivering 6 MV X-rays and a 3D conformal irradiation approach based on CT imaging. Dose calculations for 200, 400 and 600 cGy were performed using Monaco Version 5.11. The irradiation geometry was optimized to achieve distinct and well-separated dose regions while preserving dose uniformity within each dose level. Treatment planning showed good agreement between estimated and prescribed dose levels, with mean dose deviation ranging from 0.35-1.63%. Physical verification using TLDs and radiochromic films demonstrated high dosimetric accuracy, showing deviations of 0.5-1.0% and 0.57-3.0%, respectively, expressed as the deviation of the measured mean dose from the nominal administered dose levels. Biological assessment included clonogenic assays in human tumor cell lines and a metabolic assay. Clonogenic assays showed a high concordance between the multidose and single-dose irradiation, with comparable linear-quadratic model fits (extra sum-of-squares F-test, p = 0.0923), confirming preservation of the intrinsic radiobiological response under simultaneous irradiation. ConclusionsThese results support the reliability of the proposed multidose irradiation system for in vitro radiobiology. This robust and reproducible system enables efficient characterization of radiobiological parameters.

cell biology↗

bioRxiv2025

Fission yeast cells use distinct cell size control mechanisms for size adaptation to osmotic, oxidative, or low glucose conditions

Cells maintain an appropriate size to function, yet the mechanisms that enable size adaptation to environmental stress remain poorly understood. Fission yeast cells enter mitosis and divide at a threshold size when cyclin-dependent kinase (Cdk1) is activated through size- and time-dependent scaling of its regulators: Cdr2 kinase with cell surface area, Cdc25 phosphatase with cell volume, and mitotic cyclin Cdc13 with cell cycle time. This integrated size control network is characterized in nutrient-rich conditions, but under stress it remains unclear which size parameters cells monitor, and which size- or time-sensing pathways mediate adaptation. Using high-throughput image analysis, we quantified the geometry of dividing cells under osmotic, oxidative, and low glucose conditions. Wild-type cells increased their surface area-to-volume (SA:Vol) ratio in low glucose but decreased it under osmotic or oxidative stress, revealing distinct geometric strategies for environmental size adaptation. Genetic perturbations of size- and time-sensing pathways revealed that Cdc25 is required for volume-based adaptation to oxidative and osmotic stress, Cdc13 contributes to osmotic stress response, and Cdr2 promotes surface area-based expansion in low glucose. Although disrupting individual pathways altered normal geometric responses, cells remained viable, suggesting that a modular size control system enables flexible geometric adaptation to changing environments.

cell biology↗