Shinde, I. | bioRxiv Science

bioRxiv2026

Developmental regulation of progenitor aging shapes long-term intestinal homeostasis in Drosophila

Aging causes a progressive loss of tissue homeostasis, with stem cell exhaustion as a major hallmark. Age-associated decline in organ function is widely perceived as emanating from progressive accumulation of cellular damage in adult tissues. However, whether aging trajectories are established early on during development remains an open question. Here, we demonstrate that genetic modulation of cellular aging pathways in larval adult midgut progenitors (AMPs), which serve as the precursors of adult intestinal stem cells and differentiated epithelial cells, dictates the long-term trajectory of intestinal aging in Drosophila. Accelerated cellular aging by genetic perturbation employing Toll or Imd pathway overactivation or elevation of reactive oxygen species (ROS) using ND42 (mitochondrial complex I) knockdown in the AMPs results in aberrant progenitor proliferation, skewed lineage allocation, epithelial barrier dysfunction, and genomic instability. These alterations are accompanied by marked destabilization of AMP islet architecture and widespread changes in age-related molecular signatures, as revealed by bulk transcriptomic analysis. In contrast, decelerated cellular aging mediated by Foxo or Atg8a overexpression results in a decrease in enteroendocrine population and the intestinal barrier remained unaffected. Intriguingly, early-life activation of immune and oxidative stress signaling manifested later in the adult gut as elevated enteroendocrine differentiation, highlighting lasting effects on intestinal regenerative capacity and lineage balance. Together, our findings demonstrate that cellular aging is tightly regulated early on in development and its perturbation can cause developmental disruption hampering adult gut homeostasis, establishing AMPs as key developmental determinants that regulate the trajectory of intestinal aging in Drosophila.

developmental biology↗

bioRxiv2019

Correlation between Retinal Ganglion Cell Loss and Nerve Crush Force-Impulse Established with an Instrumented Tweezers in Mice

ObjectivesRodent models of optic nerve crush (ONC) have often been used to study degeneration and regeneration of retinal ganglion cells (RGCs) and their axons as well as the underlying molecular mechanisms. However, ONC results from different laboratories exhibit a range of RGC injury with varying degree of axonal damage. We developed an instrumented tweezers to measure optic nerve (ON) crush forces in real time and studied the correlation between RGC axon loss and force-impulse, the product of force and duration, applied through the instrumented tweezers in mice.\n\nMethodsA pair of standard self-closing #N7 tweezers were instrumented with miniature foil strain gauges at optimal locations on both tweezer arms. The instrumented tweezers were capable of recording the tip closure forces in the form of voltages, which were calibrated through load cells to corresponding tip closure forces over the operating range. Using the instrumented tweezers, the ONs of multiple mice were crushed with varied forces and durations and the axons in the immunostained sections of the crushed ONs were counted.\n\nResultsWe found that the surviving axon density correlated with crush force, with longer duration and stronger crush forces producing consistently more axon damage.\n\nDiscussionThe instrumented tweezers enable a simple technique for measurement of ONC forces in real-time for the first time. Using the instrumented tweezers, experimenters can quantify crush forces during ONC to produce consistent and predictable post-crush cell death. This should permit future studies a way to produce nerve damage more consistently than is available now.

neuroscience↗