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Biology subjects

Ham, A.

Publications and source records attributed to Ham, A..

2 recordsLinked to original sources

Diapause and Developmental Arrest as Drivers of Population Resilience Through Stress

Dauer formation and L1 arrest are stress-responsive developmental strategies that enable Caenorhabditis elegans to survive unfavorable conditions. These responses are regulated by environmental cues, including food availability and pheromone signals that communicate population density. However, how dauer entry, L1 arrest, and density-dependent signaling collectively influence long-term population dynamics remains poorly understood. In this study, populations of daf-22 and daf-16 mutants with impaired dauer formation, starvation arrest, and pheromone signaling were compared under control and starvation stress. Measurements of developmental stages were used to evaluate how genotype influenced population growth, developmental stage composition, starvation response, and recovery over time. This population-level approach links individual developmental decisions and inter-organismal communication to broader patterns of persistence and population change. The results show that daf-16 and daf-22 mutant populations differed from wild type in their recovery ability following nutrient deprivation as well as in the stage distributions within the population. These findings suggest that dauer signaling contributes broadly to population persistence by coordinating developmental arrest, reproduction, survival, and recovery. Overall, this work supports the interpretation of dauer formation as a larger population level survival program rather than a single isolated developmental outcome.

genetics↗

c-MAF transduces motor neuron firing to sustain fast-glycolytic myofibers and neuromuscular junctions

This study examined how motoneuron activity influences transcription factor binding in mouse fast glycolytic Myh4+ muscle fibers. Single nucleus multiomics of innervated versus denervated tibialis anterior muscles revealed altered chromatin accessibility: SIX and c-MAF binding sites decreased while JUN, FOS, and RUNX1 sites increased in denervated Myh4+ myonuclei. c-MAF showed strong nuclear enrichment after 100 Hz stimulation and periods of increased motoneuron activity but was absent following denervation, establishing it as a primary readout of fast motoneuron firing. Genome-wide analysis demonstrated that c-MAF binding site spacing encodes functionally distinct muscle gene programs. Analysis of constitutive and inducible skeletal muscle-specific c-Maf mutants revealed that c-MAF loss caused region-specific MYH4+ fiber atrophy, MYH1/MYH2 fiber type shifts resembling ALS G93A mouse phenotypes, and progressive neuromuscular junction fragmentation with increased motoneuron terminal sprouting and ectopic reinnervation. These findings establish c-MAF as a critical mediator linking motoneuron activity to muscle gene regulation, fiber integrity, and neuromuscular junction maintenance in fast glycolytic fibers.

physiology↗