Age-Dependent Regulation of Notch Family Members in the Neuronal Stem Cell Niches of the Short-Lived Killifish .

The annual killifish is a new experimental model organism in biology, since it represents the vertebrate species with the shortest captive life span and also shows the fastest maturation and senescence recorded in the laboratory. Here, we use this model to investigate the age-dependent decay of neurogenesis in the telencephalon (brain region sharing the same embryonic origin with the mammalian adult niches), focusing on the expression of the Notch pathway genes. We observed that the major ligands/receptors of the pathway showed a negative correlation with age, indicating age-dependent downregulation of the Notch pathway. Moreover, expression of was clearly limited to active neurogenic niches and declined during aging, without changing its regional patterning. Expression of is not visibly influenced by aging. Both expression pattern and regulation differ between and , with the former being limited to mitotically active regions and reduced by aging and the latter being present in all cells with a neurogenic potential, regardless of the level of their actual mitotic activity, and so is less influenced by age. This finally suggests a possible differential role of the two receptors in the regulation of the niche proliferative potential throughout the entire fish life.