{'fraction_non_alphanumeric': 0.015188335358444714, 'fraction_numerical': 0.0018226002430133657, 'mean_word_length': 5.145522388059701, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Live imaging of adult neural stem cell behavior in the intact and injured zebrafish brain

How to maintain a zebrafish brain Even in the zebrafish brain, which seems better able than the human brain to generate new neurons, regenerative capacity may not be unlimited. Barbosa et al. mapped the fates of individual neuronal cells in live zebrafish over time. Seen as glowing dots, neural stem cells sustain the population of neurons, although not quite at full replacement rates. After injury to the brain, more of the stem cells were pulled into neuronal pathways, with fewer remaining to feed future replacement. Science, this issue p. 789 In zebrafish brains, changes in the behavior of stem cells underlie generation of additional neurons during regeneration. Adult neural stem cells are the source for restoring injured brain tissue. We used repetitive imaging to follow single stem cells in the intact and injured adult zebrafish telencephalon in vivo and found that neurons are generated by both direct conversions of stem cells into postmitotic neurons and via intermediate progenitors amplifying the neuronal output. We observed an imbalance of direct conversion consuming the stem cells and asymmetric and symmetric self-renewing divisions, leading to depletion of stem cells over time. After brain injury, neuronal progenitors are recruited to the injury site. These progenitors are generated by symmetric divisions that deplete the pool of stem cells, a mode of neurogenesis absent in the intact telencephalon. Our analysis revealed changes in the behavior of stem cells underlying generation of additional neurons during regeneration.