Chapman Judith A, Weinstein Joshua L, Simmons Andrea Megela
Department of Psychology, Brown University, Providence, Rhode Island 02912-1853, USA.
J Neurobiol. 2006 Feb 5;66(2):115-33. doi: 10.1002/neu.20209.
During metamorphic development, bullfrogs (Rana catesbeiana) undergo substantial morphological, anatomical, and physiological changes as the animals prepare for the transition from a fully-aquatic to a semi-terrestrial existence. Using BrdU incorporation and immunohistochemistry, we quantify changes in cell proliferation in two key auditory brainstem nuclei, the dorsolateral nucleus and the superior olivary nucleus, over the course of larval and early postmetamorphic development. From hatchling through early larval stages, numbers of proliferating cells increase in both nuclei, paralleling the overall increase in total numbers of cells available for labeling. Numbers of proliferating cells in the superior olivary nucleus decrease during the late larval and deaf periods, and significantly increase during metamorphic climax. Proliferating cells in the dorsolateral nucleus increase in number from hatchling to late larval stages, decrease during the deaf period, and increase during climax. In both nuclei, numbers of proliferating cells decrease during the postmetamorphic froglet stage, despite increases in the number of cells available for label. Newly generated cells express either glial- or neural-specific phenotypes beginning between 1 week and 1 month post-BrdU injection, respectively, while some new cells express gamma-aminobutyric acid within 2 days of mitosis. Our data show that these auditory nuclei dramatically up-regulate mitosis immediately prior to establishment of a transduction system based on atmospheric hearing.
在变态发育过程中，牛蛙（Rana catesbeiana）会经历显著的形态、解剖和生理变化，以准备从完全水生过渡到半陆生生活。我们使用溴脱氧尿苷掺入法和免疫组织化学技术，量化了幼体和变态后早期发育过程中两个关键听觉脑干核团，即背外侧核和上橄榄核中细胞增殖的变化。从孵化到幼体早期阶段，两个核团中增殖细胞的数量均增加，这与可标记细胞总数的总体增加情况一致。上橄榄核中增殖细胞的数量在幼体后期和失聪期减少，在变态高峰期显著增加。背外侧核中增殖细胞的数量从孵化到幼体后期阶段增加，在失聪期减少，在高峰期增加。在两个核团中，尽管可标记细胞数量增加，但在变态后的幼蛙阶段增殖细胞数量减少。分别在注射溴脱氧尿苷后1周和1个月之间，新生成的细胞开始表达胶质细胞或神经特异性表型，而一些新细胞在有丝分裂后2天内表达γ-氨基丁酸。我们的数据表明，这些听觉核团在基于大气听觉的转导系统建立之前，会显著上调有丝分裂。
