Brain metabolic DNA (BMD) is continuously synthesized by reverse transcription in presynaptic synaptosomes and astroglia, and is partly transferred to nuclei after acquiring the double stranded configuration. Synthesis and turnover of BMD are markedly dependent on brain activity, as shown by circadian oscillations, environmental enrichment and impoverishment, and a variety of learning protocols. In rodents learning a two-way active avoidance task, BMD synthesis doubles, thus raising the possibility that sequences of learning BMD may differ from control BMD. The hypothesis has now been examined by sequencing cytoplasmic BMD. The present data indicate that most high-quality mapped BMD fragments hosting more than seven sequences are present in all mice. Three of them are exclusively present in learning BMD and four in control BMD. In addition, the annotated genes closest to them are mostly involved in modulating synaptic activity. The data support the conclusion that learning BMD sequences encode brain responses to the modified environment.

中文翻译：

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逆转录脑DNA的序列通过学习进行修改。

脑代谢DNA（BMD）通过突触前突触小体和星形胶质细胞中的逆转录连续合成，并在获得双链构型后部分转移到核中。BMD的合成和周转明显取决于大脑活动，如昼夜节律振荡，环境丰富和贫困以及各种学习方案所表明的那样。在学习双向主动回避任务的啮齿动物中，BMD合成加倍，从而增加了学习BMD的顺序可能与对照BMD不同的可能性。现在已经通过对细胞质BMD进行测序来检验该假说。目前的数据表明，在所有小鼠中都存在着包含七个以上序列的大多数高质量定位BMD片段。其中三个专门用于学习BMD，四个专门用于控制BMD。此外，最接近它们的注释基因主要参与调节突触活性。数据支持这样的结论：学习BMD序列编码大脑对修改后的环境的反应。