The chief problem with previous methods for visualizing transcription in mammalian cells is that these require researchers to blast cells with hundreds of copies of the specially tagged gene.

以前的哺乳动物细胞基因转录可视化方法存在一个主要问题，那就是需要向细胞注入上百个特别标记的基因。

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The impressively named chief cells secrete pepsinogen which, when it mixes with stomach acid, becomes an enzyme called pepsin.

而令人印象深刻的主细胞则分泌胃蛋白酶原，当它与胃酸混合时，就形成一种酶，叫做胃蛋白酶。

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Chief cells make and secrete pepsinogen.

主细胞制造和分泌胃蛋白酶原。

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But Axona, which as been on the market since 2009, might keep healthy brain cells alive longer, says Chief Executive Holger Kunze.

WSJ: 'Medical Foods' and Supplements for Brain Health Advance

The price of silicon, the chief component of photovoltaic cells, is already falling.

ECONOMIST: Clean technology in the downturn

"The fifth base is like a switch - switching on the genes and making cells healthy or diseased, " Alex Olek, the chief executive of Epigenomics, told the BBC.

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