Reverse Northern Blot
A variant of the procedure known as the reverse northern blot is occasionally used. In this procedure, the substrate nucleic acid (that is affixed to the membrane) is a collection of isolated DNA fragments, and the probe is RNA extracted from a tissue and radioactively labelled.
The use of DNA microarrays that have come into widespread use in the late 1990s and early 2000s is more akin to the reverse procedure, in that they involve the use of isolated DNA fragments affixed to a substrate, and hybridization with a probe made from cellular RNA. Thus the reverse procedure, though originally uncommon, enabled northern analysis to evolve into gene expression profiling, in which many (possibly all) of the genes in an organism may have their expression monitored.
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Famous quotes containing the words reverse, northern and/or blot:
“They shall beat their swords into plowshares, and their spears into pruninghooks: nation shall not lift up sword against nation, neither shall they learn war any more.”
—Bible: Hebrew Isaiah, 2:4.
The words reappear in Micah 4:3, and the reverse injunction is made in Joel 3:10 (”Beat your plowshares into swords ...”)
“Warmest climes but nurse the cruelest fangs: the tiger of Bengal crouches in spiced groves of ceaseless verdure. Skies the most effulgent but basket the deadliest thunders: gorgeous Cuba knows tornadoes that never swept tame northern lands.”
—Herman Melville (1819–1891)
“Lo, thus, as prostrate, ‘In the dust I write
My heart’s deep languor and my soul’s sad tears.’
Yet why evoke the spectres of black night
To blot the sunshine of exultant years?”
—James Thomson (1834–1882)