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 ...”)
“Sophocles long ago
Heard it on the Aegaean, and it brought
Into his mind the turbid ebb and flow
Of human misery; we
Find also in the sound a thought,
Hearing it by this distant northern sea.”
—Matthew Arnold (1822–1888)
“It is extraordinary how the house and the simplest possessions of someone who has been left become so quickly sordid.... Even the stain on the coffee cup seems not coffee but the physical manifestation of one’s inner stain, the fatal blot that from the beginning had marked one for ultimate aloneness.”
—Coleman Dowell (1925–1985)