Transposon corn cob in my office

I have been packing my office today in preparation for the move to the new building. Most of the effort has gone into sorting out research papers. But among my things I found the corn cob that I found some years ago while walking in Turkey. We were staying overnight in a farm, and the farmer had a harvest of cobs lying out to dry. I spotted this one and got very excited – and he very kindly gave it to me (neither he nor my fellow walkers could understand why I was so happy!)

It was by studying corn cobs like these that Barbara McClintock won the Nobel Prize for discovering mobile genetic elements, in this case transposons (we are doing some work on plasmids – see previous post).

On this cob, note that most of the ears are yellow, and a few are blue. These are genetically different, and have inherited their genes in ‘normal’ Mendelian fashion. The interesting ears are the three in the centre of the image, which are yellow with coloured streaks, that are immediately below the block of five blue ears. Barbara McClintock discovered that colour streaks are caused by mobile genetic elements – pieces of DNA that have been excised and spliced – a complete different process from meiotic recombination that gives rise to Mendelian inheritance. Nobel Prize winning stuff!


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