The year was 1948. It had only been about half a century since scientists had rediscovered Gregor Mendel’s work on inheritance in pea plants. This year, a scientist working on the genetics of the maize plant would challenge the then prevailing concept that genes are stable and arranged in an orderly manner on the chromosome.
Barbara McClintock at the Carnegie Institution found that some genes were able to move around within the genome. These genes were called mobile elements or transposons. Prof.
McClintock also made another significant observation: depending on where the mobile elements were inserted, they had the ability to reversibly alter gene expression. She used corn kernels’ colours as a surrogate to understand hereditary characteristics, and this way figured out transposons moved about in the genome of the maize plant. She was awarded the Nobel Prize in Physiology or Medicine in 1983 for this work.
Between 1948 and 1983, researchers found transposons in an array of life-forms, including bacteriophages, bacteria, plants, worms, fruit flies, mosquitos, mice, and humans. They were nicknamed ‘jumping genes’. ‘Sleeping beauty’ transposon The discovery of transposons revolutionised our understanding of genetics, in particular their role in enabling nature’s wondrous diversity.
Transposons influence the effects of genes by turning ‘on’ or ‘off’ their expression using a variety of epigenetic mechanisms. They are thus rightly called the tools of evolution.
