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In 1952 Esther and Joshua Lederberg used a square of velvet like a stamp to copy colonies of bacteria from one dish to others. Each colony kept its place, so they could see which ones grew on dishes laced with a virus or an antibiotic. Some bacteria, they found, were resistant before they ever met the threat.

Historical account — Stanford Medicine; Joshua and Esther Lederberg (1952)

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The experiment settled a long debate: did bacteria become resistant in response to a threat, or did random mutations, changes in their genes, arise first and the threat simply weed out the rest? The Lederbergs showed the second. Joshua shared the 1958 Nobel Prize in Physiology or Medicine for discoveries in bacterial genetics; Esther, his wife and research partner, did much of the laboratory work but received far less recognition. In 1950 she also discovered lambda, a virus that infects bacteria and became a key tool of molecular biology.

Türkçe oku
Esther ve Joshua Lederberg 1952'de bir parça kadifeyi mühür gibi kullanarak bakteri kolonilerini bir kaptan başka kaplara kopyaladı. Her koloni aynı yerde kaldığı için, virüs ya da antibiyotik eklenmiş kaplarda hangilerinin çoğaldığını görebildiler. Böylece bazı bakterilerin bu tehditle hiç karşılaşmadan önce dirençli olduğunu gösterdiler.

Deney uzun süren bir tartışmayı çözdü: Bakteriler bir tehditle karşılaşınca mı direnç kazanıyordu, yoksa genlerdeki rastgele değişiklikler, yani mutasyonlar önceden ortaya çıkıyor ve tehdit yalnızca dirençsiz olanları mı eliyordu? Lederberg çifti ikincisinin doğru olduğunu gösterdi. Joshua, bakteri genetiğindeki buluşlarıyla 1958 Nobel Fizyoloji veya Tıp Ödülü'nü paylaştı. Eşi ve araştırma ortağı Esther, laboratuvar çalışmalarının önemli bir kısmını yürütmesine rağmen çok daha az tanındı. Esther 1950'de, bakterileri enfekte eden ve moleküler biyolojinin temel araçlarından biri hâline gelen lambda virüsünü de keşfetti.

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