The 50th anniversary celebrations marking the discovery of the three-dimensional structure of DNA provide an opportunity to reflect on the key developments in the field of genetics over the past 50 years and to consider the future of genetic research (TIMELINE).

Timeline | DNA milestones

Before Watson and Crick's 1953 paper, Avery, MacLeod and McCarty in 1944, and Hershey and Chase in 1952, had provided the experimental data that established DNA as the heritable genetic material. With the knowledge of the structure of DNA, research then focused on its replication and information-encoding properties. In 1958, Meselson and Stahl showed that DNA replication is semi-conservative: new molecules consist of one original strand from the parental molecule and one new strand. Contributions by Crick, Brenner, Nirenberg, Khorana, Matthaei and Holley, among others, enabled the genetic code to be cracked by 1966. However, a remaining challenge is to understand the information that is encoded in regulatory DNA.

DNA sequencing has revolutionized genetics. The Sanger and Maxam-Gilbert methods were published in 1977. The first genome to be sequenced was the bacteriophage FX174 (∼5 kb) in 1980 and the first free-living organism to be sequenced was Haemophilus influenzae (∼1.8 Mb) in 1995. Recent advances have reduced the cost and enhanced the speed of sequencing, so the sequences of several whole genomes, from a wide taxonomic distribution, including the much anticipated human genome in 2001, are now published.

Another important technical breakthrough occurred in 1983 when Mullis developed the polymerase chain reaction (PCR). Many other tools for molecular biology have been developed over the past 50 years, including restriction enzymes, nucleic acid hybridization techniques, cloning and genetic engineering. The application of these methods has led to some interesting applications. Notably, gene therapy was first used in 1990 to treat a patient suffering with the immune disorder adenosine deaminase (ADA) deficiency; the first transgenic food — the FlavrSavr tomato — reached the supermarkets in 1994; and 'Dolly the sheep' — the first cloned mammal — was born in 1996.

Combining molecular biology techniques with the ever-expanding volume of genomic, proteomic and phenotypic data should enable geneticists to make further exciting developments over the next 50 years. There is little doubt that genetics will continue to benefit society, in particular through improvements in healthcare and agriculture.