John Dennehy at Evilutionary Biologust has done it again. This week's citation classic is, indeed, a classic. It's the Meselson-Stahl paper from 1958 demonstrating that DNA is replicated semi-conservatively [The Most Beautiful Experiment in Biology].
The description of the experiment as the "most beautiful experiment in biology" comes from John Cairns as quoted in Horace Judson's book The Eight Day of Creation [see The Story of DNA (Part 1)]. It's a description that few of us could dispute. I grew up on the stories of famous experiments like this one and everyone around me at the time wanted to be like Matt Meselson or Franklin Stahl. If they couldn't be Meselson or Stahl then maybe Jacob, Monod, Hershey, Pardee or a host of other members of the phage group. Personally, I was envious of those who worked on bacteriophage lambda.
Over the years we kept reminding each new generation of the Meselson-Stahl experiment by describing it in the textbooks. The figure on the left is from my 1994 book. I'm sure that any student who took biochemistry or molecular biology in the 70's, 80's, and even part of the 90's, was taught this experiment.
Alas, it's no longer in the textbooks and the current generation of students probably has no idea who Meselson and Stahl are. They're probably befuddled by the reference to the most beautiful experiment in biology.
I vividly remember the debate when we decided to take it out of the textbook. Now that we can describe the molecular machinery of DNA replication it follows naturally that replication has to be semi-conservative. It no longer seems necessary to describe a separate experiment that demonstrates this obvious fact. In fact, it is often counter-productive to do so since it requires setting up the context—a time when this strong prediction of Watson and Crick had not been tested. That's not easy when even high school students know the facts.
So out it went, but not without some sadness for the passing of an era. I suppose it won't be long before some other experiment takes its place as the most beautiful. It will probably be something to do with microarrays or florescent dyes.
Many of the classic experiments are no longer taught to undergraduates. It's the nature of the beast, I suppose. Those experiments became classics because they showed us something we didn't know previously. That "something" was so important that it now seems obvious. We don't need to teach it.