Michael Andreucci

Mullers role in his team at Columbia University had been to study mutations and figure out what specific genes were connected to certain chromosomes. What set Muller apart from other geneticists in his field was that Muller was strictly “interested in the physical and chemical nature and operations of genes” (Culliton). Muller conducted his experiments on fruit flies to test his hypothesis. The reason why Muller chose to use fruit flies was because he and his associates had noticed the rare “White-eyed” fruit fly. They knew it was a mutation but did not know much more about what caused it or how many fruit flies had white eyes. Muller was intrigued and decided to do some digging to figure out what outside source could have caused this mutation. He saw that X-rays had an effect on genes and decided to test his hypothesis that radiation could mutate the genes of a fruit fly. Mullers experiment was designed to test if radioactive particles would have an affect on single genes which would then lead to point mutations.  Muller wanted to forcibly modify the genes of a fruit fly to see how radioactivity would affect a fruit fly.

Hermann Muller used male fruit flies and subjected them to high doses of radiation. After he exposed them to the radiation he had them mate with female fruit flies. After a few weeks of trials Muller was able to successfully produce more than one-hundred genetic mutations to the fruit flies. He did this to multiple generations of fruit flies and found that every male fruit fly that was born that contained a certain gene was killed by the radiation and the other flies that did not have that gene survived. Most of the fruit flies that survived had some sort of mutation but there were some that showed no signs of mutation. Muller was responsible for inducing about half of the total number of mutations discovered in fruit flies over the previous fifteen years.

The mutations Muller induced had mixed effects on the fruit flies. Some of the mutations produced fatal results while others were non lethal. In a paper that Muller wrote in 1927 that addressed his experiment he claimed that “radioactive particles passing through the chromosomes randomly affected the molecular structure of individual genes, rendering them either inoperative or altering their chemical functions.”