Muller conducted experiments in the 1920s exposing fruit flies to x-rays to induce genetic mutations. He found that x-ray exposure did cause mutations in the flies' genes, especially in egg and sperm cells. This helped establish the link between radiation exposure and genetic mutations. Muller developed methods like the CLB and Muller 5 techniques to efficiently screen flies for recessive mutations on the X chromosome. His pioneering research on environmental mutagens like radiation and temperature laid the foundations for the field of genetics.

1. DETECTION OF
MUTATION BY CLB
AND MULLER METHOD

2. INTRODUCTION

3. • Hermann Joseph Muller conducted three experiments between 1926 and 1927 to
investigate the effects of x-ray exposure on genetic mutations.
• He used fruit flies (Drosophila) as his experimental subjects due to their short
lifespan, ease of breeding, and well-defined genetic characteristics.
• Muller exposed the fruit flies to x-rays, a form of high-energy radiation, to induce
genetic mutations in their DNA.
• After exposing the flies to x-rays, Muller mated them and observed the offspring to
assess the frequency and nature of genetic mutations.
• His experiments demonstrated that x-ray exposure caused mutations in the genes
of fruit flies, particularly in their egg and sperm cells.
• Muller's findings were published in two seminal papers in 1927: "Artificial
Transmutation of the Gene" and "The Problem of Genic Modification."

4. • These papers detailed the results of his experiments and their implications for
understanding the mechanisms of genetic mutation.
• Muller's research laid the groundwork for understanding the relationship between
radiation exposure and genetic mutations.
• His work highlighted the importance of studying the effects of environmental factors
on genetic material and contributed significantly to the field of genetics.
• In recognition of his pioneering research, Muller was awarded the Nobel Prize in
Physiology or Medicine in 1946.
• Muller studied the role of temperature as a possible mutagen, or cause of genetic
mutations.
• He showed that high temperatures had the capability to mutate genes. Through his
work studying the effects of temperature on genetic mutations, Muller developed a
method to quantify the number and frequency of mutations which he used in his later
experiments with radiation.

5. CLB METHOD

6. A technique devised by Muller to rapidly screen fruit flies for recessive X chromosome lethal
mutations. The ClB chromosome carries a recessive lethal (l) a dominant marker (B) and an
inversion (crossover suppressor C).
Phenotypic ratio
2:1 – not mutated
Only female-mutated

7. Muller 5 Method

8. • This method was also developed by Muller to detect sex linked mutation in Drosophila.
This method is an improved version of CIB method.
• This method differs from CIB method in two important aspects.
1) First, this method utilizes apricot recessive gene in place of recessive lethal in
CIB method.
2) Second, the female is homozygous for bar apricot genes, whereas it is
heterozygous for IB genes in CIB method.
• In this method, the mutation is detected by the absence of wild males in F2 progeny.

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