Muller was a student of TH Morgan, and his search for a more efficient way of generating observable mutational changes led to the discovery of the mutagenic properties of X-rays and other forms of ionizing radiation. For this, he received the Nobel Prize in 1946. Muller held Marxist political views, and experienced difficulties in his initial faculty positions at Rice University in Houston and the University of Texas, Austin. He lived and worked in the Soviet Union between 1932 ~ 1936, before the increasingly anti-Mendelian influence of TD Lysenko made his position untenable. In later years he spoke out against the negative health effects of radiation and nuclear weapons testing.