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Theophilus Shickel Painter studied the structure and
function of chromosomes in the US during in the early to mid-twentieth century. Painter worked at
the University of Texas at Austin in Austin, Texas. In the 1920s
and 1930s, Painter studied the chromosomes of the salivary gland
giant chromosomes of the fruit fly (Drosophila
melanogaster), with Hermann J. Muller. Muller and Painter
studied the ability of X-rays to cause changes in the chromosomes
of fruit flies. Painter also studied chromosomes in mammals.
Dennis Lo, also called Yuk Ming Dennis Lo, is a
professor at the Chinese University of Hong Kong in Hong Kong,
China. In 1997, Lo discovered fetal DNA in maternal
plasma, which is the liquid component of a pregnant woman's
blood. By 2002, Lo distinguished the DNA differences between pregnant women
and their fetuses, enabling scientists to identify fetal DNA in pregnant
women's blood. Lo used his discoveries to develop several
non-invasive and prenatal genetic tests, including tests for blood
David Michael Rorvik is a science journalist who publicized advancements in the field of reproductive medicine during the late twentieth century. Rorvik wrote magazine articles and books in which he discussed emerging methods and technologies that contributed to the progression of reproductive health, including sex determination, in vitro fertilization, and human cloning. During that time, those topics were controversial and researchers often questioned Rorvik’s work for accuracy.
Max Ludwig Henning Delbrick applied his knowledge of theoretical physics to biological systems such as bacterial viruses called bacteriophages, or phages, and gene replication during the twentieth century in Germany and the US. Delbrück demonstrated that bacteria undergo random genetic mutations to resist phage infections. Those findings linked bacterial genetics to the genetics of higher organisms. In the mid-twentieth century, Delbrück helped start the Phage Group and Phage Course in the US, which further organized phage research.
Stanley Alan Plotkin developed vaccines in the United States during the mid to late twentieth century. Plotkin began his research career at the Wistar Institute in Philadelphia, Pennsylvania, where he studied the rubella virus. In pregnant women, the rubella virus caused congenital rubella syndrome in the fetus, which led to various malformations and birth defects. Using WI-38 cells, a line of cells that originated from tissues of aborted fetuses, Plotkin successfully created RA27/3, a weakened strain of the rubella virus, which he then used to develop a rubella vaccine.
Arthur W. Galston studied plant hormones in the United States during the late-twentieth century. His dissertation on the flowering process of soybean plants led others to develop Agent Orange, the most widely employed herbicide during the Vietnam War, used to defoliate forests and eliminate enemy cover and food sources. Galston protested the spraying of those defoliants in Vietnam, as they could be harmful to humans, animals, and the environment.