Critics attacked the validity of the work and questioned whether prions exist at all, which claim had been criticized by other researchers as not yet proven. The existence of prions was not fully accepted by the scientific community for at least a decade after the awarding of the prize. 1993 The 1993 prize went to Phillip Allen Sharp and Richard J. Roberts "for their discoveries of split genes", the discovery of introns in eukaryotic DNA, and the mechanism of gene splicing. Several other scientists, such as Norman Davidson and James Watson, argued that Louise T. Chow, a China-born Taiwanese researcher who collaborated with Roberts, should have had part of the prize. In 1976, as Staff Investigator, Chow carried out the studies of the genomic origins and structures of adenovirus transcripts that led directly to the discovery of RNA splicing and alternative RNA processing at Cold Spring Harbor Laboratory on Long Island in 1977. Norman Davidson, a Caltech expert in electron microscopy under whom Chow apprenticed as a graduate student, affirmed that Chow operated the electron microscope through which the splicing process was observed, and was the crucial experiment's sole designer, using techniques she had developed. 1952 The 1952 prize was awarded to Selman Waksman "for his discovery of streptomycin, the first antibiotic effective against tuberculosis". Albert Schatz, who was a graduate student working under Waksman's direction at the time of discovery in 1943, petitioned the Nobel committee saying he had done all the work in isolating the antibiotic properties of Streptomyces griseus. Schatz, who two years earlier had successfully sued Waksman and Rutgers University for his share in the discovery, patent, and resulting royalties, was turned down by the Nobel committee. It was a reflection of the times when department heads were normally awarded the prize and has been looked on as a considerable mistake. 1935 The 1935 prize was awarded to Hans Spemann "for his discovery of the organizer effect in embryonic development". In 1991 Howard M. Lenhoff, then Professor of Developmental and Cell Biology at the University of California, published a paper pointing out that Ethel Browne Harvey should have shared in Spemann's Nobel Prize, because, as a graduate student, she had made a similar discovery many years earlier and understood its significance. Her work, done in 1909, preceded the experiments in 1924 by Spemann and Hilde Mangold that are credited with discovering the "organizer" — the work