Definition: In this task, you're given a passage, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.
Input: Passage: Hebert Boyer was born in 1936 in Derry, corner of western Pennsylvania where railroads and mines were the destiny of most young men. He received his bachelor's degree in biology and chemistry from Saint Vincent College in Latrobe, Pennsylvania, in 1958. He married his wife Grace the following year. He received his PhD at the University of Pittsburgh in 1963 and participated as an activist in the civil rights movement. He spent three years in post-graduate work at Yale University in the laboratories of Professors Edward Adelberg and Bruce Carlton, then became an assistant professor at the University of California, San Francisco and a Professor of Biochemistry from 1976 to 1991, where he discovered that genes from bacteria could be combined with genes from eukaryotes. In 1977, Boyer's laboratory and collaborators Keiichi Itakura and Arthur Riggs at City of Hope National Medical Center described the first-ever synthesis and expression of a peptide-coding gene. In August 1978, he produced synthetic insulin using his new transgenic genetically modified bacteria, followed in 1979 by a growth hormone.
 Link Information:  He obtained a PhD in Organic Chemistry at Tokyo Pharmaceutical College in 1970. Question: Which of Boyer's collaborators in 1977 completed their education first?
Output:
Answer: Arthur Riggs