sentences:  During summers while he was in college, Haussler worked for his brother, Mark Haussler, a biochemist at the University of Arizona studying vitamin D metabolism.They were the first to measure the levels of 1alpha,25-dihydroxyvitamin D3, the hormonal form of vitamin D, in the human bloodstream.Between 1975 and 1979 he traveled and worked a variety of jobs, including a job at a petroleum refinery in Burghausen, Germany, tomato farming on Crete, and farming kiwifruit, almonds, and walnuts in Templeton, CA.