Arnold-StraubMr. and Mrs. Rudolph L. Arnold Jr. of Mount Sinai, Long Island,N.Y., announce the engagement of their daughter, Leslie Elizabeth,to Scott Griffin Straub, son of retired Lt, Col. and Mrs. Peter G.Straub, Fort Walton Beach.The wedding is scheduled June 9 at East Setauket, Long Island,NY.The bride-elect received a degree in marine biology from Florida Institute of Technology, Melbourne. She is employed as a research biologist at the Veterans Administration Medical Center, Gainesville.Her fiance, a graduate of Choctawhatchee High School, also is an alumnus of Florida Institute of Technology. He is a research biologist at VAMC and Shands Teaching Hospital, Gainesville.