Larry Simpson

Larry Simpson is an American molecular parasitologist and emeritus professor of microbiology, Immunology, and Molecular Genetics at the University of California, Los Angeles. He is known as one of the founders of modern molecular parasitology and for his research on the structure and function of kinetoplast DNA (kDNA) and for the discovery of guide RNAs in trypanosomatid parasites.

He became a Fellow of the American Academy of Microbiology in 2010 and a Member of the American Academy of Arts and Sciences in 2012.

Early life and education Simpson was born in Philadelphia, Pennsylvania, where he developed an early fascination with science through frequent visits to libraries and natural history museums.

Academic career After completing a postdoctoral fellowship in Brussels, Simpson joined the faculty at UCLA in 1968, where he would spend the remainder of his career. From 1992 to 2005, he served as a Howard Hughes Medical Institute Investigator. Upon his retirement in 2014, Simpson was named emeritus Professor of Microbiology, Immunology, and Molecular Genetics at UCLA. Under his guidance, the lab identified the arrangement of interlocked minicircles and maxicircles, described replication sites within the network, and advanced models of kinetoplast DNA maintenance.

Research Simpson's early research revealed that kinetoplast DNA consists of thousands of interlocked minicircles and maxicircles, organized into species-specific networks. His group identified the antipodal nodes that were initially thought to serve as sites of minicircle DNA replication but actually served as sites of catenation of newly replicated minicircles. He also demonstrated that all mitochondrial tRNAs in kinetoplastid parasites are imported from the nucleus and undergo novel intramitochondrial editing events.

He also created the U-insertion/deletion Edited Sequence Database, an online resource for researchers studying RNA editing, and co-developed one of the first freely available online courses in molecular parasitology.

His laboratory had previously sequenced a portion of the Leishmania maxicircle mitochondrial DNA and he searched for small sequences that could base pair with the edited regions. The search was successful only when GU base pairs, which were found in tRNAs and ribosomal RNAs, were allowed, in addition to GC base pairs. Seven such regions of base pairing were identified and the resulting small transcripts were coined "Guide RNAs". He and his colleagues discovered later that guide RNAs were encoded by kDNA minicircles in other cryptogenes rather than by maxicircles.

Awards He was named a Howard Hughes Medical Institute Investigator in 1992,

Selected publications