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Discusses the multistate outbreaks of Salmonella serotype Poona infections associated with eating cantaloupe imported from Mexico in the spring of consecutive years during 2000-2002. Background on pulsed-field gel electrophoresis; Number of cases reported in the U.S.; Information on the traceback investigations of cantaloupe purchased by patients, conducted by the U.S. Food and Drug Administration.

Isozymes of leucine aminopeptidase (LAP) in leaf tissue of the cultivated chenopods (Chenopodium quinoa and C. nuttalliae) and their sympatric weedy relatives (C. hircinum and C. berlandieri) can be electrophoretically resolved into a sum total of five anodally migrating bands. These are the products of two unlinked gene loci which apparently reflect genetic duplication via allotetraploidy. Accessions from the Andean and Mexican areas of cultivation are characterized by a lack of electrophoretically detectable variation. Andean weed and cultigen accessions appear to be genetically identical at both Lap loci, as do weed and cultigen material from Mexico. The two cultigens, and their sympatric weeds, can be differentiated by variation at the Lap-B locus, whereas they are monomorphic at Lap-A. This locus is, however, highly polymorphic in weedy C. berlandieri populations of western North America.