Giardia lamblia (syn. Giardia intestinalis, Giardia duodenalis) is an enteric protozoan parasite with two nuclei, and it might be one of the earliest branching eukaryotes. However, the discovery of at least rudimentary forms of certain features, such as Golgi and mitochondria, has refuted the proposal that its emergence from the eukaryotic lineage predated the development of certain eukaryotic features. The recent recognition of many of the genes known to be required for meiosis in the genome has also cast doubt on the idea that Giardia is primitively asexual, but so far there has been no direct evidence of sexual reproduction in Giardia, and population data have suggested clonal reproduction. We did a multilocus sequence evaluation of the genotype A2 reference strain, JH, and five genotype A2 isolates from a highly endemic area in Peru. Loci from different chromosomes yielded significantly different phylogenetic trees, indicating that they do not share the same evolutionary history; within individual loci, tests for recombination yielded significant statistical support for meiotic recombination. These observations provide genetic data supportive of sexual reproduction in Giardia.

Background Giardia lamblia is ubiquitous in multiple communities of non-industrialized nations. Genotypes A1, A2, and B (Nash groups 1, 2, and 3, respectively) are found in humans, while genotypes C and D are typically found in dogs. However Genotypes A and B have occasionally been identified in dogs. Methods Fecal Giardia isolates from 22 families and their dogs, living in Pampas de San Juan, were collected over seven weeks in 2002 and six weeks in 2003. Samples were genotyped, followed by sequencing and haplotyping of many of these isolates, using loci on chromosomes 3 and 5. Results Human infections were all caused by isolates of genotypes A2 and B. Human co-infections with Genotypes A2 and B were common, and the reassortment pattern of different subtypes of A2 isolates supports prior observations suggesting recombination among Genotype A2 isolates. All dogs had genotypes C and/or D with one exception of a dog with a mixed B/D genotype infection. Conclusions In a highly endemic region where infected dogs and humans constantly commingle, different genotypes of Giardia are almost always found in dogs and humans, suggesting that zoonotic transmission is very uncommon.

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Campylobacter jejuni is one of the leading causes of bacterial gastroenteritis in the world; however, there is only one complete genome sequence of a poultry strain to date. Here we report the complete genome sequence and annotation of the second poultry strain, C. jejuni strain S3. This strain has been shown to be nonmotile, to be a poor invader in vitro , and to be a poor colonizer of poultry after minimal in vitro passage.

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