FIG. 3.

Phylogenetic tree showing the relatedness of chick intestinal 16S rRNA sequences to sequences of Campylobacter species. The 16S rRNA clone libraries were produced by amplification of DNA extracted from the ileum, cecum, and yolk contents of day-of-hatching chicks and from the ileal and cecal contents of chickens that were 3 to 49 days old (23). The tree was constructed by neighbor-joining analysis of a distance matrix obtained from a multiple-sequence alignment of clone library sequences and GenBank ɛ-proteobacterial 16S rRNA sequences. Bootstrap values (expressed as percentages of 100 replications) are indicated at branch points. Branches labeled with DOH represent sequences obtained from the clone library from day-of-hatching chicks; branches labeled ileum or cecum (but without DOH) represent sequences obtained from clone libraries of older chickens. Branches labeled with a specific organism's name and accession number represent sequences obtained from the GenBank database.