In this study, we determined the sequences of four intimin variant genes detected in attaching and effacing Escherichia coli isolates of human origin. Three of them were novel and were designated eae-(eta), eae-(iota), and eae-(kappa). The fourth was identical to the recently described eae-(zeta), isolated from a bovine E. coli O84:NM isolate. We compared these sequences with those of published intimin-␣, intimin-␤, intimin-␥1, intimin-␥2, intimin-, and intimin-alleles. Sequence analysis of these 10 intimin alleles confirmed extensive genetic diversity within the intimin gene family in E. coli. The genetic diversity was more prominent in the 3 region (starting at bp 2112), which encodes the binding domain of intimin. Phylogenetic analyses revealed four groups of closely related intimin genes: ␣ and ; ␤ and ; ␥1 and ␥2/; and and . Calculation of homoplasy ratios of sequences of the 5 region of eae (positions 1 to 2111) revealed evidence for intragenic recombination. Split decomposition analysis also indicates that recombination events have played a role in the evolutionary history of eae. In conclusion, we recommend an eae nomenclature system based on the Greek alphabet and provide an updated PCR scheme for amplification and typing of E. coli eae.

The effect of 2 different blends of essential oils on Clostridium perfringens (Cp) in the intestine and feces of broiler chickens was tested in 6 field trials for each blend. One hundred parts per million of the blends were mixed in a commercial corn-based diet throughout the entire growing period for experimental flocks. Samples from the jejunum, cecum, cloaca, and feces were taken on d 14, 21, and 30 from experimental and control flocks and tested quantitatively for Cp via blood agar plate, litmus milk medium, and ELISA. Blend A reduced (P < or = 0.05) the average Cp concentration in the feces on all sampling days, in the jejunum and cecum on d 14 and 21, and in the cloaca on d 14. Blend B effected a significant reduction of Cp concentration in the jejunum on d 14 and 30 and in the cloaca on d 14. The percentages of specimens from the control group that tested positive for Cp were 83.3% for feces, 88.0% for jejunum and cloaca, and 82.6% for cecum. Specimens from the feces and 3 sections of the intestine were Cp positive in groups treated with blend A (60.8, 64.6, 47.9, and 70.8%) and with blend B (65.9, 63.6, 63.6, and 72.7%). Our results indicate that specific blends of essential oil components can control Cp colonization and proliferation in the gut of broilers and therefore may be of help to prevent problems with Cp and necrotic enteritis.

Following the approach of Yu, Singh, and Krakauer [Phys. Rev. B 43 (1991) 6411] we extended the linearized augmented plane wave code WIEN of Blaha, Schwarz, and coworkers by the evaluation of forces. In this paper we describe the approach, demonstrate the high accuracy of the force calculation, and use them for an efficient geometry optimization of poly-atomic systems.

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Recent measurements of the scattering of He and Ne atoms at Rh (110) suggest that these two rare-gas atoms measure a qualitatively different surface corrugation: While Ne atom scattering seemingly reflects the electrondensity undulation of the substrate surface, the scattering potential of He atoms appears to be anticorrugated. An understanding of this perplexing result is lacking. In this paper we present density functional theory calculations of the interaction potentials of He and Ne with Rh (110). We find that, and explain why, the nature of the interaction of the two probe particles is qualitatively different, which implies that the topographies of their scattering potentials are indeed anticorrugated.