Lawsonia intracellularis in rodents from pig farms with the occurrence of porcine proliferative enteropathy.

AIM: Lawsonia intracellularis is an obligate intracellular bacterium causing proliferative enteropathy in certain species of domestic, laboratory and captive animals. The aim of our study was to detect L. intracellularis in free-living rodents from pig farms in the Czech Republic. METHODS AND RESULTS: Lawsonia intracellularis was demonstrated, using nested polymerase chain reaction, in the intestinal mucous membranes of 107 (36%) out of 296 small terrestrial mammals collected. In rodents, the bacterium was detected in 91 of 213 house mice, one of six brown rats, eight of 51 striped field mice, three of 12 yellow-necked mice and three of nine common voles. Moreover, one of one tested lesser white-toothed shrew (Insectivora) was positive. In 17 out of 69 (25%) rodents tested, serum IgG antibodies against L. intracellularis were detected using an indirect immunofluorescence antibody test. All seropositive animals were house mice. CONCLUSIONS: Free-living rodents may be serving as host or reservoir species and may be playing a role in the spread of L. intracellularis both within pig farms and in its transmission between farms and into the natural environment. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first detection of L. intracellularis in free-living small mammalian terrestrial species.

Developmental effects of magnetic field (50 Hz) in combination with ionizing radiation and chemical teratogens.

The influence of a 50 Hz magnetic field (MF) on avian and mammalian embryogenesis, the MF level and vector, as well as the effect of exposure to MF (50 Hz, 10 mT) in combination with X-rays has been recently reported [2,3]. No significant alterations of chick or rat embryogenesis were found after repeated exposures to 50 Hz MF at 10 mT or 6 microT or with different vectors. However, X-ray chick embryotoxicity was significantly affected by repeated exposures of developing organisms to MF. A strong dependence of effect on the type of interaction was revealed. A decrease of X-ray induced teratogenicity was observed when MF preceded X-ray exposure (indirect interaction), while MF exposure applied immediately after X-ray radiation (direct interaction) non-significantly potentiated adverse developmental effects of ionizing radiation. This study deals with the effects of MF in combination with insulin or tetracycline. Exposure of chick embryos to MF influenced the sensitivity of embryonic morphogenetic systems to the subsequently administered chemical teratogens, insulin and/or tetracycline. A protective effect of MF was detected similarly as in the case of indirect interaction with ionizing radiation.

Genotoxic and embryotoxic effects of 5-bromodeoxyuridine in the chick embryo.

Chick embryos were exposed intra-amniotically to the thymidine analog bromodeoxyuridine (BrdU) in order to study its embryotoxic and genotoxic effects. Teratogenic effects were observed at doses of BrdU which failed to produce mitotic inhibition, clastogenic effects or any significant increase in sister chromatid exchanges. Clastogenic effects and depressed cell proliferation were observed only at high embryolethal doses. Thus, BrdU-induced teratogenicity was independent of genotoxic effects manifested at chromosomal level. On the contrary, a significant increase of DNA single strand breaks was detected even 24 hours after the administration of teratogenic dose. BrdU incorporation in the DNA does not appear to prevent embryonic cells from mitotic proliferation. Whether the single strand breaks in DNA would ultimately lead to BrdU-induced teratogenesis in chick embryos remained undetermined.