Psychological prenatal stress reduced the number of BrdU immunopositive cells in the dorsal hippocampus without affecting the open field behavior of male and female rats at one month of age.

We examined whether prenatal psychological stress with little physical stress causes changes in the behavior and neurogenesis of the offspring of Sprague-Dawley rats at one month. Dams in the last trimester of gestation were psychologically stressed by placing them in a social communication box and shocking a rat on the other side of a transparent wall. They suffered little physical stress.

Prenatal psychological stress causes higher emotionality, depression-like behavior, and elevated activity in the hypothalamo-pituitary-adrenal axis.

In humans, stressful events during pregnancy may raise the risk of psychiatric disorders in offspring, and studies with rodents have found that physical prenatal stress can cause changes in the physiology, neurobiology, and behavior of offspring. In the present study, we examined whether psychological prenatal stress with little physical stress could cause changes in the neurobiology and behavior of offspring in Sprague-Dawley rats, as physical prenatal stress did. Dams received psychological stress by observing a rat being electrically shocked behind a transparent wall in the social communication box during the last trimester of gestation but were not exposed to any physical stress.

Distribution of the secondary type III secretion system locus found in enterohemorrhagic Escherichia coli O157:H7 isolates among Shiga toxin-producing E. coli strains.

The ability of the complete genome sequence of enterohemorrhagic Escherichia coli O157 led to the identification of a 17-kb chromosomal region which contained a type III secretion system gene cluster at min 64.5. This locus contains open reading frames whose amino acid sequences show high degrees of similarity with those of proteins that make up the type III secretion apparatus, which is encoded by the inv-spa-prg locus on a Salmonella SPI-1 pathogenicity island.