Infrasound initiates directional fast-start escape responses in juvenile roach Rutilus rutilus.

Acoustic stimuli within the sonic range are effective triggers of C-type escape behaviours in fish. We have previously shown that fish have an acute sensitivity to infrasound also, with acceleration thresholds in the range of 10(-5) m s(-2). In addition, infrasound at high intensities around 10(-2) m s(-2) elicits strong and sustained avoidance responses in several fish species.

The small bovine amelogenin LRAP fails to rescue the amelogenin null phenotype.

Amelogenins are the most abundant secreted proteins in developing dental enamel. These evolutionarily-conserved proteins have important roles in enamel mineral formation, as mutations within the amelogenin gene coding region lead to defects in enamel thickness or mineral structure. Because of extensive alternative splicing of the primary RNA transcript and proteolytic processing of the secreted proteins, it has been difficult to assign functions to individual amelogenins.

Over- and ectopic expression of Wnt3 causes progressive loss of ameloblasts in postnatal mouse incisor teeth.

Intercellular signaling is essential for the development of teeth during embryogenesis and in maintenance of the continuously growing incisor teeth in postnatal rodents. WNT intercellular signaling molecules have been implicated in the regulation of tooth development, and the Wnt3 gene shows specific expression in the enamel knot at the cap stage. We demonstrate here that Wnt3 also is expressed in specific epithelial cell layers in postnatal incisor teeth.

Expression, gene regulation, and roles of Fisp12/CTGF in developing tooth germs.

Odontogenesis involves multiple events, including tissue-tissue interactions, cell proliferation, and cell differentiation, but the underlying mechanisms of regulation are far from clear. Because Fisp12/CTGF is a signaling protein involved in similar events in other systems, we asked whether it is expressed in developing tooth germs and what roles it may have. Indeed, Fisp12/CTGF transcripts were first expressed by dental laminas, invaginating epithelium, and condensing mesenchyme at the bud stage, and then became abundant in enamel knot and preameloblasts.

Amelogenin-deficient mice display an amelogenesis imperfecta phenotype.

Dental enamel is the hardest tissue in the body and cannot be replaced or repaired, because the enamel secreting cells are lost at tooth eruption. X-linked amelogenesis imperfecta (MIM 301200), a phenotypically diverse hereditary disorder affecting enamel development, is caused by deletions or point mutations in the human X-chromosomal amelogenin gene. Although the precise functions of the amelogenin proteins in enamel formation are not well defined, these proteins constitute 90% of the enamel organic matrix.