[Effects of fluoride on oxidative stress and apoptosis in primary culture of rat sertoli cells].

OBJECTIVE: To study effects of fluoride on oxidative stress and apoptosis in rat sertoli cells. METHODS: Intracellular reactive oxygen species (ROS) , malondialdehyde (MDA) content, superoxide dismutase (SOD) activity, mitochondrial membrane potential and percentage of apoptosis were measured after the rat sertoli cells were incubated with 0, 6, 12 and 24 microg/ml sodium fluorides or 24 hours in vitro. RESULTS: Fluoride decreased the cell activity significantly (P < 0.01). The results suggested that exposure to fluoride significantly increased the level of ROS and MDA content (P < 0.01), fluoride also decreased SOD activity significantly (P < 0.05 or P < 0.01). In addition, with the NaF dose increased, there is a significantly decreasing in mitochondrial membrane potential and a significantly increasing in early apoptosis rate (P < 0.01). CONCLUSION: Fluoride can induce excessive oxidative stress and increased apoptosis rate in rat sertoli cells.

Motion-driven flow in an unusual piscine nasal region.

Fishes have several means of moving water to effect odorant transport to their olfactory epithelium ('olfactory flow'). Here we show that olfactory flow in the adult garpike Belone belone (Belonidae, Teleostei), a fish with an unusual nasal region, can be generated by its motion relative to water (swimming, or an external current, or both). We also show how the unusual features of the garpike's nasal region influence olfactory flow. These features comprise a triangular nasal cavity in which the olfactory epithelium is exposed to the external environment, a papilla situated within the nasal cavity, and an elongated ventral apex. To perform our investigation we first generated life-like plastic models of garpike heads from X-ray scans of preserved specimens. We then suspended these models in a flume and flowed water over them to simulate swimming. By directing filaments of dye at the static models, we were able to visualise flow in the nasal regions at physiologically relevant Reynolds numbers (700-2,000). We found that flow of water over the heads did cause circulation in the nasal cavity. Vortices may assist in this circulation. The pattern of olfactory flow was influenced by morphological variations and the asymmetry of the nasal region. The unusual features of the nasal region may improve odorant sampling in the garpike, by dispersing flow over the olfactory epithelium and by creating favourable conditions for odorant transport (e.g. steep velocity gradients). Unexpectedly, we found that the mouth and the base of the garpike's jaws may assist the sampling process. Thus, despite its apparent simplicity, the garpike's nasal region is likely to act as an effective trap for odorant molecules.