Mandibular bone fluoride levels and occurrence of fluoride induced dental lesions in populations of wild red deer (Cervus elaphus) from Central Europe.

Mandibular bone fluoride concentrations as well as frequency and intensity of fluoride-induced dental lesions were studied in four red deer populations from Czechia and Germany exposed to different levels of environmental fluoride. The degree of fluorosis in the permanent cheek teeth was recorded by a scoring system and the individual mandibles assigned to one of three categories (unfluorosed, slightly to moderately fluorosed, and markedly to severely fluorosed) on the basis of the tooth scores. An increase in the frequency and severity of dental fluorosis was positively associated with an increase in bone fluoride level, which itself was significantly different between the four samples. In all samples, the rate of bone fluoride accumulation was higher in younger than in older deer. The results of this study show that frequency and intensity of dental fluorosis can be used as valid indicators of increased fluoride exposure of deer populations, and thus as a quick, easy, economic and reliable means of monitoring fluoride pollution in areas inhabited by wild deer.

Mandibular bone fluoride accumulation in wild red deer (Cervus elaphus L.) of known age.

Mandibular bone fluoride concentration and its relation to age were studied in a sample of 39 red deer of known age (between 2 and 18 years) from an area not exposed to increased fluoride deposition (Harz mountains, Germany). Bone fluoride level ranged from 208 to 1026 ppm dry weight and was positively correlated with age (r = 0.808, P < 0.001), the rate of skeletal fluoride accumulation being higher in younger individuals. This indicates that during the period of skeletal growth, fluoride uptake is more rapid than in later life when accumulation at a lower rate occurs during normal bone turnover. Bone fluoride levels found in the present sample are regarded as resulting from "normal" fluoride exposure in a recent central European red deer population.

Mandibular fluoride concentration and its relation to age in roe deer (Capreolus capreolus L.).

1. Mandibular fluoride content was recorded in 63 roe deer (33 males, 30 females) between 9 months and 10 years of age, taken from an area in SW Germany not exposed to increased fluoride deposition. 2. Bone fluoride level was positively correlated with age (t-test, P less than or equal to 0.001), the increase in concentration being higher in younger animals and declining in older deer. 3. In the sample studied, no significant sex specific difference in mean mandibular fluoride concentration was found (t-test, P greater than 0.05).

Differential growth in the brain of the weakly electric fish, Apteronotus leptorhynchus (Gymnotiformes), during ontogenesis.

Growth characteristics of the total brain and of several individual brain regions are described in Apteronotus leptorhynchus. The increase of brain volume relative to total length growth results in a sigmoid growth curve, in which three phases--proportional growth, positive-allometric and negative-allometric growth--could be distinguished. This type of enlargement of the total brain is due to the differential volume increase of individual brain regions and to the increase in the volume of the rhombencephalic structures in particular. Pros- and mesencephalic regions mainly grow in accordance with the overall enlargement of the total brain throughout development, whereas rhombencephalic and certain nuclear structures show such isometric growth only with the onset of the juvenile period. The results are interpreted in the view of functionality of the individual brain regions.