Branchial osteogenetic neoplasm in barbel Barbus barbus plebejus.

A branchial osteogenetic neoplasm affecting a barbel Barbus barbus plebejus (Valenciennes, 1829) is described. The osteoblasts' pleomorphism, the lack of a well-developed and complete separation, the presence of eccentric, terminal proliferative edges infiltrating the lining tissues and the abundant tumour matrix suggest a histopathological diagnosis of a 'productive osteoblastic osteosarcoma'. The occurrence of eosinophilic granule cells (EGCs) scattered among neoplastic tissue is discussed in relation to the neoplastic growth and the inflammatory reaction, with reference to recent discoveries in mammalian mast cell biology.     

Seasonal changes of zinc, copper, and iron in gilthead sea bream (Sparus aurata) fed fortified diets

Four groups of gilthead sea bream (Sparus aurata) were fed diets with additional metal contents: a basal diet (diet A) contained Zn at 60.9 ± 1.9 mg/kg diet, Cu at 3.9 ± 0.9 mg/kg diet, and Fe at 138.3 ± 6.8 mg/kg diet; the other diets were supplemented with copper (20 mg/kg, diet B), iron (100 mg/kg, diet C), or zinc (300 mg/kg, diet D). Two consecutive year-classes (0⁺ and 1⁺ age fish) from the same parent stock were examined. Several fish tissues were analyzed for metal contents in five different periods of each year in order to determine (1) the sensitivity of certain tissues as indicators of trace element metabolism and (2) possible seasonal variations. Growth data were similar for gilthead sea bream fed the basal diet and the metal-fortified diets. Mineral concentrations in tissues were found to be little affected by the dietary supplementation of trace elements, suggesting an efficient homeostatic control of these three metal concentrations. Tissues involved in metal metabolism (e.g., liver, kidney, gills) presented greater variations between minimum and maximum values with respect to other tissues (e.g., brain, muscle, eye). Seasonal variations were observed during the 2 yr of this study and were especially evident for zinc and copper concentrations in the liver. The overall pattern of metal variations showed a decreasing trend during the 2 yr. Results from this study indicate that (1) trace element concentrations in fish tissues vary with age and life cycle and (2) trace element requirements may vary in function of age and life cycle.     

Lack of excitatory amino acid-induced effects on calcium fluxes measured with45Ca2+ in rat cerebral cortex synaptosomes

Ca²⁺ uptake was measured in purified rat cerebral cortex synaptosomes (P₃ pellets) using⁴⁵Ca²⁺ as a tracer. Ca²⁺ influx increased in time, and with an increase in external K⁺ concentration and temperature. The net (external K⁺-induced, depolarization-dependent) uptake follows a two-component course. The exponential term, due to the opening of voltage-operated calcium channels (VOC), has a rate constant which increases with an increase in the depolarization level (1.04 versus 0.54 nmol/s/mg protein for 50 mM—versus 15 mM [K⁺]-dependent net influx). The linear term, due to the Na⁺/Ca²⁺ exchange system, has a similar rate constant at all depolarization levels (0.16+/–0.05 and 0.11+/–0.02 nmol/s/mg protein). Excitatory amino acids (glutamate, kainate and n-methyl-d-aspartate-NMDA-) were tested on this preparation at doses ranging between 5×10^–5 M and 5×10^–3M and at multiple incubation times, under resting conditions and under two depolarizing conditions (partial depolarization: 15 mM external K⁺ and maximal depolarization: 50 mM external K⁺). NMDA was also tested in the absence of Mg²⁺. No effect was detectable under any of these experimental conditions. Hypotheses to interpret these data are discussed. Further studies on other preparations are needed in order to directly investigate the presynaptic effects of excitatory amino acids.