Altered acetylcholine release in the hippocampus of dystrophin-deficient mice.

Mild cognitive impairments have been described in one-third of patients with Duchenne muscle dystrophy (DMD). DMD is characterized by progressive and irreversible muscle degeneration caused by mutations in the dystrophin gene and lack of the protein expression. Previously, we have reported altered concentrations of α7- and ß2-containing nicotinic acetylcholine receptors (nAChRs) in hippocampal membranes of dystrophic (mdx) mice. This suggests that alterations in the central cholinergic synapses are associated with dystrophin deficiency. In this study, we examined the release of acetylcholine (ACh) and the level of the vesicular ACh transporter (VAChT) using synaptosomes isolated from brain regions that normally have a high density of dystrophin (cortex, hippocampus and cerebellum), in control and mdx mice at 4 and 12months of age. ACh release evoked by nicotinic stimulation or K(+) depolarization was measured as the tritium outflow from superfused synaptosomes preloaded with [(3)H]-choline. The results showed that the evoked tritium release was Ca(2+)-dependent and mostly formed by [(3)H]-ACh. ß2-containing nAChRs were involved in agonist-evoked [(3)H]-ACh release in control and mdx preparations. In hippocampal synaptosomes from 12-month-old mdx mice, nAChR-evoked [(3)H]-ACh release increased by 57% compared to age-matched controls. Moreover, there was a 98% increase in [(3)H]-ACh release compared to 4-month-old mdx mice. [(3)H]-ACh release evoked by K(+) depolarization was not altered, while the VAChT protein level was decreased (19%) compared to that of age-matched controls. In cortical and cerebellar preparations, there was no difference in nAChR-evoked [(3)H]-ACh release and VAChT levels between mdx and age-matched control groups. Our previous findings and the presynaptic alterations observed in the hippocampi of 12-month-old mdx mice indicate possible dysfunction of nicotinic cholinergic synapses associated with dystrophin deficiency. These changes may contribute to the cognitive and behavioral abnormalities described in dystrophic mice and patients with DMD.

Characterization of the fishes and of subsistence fishing in the Pantanal of Mato Grosso, Brazil

Fishing is one of the oldest human activities in the Pantanal of Mato Grosso in Central Brazil. In the of Bento Gomes River Basin (Pantanal of Poconé) the presence of fishermen is very common. The objective of this study is to describe the fishing activity in the basin in view of the elaboration of proposals for the sustainable use of this natural resource. Of the 256 fishermen that were registered most are fishing for their subsistence (92 percent) and the rest (8 percent) are occasional fishermen (locally called "de lufada" fishermen). "Traíra" (Hoplias gr. malabaricus) and "piranhas" (Serrasalmus marginatus, Serrasalmus spilopleura and Pygocentrus nattereri) were the species most frequently captured for human consumption. The fishing is more intensive during the ebb season and at the beginning of the drought season, when the waters begin to recede for the river channel, as the catch is facilitated by the concentration of fishes at the river margin. The fishermen and their families consume fish three to four times a week, twice a day. Fish meat is one of the only means of obtaining animal protein for dozens of poor families in the area. The number of fishermen, as well as the actual number of catches do not appear to compromise the natural fish stocks, although no specific capture criteria is obeyed by the fishing activity

Characterization of the fishes and of subsistence fishing in the Pantanal of Mato Grosso, Brazil.

Fishing is one of the oldest human activities in the Pantanal of Mato Grosso in Central Brazil. In the of Bento Gomes River Basin (Pantanal of Poconé) the presence of fishermen is very common. The objective of this study is to describe the fishing activity in the basin in view of the elaboration of proposals for the sustainable use of this natural resource. Of the 256 fishermen that were registered most are fishing for their subsistence (92%) and the rest (8%) are occasional fishermen (locally called "de lufada" fishermen). "Traíra" (Hoplias malabaricus) and "piranhas" (Serrasalmus marginatus, Serrasalmus spilopleura and Pygocentrus nattereri) were the species most frequently captured for human consumption. The fishing is more intensive during the ebb season and at the beginning of the drought season, when the waters begin to recede for the river channel, as the catch is facilitated by the concentration of fishes at the river margin. The fishermen and their families consume fish three to four times a week, twice a day. Fish meat is one of the only means of obtaining animal protein for dozens of poor families in the area. The number of fishermen, as well as the actual number of catches do not appear to compromise the natural fish stocks, although no specific capture criteria is obeyed by the fishing activity.