Effects of species turnover on reserve site selection in a fragmented landscape

Changes in species composition is an important process in many ecosystems but rarely considered in systematic reserve site selection. To test the influence of temporal variability in species composition on the establishment of a reserve network, we compared network configurations based on species data of small mammals and frogs sampled during two consecutive years in a fragmented Atlantic Forest landscape (SE Brazil). Site selection with simulated annealing was carried out with the datasets of each single year and after merging the datasets of both years. Site selection resulted in remarkably divergent network configurations. Differences are reflected in both the identity of the selected fragments and in the amount of flexibility and irreplaceability in network configuration. Networks selected when data for both years were merged did not include all sites that were irreplaceable in one of the 2 years. Results of species number estimation revealed that significant changes in the composition of the species community occurred. Hence, temporal variability of community composition should be routinely tested and considered in systematic reserve site selection in dynamic systems.

Voluntary action and causality in temporal binding

Previous studies have documented temporal attraction in perceived times of actions and their effects. While some authors argue that voluntary action is a necessary condition for this phenomenon, others claim that the causal relationship between action and effect is the crucial ingredient. In the present study, we investigate voluntary action and causality as the necessary and sufficient conditions for temporal binding. We used a variation of the launching effect proposed by Michotte, in which participants controlled the launch stimulus in some blocks. Volunteers reported causality ratings and estimated the interval between the two events. Our results show dissociations between causality ratings and temporal estimation. While causality ratings are not affected by voluntary action, temporal bindings were only found in the presence of both voluntary action and high causality. Our results indicate that voluntary action and causality are both necessary for the emergence of temporal binding.

CCP1/Nna1 functions in protein turnover in mouse brain: Implications for cell death in Purkinje cell degeneration mice

Purkinje cell degeneration (pcd) mice have a mutation within the gene encoding cytosolic carboxypeptidase 1 (CCP1/Nna1), which has homology to metallocarboxypeptidases. To assess the function of CCP1/Nna1, quantitative proteomics and peptidomics approaches were used to compare proteins and peptides in mutant and wild-type mice. Hundreds of peptides derived from cytosolic and mitochondrial proteins are greatly elevated in pcd mouse hypothalamus, amygdala, cortex, prefrontal cortex, and striatum. However, the major proteins detected on 2-D gel electrophoresis were present in mutant and wild-type mouse cortex and hypothalamus at comparable levels, and proteasome activity is normal in these brain regions of pcd mice, suggesting that the increase in cellular peptide levels in the pcd mice is due to reduced degradation of the peptides downstream of the proteasome. Both nondegenerating and degenerating regions of pcd mouse brain, but not wild-type mouse brain, show elevated autophagy, which can be triggered by a decrease in amino acid levels. Taken together with previous studies on CCP1/Nna1, these data suggest that CCP1/Nna1 plays a role in protein turnover by cleaving proteasome-generated peptides into amino acids and that decreased peptide turnover in the pcd mice leads to cell death.-Berezniuk, I., Sironi, J., Callaway, M. B., Castro, L. M., Hirata, I. Y., Ferro, E. S., Fricker, L. D. CCP1/Nna1 functions in protein turnover in mouse brain: Implications for cell death in Purkinje cell degeneration mice. FASEB J. 24, 1813-1823 (2010). www.fasebj.org

Effects of voluntary running on spatial memory and mature brain-derived neurotrophic factor expression in mice hippocampus after status epilepticus

Voluntary physical activity improves memory and learning ability in rodents, whereas status epilepticus has been associated with memory impairment. Physical activity and seizures have been associated with enhanced hippocampal expression of BDNF, indicating that this protein may have a dual role in epilepsy. The influence of voluntary physical activity on memory and BDNF expression has been poorly studied in experimental models of epilepsy. In this paper, we have investigated the effect of voluntary physical activity on memory and BDNF expression in mice with pilocarpine-incluced epilepsy. Male Swiss mice were assigned to four experimental groups: pilocarpine sedentary (PS), pilocarpine runners (PRs), saline sedentary (SS) and saline runners (SRs). Two days after pilocarpine-induced status epilepticus, the affected mice (PR) and their running controls (SR) were housed with access to a running wheel for 28 days. After that, the spatial memory and the expression of the precursor and mature forms of hippocampal BDNF were assessed. PR mice performed better than PS mice in the water maze test. In addition, PR mice had a higher amount of mature BDNF (14 kDa) relative to the total BDNF (14 kDa + 28 kDa + 32 kDa forms) content when compared with PS mice. These results show that voluntary physical activity improved the spatial memory and increased the hippocampal content of mature BDNF of mice with pilocarpine-induced status epilepticus. (C) 2009 Elsevier B.V. All rights reserved.