The interaction of postural and voluntary strategies for stability in Parkinson's disease

de Lima-Pardini AC, Papegaaij S, Cohen RG, Teixeira LA, Smith BA, Horak FB. The interaction of postural and voluntary strategies for stability in Parkinson's disease. J Neurophysiol 108: 1244-1252, 2012. First published June 6, 2012; doi:10.1152/jn.00118.2012.-This study assessed the effects of stability constraints of a voluntary task on postural responses to an external perturbation in subjects with Parkinson's disease (PD) and healthy elderly participants. Eleven PD subjects and twelve control subjects were perturbed with backward surface translations while standing and performing two versions of a voluntary task: holding a tray with a cylinder placed with the flat side down [low constraint (LC)] or with the rolling, round side down [high constraint (HC)]. Participants performed alternating blocks of LC and HC trials. PD participants accomplished the voluntary task as well as control subjects, showing slower tray velocity in the HC condition compared with the LC condition. However, the latency of postural responses was longer in the HC condition only for control subjects. Control subjects presented different patterns of hip-shoulder coordination as a function of task constraint, whereas PD subjects had a relatively invariant pattern. Initiating the experiment with the HC task led to 1) decreased postural stability in PD subjects only and 2) reduced peak hip flexion in control subjects only. These results suggest that PD impairs the capacity to adapt postural responses to constraints imposed by a voluntary task.

Changes in spatial and temporal gene expression during incompatible interaction between common bean and anthracnose pathogen

Common bean, one of the most important legumes for human consumption, may have drastic reduction in yield due to anthracnose, a disease caused by the fungus Colletotrichum lindemuthianum. Rapid induction of the plant defense mechanisms is essential to establish an incompatible interaction with this pathogenic fungus. In this study, we evaluated spatial (leaves, epicotyls and hypocotyls) and temporal (24, 48, 72 and 96 hours after inoculation [HAI]) relative expression (RE) of 12 defense-related transcripts selected from previously developed ESTs libraries, during incompatible interaction between the resistant common bean genotype SEL 1308 and the avirulent anthracnose pathogen race 73, using real time quantitative RT-PCR (RT-qPCR) analysis. All selected transcripts, including the ones coding for pathogenesis-related (PR) proteins (PR1a, PR1b, PR2, and PR16a and PR16b) were differentially regulated upon pathogen inoculation. The expression levels of these transcripts were dependent on the tissue and time post inoculation. This study contributes to a better understanding of the kinetics of induced defenses against a fungal pathogen of common bean and may be used as a base line to study defenses against a broad range of pathogens including bacteria as well as non-host resistance. (C) 2012 Elsevier GmbH. All rights reserved.