Cell homeostasis in a Leishmania major mutant overexpressing the spliced leader RNA is maintained by an increased proteolytic activity

Although several stage-specific genes have been identified in Leishmania, the molecular mechanisms governing developmental gene regulation in this organism are still not well understood. We have previously reported an attenuation of virulence in Leishmania major and L braziliensis carrying extra-copies of the spliced leader RNA gene. Here, we surveyed the major differences in proteome and transcript expression profiles between the spliced leader RNA overexpressor and control lines using two-dimensional gel electrophoresis and differential display reverse transcription PCR, respectively. Thirty-nine genes related to stress response, cytoskeleton, proteolysis, cell cycle control and proliferation, energy generation, gene transcription, RNA processing and post-transcriptional regulation have abnormal patterns of expression in the spliced leader RNA overexpressor line. The evaluation of proteolytic pathways in the mutant revealed a selective increase of cysteine protease activity and an exacerbated ubiquitin-labeled protein population. Polysome profile analysis and measurement of cellular protein aggregates showed that protein translation in the spliced leader RNA overexpressor line is increased when compared to the control line. We found that L major promastigotes maintain homeostasis in culture when challenged with a metabolic imbalance generated by spliced leader RNA surplus through modulation of intracellular proteolysis. However, this might interfere with a fine-tuned gene expression control necessary for the amastigote multiplication in the mammalian host. (c) 2010 Elsevier Ltd. All rights reserved.

Evaluation of the performance of normal elderly in a limb praxis protocol: Influence of age, gender, and education

Limb praxis can be influenced by age, gender, and education. The present Study investigated the influence of these variables on gesture production by healthy elderly Subjects. We evaluated 96 individuals divided into two age groups (60-74 and 75-88 years). Each group contained 48 men and 48 women and was subdivided into four groups according to education: illiterates and 1-3, 4-7, and 8 or more years of education. Individuals were requested to carry Out tasks oil verbal command and imitation. There were no differences between the performance of men and women, while older individuals performed worse than their younger counterparts. Regarding educational level, three major groups emerged: illiterates, individuals with 1-7 years of education, and those with 8 or more years of education. In conclusion, age and education significantly influenced the performance of individuals in limb praxis tests. (JINS, 2009, 157 618-622.)