RESUMO
Aim: In the present study, we exploited DNA microarray-based transcriptome analysis and showed overall changes in gene expression in vivo of amoebic trophozoites that interact with animal soluble factors using an intraperitoneal dialysis bag model to elucidate putative molecular pathways and genes involved in this interaction. Study Design: We exploited DNA microarray-based transcriptome analysis. Results: An analysis from a network including the interactions of up-regulated genes and their neighbors revealed the presence of 11 functionally related modules. Six of the modules obtained were related to endoplasmic reticulum (ER) functions, such as degradation, stress, proteasome-ubiquitination, phosphorylation, lipid metabolism, and protein sorting. Furthermore, major transcriptional changes displayed by the parasite at the beginning of interaction were attributed to the response to the host defense. These data are consistent with the notion that the concerted expression of genes necessary for survival such as increment in protein synthesis, cytoskeleton rearrangement, vesicular traffic and genes involved in cell death including calcium imbalance and the ER signals associated with protein degradation (ERAD) is an overall landscape during the in vivo interaction between the amoebic trophozoites and animal soluble factors, and suggest that the ER stress is one of the main pathways leading to programmed cell death in E. histolytica. Conclusion: The present findings on the global transcriptional changes displayed by the parasite at the early stages of interaction with host environments in peritoneal implantation indicate that a substantial proportion of concerted changes in gene expression in amoebic trophozoites are attributable to the parasite’s response for cell death signals due to ER stress. A detailed knowledge of the underlying molecular mechanism might suggest the efficient elimination of this parasite by promoting their death pathways.
RESUMO
Pressure-driven and temperature-driven transitions of two thermoresponsive polymers, poly(N-isopropylacrylamide) (pNIPAM) and poly(N-vinylisobutyramide) (pNVIBA)), in both a soluble linear polymer form and a cross-linked hydro-gel form, were examined by a dynamic light-scattering method and direct microscopic observation, respectively. Their behavior was compared with that of protein systems. Changes in some characteristic parameters in the time-intensity correlation functions of dynamic light-scattering measurement of aqueous solutions of pNIPAM at various pressures and temperatures showed no essential differences during temperature and pressure scanning and, as a whole, the motions of polymers in aqueous solutions were similar in two types of transitions until chain shrinkage occurred. The gels (cross-linked polymer gels) prepared from the thermoresponsive polymers also showed similar volume transitions responding to the pressure and temperature increase. In temperature transitions, however, gels showed drastic volume shrinkage with loss of transparency, while pressure-induced transition showed a slow recovery of transparency while keeping the size, after first transient drastic volume shrinkage with loss of transparency. At a temperature slightly higher than the transition under atmospheric temperature, so-called reentry of the volume change and recovery of the transparency were observed during the pressure-increasing process, which implies much smaller aggregation or non-aggregated collapsed polymer chains in the gel at higher pressures, indicating a certain mechanistic difference of the dehydration processes induced by temperature and pressure.