4 results
Search Results
Now showing 1 - 4 of 4
Item Variation of chemical compounds in leaves of Drimys spp. (Magnoliophyta : Winteraceae) populations in ChileAutores: Munoz-Concha, D.; Vogel, H.; Razmilic, I.Canelo (Drimys winteri) is a Chilean native tree with medicinal properties and sacred to mapuche people. This species contains chemical compounds with biological activity such as: essential oils, terpenes and flavonoids, which were quantified in leaves of five D. winteri and one D. andina populations by hydrodistillation (essential oils), hexane Soxhlet extraction (terpenes), and spectrophotometry (flavonoids). Mean concentrations of 0.5 mL 100 g(-1) for essential oils, 7.1 % for terpenes and 1.8 % for flavonoids in leaves (dry mass) were determined. Despite the great variation found, significant differences among populations were detected in concentrations of all groups of chemical compounds studied. Populations from the central region of Chile presented the highest values of essential oils (0.68 mL 100 g(-1) in Huerta de Maule population). terpenes, and flavonoids (9.47 and 2.37 %, respectively, both in the Pangal population). The Southernmost population, located in Chiloe Island, showed the lowest values for the three groups of compounds: 0.22 mL 100 g(-1) for essential oils, 3.36 % for terpenes and 1.21 % for flavonoids. D. winteri and D. andina populations from the IX region, geographically close to each other, had different concentrations of essential oils and flavonoids. It is concluded that different Drimys populations actually contain different quantities of essential oils, terpenes, and flavonoids.Item Signal transduction and gene expression regulated by calcium release from internal stores in excitable cellsAutores: Carrasco, M.A.; Jaimovich, E.; Kemmerling, U.; Hidalgo, C.Calcium regulation of several transcription factors involves different calcium-dependent signaling cascades and engages cytoplasmic as well as nuclear calcium signals. The study of the specific sources of calcium signals involved in regulation of gene expression in skeletal muscle has been addressed only recently. In this tissue, most cytoplasmic and nuclear calcium signals originate from calcium release from internal stores, mediated either by ryanodine receptor (RyR) or IN receptor (IP3R) channels. The latter are located both in the sarcoplasmic reticulum (SR) and in the nuclear membrane, and their activation results in long-lasting nuclear calcium increase. The calcium signals mediated by RyR and IP3R are very different in kinetics, amplitude and subcellular localization; an open question is whether these differences are differentially sensed by transcription factors. In neurons, it is well established that calcium entry through L-type calcium channels and NMDA receptors plays a role in the regulation of gene expression. Increasing evidence, however, points to a role for calcium release from intracellular stores in this process. In this article, we discuss how RyR-mediated calcium release contributes to the activation of the calcium-dependent transcription factor CREB and the subsequent LTP generation. We present novel results from our laboratory showing ERK-mediated CREB activation by hydrogen peroxide. This activation takes place in the absence of extracellular calcium and is blocked by inhibitory ryanodine concentrations, suggesting it is caused by redox activation of RyR-mediated calcium release.Item Transcriptome analysis and crop improvement (A review)Autores: Dunwell, J.M.; Moya-Leon, M.A.; Herrera, R.The identification and characterization of differential gene expression from tissues subjected to stress has gained much attention in plant research. The recognition of elements involved in the response to a particular stress enhances the possibility of promoting crop improvement through direct genetic modification. However, the performance of some of the `first generation' of transgenic plants with the incorporation of a single gene has not always been as expected. These results have stimulated the development of new transgenic constructions introducing more than one gene and capable of modifying complex pathways. Several techniques are available to conduct the analysis of gene regulation, with such information providing the basis for novel constructs specifically designed to modify metabolism. This review deals with techniques that allow the identification and characterization of differentially-expressed genes and the use of molecular pathway information to produce transgenic plants. (Biol Res 2001; 34 3-4: 153-164)Item Stimulus specificity in the acquisition and extinction of conditioned taste aversionAutores: Vogel, E.H.; Soto, F.A.; Castro, M.E.; Solar, P.A.An experiment evaluated whether the acquisition and extinction of conditioned taste aversion in the rat is stimulus-specific by testing the degree of response transfer between sweet and salty tastes. Animals in the paired-same and paired-different groups received a presentation of a gustatory CS and a cyclophosphamide injection US. Nonconditioned control groups received unpaired CS /US presentations or the CS followed by a vehicle injection. Taste avoidance was evaluated in three nonreinforced test sessions. In the paired-same, unpaired and vehicle groups, all test sessions were conducted with the same flavor as originally used in training, whereas the paired-different group was tested with a novel flavor on the first and second sessions and with the originally trained flavor in last session. Stimulus specific acquisition was apparent in the first test session, when the animals in the group paired-same exhibited lower fluid intake than the other three groups. Evidence of specificity of extinction was apparent in the last test session, when animals in the group paired-different exhibited lower fluid intake than the other three groups. These results provide further evidence of stimulus specificity in acquisition and extinction of conditioned taste aversion, supporting the associative interpretation of these phenomena
