The well-documented ability to degrade lignin and a variety of complex chemicals showed by the white-rot fungus Phanerochaete chrysosporium has made it the subject of many studies in areas of ...environmental concern, including pulp bioleaching and bioremediation technologies. However, until now, most of the work in this field has been focused on the ligninolytic sub-system but, due to the great complexity of the involved processes, less progress has been made in understanding the biochemical regulatory structure that could explain growth dynamics, the substrate utilization and the ligninolytic system production itself. In this work we want to tackle this problem from the perspectives and approaches of systems biology, which have been shown to be effective in the case of complex systems. We will use a top-down approach to the construction of this model aiming to identify the cellular sub-systems that play a major role in the whole process. We have investigated growth dynamics, substrate consumption and lignin peroxidase production of the P. chrysosporium wild type under a set of definite culture conditions. Based on data gathered from different authors and in our own experimental determinations, we built a model using a GMA power-law representation, which was used as platform to make predictive simulations. Thereby, we could assess the consistency of some current assumptions about the regulatory structure of the overall process. The model parameters were estimated from a time series experimental measurements by means of an algorithm previously adapted and optimized for power-law models. The model was subsequently checked for quality by comparing its predictions with the experimental behavior observed in new, different experimental settings and through perturbation analysis aimed to test the robustness of the model. Hence, the model showed to be able to predict the dynamics of two critical variables such as biomass and lignin peroxidase activity when in conditions of nutrient deprivation and after pulses of veratryl alcohol. Moreover, it successfully predicts the evolution of the variables during both, the active growth phase and after the deprivation shock. The close agreement between the predicted and observed behavior and the advanced understanding of its kinetic structure and regulatory features provides the necessary background for the design of a biotechnological set-up designed for the continuous production of the ligninolityc system and its optimization.
The amplification of signals, defined as an increase in the intensity of a signal through networks of intracellular reactions, is considered one of the essential properties in many cell signalling ...pathways. Despite of the apparent importance of signal amplification, there have been few attempts to formalise this concept.
In this work we investigate the amplification and responsiveness of the JAK2-STAT5 pathway using a kinetic model. The recruitment of EpoR to the plasma membrane, activation by Epo, and deactivation of the EpoR/JAK2 complex are considered as well as the activation and nucleocytoplasmic shuttling of STAT5. Using qualitative biological knowledge, we first establish the structure of a general power-law model. We then generate a family of models from which we select suitable candidates. The parameter values of the model are estimated from experimental quantitative time-course data. The final model, whether it is conventional model with fixed predefined integer kinetic orders or a model with variable non-integer kinetic orders, is selected on the basis of a good agreement between simulations and the experimental data. The model is used to analyse the responsiveness and amplification properties of the pathway with sustained, transient, and oscillatory stimulation.
The selected kinetic model predicts that the system acts as an amplifier with maximum amplification and sensitivity for input signals whose intensity match physiological values for Epo concentration and with duration in the range of one to 100 minutes. The response of the system reaches saturation for more intense and longer stimulation with Epo. We hypothesise that these properties of the system directly relate to the saturation of Epo receptor activation, its low recruitment to the plasma membrane and intense deactivation as predicted by the model.
A field study of medicinal plants of the Canary Islands flora used for the treatment of kidney and urinary diseases revealed that 63 plants, belonging to 32 families, about 34% of which are endemic, ...are used as diuretic, antiseptic or calculolytic agents. This wide range of ethnomedicinal uses involves approximately 10% of the total medicinal flora of the Canaries, indirectly indicating the high incidence of these pathologies in the insular population. The botanical family and vernacular names are given along with data on plant parts used, methods of preparation and administration, frequency of use and medicinal application of each species.
A series of 1,2,4-triazolyl heterocarboxylic derivatives were tested for acute toxicity and CNS effects in mice. Several of these compounds demonstrated clear psychostimulant effects. Other ...components of the series, however, showed a definite central depressant activity. Some of the screened derivatives showed interesting anxiolytic properties.
A chemical study of Visnea mocanera leaves was carried out giving lupeol and beta-sitosterol fatty esters, as well as beta-sitosterol and the triterpenic betulinic, ursolic, platanic and ...2-alpha,3-beta-dihydroxy-ursan-12-en-28-oic and 2-alpha,3-beta-dihydroxy-olean-12-en-28-oic acids. Studies of the antimicrobial activity of acetone and methanol extracts as well as an aqueous infusion were also performed and the good experimental results obtained justify the folk use of this species as a cicatrizant and vulnerary agent.
A series of aryl and hetarylsulfonylhydrazones of aromatic aldehydes were tested for acute toxicity and anticonvulsant activity in mice. Some of these compounds were effective in the MES, pentetrazol ...and strychnine tests. Thiophene derivatives were the most active terms of the series.
We present in this paper a report of 155 species used for medicinal purpose in the Canary Islands. These species have been compiled in 13 tables in accordance with their main medicinal use, ...indicating also other possible popular uses. We have made a short inventory of the rates of the most important medicinal applications. This new compilation shows once more the traditional use of the phytotherapeutic resources by the Canary population and also the wide possibilities of the phytochemical and pharmacological investigations of the Canary Islands Flora.
A number of thieno and pyrazolo2,1benzothiazepine derivatives as well as several synthetic intermediate compounds were tested for acute toxicity and antidepressant activity in mice. Some of these ...compounds were effective in the tetrabenazine and Porsolt tests.
A series of 4-phenyl-2-thioxo-benzo4,5thieno2,3-dpyrimidine derivatives endowed with anti-inflammatory and related pharmacological properties were submitted to a more extensive study to know their ...exact pharmacological profile and their possible side effects. The studied compounds possess a remarkable analgesic activity, devoid of central effects. They also show an interesting anti-inflammatory profile evidenced by their effectiveness in different experimental models of inflammation. In addition, these compounds exhibit none or very little activity on CNS, scarce toxicity and low gastrointestinal aggressivity.
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