| Abstract [eng] |
To survive in changing environmental conditions, plants must respond to external stressors by rapidly transmitting information from the locally affected area of the plant to other parts of their body and initiating a wide range of responses. This signal transduction function is carried out by electrical signals, i.e. membrane polarisation waves. The mechanism of action potential generation in plants is functionally understood: the initial depolarisation is triggered by an increase in the cytoplasmic Ca2+ concentration which activates Cl- channels; the activity of K+ channels and H+-ATPases realises the repolarisation. However, there is a lack of knowledge on the electrophysiological properties of Ca2+ channels and their potential control by second messengers. It has been hypothesised that, in analogy with animal systems, Ca2+ channels may be activated by inositol phosphates, but no receptor homologues have been found in plants. In this thesis, the effects of Ca2+ channel modulators on the Characean alga Nitellopsis obtusa were investigated using electrophysiological methods: the potential blockers verapamil, tetrandrine, NED-19, La3+ were used to block Ca2+ channels, while the potential activators inositol 1,4,5-trisphosphate (IP3) and inositol hexakisphosphate (IP6) were used to activate them. Most of the blockers were found to have non-specific effects and IP6 was found to be more consistent with the function of a hypothetical secondmessenger than IP3. Translated with DeepL.com (free version). |
