Unrevealing the neurophysiological mechanisms responsible for OWA induced behavioral changes in polar fish: an NMR approach
Final Report Abstract
In summary of the project, it could be shown that the 1H chemical shifts and J-coupling constants of 15 important metabolic compounds in 1H NMR spectra show a significant dependence on pH and temperature, especially for cold-blooded animals. Thus, the work can contribute to avoiding or minimizing errors in the quantification of spectra or the adaptation of spectral editing sequences, especially in the presence of variations or changes in pH or temperature, whether due to physiological conditions, the model organism or experimental conditions. It could be shown the 1CH2 signal of taurine exhibits a remarkable pH dependence. Simulations of the brain's typical in vivo 1H NMR spectra demonstrated the possibility of estimating the pHi by evaluating the chemical shift difference between the Tau 1CH2 resonance and a reference signal, even for relatively poor experimental conditions. Initial applications to rodent brains indicate that the new method allows non-invasively determining relative changes in pH and absolute pH values. However, further systematic studies will be required to investigate the necessary modification of the titration curve and the accuracy of this new approach for pH measurements. Since the proposed method is essentially a modified way to evaluate high-quality 1H MRS or MRSI data quantitatively, it will broaden the information content of such measurements. Thus, the presented Tau pH indicator method will be applicable to future studies as well as to data acquired in previous studies. The in-depth study of the CEST effect for the different animal models, concerning their pH and temperature dependence, allows the determination of the optimal experimental NMR parameters of the CEST effect for polar and marine organisms, such as fishes from Antarctic waters. Thus, the 1H NMR spectroscopy and CEST imaging in combination with the newly developed method for pHi measurements can be a valuable tool for unraveling the neurophysiological mechanisms responsible for ocean warming and acidification induced behavioral changes in polar fish.
Publications
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A novel in vivo method for spatially resolved pH measurements using the 1H chemical sift of taurine as pH indicator in NMR and MRI; NMR in Biomedicine (in revision)
Wermter FC; Dreher W; Meier M & Bock C
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Temperature and pH dependence of 1H NMR chemical shifts and J- coupling constants; NMR in Biomedicine (in revision)
Wermter FC; Bock C & Dreher W
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Characterization of amine proton exchange for analyzing the specificity and intensity of the CEST effect: from humans to fish. NMR in Biomedicine, 35(2).
Wermter, Felizitas C.; Bock, Christian & Dreher, Wolfgang
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pH-dependence of taurine 1H NMR chemical shifts: A potential method for pH determination and imaging. ISMRM Annual Meeting. ISMRM.
Wermter, Felizitas; Dreher, Wolfgang & Bock, Christian
