Abstract
The spatial distribution of cations was assayed qualitatively and quantitatively in tentacular nematocytes of Hydra vulgaris in a scanning transmission electron microscope by means of x-ray microanalysis performed on 100 nm thick freeze-dried cryosections. The matrix of undischarged cysts (stenoteles, desmonemes and isorhizas) was found to contain mainly K+. In isolated nematocysts of Hydra the intracapsular potassium can be readily substituted by practically any other mono- and divalent cation (Na+, NH4 +, Mn2+, Co2+, Mg2+, Ca2+, Fe2+) all, except Fe2+, without impairing the ability of the cyst to respond to the chemical triggering with dithioerythritol or proteases. Monovalent cations increase the osmotically generated intracapsular pressure compared to divalent ions.
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Gerke, I., Zierold, K., Weber, J. et al. The spatial distribution of cations in nematocytes of Hydra vulgaris . Hydrobiologia 216, 661–669 (1991). https://doi.org/10.1007/BF00026528
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DOI: https://doi.org/10.1007/BF00026528