Recently, genome sequences from different fungi have become available. This information reveals that yeasts and filamentous fungi possess up to five aquaporins. Functional analyses have mainly been performed in budding yeast, Saccharomyces cerevisiae, which has two orthodox aquaporins and two aquaglyceroporins. Whereas Aqy1 is a spore-specific water channel, Aqy2 is only expressed in proliferating cells and controlled by osmotic signals. Fungal aquaglyceroporins often have long, poorly conserved terminal extensions and differ in the otherwise highly conserved NPA motifs, being NPX and NXA respectively. Three subgroups can be distinguished. Fps1-like proteins seem to be restricted to yeasts. Fps1, the osmogated glycerol export channel in S. cerevisiae, plays a central role in osmoregulation and determination of intracellular glycerol levels. Sequences important for gating have been identified within its termini. Another type of aquaglyceroporin, resembling S. cerevisiae Yfl054, has a long N-terminal extension and its physiological role is currently unknown. The third group of aquaglyceroporins, only found in filamentous fungi, have extensions of variable size. Taken together, yeasts and filamentous fungi are a fruitful resource to study the function, evolution, role and regulation of aquaporins, and the possibility to compare orthologous sequences from a large number of different organisms facilitates functional and structural studies.

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Background and Purpose Brain radiotherapy is limited in part by damage to white matter, contributing to neurocognitive decline. We utilized diffusion tensor imaging (DTI) with multiple b-values (diffusion weightings) to model the dose-dependency and time course of radiation effects on white matter. Materials and Methods Fifteen patients with high-grade gliomas treated with radiotherapy and chemotherapy underwent MRI with DTI prior to radiotherapy, and after months 1, 4-6, and 9-11. Diffusion tensors were calculated using three weightings (high, standard, and low b-values) and maps of fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (λ‖), and radial diffusivity (λ⊥) were generated. The region of interest was all white matter. Results MD, λ‖, and λ⊥increased significantly with time and dose, with corresponding decrease in FA. Greater changes were seen at lower b-values, except for FA. Time-dose interactions were highly significant at 4-6 months and beyond (p < .001), and the difference in dose response between high and low b-values reached statistical significance at 9-11 months for MD, λ‖, and λ⊥ (p < .001, p < .001, p = .005 respectively) as well as at 4-6 months for λ‖ (p = .04). Conclusions We detected dose-dependent changes across all doses, even <10 Gy. Greater changes were observed at low b-values, suggesting prominent extracellular changes possibly due to vascular permeability and neuroinflammation.

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