Uptake and compartmentalisation of fluorescent probes byPisolithus tinctorius hyphae: evidence for an anion transport mechanism at the tonoplast but not for fluid-phase endocytosis |
| |
Authors: | L Cole G J Hyde A E Ashford |
| |
Institution: | (1) School of Biological Sciences, The University of New South Wales, 2052 Sydney, NSW, Australia |
| |
Abstract: | Summary Membrane-impermeant fluorescent probes, such as Lucifer Yellow carbohydrazide, 6-carboxyfluorescein, and high-molecular-mass
fluorescent dextrans (10 and 70 kDa) are not internalised by actively-growing hyphal tip-cells ofPisolithus tinctorius even after prolonged exposure to the probe. These findings suggest that fluid-phase endocytosis may not occur in these fully
turgid tip-growing hyphae. In contrast, a number of membrane-permeant fluorescent probes, including 6-carboxfluorescein diacetate,
the novel fluorescein-substitute Oregon Green 488 carboxylic acid diacetate, and the thiol-reactive Cell Tracker reagents
7-amino-4-chloro-methylcoumarin and 5-chloromethylfluorescein diacetate, are taken up by these hyphae and their fluorescent
products accumulate in the vacuole system. Accumulation of the fluorescent products of both 6-carboxyfluorescein diacetate
and Oregon Green 488 carboxylic acid diacetate in the vacuole system is inhibited by the anion transport inhibitor probenecid
and instead these fluorochromes remain in the cytoplasm. These results suggest that the membrane-permeant esters 6-carboxyfluorescein
diacetate and Oregon Green 488 carboxylic acid diacetate are first hydrolysed in the cytoplasm and that their fluorescent
products are subsequently sequestered across the tonoplast via an anion transport mechanism. Such an anion transport mechanism
has been hitherto unrecognised in fungi and may serve to detoxify the fungal cytoplasm by the removal of naturally-occurring
unwanted anions. Probenecid-inhibitable organic anion transporters are also located at the limiting membrane of the animal
endosomal/lysosomal system and at the tonoplast of higher plants. Our results further support the idea that the tubular vacuole
system inP. tinctorius is similar to animal endosomal/lysosomal and plant vacuole systems. |
| |
Keywords: | Anion transport Fluid-phase endocytosis Fungal vacuoles Lucifer Yellow carbohydrazide Pisolithus tinctorius Probenecid |
本文献已被 SpringerLink 等数据库收录! |
|