TY - JOUR
T1 - Intracellular vesicular trafficking in the gill epithelium of urea-excreting fish
AU - Laurent, P.
AU - Wood, C. M.
AU - Wang, Y.
AU - Perry, S. F.
AU - Gilmour, K. M.
AU - Part, P.
AU - Chevalier, C.
AU - West, M.
AU - Walsh, P. J.
N1 - Funding Information:
This work was supported by grants from the National Science Foundation (IBN 0090355) to P.J.W. and the NSERC Research Program to C.M.W., S.F.P., and K.M.G.
PY - 2001
Y1 - 2001
N2 - Most teleost fish are ammoniotelic, and relatively few are ureotelic, in which the majority of nitrogenous waste is excreted as urea. This study aimed to determine whether the gill ultrastructure of ureotelic fish might have specific, unique characteristics compared with ammoniotelic fish. The gill morphology was studied in three closely related species of the family Batrachoididae: Opsanus beta, the gulf toadfish; Opsanus tau, the oyster toadfish; and Porichthys notatus, the plainfin midshipman, because prior studies have demonstrated that the two former species are ureotelic and excrete urea in unique, short daily pulses, whereas the latter is ammoniotelic. Ultrastructural studies demonstrated significant trafficking of dense-cored vesicles (50-200 nm) between the Golgi apparatus and the apical membrane of epithelial cells surrounding gill filaments and lamellae in these two Opsanus spp. The material constituting the core of these vesicles was intensely stained by lead salt and was unloaded externally when vesicles contacted the apical membrane. Another characteristic of these urea-secreting fish was the presence of numerous large, black-stained lysosomes, which contained cored vesicles, suggesting a second destination for the dense-cored vesicles. As a working hypothesis, the present data suggest that the urea-transporter protein, recently found in toadfish gills, is inserted in the vesicle. Subsequently, it could serve to either sequester cytosolic urea that ultimately is secreted into the water after contact of these vesicles with the pavement cell apical membrane, or it could allow facilitated diffusion of urea across the plasma membrane following insertion into the membrane. As further comparative evidence, the ammoniotelic P. notatus exhibited neither the vesicular trafficking nor the population of lysosomes both found in Opsanus spp.
AB - Most teleost fish are ammoniotelic, and relatively few are ureotelic, in which the majority of nitrogenous waste is excreted as urea. This study aimed to determine whether the gill ultrastructure of ureotelic fish might have specific, unique characteristics compared with ammoniotelic fish. The gill morphology was studied in three closely related species of the family Batrachoididae: Opsanus beta, the gulf toadfish; Opsanus tau, the oyster toadfish; and Porichthys notatus, the plainfin midshipman, because prior studies have demonstrated that the two former species are ureotelic and excrete urea in unique, short daily pulses, whereas the latter is ammoniotelic. Ultrastructural studies demonstrated significant trafficking of dense-cored vesicles (50-200 nm) between the Golgi apparatus and the apical membrane of epithelial cells surrounding gill filaments and lamellae in these two Opsanus spp. The material constituting the core of these vesicles was intensely stained by lead salt and was unloaded externally when vesicles contacted the apical membrane. Another characteristic of these urea-secreting fish was the presence of numerous large, black-stained lysosomes, which contained cored vesicles, suggesting a second destination for the dense-cored vesicles. As a working hypothesis, the present data suggest that the urea-transporter protein, recently found in toadfish gills, is inserted in the vesicle. Subsequently, it could serve to either sequester cytosolic urea that ultimately is secreted into the water after contact of these vesicles with the pavement cell apical membrane, or it could allow facilitated diffusion of urea across the plasma membrane following insertion into the membrane. As further comparative evidence, the ammoniotelic P. notatus exhibited neither the vesicular trafficking nor the population of lysosomes both found in Opsanus spp.
KW - Gill epithelium
KW - Lysosome vesicle trafficking
KW - Opsanus beta
KW - Opsanus tau
KW - Pavement cell
KW - Porichthys notatus (Teleostei, Batrachoididae)
KW - Ultrastructure
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U2 - 10.1007/s004410000312
DO - 10.1007/s004410000312
M3 - Article
C2 - 11291766
AN - SCOPUS:0035111481
VL - 303
SP - 197
EP - 210
JO - Zeitschrift für Zellforschung und mikroskopische Anatomie (Vienna, Austria : 1948)
JF - Zeitschrift für Zellforschung und mikroskopische Anatomie (Vienna, Austria : 1948)
SN - 0302-766X
IS - 2
ER -