Biol. Bull.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Full Text (PDF) Free
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by McNamara, J. C.
Right arrow Articles by Lima, A. G.
Right arrow Search for Related Content
PubMed
Right arrow Articles by McNamara, J. C.
Right arrow Articles by Lima, A. G.

The Biological Bulletin, Vol 192, Issue 2 321-331, Copyright © 1997 by Marine Biological Laboratory

PHYSIOLOGY

The Route of Ion and Water Movements Across the Gill Epithelium of the Freshwater Shrimp Macrobrachium olfersii (Decapoda, Palaemonidae): Evidence From Ultrastructural Changes Induced by Acclimation to Saline Media

J. C. McNamara and A. G. Lima
Departmento de Biologia, FFCLRP, Universidade de Sao Paulo, Ribeirao Preto 14040-901 SP, Brazil

The ultrastructure of the pillar cells in the gill lamellae of the freshwater shrimp Macrobrachium olfersii was examined to evaluate the routes of salt and water movement across the gill epithelium and into the hemolymph. Alterations were morphometrically quantified in shrimp maintained in fresh water (FW, <0.5{permill} salinity) and after acclimation to saline media (21{permill} or 28{permill} salinity). The tissue interface between the hemolymph and the external medium consists exclusively of the thin apical flange regions of the pillar cells, the upper membrane of which is highly amplified by dense microvilli and overlain by a thin cuticle. The lower flange membrane, bathed by the hemolymph, is smooth and not invaginated. Contiguous flanges are strongly bound by junctional structures including desmosomes and septate junctions. The basal surface of the pillar cell perikaryon is linked to the adjacent septal cells through many basolateral junctions. The septal cell plasmalemma is abundantly and deeply invaginated, each infolding enclosing numerous mitochondria; these characteristics are typical of salt-transporting machinery. After shrimps were acclimated to saline media for 10 days, the thickness of the pillar cell flanges was significantly reduced (from 1.3 to {approx}0.4 {mu}m), as was the height (from 0.8 to 0.3 {mu}m) and density (from 4.0 to {approx} 1.8 microvilli/{mu}m) of the apical microvilli. This reduction in the apical surface area of the pillar cells appears to lead to decreased ionic permeability, concomitant with a reduction in Na+/K+-ATPase activity, thus limiting Na+ uptake. In contrast to the brachyurans, in which the respiratory and ion-transporting mechanisms are differentially located in the anterior and posterior gills, in palaemonid shrimps the pillar cells apparently play a dual role: ions move preferentially through ion transporters in the microvilli above the pillar cell perikaryon, while respiratory gases are exchanged through the fine flange regions in contact with the hemolymph.


This article has been cited by other articles:


Home page
 J. Exp. Biol.Home page
D. Weihrauch, J. C. McNamara, D. W. Towle, and H. Onken
Ion-motive ATPases and active, transbranchial NaCl uptake in the red freshwater crab, Dilocarcinus pagei (Decapoda, Trichodactylidae)
J. Exp. Biol., December 15, 2004; 207(26): 4623 - 4631.
[Abstract] [Full Text] [PDF]

Home page
 J. Exp. Biol.Home page
H. Onken and J. C. McNamara
Hyperosmoregulation in the red freshwater crab Dilocarcinus pagei (Brachyura, Trichodactylidae): structural and functional asymmetries of the posterior gills
J. Exp. Biol., January 15, 2002; 205(2): 167 - 175.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1997 by the Marine Biological Laboratory.