Mucocyte distribution and relationship to particle transport on the pseudolamellibranch gill of Crassostrea virginica (Bivalvia:Ostreidae)

Abstract

To investigate particle transport mechanisms on the bivalve pseudolamellibranch gill, the mucocyte secretion types and distribution were determined for this organ in the eastern oyster Crassostrea virginica, and related to previous endoscopic data. Three adult oysters were collected from Shediac Bay (New Brunswick, Canada) in July 1994, immediately fixed, then dissected and processed for histology and whole mount rnucocyte mapplng uslng a modification of the penodic acidSchiff-alcian blue protocol. One type of mucocyte contained acid-secretion rnucopolysaccharides (AMPS), while the other type contained neutral rnucopolysaccharldes (NhIPS). A clear grad~ent in nlucocyte density was observed from the plical crest to the trough; for all but the anteriorn~ost 15 plicae the proportions of each mucocyte type remained constant; the 15 anteriormost plicae presented an increased proportion of AMPS. These proportions would produce a relahvely viscous acid-dominant mucus after mixing on the c~liated gill surfacr. The principal filament troughs contained relatively few Inucocytes, aligned on the median ndge This arrangement could account for the observed range of partlcle velocities in these filaments. The results of the present study conform to a pattern of specialization of nlucus types and functions on the diverse types of bivalve gill, depending on particle trajectory, transporting surface architecture, and dominant current flow.

Mechanisms contributing to low domoic acid uptake by oysters feeding on Pseudo-nitzschia cells. II. Selective rejection

“…Mucocytes of the pallial organs secrete mucus of varying viscosity for different functions (Beninger & Dufour 1996, Beninger & St.-Jean 1997. Except for the dorsal tracts and principal filaments, transport of particles occurs on relatively exposed sites of the oyster gills in a perpendicular or opposite direction to the prevailing inhalant current (Ward et al 1994); thus, transport is only possible if particles strongly adhere to the ciliated epithelium by mucus .…”

“…The chemical mechanisms involved in particle selection have not been elucidated, but the mapping of mucocytes on the labial palps and gill epithelium of different bivalve species is consistent with the use of mucus during the entire particle handling process (Beninger et al 1993, Beninger & Dufour 1996. Mucocytes of the pallial organs secrete mucus of varying viscosity for different functions (Beninger & Dufour 1996, Beninger & St.-Jean 1997.…”

Effects of hydrogen sulfide on the feeding activity of Manila clam Ruditapes philippinarum

“…Mucus plays a key role in all aspects of particle processing on the gill surface (Beninger et al 1991,b, Beninger & Le Pennec 1993, Beninger & Dufour 1996, Beninger & St-Jean 1997a,b, Wotton 2004. Mucus consists of polysaccharide units with associated protein components (mucopoly saccharides; MPS).…”

Acquisition of particle processing capability in the oyster Crassostrea gigas: ontogeny of the mantle pseudofeces rejection tracts

“…The mechanisms involved in oyster suspension-feeding have been investigated using a variety of modern approaches, chiefly centred upon the roles of the gills and labial palps (Newell & Jordan 1983, Ward et al 1994, Beninger & Dufour 1996, Cognie et al 2003, Beninger et al 2005. Ingestion volume control and qualitative selection both produce pseudofeces, and the transport and expulsion of pseudofeces is therefore essential to prevent fouling and unnecessary re-treatment in the suspension-feeding system.…”