Glycosaminoglycans in gills of an intertidal crab (Carcinus maenas): Changes in the GAG population in response to prolonged air exposure

Abstract

Glycosaminoglycans (GAGs) in the gills of an intertidal crab (Carcinus maenas) were determined by biochemical analysis and digestion by specific enzymes. In control (submerged) crabs, gill total GAG content was 14.58 ± 0.97 mg · g–1 of dry defatted weight of tissue (n= 12). Half of it consisted of sulfated GAGs: chondroitin sulfate (CS), keratan sulfate (KS), and heparan sulfate (HS) for 12%, 15%, and 24.5% of total GAGs, respectively; the other half consisted of nonsulfated GAGs: hyaluronan (HA) for 18% and a chondroitin-like compound for 30%. In crabs exposed to air for up to 72 hr, a 73% increase in gill total GAG content was observed. HA was fully responsible for the GAG increase occurring within the first 24 hr of air exposure. Both HA and chondroitin contents increased during the next 24 hr, whereas the sulfated GAGs remained at their control level. Significant changes in total sulfated GAG content occurred only after 48 hr of air exposure, and the final 32% increase was only attributable to CS. Increase in gill CS content was coupled with the main (50%) increase in gill chondroitin content. The initial increase in gill HA content is discussed in relation to the GlcNAc synthesis that we observed previously in the gills of crabs exposed to air for 24 hr. Air exposure–induced changes in the GAG population of gills and their possible implications in gill tissue homeostasis, when crabs have to face dehydration, acidosis, and internal ammonia overload, are discussed. J. Exp. Zool. 281:554–564, 1998. © 1998 Wiley-Liss, Inc.