the acid mucopolysaccharide material could be heparin precursor in varying 

 degrees of acidity and sulphation. The neutral mucosubstance also varies in 

 quantity, possibly in relation to variation in glycosaminoglycan. Mucous 

 secretions in the 2nd fold are distinctly different from those in the 1st 

 fold, suggesting a completely different function, and adding support to the 

 hypothesis that these materials play a far more sophisticated role in life 

 activity of the clam than suspected previously. - J.L.M. 



848 



Hillman, Robert E. 1970. 



An unusual occurrence of internal calcification in the mantle of the quahog. 

 Proc. Natl. Shellf. Assn. 60: 5 (abstract). 



During investigations of mucosubstances in the mantle of the hard clam, one 

 clam was found with an internal deposit of calcium carbonate. Histological 

 investigations showed that calcification was due to an involution of the 

 outer epithelium of the mantle. Histochemical studies showed deposits of 

 glucosaminoglycan underlying the epithelial cells. This material was 

 alcianophilic at pH 1.0 and 2.5 and reacted with aldehyde fuchsin following 

 the alcian blue/aldehyde fuchsin reaction. More acidic mucous material was 

 found in the mantle connective tissue around the involution than is normally 

 found in mantle connective tissue. The relationship between glycosamino- 

 glycans and calcification was discussed. - D.L. 



849 



Hillman, Robert E. 1971. 



The role of mucosubstances in the quahog. Proc. Natl. Shellf. Assn. 61: 5 

 (abstract) . 



Based on the results of histochemical studies of mucosubstances in the mantle 

 of the quahog, Mercenaria mercenaria, several physiological roles are pro- 

 posed for various mucosubstances, particularly connective tissue mucus. 

 Besides assisting in such expected functions as lubrication, food capture and 

 protection, it is proposed that quahog mucous materials aid in active trans- 

 port across cell membranes, especially for handling calcium for shell 

 deposition and osmo-regulation. It is also suggested that one glycosamino- 

 glycan may serve as a vehicle for sorting certain sulfated compounds and 

 releasing them as needed by the quahog. - D.L. 



850 



Hillman, Robert E. 1973. 



Mucus in marine invertebrates . Littoral Lines 8 . 



851 



Hillman, Robert E. 1974., 



Effect of salinity on mucus in the mantle of the quahog, Mercenaria mercenaria. 

 Proc. Natl. Shellf. Assn. 64: 3-4 (abstract). 



Six separate groups of hard clams were held in seawater, one group at salinity 

 35°/<>o, one at 30°/oo, one at 25°/°o, one at 20°/°o, one at 15°/°°, and one at 

 10°/°°. After one week histochemical studies were made of the first fold of 

 the mantle edge. Salinity and mucus production were related in that as 

 salinity increased, the amount of reactive acid mucopolysaccharide increased. 

 - modified author's abstract - D.L. 



852 



Hillman, Robert E. 1978. 



Invertebrate mucus: Model systems for studying diseases in man. In Drugs 

 and Food from the Sea: Myth or Reality? Pushkar N. Kaul and Carl J. 

 Sindermann (eds.) . Univ. Okla., Norman: 17-25. 



It is quite possible that mucus production in the mantle of the hard clam, 

 Mercenaria mercenaria, is similar in the mechanisms involved, to mucus 



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