2117 



Elner, Robert W. 1980. 



The influence of temperature, sex and chela size in the foraging strategy of 

 the shore crab, Carcinus maenas (L.). Mar. Behavior Physiol. 7(1): 



15-24. 



No mention of Mercenaria mercenaria. - M.W.S. 



2118 



Endean, Robert. 1972. 



Aspects of molluscan pharmacology. In Chemical Zoology. VII. Mollusca. 

 Marcel Florkin and Bradley T. Scheer (eds.) . Academic Press, New York: 421- 

 466. 



Cottrell (1966) showed that a large percentage of the total 5HT in nervous 

 tissue of Mercenaria mercenaria is particle bound, he was unable to identify 

 these particles with disrupted portions of the endoplasmic reticulum. Cot- 

 trell and Maser (1967) stated that the subcellular localization of 5HT in the 

 bivalve nervous system is still an open question. Cottrell (1966) showed 

 that a large proportion of the ACh present in nervous tissue of Mercenaria 

 mercenaria was bound to subcellular particles, and it was suggested that the 

 sedimentation properties of ACh particles resembled those prepared similarly 

 from mammalian brain. Hill and Welsh (1966) listed values of 5HT in hearts 

 of Mercenaria mercenaria. There is no appreciable dopamine content in heart 

 of Mercenaria mercenaria (Sweeney 1963). Cottrell (1966) studied particles 

 obtained from macerated Mercenaria mercenaria ganglia and reported that the 

 greater part of substance X was particle bound. Later studies have shown 

 that substance X is a mixture of molluscan cardioexcitor compounds rather 

 than a single compound. Frontali et al. (1967) thought that the substance X 

 they extracted from hearts of M. mercenaria could be a mixture of peptides, 

 but this was challenged by Agarwal and Greenberg (1969) , who postulated that 

 their cardioexcitor agent could include a nucleotide and that it might be a 

 long duration, long distance substitution for neurotransmitters involved in 

 long-term rhythmicity of active hearts. Frontali et al. (1967) disc6vered 

 compounds with excitatory activity on molluscan hearts in extracts of hearts 

 and ganglia of M. mercenaria. A growth inhibiting substance was found to be 

 highly concentrated in Mercenaria and was called mercenene (Schmeer 1963, 

 1964a, b, 1965, 1966, 1967a; Schmeer and Beery 1965; Schmeer and Cassidy 1966; 

 Schmeer and Huala 1965; Hegyeli 1964; Li et al. 1965) . Systems against which 

 the substance is active include HeLa cells, Krebs 2 carcinoma, and sarcoma 

 180 in mice (Schmeer 1963, 1964a, b; Schmeer and Beery 1965), murine leukemia 

 induced by Moloney virus (Judge 1966), and adenovirus 12 tumors in hamsters 

 (Li et al. 1968) . Mercenene has no inhibitory activity or toxic effects on 

 normal human amnion cells (Schmeer and Beery 1965) , and although it did not 

 extend the longevity of mice infected with Friend leukemia virus, it inhib- 

 ited the splenomegalic response of such animals (Judge 1966). Studies on the 

 chemical nature of mercenene have shown that the compound is slowly dialyz- 

 able, heat stable (Schmeer et al.1966) and possesses a molecular weight 1000 

 (Schmeer 1966) . It has been suggested that at least part of the active prin- 

 ciple of mercenene extracts is a substance of molecular weight 1000 to 2000 

 which may have a glycopeptide type of structure (Schmeer et al.1966) . The 

 proposal that mercenene is a volatile derivative of methylglyoxal (Szent- 

 Gyorgyi 1965; Egyud 1965) is considered improbable (Schmeer 1966). Attempts 

 to identify mercenene ' s site of action resulting in its antineoplastic ef- 

 fectiveness have so far failed (Schmeer 1967b, 1968, 1969). However, it 

 has been established (Schmeer 1968) that mercenene prevents tumor cells from 

 entering the DNA synthetic period of the mitotic cell cycle. It remains to 

 be shown whether mercenene possesses activity against spontaneous cancers 

 comparable with its effects on cancers transplanted into mice. Nonetheless, 

 since mercenene kills only neoplastic cells in vitro and in vivo, it is of 

 potentially great significance as an anticancer drug and as a tool for cyto- 

 logical research. The adaptive significance of the presence of mercenene in 

 the tissues of marine organisms is worthy of investigation. Is it a metabolic 

 accident, or has the compound been evolved as a defense against neoplasia? 

 Of what biological significance is the seasonal variation in mercenene con- 

 centration in clam tissues? As Schmeer and Beery (1965) have pointed out. 



589 



