human amnion lines grown on sterile glass. An extract was prepared as 

 reported earlier, and injected subcutaneously into mice that had previously 

 received 25-30 million ascites K-2 cells. Control or untreated animals 

 received 0.25 ml. physiological saline in the same dosage schedule as the 

 treated groups. On the eighth day after initial treatment was begun, tumors 

 from all treated and untreated mice were excised and prepared for light 

 microscopy investigation. Many tumors from repeated experiments were studied. 

 Among the observations made, it was noted that the treated mice had smaller 

 tumors, and that sections of these tumors showed a great infiltration of 

 fibroblasts, fewer mitotic cells, less necrosis, small numbers of white blood 

 cells as compared with control or untreated tumors, little polyploidy, normal 

 nuclear-cytoplasmic ratio, and few cells with enlarged nuclei usuallv 

 predominant in the K-2 tumor. HeLa cell cultures showed a 4+ degeneration in 

 48-72 hours after initial treatment with Mercenene , while normal human amnion 

 cells showed little to no degeneration for the same period of time. - Entire 

 article, as published, except for acknowledgments. - J.L.M. 



1632 



Schmeer, M. Rosarii, and Grace Beery. 1965. 



Mercenene: Growth-inhibitor extracted from Mercenaria campechiensis . In vivo 

 and in vitro activity. Biol. Bull. 129(2): 420-421. 



It has been previously reported that a growth-inhibitor called Mercenene was 

 extracted from a species of edible clam, Mercenaria mercenaria. This clam 

 is very abundant in Rhode Island and Cape Cod marine waters. Testing our 

 theory that the growth-inhibitor may be due to some special feeding habit of 

 the animal, we tested another species of Mercenaria, Mercenaria campechiensis , 

 that is relatively abundant south of the Chesapeake Bay area. Water extracts 

 of the fresh, raw clam were prepared in an identical procedure used for the 

 preparation of extracts of M. mercenaria. Previously implanted CF1 mice 

 received 0.25 ml of various concentrations of the extract, each day for seven 

 full days. Control, untreated animals had an identical dosage schedule, but 

 received, in place of the extract, 0.25 ml physiological saline. On the 

 eighth day after initial treatment with Mercenene, the Krebs-2 carcinoma 

 tumors were excised and weighed. Control animal tumors were also weighed at 

 the same time. It was observed that a 2 5% concentration of the water extract 

 induced the greatest regression and inhibition of tumor. In vitro investi- 

 gations using the HeLa and normal human amnion cell lines suggest a toxic 

 effect on the HeLa lines, with very little or no degeneration of the human 

 amnion cell line. The presence of Mercenene in an additional species of 

 edible clam may indicate a selective feeding habit, or it may suggest that 

 the clam ingests some agent or agents in the marine environment, changes it 

 in vivo, and produces a chemically modified principle that possesses anti- 

 cancer activity. - Entire article as published. - J.L.M. 



1633 



Schmeer, M. Rosarii, and Grace Beery. 1965. 



Mercenene: Growth-inhibitor extracted from the clam Mercenaria campechiensis. 

 A preliminary investigation of in vivo and in vitro activity. Life Sci. 4: 

 2157-2163. 



Mercenaria mercenaria had the greatest concentration of antitumor material of 

 all mollusks studied to date. Availability of clams, low cost, ease in 

 handling extract, and stability under usual conditions, make hard clam an 

 attractive potential source of antitumor material. However, the known capacity 

 of hard clams to concentrate materials present in the environment suggested 

 that clams used in previous experiments might have been ingesting something 

 from Massachusetts waters that was the source of the antitumor principle. 

 Consequently, it was decided to investigate the closely related southern 

 species of Mercenaria from waters south of the Chesapeake Bay area. 

 (Abstracter's note: although it is not stated, it might have been in the 

 minds of the researchers that substances derived from water pollution might 

 have been responsible for the antiviral properties of M. mercenaria and that 

 such substances would be less likely to be present in clams from less- 

 polluted southern watersj Extracts from M. campechiensis showed antitumor 



452 



