772 



Hanson, Jean, and J. Lowy. 1959. 



Evidence for a sliding filament contractile mechanism in tonic smooth muscles 

 of lamellibranch molluscs. Nature 184(4682): 286-287. 



Mercenaria (Venus) mercenaria is not mentioned, but the discussion is 

 generally applicable. Structural evidence for a sliding filament contractile 

 mechanism in cross-striated muscle is well established, based on the 

 following points: 1) existence of 2 kinds of filament; 2) existence of 

 bridges between them; 3) discontinuity of filaments along the fibril; 4) 

 constancy of filament length at different muscle lengths; 5) changes in 

 relative positions of the 2 kinds of filament as the muscle shortens; and 

 6) similarity of X-ray diffraction patterns at different muscle lengths. 

 Information about smooth muscles is much less complete, but 1 and 2 have been 

 demonstrated in funnel retractor and mantle muscles of Loligo and pharynx 

 retractor of Helix. This paper concludes from electron micrographs of 

 Mytilus edulis that 1 and 2 are true and 3 and 4 very likely true. Similar 

 results were obtained for the translucent (yellow) part of adductor muscle 

 of Gryphaea angulata. - J.L.M. 



773 



Hanson, Jean, and J. Lowy. 1961. 



The structure of the muscle fibres in the translucent part of the adductor of 

 the oyster Crassostrea angulata. Proc. Royal Soc. London, Ser. B 154(955): 

 173-193. 



Venus is mentioned only in reference to a paper by Selby and Bear (1956) , 

 abstracted elsewhere in this bibliography. - M.W.S. and J.L.M. 



774 



Hanzel, Melvin E. , and Gary P. Carlson. 1974. 



Azoreductase activity in the hard clam, Mercenaria meroenaria (L. ) . J. Exp. 

 Mar. Bio. Ecol. 14(3): 225-229. 



Hard clam is deficient in ability to carry out mixed function oxidase re- 

 actions, but can reduce nitro groups to amino groups. The azo linkage is 

 commonly found in pesticides, industrial dyes, food colorings, and drugs. 

 Thus, hard clam can detoxify certain components of pollutants. Azoreductase 

 activity of the hepatopancreas was higher at 37 °C than at 22 °C and pH optimum 

 was 8.0. The reaction was stimulated by flavin mononucleotide and inhibited 

 by air. The 105,000 g soluble and the microsomal fractions of the hepato- 

 pancreas were active. - J.L.M. 



775 



Hare, P. E., and P. H. Abelson. 1968. 



Racemization of amino acids in fossil shells. Carnegie Inst. Wash. Yearbook 

 66: 526-528. 



The proteins of all living forms consist principally of L-amino acids. Why 

 was one isomer chosen, and what factors determined the choice? The present 

 study was devoted to determining the optical configuration of amino-acids in 

 Recent and fossil Mercenaria shells. The results indicate that for most 

 amino acids the mixture of stereo forms accumulating in a primitive ocean 

 would be racemic. If some unknown process presented a slight advantage to 

 one form or another, racemization would tend to vitiate that advantage. On 

 the other hand, once a decision was made to use the L form, supplies of it 

 would be replenished by racemization from the D form as the L isomer was 

 used up. - J.L.M. 



215 



