1648 



Segal, Earl. 1961. 



Acclimation in molluscs. Am. Zool. 1: 235-244. 



Poikilotherms , including Venus meraenaria, do not regulate their body temp, 

 yet show varying degrees of homeostasis of rate functions and shifts in 

 tolerance levels in response to seasonal and latitudinal temp changes, in 

 different parts of a microgeographic range, and in laboratory experiments. 

 This compensatory response or acclimation has been demonstrated in various 

 gastropods and pelecypods from land, sea and fresh water. All mollusks have 

 a similar order-of -magnitude response. Most of this knowledge has come from 

 eurythermal species, but insufficient data are available to deny that 

 stenothermal species do not or are less able to acclimate. The compensatory 

 adaptation might be pheno- or genotypic, but only a few species appear to be 

 genotypic in this respect. The limit to which an animal may be acclimated 

 is not necessarily the temp at which it will show its greatest ability to 

 acclimate. In some animals there is much evidence that nervous and hormonal 

 factors play a decided role. But acclimation of isolated tissues and certain 

 enzyme systems points to the cell as the site of the mechanism. The nature of 

 the mechanism is not known. - J.L.M. 



1649 



Segar, D. A., J. D. Collins, and J. P. Riley. 1971. 



The distribution of the major and some minor elements in marine animals. 

 Part II. Molluscs. J. Mar. Biol. Assn. U.K. 51(1): 131-136. 



Specimens of Meraenaria meraenaria e_xamined were from the northern side of 

 the Solent, close to Lee-on-Solent, in southern England. Elemental 

 composition of shells, expressed as ppm dried at 60°C, was: Fe 1,600; Mn 1.5; 

 Co 1.2; Ni 2.4; Cd 0.80; Cu 1.7; Pb 0.43; Zn 3.4; Ag 0.21; Cr 0.37; Al 71; 

 Na 5,700; K 230; Ca 330,000; Mg 48; Sr 170; and P 28. Composition of entire 

 soft parts was: dry weight 20.0%; Fe 5,400; Mn 18; Co 4.3; Ni 11; Cd 2.1; Cu 

 25; Pb 18; Zn 94; Ag 1.3; Cr 0.79; Al 615; Na 17,000; K 11,000; Ca 3,200; Mg 

 2,700; Sr 13; and P 4,200. Concentration of major elements in soft parts of 

 the 12 species examined was relatively constant, except for low Na in 

 M. meraenaria and 2 others, and Ca in 2 species. - J.L.M. 



1650 



Selby, Cecily Cannan, and Richard S. Bear. 1956. 



The structure of actin-rich filaments of muscles according to X-ray 

 diffraction. J. Biophys. Biochem. Cytol. 2(1): 71-85. 



A second type of fibrous muscle component, which is possibly of greater 

 significance than paramyosin, was found in smooth and striated muscle from 

 vertebrates and invertebrates. This was originally designated type II, but 

 subsequent studies showed that it was an actin-rich fibrous system, if not 

 composed of actin alone. Actin component was extracted from the "tinted" 

 (red) portion of Venus meraenaria adductor muscle, which is richer than the 

 "white" part in actin. From analysis of moderate- to small-angle X-ray 

 diffraction patterns the structure and configuration of actin-rich filaments 

 were deduced. - J.L.M. 



1651 



Seraichekas, H. R. , D. A. Brashear, J. A. Barnick, P. F. Carey, and 0. C. Liu. 

 1968. 



Viral depuration by assaying individual shellfish. Appl. Microbiol. 16(12): 

 1865-1871. 



Using Meraenaria meraeno.ria as experimental animals, individual clams were 

 polluted with LSc 2ab strain of type 1 poliovirus by introducing virus in 

 controlled amounts into the aquarium. Under controlled hydrographic 

 conditions, uptake of virus by individual clams varied 10 to 100 fold. This 

 explains the wide variability of viral contents of pooled samples. Although 

 most clams were free of virus in relatively short time of depuration, some 



457 



