. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figure 6. Symbiotic algae in tertiary tubules in the gills of Corculum cardissa, showing (a) several symbionts in a tubule and (b) high magnification of the two cells in 6a. Scale bar = 1 Figure 7. Schematic representation of the relation between the alga (A), the tubule cells of the tertiary tubules (TC), and the hemolymph containing blood cells (be), n, nucleus; cp. chloroplast. 2000). In neither example are the "signals" that elicit the developmental response in the host known. In the case of the dinoflag


. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figure 6. Symbiotic algae in tertiary tubules in the gills of Corculum cardissa, showing (a) several symbionts in a tubule and (b) high magnification of the two cells in 6a. Scale bar = 1 Figure 7. Schematic representation of the relation between the alga (A), the tubule cells of the tertiary tubules (TC), and the hemolymph containing blood cells (be), n, nucleus; cp. chloroplast. 2000). In neither example are the "signals" that elicit the developmental response in the host known. In the case of the dinoflagellate associations, the exopolysaccharides ex- uded by Symbiontinium (Markell el al., 1992; Markell and Trench, 1993) may be a source of the signals. For instance, in the process of root nodulation in leguminous plants, the initiation of root hair curling and infection thread formation are dependent on chemical signals from the bacterial sym- bionts (Brewin. 1991). A system of tubules originating in the stomach and ramifying through the hemolymph is uncommon in bi- valve molluscs and appears to be directly related to symbiosis with dinoflagellates. As far as is known, no nonsymbiotic bivalves demonstrate this feature. In addi- tion to the tridacnine clams and Corculum cardissa de- scribed here, the bivalve Fraguin fragum has also been reported to harbor symbiotic dinoflagellates (Kawaguti, 1983). and recent TEM images (Kempf, unpubl.) show morphological features similar to those presented here for C. cardissa. This finding supports the interpretation. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Cla


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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology