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Dietary iron exists as heme and non-heme iron. Heme iron is more bioavailable making it more useful in meeting the RDA. Conversely, heme iron may be a risk factor for colorectal cancer. Therefore, it is important to know the heme iron content of foods. Clams have been purported to be excellent sources of both heme and non-heme iron. However, there are limited data on iron composition among bivalves. Our objective was to measure mineral composition in commonly consumed bivalves and highlight differences in heme iron content. Manila clams, Pacific oysters, frozen blood clams ( A. granosa ), canned blood clams, and canned akagai ( A. broughtonii ) were assayed. Beef liver was included as a reference food rich in heme iron. Heme iron content, expressed as mg/100 g edible portion (EP), ranged from 0.5 ± 0.1 in Manila clams and 0.85 ± 0.03 in Pacific oysters, to 5.8 ± 0.3 in frozen blood clams. Beef liver contained 3.6 ± 0.2 mg/100 g EP. Non-heme iron ranged from 4.5 ± 0.4 in Manila clams to 9.8 ± 0.6 mg/100 g EP in canned blood clams. Most products contained nutritionally high levels (>10% DV) of Cu, Mn, Se, and Zn. Pacific oysters and canned blood clams contained potentially toxic levels of Cd if eaten regularly. We conclude that a broader analysis of bivalve products is needed to strengthen food composition databases for heme iron and potentially toxic minerals, and that blood clams would be a more reliable source of bioavailable iron than other bivalves. [ABSTRACT FROM AUTHOR]

Complete lectin mapping of molluscs with their diversified recognition pattern and possible role in lectin-carbohydrate interaction based immune response triggering need much attention. In this communication, Gal/GalNAc specific three lectins AGL-IA ( Anadara granosa lectin-IA), AGL-IB ( A . granosa lectin-IB) and AGL-IV ( A . granosa lectin-IV) and a lectin having hemolytic activity AGL-III ( A. granosa lectin-III) were purified from the plasma of A. granosa bivalve by a combination of gel filtration and affinity chromatography. AGL-IA and IB were oligomeric lectins whereas, AGL-III and IV were monomeric. The molecular weight of AGL-IA, IB, III and IV were 375, 260, 45 and 33 kDa respectively. AGL-IA and IV agglutinated both rabbit and pronase treated human erythrocytes, whereas AGL-IB agglutinated only rabbit erythrocytes. AGL-III was found to agglutinate rabbit erythrocytes, however, it caused hemolysis of pronase treated human erythrocytes. The activity of all four lectins was calcium dependent and maximum at a pH range 7–8. Apart from Gal/GalNAc specific, the four lectins showed substantial differences in their carbohydrate recognition pattern. Moreover, there was a difference in the carbohydrate specificity between AGL-III and other three lectins (AGL-IA, AGL-IB and AGL-IV) towards polyvalent glycotope. On the one hand, ‘cluster glycoside effect’ i.e ., an enhancement of the activity of a multivalent ligand, was observed for carbohydrate specificities of AGL-IA, AGL-IB, AGL-IV. On the other hand, the effect of multivalent ligands on the carbohydrate specificity of AGL-III was opposite of cluster glycoside effect. The affinity of AGL-IA, AGL-IB and AGL-IV for ligands can be ranked as follows: glycoproteins >> polysaccharide > oligosaccharides and monosaccharides. However, Gal related monosaccharides were the best inhibitors of AGL-III and the inhibitory activity decreased gradually in the following order: monosaccharide > disaccharide > polysaccharide. Thus, the diverse specificity of multiple lectins in A. granosa plasma possibly enables to recognize a wide range of microorganisms. [ABSTRACT FROM AUTHOR]

Abstract: Metrical analyses of complete mollusc shells have commonly been used to examine aspects of prehistoric mollusc demography, and by extension to investigate potential human exploitation of a variety of species. Recently it has been highlighted that several taphonomic processes, such as fragmentation, have the potential to introduce size bias into these archaeological samples, particularly towards smaller size classes, and thus the potential to significantly skew results of these metrical analyses. This is investigated here by deriving morphometric equations for the sand/mudflat bivalve Anadara granosa, a species prevalent in archaeological sites across northern Australia. A linear regression model based on a series of valve measurements, resulting in high coefficients of determination, demonstrates strong predictive power for size reconstruction. The effects of fragmentation on assemblages from two case study sites are then examined as a means of reviewing issues of differential size preservation, variation in mean valve size, and evaluating the strength of previous interpretations of intensive human exploitation in Blue Mud Bay. Based on these analyses it appears that A. granosa mean size is not significantly affected by fragmentation as other species described in the literature, and previous interpretations retain their validity. [Copyright &y& Elsevier]

Abstract: Explanatory frameworks relating to the appearance of shell mounds and the exploitation of molluscs (particularly the sand/mudflat bivalve Anadara granosa) during the late Holocene have tended to emphasise stasis and continuity. Very few analyses have adequately investigated the intensity of human predation during the mound period and the potential effects on the particular prey species. To this end, the biological and ecological characteristics of A. granosa, the dominant molluscan species for much of the known period of occupation in the region, are considered in detail, in combination with assessing the potential for human impact through predation via the measurement of 9106 A. granosa valves from three shell mounds. In explaining long-term economic change in this region of northern Australia, the focus has been placed on the analysis of relative changes and trends through time in prehistoric resource exploitation. [Copyright &y& Elsevier]