CALCIUM PHOSPHATE GRANULES IN THE HEPATOPANCREAS OF THE BLUE CRAB CALLINECTES SAPIDUS

Abstract

The hepatopancreas of the adult male blue crab Callinectes sapidus in intermolt was found to contain substantial amounts of calcium, magnesium, and inorganic phosphorus, averaging about 260, 20, and 250 µg-atoms per g wet tissue, respectively, accounting for over 10% of the tissue dry weight . Electron microscopy of the intact tissue showed three qualitatively different granular structures having electron densities suggestive of high mineral content . After fractionation of the tissue using centrifugal techniques, almost 95% of the total mineral was found to reside in a heavy, nonmitochondrial particulate fraction(s) . The bulk of the low-speed pellet consisted of relatively dense, roughly spherical granules 1-5 µm in diameter, which could be considerably purified by repeated suspension in water and low-speed sedimentation. In the electron microscope the isolated granules appeared basically similar to one of the three characteristic types of electron-dense granules seen in the intact tissue . Although the freshly isolated granules lost approximately 50% of their wet weight when dried at 105°C, only 10% more was lost upon dry ashing at 450°C, suggesting a fairly low content of organic material . Chemical analysis revealed calcium, magnesium, and inorganic phosphate at 5 .7, 2 .1, and 4 .4,ug-atoms per mg dried granules, respectively, accounting for 69% of the dry weight of the fraction . By specific enzymatic assays, the freshly isolated granules were found to contain ATP, ADP, and AMP at levels of 0.13, 0 .03, and 0 .01 umol/mg, or 8% of their total dry weight . The remainder of the total phosphorus contributed an additional 3 0/,, whereas carbonate, citrate, oxalate, and protein each constituted no more than 1 % .The mineral granules of the crab hepatopancreas appear to function as storage forms of calcium and phosphate during the intermolt period . This tissue appears promising as a model for study of the cellular events associated with biological calcification, since conventional biochemical techniques can be employed . Furthermore, the major mineralized component of the tissue can be obtained in large amounts for direct study by a simple fractionation procedure .In preceding papers it was shown that mitocapable of energy-dependent accumulation of chondria isolated from the hepatopancreas of the large amounts of Cal+ and phosphate from the blue crab Callinectes sapidus are capable of vigorous suspending medium (2) . After such accumulation respiration and phosphorylation (1) and are also of Cat+, large electron-dense deposits or clusters 3 16

High-resolution structural and elemental analyses of calcium storage structures synthesized by the noble crayfish Astacus astacus

“…It was previously observed that decapods, which do not develop gastroliths, can store, in other storage sites such as hepatopancreas or haemolymph, not only calcium and carbonate but also phosphate ions used for the mineralization of each new cuticle (Becker et al, 1974;Corrêa, 2002Corrêa, , 2009Sparkes and Greenaway, 1984;Travis, 1955).…”

Contribution of X-Ray Spectroscopy to Marine Ecotoxicology: Trace Metal Bioaccumulation and Detoxification in Marine Invertebrates

“…Once in the gut, the reabsorption of the ions after the granule chemical and enzymatic dissolution may also occur, as suggested by Becker et al (1974). Nott and Nicolaidou (1993), fed a carnivorous gastropod (Nassarius reticulatus) with another gastropod (Littorina littorea) hepatopancreas which contained intracellular phosphate granules.…”

“…In some species, these concretions remain in the cell for a relatively long period of time before they are excreted (Fowler, 1987;Sullivan et al, 1988;Nott, 1991). Actually granules were found in the digestive lumen of the crab Callinectes sapidus (Becker et al, 1974;Guary & Negrel, 1981) and of the copepod Tigriopus brevicornis (Barka, 2007) suggesting that metal detoxification occurs (if the release of granules into the lumen is followed by an excretion in the gut) (Fig. 6).…”

“…These granules may act as a calcium reservoir serving as a source of calcium for metabolic needs, maintaining Ca homeostasis, exosqueleton replacement after moulting as suggested for crabs (Becker et al, 1974) or building material of skeletal tissue in molluscs (Jacob et al, 2011). However, several authors proposed a metal detoxification role for Ca granules (Mason & Simkiss, 1982;Simkiss, 1981).…”

Transporte de cálcio em células isoladas de hepatopâncreas do caranguejo dulcícola Dilocarcinus pagei: efeito do ATP e Ca2+

“…Outro papel é a absorção de nutrientes e outros componentes da dieta (YONGE, 1924;LOIZZI, 1971;LOIZZI & PETERSON, 1971;GIBSON & BARKER, 1979;JOHNSON, 1980). O hepatopâncreas também é responsável pelo armazenamento de cálcio e fosfato do exoesqueleto durante o ciclo da muda (BECKER et al,1974;CHEN et al, 1974;LORET & DEVOS, 1992) e glicogênio e lipídeos durante períodos de abundância de alimentos (YONGE, 1924; VAN WEEL, 1974;GIBSON & BARKER, 1979;JOHNSON, 1980). Pelo menos 4 tipos celulares são reconhecidos nesse órgão e foram classificadas de acordo com JACOBS em (1928): (1) células "E" (embrionárias), que se originam por mitose na região distal do túbulo e se diferenciam quando migram proximalmente; (2) "F" (fibrilares), que possuem um citoplasma granular e um vacúolo supranuclear que se expande conforme a maturação da célula; (3) "R" (absortivas), que contém gotículas de glicogênio e lipídeos; e (4) "B" (blister, vesiculares), que contém um único e grande vacúolo enzimático cercado por um fino citoplasma.…”