Zinc accumulation in phosphate granules of Ucides cordatus hepatopancreas

Abstract

Amorphous phosphate granules are present in vertebrate and invertebrate organisms. The functions attributed to these structures depend on their mineral contents and organic matrix composition. In the present study we have determined zinc concentrations in the hepatopancreas of the crab Ucides cordatus from regions contaminated with zinc, and the elemental composition of hepatopancreal phosphate granules. Organisms were collected from the contaminated areas of Sepetiba Bay (SB) and Guanabara Bay (GB), and from a non-contaminated area, Ribeira Bay (RB). The first two sites are located near the metropolitan region of Rio de Janeiro city, Brazil. Atomic absorption spectroscopy (AAS) showed a significant difference (P<0.05) for zinc concentration in the hepatopancreas from organisms collected at the contaminated sites GB (210 ± 20 µg/g dry weight) and SB (181 ± 16 µg/g dry weight) compared to the non-contaminated site RB (76 ± 14 µg/g dry weight). Phosphate granules isolated from hepatopancreatic tissue were studied by electron diffraction (ED), energy dispersive Xray analysis (EDX) and electron spectroscopic imaging (ESI). ED of granules presented no diffraction spots, indicating that these structures are in an amorphous state, while EDX of granules isolated from a contaminated area contained P, Ca and Zn. Mg, Cl and Fe were also found in some of the spectra. ESI showed that O, P and Ca were colocalized in the mineralized layers of most granules observed. The correlation between the results obtained by AAS and those obtained by microanalytical techniques suggests that the hepatopancreatic granules of U. cordatus may be related to the phenomenon of heavy metal retention.

Controls on Gut Phosphatisation: The Trilobites from the Weeks Formation Lagerstätte (Cambrian; Utah)

“…These spherites are thought to be involved in various vital processes (e.g. excretion [45], [46], detoxification [41], [48], and storage of ions [43], [46]). They are usually released into the digestive lumen [42], or dissolved intracellularly to permit the remobilisation of their elements [43], [45].…”

Chapter 10. The Crab Ucides cordatus (Malacostraca, Decapoda, Brachyura) and Other Related Taxa as Environmental Sentinels for Assessment and Monitoring of Tropical Mangroves from South America

“…43 Toxic metals may also be captured by lysosomes, 42 or even compartmentalized into granules in detoxification organs, such as the hepatopancreas. 44 Gills, on the other hand, as the first organ affected by pollutants, represent a selective organ that is in contact with both the internal and external environments, acting as a temporary store for accumulated metals. 45 The damage involves a cascade of events promoted by stressors 46 where bioindicator responses act at several levels of biological organization to show sublethal stress effects, serving as early warning signals in a causal relationship between stressors and effects, later manifested at higher levels of biological organization.…”

Insight of EDX analysis and EFTEM: Are spherocrystals located in strombidae digestive gland implied in detoxification of trace metals?

“…Such structures are known to be involved in mineral and trace metal storage and in a not well understood detoxification process. Several studies focused on the spherocrystals capacity to incorporate metal ion in their structure (Corrêa Junior et al,2000; Taylor et al,1989, 1990; Walker et al,1975). The digestive gland of Gastropods is supposed to be implied in detoxification pathways (Simkiss and Mason,1988) but knowledge is scarce about the process involved.…”