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In decapod crustaceans, the digestive gland is concerned with the digestion, absorption of nutrients, the storage of reserves and excretion. The metabolism and the histological and histochemical changes of the hepatopancreas are observed in response to physiological demands as moult, reproduction, digestive process. Thus the hepatopancreas structure should be recognized to provide important morphological information to future studies involving the nutrition requirements of freshwater prawn culture. In this study, second-generation Macrobrachium amazonicum produced from wild broodstock collected in the state of Para in Brazil were used. Thirty adult male and female M. amazonicum were selected and randomly transferred to five experimental units for macroscopic and microscopic studies. The hepatopancreas of M. amazonicum is a large, yellowish-brown, compact organ, which occupies much of the cephalothoracic cavity. It has right and left halves that are enclosed together in a laminar connective tissue capsule, and at the same time they are separated by an interstitial connective tissue. The two halves are thereby called the right and left hepatopancreatic lobes. The principal tubule gives rise to four secondary tubules at each hepatopancreatic lobe. The morphological and functional unit consists of a blind-ended hepatopancreatic tubule, considered in the present study as the hepatopancreatic lobule. Each hepatopancreatic tubule can be subdivided into distal, medial and proximal zones. The hepatopancreatic tubule is lined by a pseudostratified epithelium that consists of five different cell types, which include the E-cell (embryonic), F-cell (fibrillar), B-cell (blister-like), R-cell (resorptive) and M-cell (midgut or basal). It is important to emphasize that the function of each cell type in the hepatopancreas during the digestive cycle is not yet established for decapods. [ABSTRACT FROM AUTHOR]

Crabs can be infected by a variety of pathogenic micro-organisms but the most damaging are viruses. Naturally-occurring Callinectes sapidus reovirus 1 (CsRV1) is thought to contribute to mortality of Callinectes sapidus in soft crab culture in the USA. In Brazil, soft crabs are frequently produced using Callinectes danae, which suffers a similar rate of mortality in culture as C. sapidus. This study investigated whether CsRV1 could be detected in healthy or dead Callinectes danae from Paraná, Brazil and kept in captivity, we also evaluated the relationship between viral infection, and biochemical and behavioral parameters. C. danae from Paranaguá Bay were kept in a recirculation system for 14 days and subjected to weekly biochemical analyses and a reflex action mortality predictors (RAMP) test. RT-qPCR assays for CsRV1 were negative for all samples. However, electrophoretic analysis of extracted RNA from some crabs showed a pattern of 12 dsRNA bands that indicated intense infection by a reovirus with a genome organization different from CsRV1. The banding pattern was indistinguishable from a putative novel reovirus detected in C. sapidus in Rio Grande do Sul, Brazil, provisionally called CsRV2. The prevalence of dsRNA of CsRV2 showed no significant difference between crabs that died and survived. Interestingly, the presence of CsRV2 dsRNA was correlated with a significant reduction in glycogen concentration in hepatopancreas and a decrease in reflex action. The results obtained in this study are an early glimpse of the occurrence of reoviruses in C. danae and their potential effects in soft-shell crab systems in Brazil., (Copyright © 2022 Elsevier Inc. All rights reserved.)

In this study, we analyzed biomarkers and heavy metals in Ucides cordatus specimens caught in mangrove areas [A1 = reference (low impact area); A2, A3 and A4 = port complex (potentially impacted area)] of the Amazonian northern coast of Brazil. Sediments and crab muscles sampled from the potentially impacted mangroves showed high levels of metals. Additionally, catalase and glutathione S-transferase enzymes in the gills and hepatopancreas of the collected crabs were elevated in crabs from A2, A3 and A4 relative to those from A1. The histological characteristics of the gills and hepatopancreas differed in crabs collected from A2, A3 and A4 compared with those collected from A1. The crabs were larger and heavier in the rainy season in A1 and A3 and heavier in the dry season in A4. Heavy metal analyses of sediments, crab muscles and biological responses indicated that the animals are subjected to stress levels differentiated in the mangroves due to a gradient (A4>A3>A2>A1) of anthropogenic pressure in São Marcos Bay. In conclusion, the analyses of metals in the sediment and in the muscles of crabs, as well as the biochemical biomarker and histological analyses, suggest that crabs from mangroves in the port complex region are subject to pollutants that compromise their health. [Display omitted] • Cordatus was used as a biomonitor of impacted harbors. • Trace metal concentrations in the sediment and in the crab tissues were higher in port areas. • CAT activity in the crab gills did not differ between the rainy and dry periods. • Biological responses in crabs can affect the biodiversity of the Amazon region. [ABSTRACT FROM AUTHOR]

Metals are persistent pollutants, able to accumulate in the biota and magnify in trophic web. In the specific case of cadmium contamination, it has been the subject of considerable interest in recent years because of its biological effects and it is one of major pollutant in estuarine areas. Ucides cordatus is considered a mangrove local sentinel crab species in Brazil and there are previous studies reporting crab subpopulations living from pristine to heavily metal impacted areas in São Paulo coast (Southeastern Brazil). Taking into account the background knowledge about these subpopulations, we proposed the hypothesis that crabs from a highly polluted mangrove (Cubatão - CUB) have developed biological tolerance to cadmium compared to animals from an Environmental Protected Area (Jureia - JUR). Aiming to verify this hypothesis, we have investigated total bioaccumulation and subcellular partition of Cd, besides biomarkers' responses during a long-term exposure bioassay (28 days, with weekly sampling) using a supposedly safe Cd concentration (0.0022 mg L -1 ). Specimens from the pristine area (JUR) accumulated higher total Cd, as such as in its biologically active form in gills. Animals living in the polluted site (CUB) presented higher amounts of Cd in the mainly detoxifying tissue (hepatopancreas), which could be considered a pathway leading to tolerance for this metal. Multivariate analysis indicated that bioaccumulation (active, detoxified and total Cd) is linked to geno-cytotoxic damages. CUB subpopulation was considered more tolerant since it presented proportionally less damage and more capacity to allocate Cd in the main detoxifying forms and tissues., (Copyright © 2019. Published by Elsevier B.V.)

Metal/metalloid accumulation in fish organs elicits biochemical responses indicating the overall fish and environmental health status. This study evaluated the bioaccumulation of metals and metalloid in relation to a suite of biochemical biomarkers (superoxide dismutase, catalase, glutathione-S-transferase, Na+/K+-ATPase, H+-ATPase, acetylcholinesterase activities and the levels of glutathione, metallothionein, lipid peroxidation and oxidized protein) in different organs of fish, Centropomus parallelus, in Vitória Bay and Santa Cruz estuaries (State of Espírito Santo, Brazil) with distinct contamination levels. Metal and metalloid concentrations differ in each organ and were significantly higher in winter than in summer. Chemometric evaluation performed between metal/metalloid accumulation and the biomarkers revealed a complex scenario in which the biomarker responses depend on both metal accumulation and organ/tissue sensitivity. The metal levels in gills indicate fish contamination mainly via water and the low sensitivity of this organ to most metals. Biomarker responses suggested that the metal elimination pathway is through the gills and kidney. The hepatopancreas and kidneys were the most important detoxification organs while muscle was the less reactive tissue. In general, the finding suggested that, C. parallelus is partly able to tolerate such metal contamination. However, it is emphasized that the biomarker responses imply an energetic cost and may affect the growth rate and reproduction. Given the ecological and economic importance of C. parallelus, the level of toxic metals/metalloids in juvenile fish is an important early-warning for the maintenance, conservation and commercial use of this species., (Copyright © 2018 Elsevier Inc. All rights reserved.)