Histological and Histochemical Study of the Hepatopancreas of Two Estuarine Crab Species,Cyrtograpsus angulatusandNeohelice granulata(Grapsoidea, Varunidae): Influence of Environmental Salinity

Effect of starvation and refeeding on the hepatopancreas of whiteleg shrimp Penaeus vannamei (Boone) using computer-assisted image analysis

Under normal farming conditions, shrimp can experience starvation periods attributable to disease outbreaks or adverse environmental conditions. Starvation leads to significant morphological changes in the hepatopancreas (HP), being the main organ for absorption and storage of nutrients. In the literature, limited research has described the effect on the HP of periods of starvation followed by refeeding and none in whiteleg shrimp (Penaeus vannamei) using computer-assisted image analysis (CAIA). This study describes the effect of starvation and starvation followed by refeeding on the HP of whiteleg shrimp using CAIA. Visiopharm^® software was used to quantify the following morphological parameters, measured as ratio to the total tissue area (TLA): total lumen area (TLA:TTA), haemocytic infiltration area in the intertubular spaces (HIA:TTA), B-cell vacuole area (VBA:TTA), lipid droplet area within R cells (LDA:TTA) and F-cell area (FCA:TTA). Significant changes were measured for HIA:TTA and LDA:TTA during starvation (increase in HIA:TTA associated with decrease in LDA:TTA) and starvation followed by refeeding (decrease in HIA:TTA associated with increase in LDA:TTA). In the future, HIA:TTA and LDA:TTA have the potential to be used in a pre-emptive manner to monitor the health of the HP, facilitate early diagnosis of diseases and study the pathophysiology of the organ.

Use of computer-assisted image analysis for semi-quantitative histology of the hepatopancreas in whiteleg shrimp Penaeus vannamei (Boone)

Despite the increasing use of novel molecular techniques in pathology, histology remains the standard method for monitoring tissue alterations and for assessing pathology. Histopathological evaluation is generally laborious and subjective with risk of discrepancies in semi-quantitative scoring between pathologists. In contrast, computer-assisted image analysis (CAIA) is potentially faster, more objective and thus suitable for routine screening. Limited research has been carried out on CAIA in crustacean histopathology, and the methods described were not fully automated. Therefore, the aim of this study was to develop CAIA in whiteleg shrimp (Penaeus vannamei) for the study of the hepatopancreas. Paraffin sections were immunohistochemically stained with monoclonal antibodies WSH8 against haemocytes and counterstained with Mayer's haematoxylin for detection of haemocytes and B-cell vacuoles, and modified toluidine blue protocol was used for detection of F-cells; frozen sections were stained with Oil Red O for detection of lipid droplets within R-cells. Visiopharm^® software was used to develop and validated protocols for the quantification of morphological parameters (areas of haemocyte infiltration, F-cells, B-cell vacuoles, lipid droplets and their ratios to total tissue area and total lumen area). These protocols enable the future use of CAIA for determination of the nutritional and pathological condition of this organ.

Effect of acute salinity stress on ion homeostasis, Na+/K+-ATPase and histological structure in sea cucumber Apostichopus japonicus

Background

Sea cucumbers (Apostichopus japonicus) are an imperiled fauna exposed to a variety of environmental condition such as salinity and studies are urgently needed to assess their effects to guide aquaculture efforts. The effects of acute salinity stress on coelomic fluid osmotic pressure, ion concentrations, the activity of Na⁺/K⁺-ATPase in respiratory trees and the histological variations were measured to evaluate the salinity tolerance of sea cucumbers.

Results

Significant correlations in osmotic pressure were observed between coelomic fluid and ambient environmental salinity. In coelomic fluid, Na⁺ concentration was observed fluctuated during salinity 18 psu and the inflection point presented at the 6 h. The Na⁺/K⁺-ATPase activity in respiratory trees indicated the “U-shaped” fluctuant change and the change trend was opposite with the Na⁺ concentration. The ions (K⁺, Cl⁻) concentration decreased and showed the same tendency at salinity 40 psu with salinity 18 psu. The total coelomocytes counts and phagocytosis of coelomic fluid Na⁺/K⁺-ATPase activity indicated fluctuating changes under different salinity stress. Histological variation revealed a negative relation between decreasing salt concentration and tissue integrity. Tissue damages were significantly observed in intestines, muscles and tube feet under low salinity environment (18, 23 and 27 psu). The connective tissue in intestines of A. japonicus exposed to 18 and 23 psu damaged and partly separated from the mucosal epithelium. The significant variations occurred in tube feet, which presented the swelling in connective tissue and a fracture in longitudinal muscles under low salinity (18 psu). The morphological change of tube feet showed the shrinkage of connective tissue under high salinity (40 psu). The amount of infusoria in the respiratory trees decreased or even disappeared in salinity treatment groups (18 and 23 psu).

Conclusion

The results inferred that osmoconformity and ionoregulation were seen in sea cucumbers, which contributed to understand the salinity regulatory mechanisms of A. japonicus under acute salinity stress.