Light and electron microscope localization of beta-glucuronidase activity in the stomach and digestive gland of the marine gastropod Littorina littorea

Does integrated medical insurance system alleviate the difficulty of using cross-region health Care for the Migrant Parents in China-- evidence from the China migrants dynamic survey

BACKGROUND

Many internal migrants during the urbanization process in China are Migrant Parents, the aging group who move to urban areas to support their family involuntarily. They are more vulnerable economically and physically than the younger migrants. However, the fragmentation of rural and urban health insurance schemes divided by "hukou" household registration system limit migrant's access to healthcare services in their resident location. Some counties have started to consolidate the Urban Resident Basic Medical Insurance (URBMI) and the New Rural Cooperative Medical Scheme (NRCMS) as one Integrated Medical Insurance Schemes (IMIS) from 2008. The consolidation aimed to reduce the disparity between different schemes and increase the health care utilization of migrants.

RESULTS

Using the inpatient sample of migrant parents from China Migrants Dynamic Survey in 2015, we used Ordinary Least Squares (OLS) for regression models. We found that the migrant parents covered by the IMIS are more likely to choose inpatient services and seek medical treatment in the migrant destination. We further subdivide Non-IMISs into NCMSs and URBMIs in the regression to alleviate the doubt about endogenous. The results revealed that the migrant parents in IMIS use more local medical services than both of them in URBMI and NCMS.

CONCLUSIONS

The potential mechanisms of our results could be that IMIS alleviates the difficulty of seeking medical care in migrant destinations by improving the convenience of medical expense reimbursement and enhancing health insurance benefits.

Immunohistochemical localization of hepatopancreatic phospholipase in gastropods mollusc, Littorina littorea and Buccinum undatum digestive cells

BACKGROUND

Among the digestive enzymes, phospholipase A2 (PLA2) hydrolyzes the essential dietary phospholipids in marine fish and shellfish. However, we know little about the organs that produce PLA2, and the ontogeny of the PLA2-cells. Accordingly, accurate localization of PLA2 in marine snails might afford a better understanding permitting the control of the quality and composition of diets and the mode of digestion of lipid food.

RESULTS

We have previously producted an antiserum reacting specifically with mSDPLA2. It labeled zymogen granules of the hepatopancreatic acinar cells and the secretory materials of certain epithelial cells in the depths of epithelial crypts in the hepatopancreas of snail. To confirm this localization a laser capture microdissection was performed targeting stained cells of hepatopancreas tissue sections. A Western blot analysis revealed a strong signal at the expected size (30 kDa), probably corresponding to the PLA2.

CONCLUSIONS

The present results support the presence of two hepatopancreatic intracellular and extracellular PLA2 in the prosobranchs gastropods molluscs, Littorina littorea and Buccinum undatum and bring insights on their localizations.

Stomach of Aplysia depilans (Mollusca, Opisthobranchia): a histochemical, ultrastructural, and cytochemical study

We report the results of a morphological, histochemical, and cytochemical characterization of the Aplysia depilans stomach, an organ little studied in opisthobranchs. Very thin ciliated cells with microvilli on their apical surfaces are predominant in the epithelium lining the lumen of the stomach. Many lysosomes with a strong arylsulphatase activity were present in the apical regions of these cells that could also contain some lipid droplets and glycogen. Small peroxisomes were observed, usually around lipid droplets or mitochondria. Bottle-shaped secretory cells are very common in this epithelium and produce a secretion rich in proteins and acidic mucopolysaccharides. Most of the cytoplasm of these mucus-producing cells was filled with a very high number of granules and the nucleus is dislocated to the basal region. Cisternae of rough endoplasmic reticulum were abundant around the nucleus and several Golgi stacks were also present in this area. In spite of the variation in the electron density of the granules, only one type of secretory cell seems to be present in the stomach epithelium, since granules with very different electron densities were frequently found in the same cell. A few neurons were also found in the stomach epithelium of this species. Fibrocytes, muscle cells, nerves, and amebocytes were observed in the connective tissue of the stomach wall.

Histopathology of the digestive gland of an Antarctic limpet exposed to cadmium

Histopathological alterations induced experimentally with cadmium (Cd) in Antarctic limpets (Nacella concinna), exposed for different times and concentrations were compared to controls. At the light microscope level, samples exposed to the contaminant for short periods (6, 12 and 24 h) at two different concentrations (0.25 and 0.5 mg l(-1)) showed no alterations compared to controls. After 48 h of exposure at a 0.5 mg l(-1) Cd concentration, vacuolisation of the basophilic cells was observed. After 72 h exposure, there was a marked loss of all the digestive gland structure, with cell autolysis and loss of basophilia.

Use of polyclonal antibodies for the detection of changes induced by cadmium in lysosomes of aquatic organisms

Lysosomal responses are widely accepted cellular effect biomarkers of general stress. Up to now, these biomarkers have been analysed by means of conventional techniques based on enzyme histochemical methods, where lysosomal enzymes such as acid phosphatase and beta-glucuronidase (beta-GUS) have been employed as markers of lysosomes. The aim of the present work was to develop more advanced and sensitive methods based on the use of polyclonal antibodies to measure lysosomal enzymes in different sentinel organisms. For this purpose, we have studied the cross-reactivity of two commercial polyclonal antibodies against the lysosomal enzymes acid phosphatase and beta-GUS with molluscan digestive gland by means of immunoblotting and immunohistochemistry. The antibody against acid phosphatase cross-reacted specifically with the lysosomal fraction of the digestive gland, while unspecific immunoreaction occurred with digestive gland whole homogenates and tissue sections. The antibody against beta-GUS cross-reacted specifically with digestive gland whole homogenates and tissue sections. The cross-reactivity of this antibody was tested also in crab hepatopancreas and mullet liver where the same successful results were obtained. The second aim of the present study was to test if the immuno-based approach was sensitive enough to detect lysosomal alterations provoked by contaminants. For this purpose two experiments were carried out with mussels treated with cadmium in two ways: in vivo treatment by injection and in vitro treatment using digestive gland explants. Afterwards immunoblotting studies with the antibody against beta-GUS were applied and immunoreactive bands were quantified by means of a gel analysis programme. We found that beta-GUS protein levels were higher in treated mussels when compared with controls in either in vivo or in vitro treatments. All these data suggest that the polyclonal antibody against beta-GUS is adequate to be used in immuno-based approaches to detect contaminant-induced lysosomal alterations.

The digestive cells of the hepatopancreas in Aplysia depilans (Mollusca, Opisthobranchia): ultrastructural and cytochemical study

Digestive cells are the most abundant cell type in the digestive diverticula of Aplysia depilans. These are tall columnar or club shaped cells, covered with microvilli on their apical surface. A large number of endocytic vesicles containing electron-dense substances can be found in the apical zone, but the presence of many heterolysosomes of large diameter is the main feature of these cells. Glycogen particles and some lipid droplets were also observed. Peroxisomes with a circular or oval profile were common, but crystalline nucleoids were not detected in them, although a dense spot in the matrix was observed in a few cases. These organelles were strongly stained after cytochemical detection of catalase activity. The Golgi stacks are formed by 4 or 5 cisternae, with dilated zones containing electron dense material. Arylsulphatase activity was detected in the Golgi stacks and also in lysosomes. Cells almost entirely occupied by a very large vacuole containing a residual dense mass seem to be digestive cells in advanced stages of maturation. The observation of semithin and ultrathin sections indicates that these very large vacuoles are the result of a fusion among the smaller lysosomes. Some images suggest that the content of these large vacuoles is extruded into the lumen of the digestive diverticula.

Arylsulphatase activity associated with phenanthrene induced digestive cell deletion in the marine mussel Mytilus edulis

The acid hydrolase arylsulphatase has been localized at the ultrastructural level in digestive cells of the marine mussel Mytilus edulis for control and phenanthrene-treated (200 micrograms/l) animals. In untreated mussels the activity was generally restricted to the lysosomal-vacuolar system and the Golgi apparatus. It was associated with all types of vesicle, although not all individual vesicles were reactive. In heterolysosomes which were filled with precipitate the reaction product was most densely associated with the limiting membranes. Lipid inclusions commonly occurred in the digestive cells; these sometimes showed limited reaction for enzyme activity. The striking difference between normal and phenanthrene-treated samples was the presence in all treated animals of reaction product in the inter-cellular spaces and varying degrees of cytoplasmic activity in a number of digestive cells. This is interpreted as a sign of impending cell deletion. Sections for morphological examination showed evidence of increased digestive cell deletion in phenanthrene-treated mussels. The process results in release of membrane-bound bodies into the tubule lumen.