Glycoconjugate expression in the olfactory bulb of the premetamorphic larva of the Japanese sword-tailed newt (Cynops ensicauda)

Ecological Risks Due to Immunotoxicological Effects on Aquatic Organisms

The immunotoxic effects of some anthropogenic pollutants on aquatic organisms are among the causes of concern over the presence of these pollutants in the marine environment. The immune system is part of an organism's biological defense necessarily for homeostasis. Thus, the immunotoxicological impacts on aquatic organisms are important to understand the effects of pollutant chemicals in the aquatic ecosystem. When aquatic organisms are exposed to pollutant chemicals with immunotoxicity, it results in poor health. In addition, aquatic organisms are exposed to pathogenic bacteria, viruses, parasites, and fungi. Exposure to pollutant chemicals has reportedly caused aquatic organisms to show various immunotoxic symptoms such as histological changes of lymphoid tissue, changes of immune functionality and the distribution of immune cells, and changes in the resistance of organisms to infection by pathogens. Alterations of immune systems by contaminants can therefore lead to the deaths of individual organisms, increase the general risk of infections by pathogens, and probably decrease the populations of some species. This review introduced the immunotoxicological impact of pollutant chemicals in aquatic organisms, including invertebrates, fish, amphibians, and marine mammals; described typical biomarkers used in aquatic immunotoxicological studies; and then, discussed the current issues on ecological risk assessment and how to address ecological risk assessment through immunotoxicology. Moreover, the usefulness of the population growth rate to estimate the immunotoxicological impact of pollution chemicals was proposed.

Characterization of glycoconjugates and sialic acid modification in the olfactory bulb of the Chinese fire-bellied newt (Cynops orientalis)

Diverse glycoconjugates are expressed in the vertebrate olfactory bulb and serve as guidance cues for axons of nasal receptor neurons. Although the involvement of glycoconjugates in the segregation of the olfactory pathway has been suggested, it is poorly understood in salamanders. In this study, lectin histochemistry was used to determine glycoconjugate distribution in the olfactory bulb of the Chinese fire-bellied newt (Cynops orientalis). Succinylated wheat germ agglutinin (sWGA), Ricinus communis agglutinin-I and Lens culinaris agglutinin showed different bindings in the nerve fibre layer or glomerular layer, or both, between the main and accessory olfactory bulbs. We then investigated the lectin-binding pattern after the removal of terminal sialic acids using neuraminidase. Desialylation resulted in a change in the binding reactivities with seven lectins. Wheat germ agglutinin, sWGA, soybean agglutinin (SBA) and peanut agglutinin showed different degrees of binding between the main and accessory olfactory bulbs. In addition, SBA showed a heterogeneous labelling of glomeruli in the rostral region of the main olfactory bulb. Our results suggest that terminal sialic acids mask the heterogeneity of glycoconjugates in the olfactory bulb of C. orientalis.