Acidification Gradient Research Articles

Clustering and canonical correspondence analysis of phytoplankton and environmental variables in Swedish lakes

Phytoplankton data consisting of 145 species from a limnological study of lakes from relatively undisturbed areas throughout Sweden were analysed in relation to 11 physical and chemical environmental variables. Three multivariate methods were applied: WPGMA clustering and TWINSPAN for classification, and detrended canonical correspondence analysis (DCCA), a recent technique which extracts ordination axes that can be related directly to variation in the environment. Three types of lakes were recognized consistently: acid humic lakes with Gonyostomum semen as the dominant species, very acid impoverished lakes with rather few, stress-tolerant species, and subarctic lakes with low total biomass but with a varied phytoplankton flora. DCCA allowed a straightforward display of the locations of lakes and species along environmental gradients (including the acidification gradient) reflected in phytoplankton composition. It is suggested that such analyses may be a useful tool for the early detection of environmental change.

Immunoelectron microscopic localization of acidic intracellular compartments in hepatoma cells.

Using protein A-colloidal gold immunoelectron microscopy and monospecific antibodies to the weak base primaquine, we have delineated acidic intracellular compartments in the human hepatoma cell line, HepG2. Primaquine specifically accumulated within endocytotic compartments (including CURL vesicles, multivesicular bodies and lysosomes). In addition, the Golgi cisternae were positive. However, the CURL tubules, which contain recycling asialoglycoprotein receptor, did not accumulate primaquine. Thus, there may be a gradient of acidification within the endocytotic pathway.