Linking Lysosomal Biomarkers and Ecotoxicological Effects at Higher Biological Levels - Ecological Biomarkers: Indicators of Ecotoxicological Effects - page 115

Cellular uptake, behavior and effects of organic
chemical pollutants

Hydrophilic

Fluid phase Bound to membrane protein

Endocytosis

Oxidative
damage

Endo-
cytosis

Lipophilic

Bound to natural particles,
nanoparticles, or colloids

Reactive
metabolites
form protein
and DNA
adducts

Lysosomes

Slightly lipophilic

Slightly
lipophilic

Autophagy

Mitochondrion

Autophagy

Lipophilic

Lysosomes

Lysosomes swell,
become unstable
and leak, causing
cell injury and death

Lipid
droplet

Autophagy

Extremely lipophilic

Bound to
membrane lipid

Nucleus Endocytosis

MDR

Excretion

FIGURE 5.3
Diagrammatic representation of the various routes of uptake (both diffusion and endocytotic) of contaminant
xenobiotic chemicals into the cell that can result in their accumulation in the lysosomal compartment, based
on their physical chemical characteristics. (Modified from Moore, M.N. et al., Mutat. Res ., 552, 247-268, 2004a;
Moore, M.N. et al., ICES Techniques in Marine Environmental Sciences (ICES, Copenhagen), 36, 1-31, 2004b; Rashid,
F. et al., Histochem. J. , 23, 450-459, 1991.)

Exposure of mussels to copper and some PAHs also results in increased ROS, as also does
reimmersion in seawater following a period of anoxia as described above (Regoli 2000;
Livingstone 2001; Moore et al. 2007). Reimmersion following anoxia is probably analogous
to reperfusion injury (Robin et al. 2007). Copper exposure also increases the concentration
of protein carbonyls and lipofuscin (Kirchin et al. 1992; Moore et al. 2007). Lushchak (2011)
provides a recent account of the many other pollutants that can enhance ROS levels in
aquatic animals, including a variety of trace metals, pesticides, and oil products.

5.4.3 Environmental Stress and Failed Autophagy Leading to Pathology and Disease

Autophagy is implicated in many disease processes, cell death, and adaptive responses
(Cuervo 2004; Levine 2005). This group of at least three related processes (i.e., macro- and
microautophagy and chaperonin-mediated autophagy) is essential for maintenance of cel-
lular homeostasis (Cuervo 2004), and morphological evidence has long indicated that
lysosomal autophagy is a highly conserved mechanism evolutionarily (Cuervo 2004).