PHYSICOCHEMICAL FORMS OF STORAGE OF METALS (CD, CU AND ZN) AND METALLOTHIONEIN-LIKE PROTEINS IN GILLS AND LIVER OF MARINE FISH FROM THE TUNISIAN COAST - ECOTOXICOLOGICAL CONSEQUENCES
A. Hamzachaffai et al., PHYSICOCHEMICAL FORMS OF STORAGE OF METALS (CD, CU AND ZN) AND METALLOTHIONEIN-LIKE PROTEINS IN GILLS AND LIVER OF MARINE FISH FROM THE TUNISIAN COAST - ECOTOXICOLOGICAL CONSEQUENCES, Comparative biochemistry and physiology. Part C, Pharmacology toxicology & endocrinology, 111(2), 1995, pp. 329-341
Three fish species (Diplodus annularis, Scorpaena porcus and Scorpaena
scrofa) were sampled off the coast of the industrialized area of Sfax
, The distribution of Cd, Cu and Zn was examined in different fraction
s of both gills and liver: insoluble fraction and cytosol divided into
thermolabile compounds and heat-stable compounds, In the latest fract
ion, quantitative analysis of metallothionein-like proteins (MTLP) was
achieved by using differential pulse polarography, In the gills, the
insoluble fraction was the major compartment for the storage of all th
ree metals, In the liver, 50% Cd and Cu at least were also associated
with this fraction whereas Zn was bound primarily with heat-stable com
pounds, a pattern which is probably due to the role of MTLP in Zn home
ostasis and to the fact that Zn is a constituent element of metallothi
onein, According to the species, one eighth to a little more than one
quarter of Cd, Cu or Zn was bound to the thermolabile fraction in the
liver, probably due to the presence of numerous enzymes involved in th
e metabolic functions of this organ, In both gills and liver, Cd and C
u concentrations in the thermolabile fraction were increased with incr
easing organ burden of these metals, This observation suggests an enha
ncement of the toxic hazard since this fraction includes metabolic tar
gets of metals, Statistically significant relationships have been show
n between metals and MTLP concentrations in both organs, However, the
use of MTLP as a biomarker has to be revised in the light of natural c
hanges (according to age, sex, etc.) which could conceal variations du
e to metabolic pollution.