TOXIC STRESS AND ANIMAL METABOLISM
K. RAMALINGAM *
PG & RESEARCH DEPTT. OF ZOOLOGY, GOVT. ARTS COLLEGE, NANDANAM, CHENNAI- 600 035, INDIA
*Author to whom correspondence should be addressed.
Abstract
Animals are generally endowed with various metabolic pathways, evolved as adaptations to cope up with the environmental stressors. The biodiversity that exists in every species could be attributed to the successful operation of these diverse metabolic pathways. These biosynthetic pathways involving genetic mechanisms are responsible for the derivation of a cascade of biochemical products, which manifest in either biochemical or phenotypic characters. Long before the impact of chemical stress on organisms, was felt, the biosynthetic pathways existed already and their operations were altered by various environmental parameters. Consequent to the response, organisms are categorized into tolerant/resistant and susceptible/sensitive species. The diversity among various species was kept up in good stead, despite environmental stressors by the various biomechanisms involving metabolites, enzymes and electrolytes. The various biochemical pathways such as Kreb's cycle, HMP shunt; glycolysis with reference to carbohydrate metabolism; proteolysis, protein synthesis, deamination and transmination reactions with reference to protein metabolism and the like of which in fat metabolism such as lipogenesis, lipolysis and oxidation, all contribute to the survival of species and their diversity. Chemical toxicology refers to the implications of natural cum man made toxic compounds on such aspects of animal metabolism as physiology. The results of toxicological findings have not only revealed the metabolic scopes of various organisms but also emphasize the need to redesignate their species status taxonomically. Such an appraisal could lead to the proposition of new concepts and hypotheses to attribute for the origin and evolution of a new category of species adapting to the prevailing man made environmental niches. These organisms consequent to the exposure to a chemical environment have modulated their already existing metabolic pathways to derive energy. Besides new pathways have also been established to compensate. Moreover, detoxification mechanisms like MFO, P450 enzyme systems, metallothionins have been evolved to adapt the animals to thrive. The above reorientation of metabolism and detoxification processes could answer for the prevailing biodiversity and distribution in the man-made neoenvironment. Both genetic and non-genetic mechanisms have come to stay put and operate. A perusal of literature could reveal that toxicological studies have been started since 1960 to date on various organism both aquatic and terrestrial, encompassing diverse bioassays (Warner, 1967). It is imperative to enumerate the results of these toxicological findings and observations to attribute to the metabolic scope of various organisms and to redesignate their species status taxonomically in the context of an environment which has been modified by Xenobiotics.