The role of heavy metals in the expression of stress-induced molecular markers in the tobacco hornworm (Manduca sexta)

The introduction of new chemicals into the soil from multiple sources, such as municipal waste and contaminated water, affect not only the environment, but also impact the organisms living in the ecosystem. Heavy metals (iron, zinc, copper, etc.) can be absorbed through the root systems of plants or accumulate on their leaves, secondarily affecting the organisms that depend on that plant as a food source. Exposure to these metals induces the expression of several stress proteins in an attempt to counter the molecular effects of stress, such as the denaturation of proteins. Therefore, the presence of these stress proteins in an organism could be used as a biological indicator of the health of the environment. Previous research has identified several proteins, including hsp70 and msToll, whose expression appears to be induced in response to environmental stresses. This study uses qPCR to further examine the expression of these proteins in the tobacco hornworm, Manduca sexta, correlating their level of expression to the amount of toxic metals in the diet. The future downstream application of this project is to use some of these stress proteins to ascertain the biological stress level of an organism and illustrate the effects of environmental pollution in an ecosystem.