May 12, 2009

Caterpillar gene expression reacts to diet

German scientists say they have discovered cabbage looper caterpillars are able to alter the expression of their genes in response to plant bacteria.

The scientists, led by Dalial Freitak at the Max Planck Institute for Chemical Ecology, determined the caterpillars (Trichoplusia ni) alter their genes associated with metabolism, homeostasis and immunity. And as well as tailoring gene expression within their own digestive systems, the caterpillars pass the information to their offspring.

Larval feeding on a bacteria-rich diet leads to substantial gene expression changes, potentially resulting in a reorganization of the insects' metabolism to maintain organismal homeostasis, not only in the larval, but also in the adult stage, Freitak said.

The researchers theorize having a suite of genes capable of responding to dietary composition allows the cabbage looper to fine-tune its natural defenses.

Mounting an immune response is costly and dangerous, said Freitak. The fact the insects can up regulate immunity related genes "¦ in response to the presence of bacteria, but leave them switched off in the absence of pathogens, minimizes the release of multiple potentially cytotoxic molecules, which could in turn activate other stress related defenses.

The study appears in the BMC journal Frontiers in Zoology.