Daphnia undergo characteristic changes in morphology and physiology in response to various environmental cues. These changes include the sudden surge in hemoglobin synthesis in response to hypoxia that results in a change in body color from colorless to red, the development of defensive structures such as elongated helmet and neck teeth in response to chemical substances released by predators, and the switch from parthenogenetic to bisexual reproduction in response to deteriorating environmental conditions such as decreasing food concentration, crowding, or shortening photoperiod. This project aims to elucidate the mechanisms regulating gene expression in Daphnia of characters related to these changes. The following genes are currently being analyzed.

1. Hypoxia response genes such as those encoding hemoglobin chains and hypoxia-inducible transcription factors.
2. Xenobiotic response genes and xenobiotic receptor genes (primarily those encoding bHLH-PAS proteins).
3. Hormone response genes such as those for vitellogenin and hormone receptors (primarily Zinc finger proteins).