145221
Physeter macrocephalus Genome Sequencing
Metals are a well-known cause of respiratory disease. Chromium is best known as a human lung carcinogen, however it causes other lung disease such as respiratory distress, asthenia, emphysema, chronic irritation and fibrosis. Cr(VI) is considered a particularly important and dangerous environmental chemical because it induces lung disease, and exposure to it is widespread. It is listed as one of the "Top 20 Hazardous Substances" by the Environmental Protection Agency (EPA) and the Agency for Toxic Substances and Disease Registry. Accordingly, because the potential for exposure to this carcinogen is high, it is imperative that we discover ways to prevent its toxicity. Whales are known to accumulate levels of metals that are sufficient to seriously impair or even kill terrestrial mammals. For example, the concentrations of cadmium in the kidney cortex from a bowhead have been calculated to be two hundred parts-per-million, which would harm land-dwelling animals, but the bowheads seem unaffected, as 400 necropsies have been performed and no ill health observed. Hypoxia is a well-known cause of respiratory related diseases such as sleep apnea, chronic obstructive pulmonary disease and pulmonary emphysema. Marine mammals, however, can dive to great depths for prolonged periods of time and not experience these ill effects of hypoxia. The sperm whale is one of the deepest-diving mammals in the world. Several times a day the sperm whale dives to the deep ocean in search of food. A dive commonly averages 1,312 feet and lasts about 35 min. However, dives may last over two hours and reach over 3,280 feet, and possibly even over 9,842 feet. These dives are routinely performed, suggesting sperm whales have adapted key cellular and molecular mechanisms to deal with these hypoxic stresses. A genome assembly resource for sperm whale would allow scientists to test molecular pathways that adapted to such incredible hypoxic stress.