Myoglobin production in emperor penguins.

Area of Science:

• Physiological adaptations in marine animals
• Molecular mechanisms of oxygen storage

Background:

• Marine mammals and seabirds require enhanced oxygen storage for diving.
• The molecular basis for increased oxygen storage in diving birds is not well understood.

Purpose of the Study:

• To investigate the molecular mechanisms of myoglobin (Mb) production in emperor penguins (Aptenodytes forsteri).
• To determine how Mb and Mb mRNA levels change with age and diving activity.

Main Methods:

• Spectrophotometric assays to measure Mb concentration in pectoral muscles.
• RNase protection assays to quantify Mb mRNA levels.
• Comparison of Mb and Mb mRNA in emperor penguin adults, chicks, and juveniles.

Main Results:

• Mb concentration and Mb mRNA content increased significantly from chicks to adult emperor penguins.
• Adults had 15-fold higher Mb concentration and 3-fold higher Mb mRNA than 3.5-month-old chicks.
• Mb levels in captive, non-diving adults were lower than wild adults, suggesting a role for diving-induced hypoxia.

Conclusions:

• Myoglobin production in emperor penguins is regulated at the transcriptional level.
• Diving exercise and nutritional status appear to be critical factors in achieving maximal Mb concentrations.
• The relationship between Mb mRNA and Mb concentration is complex, with potential post-transcriptional regulation involved.