Molecular cloning and expression of leptin in gray and harbor seal blubber, bone marrow, and lung and its potential role in marine mammal respiratory physiology

Leptin is a multifunctional hormone, produced predominantly in adipocytes. It regulates energy balance through its impact on appetite and fat metabolism, and its concentration indicates the size of body fat reserves. Leptin also plays a vital role in stretch-induced surfactant production during alveolar development in the fetus. The structure, expression pattern, and role of leptin have not previously been explored in marine mammals. Phocid seals undergo cyclical changes in body composition as a result of prolonged fasting and intensive foraging bouts and experience rapid, dramatic, and repeated changes in lung volume during diving. Here, we report the tissue-specific expression pattern of leptin in these animals. This is the first demonstration of leptin expression in the lung tissue of a mature mammal, in addition to its expression in the blubber and bone marrow, in common with other animals. We propose a role for leptin in seal pulmonary surfactant production, in addition to its likely role in long-term energy balance. We identify substitutions in the phocine leptin sequence in regions normally highly conserved between widely distinct vertebrate groups, and, using a purified seal leptin antiserum, we confirm the presence of the leptin protein in gray seal lung and serum fractions. Finally, we report the substantial inadequacies of using heterologous antibodies to measure leptin in unextracted gray seal serum.

How much walking should be advocated for good health in adolescent girls?

Background: It is currently not known how much walking should be advocated for good health in adolescent girls. The aim of this study was therefore to recommend health referenced standards for step defined physical activity relating to appropriate health criterion/indicators in a group of adolescent girls. Method: Two hundred and thirty adolescent girls aged between 12-15years volunteered to take part in the study. Each participant undertook measurements (BMI, waist circumference, % body fat and blood pressure) to define health status. Activity data were collected by pedometer and used to assess daily step counts and accumulated daily activity time over seven consecutive days. Results: Individuals classified as ‘healthy’ did not take significantly more steps·day−1 nor spend more time in moderate intensity activity than individuals classified as at health risk or with poor health profiles. Conclusion: ‘Healthy’ adolescent girls do not walk significantly more in term of steps·day−1 or time spent in activity than girls classified as ‘unhealthy’. This could suggest that adolescent girls may not walk enough to stratify health and health related outcomes and as a result the data could not be used to inform an appropriate step guideline for this population.