Hormonal Changes over Postnatal Development and Molting in Antarctic seals

Lead Author Affiliation

Bachelor's in Biological Sciences

Lead Author Status

Undergraduate - Senior

Second Author Affiliation

Biological Sciences

Second Author Status

Faculty Mentor

Research or Creativity Area

Natural Sciences

Abstract

The frigid and fearsome Antarctica poses a significant challenge to animals that inhabit the southernmost continent. One inhabitant superbly adapted to this challenge is the Weddell seal. The newborn Weddell seal pups undergo a dramatic molt shortly after birth during which they shed their lanugo (fetal fur) before bulking up with blubber for insulation and a shorter, sleeker coat. However, the timing and rate of molt differs between pups and the cause of this variability is unknown. The goal of this project was to measure cortisol and thyroid hormone levels in molting Weddell seal pups from week 1, 3, 5, and 7 of postnatal development. We used an enzyme-linked immunosorbent assay (or ELISA) to quantify cortisol levels and a radioactive immunoassay (RIA) to measure total triiodothyronine (tT3) levels in blood plasma of seal pups. Our results show a significant increase in cortisol from week 1 to week 3 and in tT3 levels from week 1 and week 5 of postnatal development. In addition, we found associations between cortisol and tT3 levels and molt status. These novel results give us a closer look at what is driving postnatal development in Weddell seals in tune with their environment. Our study is the first to measure hormones at this resolution in an Antarctic marine mammal. This information can be a vital baseline as climate continues to change and how that might affect the health of the species. Next, we are working on optimizing seal plasma sample preparation methods for proteome-level analyses of postnatal development in marine mammals.

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Hormonal Changes over Postnatal Development and Molting in Antarctic seals

The frigid and fearsome Antarctica poses a significant challenge to animals that inhabit the southernmost continent. One inhabitant superbly adapted to this challenge is the Weddell seal. The newborn Weddell seal pups undergo a dramatic molt shortly after birth during which they shed their lanugo (fetal fur) before bulking up with blubber for insulation and a shorter, sleeker coat. However, the timing and rate of molt differs between pups and the cause of this variability is unknown. The goal of this project was to measure cortisol and thyroid hormone levels in molting Weddell seal pups from week 1, 3, 5, and 7 of postnatal development. We used an enzyme-linked immunosorbent assay (or ELISA) to quantify cortisol levels and a radioactive immunoassay (RIA) to measure total triiodothyronine (tT3) levels in blood plasma of seal pups. Our results show a significant increase in cortisol from week 1 to week 3 and in tT3 levels from week 1 and week 5 of postnatal development. In addition, we found associations between cortisol and tT3 levels and molt status. These novel results give us a closer look at what is driving postnatal development in Weddell seals in tune with their environment. Our study is the first to measure hormones at this resolution in an Antarctic marine mammal. This information can be a vital baseline as climate continues to change and how that might affect the health of the species. Next, we are working on optimizing seal plasma sample preparation methods for proteome-level analyses of postnatal development in marine mammals.