Iron mobilization during lactation reduces oxygen stores in a diving mammal

The profound impacts that maternal provisioning of finite energy resources has on offspring survival have been extensively studied across mammals. This study shows that in addition to calories, high hemoprotein concentrations in diving mammals necessitates exceptional female-to-pup iron transfer. Nu...

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Bibliographic Details
Published in:Nature Communications
Main Authors: Shero, Michelle R., Kirkham, Amy L., Costa, Daniel P., Burns, Jennifer M.
Format: Text
Language:English
Published: Nature Publishing Group UK 2022
Subjects:
Online Access:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9345918/
https://doi.org/10.1038/s41467-022-31863-7
Description
Summary:The profound impacts that maternal provisioning of finite energy resources has on offspring survival have been extensively studied across mammals. This study shows that in addition to calories, high hemoprotein concentrations in diving mammals necessitates exceptional female-to-pup iron transfer. Numerous indices of iron mobilization (ferritin, serum iron, total-iron-binding-capacity, transferrin saturation) were significantly elevated during lactation in adult female Weddell seals (Leptonychotes weddellii), but not in skip-breeders. Iron was mobilized from endogenous stores for incorporation into the Weddell seal’s milk at concentrations up to 100× higher than terrestrial mammals. Such high rates of iron offload to offspring drew from the female’s own heme stores and led to compromised physiologic dive capacities (hemoglobin, myoglobin, and total body oxygen stores) after weaning their pups, which was further reflected in shorter dive durations. We demonstrate that lactational iron transfer shapes physiologic dive thresholds, identifying a cost of reproduction to a marine mammal.