Evolution of Pinnipedia lactation strategies: a potential role for alpha-lactalbumin?

Biol Lett. 2007 Oct 22;3(5):546-9. doi: 10.1098/rsbl.2007.0265.


Despite the considerable variation in milk composition found among mammals, a constituent common across all groups is lactose, the main sugar and osmole in most eutherians milk. Exceptions to this are the families Otariidae (fur seals and sea lions) and Odobenidae (walruses), where lactose has not been detected. We investigated the molecular basis for this by cloning alpha-lactalbumin, the modifier protein of the lactose synthase complex. A mutation was observed which, in addition to preventing lactose production, may enable otariids to maintain lactation despite the extremely long inter-suckling intervals during the mother's time at sea foraging (more than 23 days in some species).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Biological Evolution
  • Caniformia / genetics
  • Caniformia / physiology*
  • Lactalbumin / genetics*
  • Lactation*
  • Molecular Sequence Data


  • Lactalbumin