Zoological Studies

Presence or Absence of the Cl⁻ Channel Phospholemman in the Rectal Gland of Sharks: A Comparative Study

Feico M.A.H. Schuurmans Stekhoven, Sjoerd E. Wendelaar Bonga, Tsung-Han Lee, and Andrew R. Bottrill (2010) In this study on the presence or absence of phospholemman expression in the rectal glands of different orders of sharks, we observed the following.  In the clade comprised of members of the Lamniformes and Squaliformes, the channel exists, but tends to change its primary structure, and also appears to change to a form with a higher molecular weight that, according to literature data, may be located in the cytoskeleton.  In the shark orders of Orectolobiformes and Carcharhiniformes, the channel gradually disappears with Triakis scyllium as one of the last representatives containing a largely modified N-terminus.  The final members of this clade (Carcharhinidae and Sphyrnidae) lack the channel.  From these data it was concluded that the presence or absence of phospholemman is clade and family dependent, and these clades have experienced different genetic histories.