Acquisition of alanyl-alanine in an Agnathan: Characteristics of dipeptide transport across the hindgut of the Pacific hagfish Eptatretus stoutii

Alyssa M. Weinrauch, Tamzin A. Blewett, Chris N. Glover, Greg G. Goss

Research output: Contribution to journalJournal Articlepeer-review

4 Citations (Scopus)

Abstract

This study used 3H-L-alanyl-L-alanine to demonstrate dipeptide uptake using in vitro gut sacs prepared from the hindgut of the Pacific hagfish Eptatretus stoutii. Concentration-dependent kinetic analysis resulted in a sigmoidal distribution with a maximal (± SE) uptake rate (Jmax-like) of 70 ± 3 nmol cm−2 h−1 and an affinity constant (Km-like) of 1072 ± 81 μM. Addition of high alanine concentrations to transport assays did not change dipeptide transport rates, indicating that hydrolysis of the dipeptide in mucosal solutions and subsequent uptake via apical amino acid transporters was not occurring, which was further supported by a Km distinct from that of amino acid transport. Transport occurred independent of mucosal pH, but uptake was reduced by 42% in low mucosal sodium. This may implicate cooperation between peptide transporters and sodium-proton exchangers, previously demonstrated in several mammalian and teleost species. Finally, apical L-alanyl-L-alanine uptake rates (i.e., mucosal disappearance) were significantly increased following a meal, demonstrating regulation of uptake. Overall, this examination of dipeptide acquisition in the earliest extant Agnathan suggests evolutionarily conserved mechanisms of transport between hagfish and later-diverging vertebrates such as teleosts and mammals.

Original languageEnglish
Pages (from-to)1471-1479
Number of pages9
JournalJournal of Fish Biology
Volume95
Issue number6
DOIs
Publication statusPublished - 1 Dec. 2019

Keywords

  • cyclostomes
  • digestion
  • intestine
  • regulation
  • transport proteins

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