TY - JOUR
T1 - Acquisition of alanyl-alanine in an Agnathan
T2 - Characteristics of dipeptide transport across the hindgut of the Pacific hagfish Eptatretus stoutii
AU - Weinrauch, Alyssa M.
AU - Blewett, Tamzin A.
AU - Glover, Chris N.
AU - Goss, Greg G.
N1 - Funding Information:
information A.M.W. was supported by a National Science and Engineering Reseach Council (NSERC)-PGS-D, the President's Doctoral Prize of Distinction and the Donald M Ross Scholarship. T.A.B. was supported by a NSERC post-doctoral fellowship. C.N.G. was supported by Campus Alberta Innovates Program Research Chair and a NSERC Discovery Grant (251083). G.G.G. was supported by a NSERC Discovery Grant (203736). Many thanks to the support staff at Bamfield Marine Sciences Centre with particular thanks to the research coordinator Eric Clelland and to Janice Pierce and John Richards for hagfish collection.
Publisher Copyright:
© 2019 The Fisheries Society of the British Isles
PY - 2019/12/1
Y1 - 2019/12/1
N2 - 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.
AB - 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.
KW - cyclostomes
KW - digestion
KW - intestine
KW - regulation
KW - transport proteins
UR - http://www.scopus.com/inward/record.url?scp=85074850923&partnerID=8YFLogxK
U2 - 10.1111/jfb.14168
DO - 10.1111/jfb.14168
M3 - Journal Article
C2 - 31621087
AN - SCOPUS:85074850923
SN - 0022-1112
VL - 95
SP - 1471
EP - 1479
JO - Journal of Fish Biology
JF - Journal of Fish Biology
IS - 6
ER -