TY - JOUR
T1 - Determining the functional role of waterborne amino acid uptake in hagfish nutrition
T2 - a constitutive pathway when fasting or a supplementary pathway when feeding?
AU - Glover, Chris N.
AU - Blewett, Tamzin A.
AU - Wood, Chris M.
N1 - Publisher Copyright:
© 2016, Springer-Verlag Berlin Heidelberg.
PY - 2016/10/1
Y1 - 2016/10/1
N2 - Hagfish are unique among aquatic “vertebrates” in their ability to absorb amino acids directly from the water via skin and gill epithelia, but it is unknown whether this phenomenon extends beyond a few studied substrates; what effect fed state has on absorption; and what functional role this may play in hagfish nutrition. Using in vivo and in vitro transport assays, uptake and tissue distribution of the waterborne amino acids l-alanine, l-lysine, and l-phenylalanine were examined as a function of fed state. All three amino acids were shown to be taken up from the water (lysine and phenylalanine for the first time). Following immersion in radiolabelled solutions for 24 h, phenylalanine was the amino acid that accumulated at the highest levels in almost all tissues, with the highest accumulation noted in red blood cells and bile, followed by gill and liver. In general, tissues of fed hagfish displayed a significantly reduced phenylalanine accumulation compared to tissues of hagfish fasted for 3 weeks. An in vitro assay showed that phenylalanine was transported across the skin at the highest rate, with the uptake of lysine occurring at the lowest rate. Feeding status had no significant effect on in vitro transport. These data indicate that dissolved organic nutrients are a significant source of nutrition to hagfish, and may be relatively more important during periods of fasting than during periods of feeding when immersed in decaying carcasses.
AB - Hagfish are unique among aquatic “vertebrates” in their ability to absorb amino acids directly from the water via skin and gill epithelia, but it is unknown whether this phenomenon extends beyond a few studied substrates; what effect fed state has on absorption; and what functional role this may play in hagfish nutrition. Using in vivo and in vitro transport assays, uptake and tissue distribution of the waterborne amino acids l-alanine, l-lysine, and l-phenylalanine were examined as a function of fed state. All three amino acids were shown to be taken up from the water (lysine and phenylalanine for the first time). Following immersion in radiolabelled solutions for 24 h, phenylalanine was the amino acid that accumulated at the highest levels in almost all tissues, with the highest accumulation noted in red blood cells and bile, followed by gill and liver. In general, tissues of fed hagfish displayed a significantly reduced phenylalanine accumulation compared to tissues of hagfish fasted for 3 weeks. An in vitro assay showed that phenylalanine was transported across the skin at the highest rate, with the uptake of lysine occurring at the lowest rate. Feeding status had no significant effect on in vitro transport. These data indicate that dissolved organic nutrients are a significant source of nutrition to hagfish, and may be relatively more important during periods of fasting than during periods of feeding when immersed in decaying carcasses.
KW - Cutaneous
KW - Feeding
KW - Nutrients
KW - Starvation
KW - Transport
KW - Uptake
UR - http://www.scopus.com/inward/record.url?scp=84969902289&partnerID=8YFLogxK
U2 - 10.1007/s00360-016-1004-2
DO - 10.1007/s00360-016-1004-2
M3 - Journal Article
C2 - 27215782
AN - SCOPUS:84969902289
SN - 0174-1578
VL - 186
SP - 843
EP - 853
JO - Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
JF - Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
IS - 7
ER -