Meeting Abstract
13.5 Friday, Jan. 4 Characterization and functional analyses of three thiamin related transporters and a thiamin pyrophosphokinase in rainbow trout, and examination of their expression alteration in thiamin deficiency YUGE, S*; HONEYFIELD, D.C.; SALOKA, S.K.; LI, W.; Michigan State Univ., E. Lansing ; USGS-NARL, Wellsboro; Michigan State Univ., E. Lansing ; Michigan State Univ., E. Lansing shinya.yuge@gmail.com
Thiamin (Th, vitamin B1) is a micronutrient essential for metabolism. Th deficiency (TD) has caused a lethal disease in salmonids. However, little is known about molecular mechanisms of the salmonid TD. In the rainbow trout, we identified Th metabolism related genes, two th transporters (thtr1, thtr2), a th derivative transporter (thde-tr/rfc) and th pyrophosphokinase with its seven splice variants (tpk_tv1-7). The transporters are critical for cellular and body Th uptake, and the enzyme generates the active Th. Thtr1 and Thtr2, but not Thde-tr, expressed in HEK cells exhibited 3H-Th uptake. mRNA expression of thtr1, thde-tr and tpk_tv1 with two-three tpk_tv was found in all examined tissues, while thtr2 transcripts were observed only in intestine and kidney. During embryonic development, total tpk_tv transcripts increased to a peak before hatch, thtr1 and thde-tr transcripts peaked in yolk-sac fry stage, while thtr2 transcripts gradually increased toward the swim-up stage. Notably, tpk_tv5 mRNA expression was abundant in ovary and in most of the embryonic stages. In trout with TD, the mRNA expression was reduced in the following tissues: thtr2, upper and lower intestine; thde-tr, all tissues examined; total tpk_tv, gill, liver, upper intestine and muscle. In contrast, no such changes occurred in thtr1 in any of those tissues. In summary, in rainbow trout, 1) thtr1, thde-tr and tpk are active genes within all tissues and most of embryonic stages, while thtr2 may be specific for intestinal and renal Th absorption; 2) tpk_tv5 mRNA expression might be important in ovary and in embryogenesis; and 3) in TD, thtr2, thde-tr and tpk appear to be down-regulated.
