Of maternal injection of 3,5,3′-triiodo-L-thyronine (T3) on growth of newborn offspring of rockfish, Sebastes schlegeli

In the rockfish, Sebastes schlegeli, changes of thyroid hormone levels in plasma and egg of mature female broodstock and in whole body of newly born larvae were examined after maternal injection of 3,5,3'-triiodo-L-thyronine (T-3) at a dose of 20 mg/kg body weight. Also, the growth and survival rate of offspring from T-3-injected broodstock T-3 group) were compared for 30 days with those of vehicle-control (injected with DMSO: control group) and sham-control (needle inserted, but without any injection: sham group). Larvae were fed with rotifers, Artemia nauplii and commercial diet for flounder. Although there was no change of L-thyroxine (T-4) level following maternal T-3 injection, a significant increase of T-3 level was found in maternal plasma, eggs and larvae. Growth of offspring in the T-3 injection group was significantly faster than that of the two controls, and the condition factor was lower than that of controls. In addition, the survival rate of larvae from T-3-injected broodstock was significantly higher than that of larvae from the two controls. We conclude that exogenous T-3 in maternal circulation was transferred into oocytes and larvae. The transferred thyroid hormone appears to play some role in the early development of larvae and may confer a distinct advantage for the growth of offspring in rockfish, S. schlegeli. (C) 2004 Elsevier B.V. All rights reserved.