Somatic growth acceleration of juvenile abalone, Haliotis discus hannai, by immersion in and intramuscular injection of recombinant salmon growth hormone

We examined the ability of recombinant salmon growth hormone (rsGH) to accelerate somatic growth of juvenile abalone, Haliotis discus hannai, by immersion and intramuscular injection in comparison with the effects of the salmon prolactin (sPRL) and bovine serum albumin (BSA). After immersion in protein solutions at a concentration of 30 mg/l for 30 min at 4- or 7-day intervals, the rsGH-immersed abalone exhibited an increase in shell length and body mass, whereas the sPRL-immersed abalone showed an increase in body mass only. No increase in shell length and body mass was observed in the BSA-immersed abalone. This suggests that rsGH and sPRL were absorbed from the ambient water into the abalone's circulatory system and that rsGH, and also sPRL to some extent, play a role in growth stimulation in abalone. To demonstrate quantitatively the effect of rsGH on juvenile abalone, we examined the ability of rsGH to accelerate somatic growth by intramuscular injection. Injections of rsGH at doses between 2 and 20 ng/g body mass (BM) at 7-day intervals resulted in an increase in shell length and body mass, but no effect was observed at a dose exceeding 100 ng/g BM. These results indicate that rsGH has a growth stimulatory effect on juvenile abalone.