Hormonal replacement therapy in fish:human growth hormone gene function in hypophysectomized carp

Area of Science:

• Aquaculture
• Genetics
• Endocrinology

Background:

• Growth hormone is crucial for fish development.
• Transgenic technology offers potential for enhanced aquaculture traits.
• Understanding gene expression in transgenic fish is key for application.

Purpose of the Study:

• To investigate the growth of transgenic common carp expressing human growth hormone (hGH) after hypophysectomy.
• To determine if the hGH transgene can compensate for the absence of endogenous pituitary growth hormone.
• To explore the tissue-specific expression of the hGH transgene in common carp.

Main Methods:

• Production of transgenic common carp (Cyprinus carpio) using microinjection of a plasmid containing the hGH gene.
• Hypophysectomy (pituitary removal) was performed on transgenic F2 common carp, non-transgenic common carp, and non-transgenic crucian carp.
• Growth rates were monitored for 110 days, with additional experiments involving recombinant hGH injection into non-transgenic crucian carp.

Main Results:

• Hypophysectomy led to growth cessation in non-transgenic common carp and crucian carp.
• Recombinant hGH administration stimulated growth in hypophysectomized crucian carp.
• Hypophysectomized hGH-transgenic common carp exhibited continued growth, indicating transgene expression outside the pituitary.

Conclusions:

• The human growth hormone (hGH) transgene is expressed in tissues beyond the pituitary in transgenic common carp.
• Transgenic approaches can potentially overcome growth limitations associated with pituitary function in fish.
• This study provides evidence for the functional expression of heterologous growth hormone genes in aquaculture species.