Key reproductive hormone in oldest vertebrate identified

WASHINGTON - Researchers have unravelled the once-prized enigma behind the sex life of the oldest vertebrate- a hagfish- by identifying the first reproductive hormone of the eyeless, snot-covered, worm-like scavenger of the deep

University of New Hampshire professor of biochemistry Stacia Sower and colleagues at two Japanese universities have identified the first reproductive hormone of these gonadotropins.

“This is a significant breakthrough with hagfish,” said Sower.

Gonadatropins (GTHs) are a protein secreted from the pituitary, stimulating the gonads (ovaries and testes) to produce and release the sex steroid hormones, which prompt their growth and maturation.

GTHs are produced in response to hypothalamic gonadotropin-releasing hormone (GnRH), what Sower calls the “master molecule” for reproduction in vertebrates- its discovery remains the holy grail of understanding hagfish reproduction.

At 500 million years old, hagfish are the oldest living vertebrate, predating the dinosaurs.

They are notoriously difficult to study, in part because their habitat is the ocean floor at 100 meters or more.

Compounding the urgency of better understanding hagfish reproduction is their growing importance as a fishery in the Gulf of Maine. Despite their vicious nature and least appealing characteristic - the stress-induced secretion of mucous from up to 200 slime glands along their bodies - hagfish are prized, particularly in Asian markets.

Their tough, soft skin is marketed as “eel” skin for wallets, belts and other items (”Because they’re not going to sell something that says ‘hagfish,’” said Sower, pulling out her own flawless 20-year-old eel skin wallet).

The findings were published in the journal Proceedings of the National Academies of Science (PNAS) in September. (ANI)