Genes that made whales grow to giant sizes identified

Subject: Science & tech

Section : Biotech

Context:

A new study explored the genetic underpinnings of gigantism in whales, identifying four genes that appear to have played crucial roles.

Details:

These genes helped in fostering great size but also in mitigating related disadvantageous consequences including higher cancer risk and lower reproductive output.
The four genes – named GHSR, IGFBP7, NCAPG and PLAG1 – appear to have gained prominence during the evolution of large whales.

About the growth genes:

GHSR is a gene involved in releasing growth hormone through the pituitary gland, body weight, energy metabolism, appetite and fat accumulation. It also is associated with controlling cell proliferation and programmed cell death. Tumors essentially are formed by runaway cell growth.
IGFBP7 is a gene involved in promoting cell growth and division. There is evidence it acts as a cancer suppressor in prostate, breast, lung and colorectal tumors.
NCAPG, a gene associated with growth in people, horses, donkeys, cattle, pigs and chickens, is linked to increased body size, weight gain, cell proliferation and cell life cycles.
PLAG1, a gene associated with body growth in cattle, pigs, and sheep, is involved in embryo growth and cell survival.

About Cetaceans:

Cetaceans, the marine mammal group encompassing whales, dolphins and porpoises, evolved around 50 million years ago from vaguely wolf-like land-based ancestors that belonged to a mammalian assemblage called artiodactyls that includes today’s cows, pigs, sheep and many others.
The blue, fin, bowhead, grey, humpback, right and sperm whales are the largest animals alive today. In fact, the blue whale is the largest-known creature ever on Earth, topping even the biggest of the dinosaurs.
- Blue whales can reach about 100 feet (30 meters) long, fin whales about 80 feet (24 meters), sperm and bowhead whales about 60 feet (18 meters), humpback and right whales about 50 feet (15 meters) and grey whales about 45 feet (13.5 meters).
Gigantism in the current cetacean lineage is recent, estimated at approximately 5 million years ago. Before that, there were animals with large sizes, like Basilosaurus, but these were exceptions, and most cetaceans did not exceed 10 meters in length.
- Basilosaurus, a toothed apex predator from about 40 million years ago, was the largest-known early whale. The baleen whale lineage dates to roughly 36 million years ago, starting modestly in size.