The genetic secret of giant ocean creatures has finally been revealed: ScienceAlert

The genetic secret of giant ocean creatures has finally been revealed: ScienceAlert

The great size variation among cetacean species, including dolphins, whales and porpoises, is largely explained by the activity of specific gene regions, according to a recent study by scientists from the Institute of Biology at the Brazilian University of Campinas (IB-UNICAMP).

blue whales (Palaenoptera musclefor example, can reach 30 meters (98 ft) in length while the bottlenose dolphin (Tursiops severed) Usually no more than 3.5 meters long. New research not only helps explain these dramatic size differences, but may also lead to the development of cancer treatments.

The researchers looked at the DNA sequence that comes before the part of the gene that codes for proteins, called the promoter region. Examination of the promoter region of a gene called NCAPG It revealed interesting relationships between cetaceans.

Furthermore, it is possible that specific regulatory cascades play a role in managing any runaway cell proliferation in animals adapted to exponential growth.

Cetaceans are divided into two well-defined groups; Mysticeti, which includes all baleen whales such as humpback whales, and Odontoceti, which includes toothed whales, such as sperm whales, and dolphins. However, despite this distinct evolutionary classification, the entire group of aquatic mammals can be divided in another way.

“We found it in the promoter region of the gene NCAPG “The division is between those who are more or less than 10 meters tall – giants and non-giants,” says Felipe Silva, first author of the new paper and a geneticist at IB-UNICAMP.

Previous research conducted by the same group revealed that NCAPG This gene appears to be favored by evolution in giant cetaceans. New findings about this gene’s promoter and coding regions suggest that it plays an important role in cetaceans growing to enormous sizes.

Gene activity depends largely on the promoter region, which is similar to the regulator of gene expression. Silva and his team found that size-controlling proteins were more active in giant cetaceans, at the behest of their specific promoters. In contrast, cetaceans less than 10 meters long have the same genes that act as repressors, limiting the production of those proteins and, as a result, the size of the animal.

“Our findings do not change the evolutionary tree of the group but constitute new evidence that giant size has a genomic basis,” says geneticist Mariana Neri from IB-UNICAMP.

Proteins that regulate body size were more active in giant cetaceans, which explains why the sperm whale (Big-headed physeter), which is gigantic but has teeth, is closely related to Mysticeti, which is also gigantic but lacks teeth.

These same genes were suppressors in cetaceans less than 10 meters long, which explains the genetic link between the 8.8-meter-long common toothless minke whale (Balaenoptera acutorostrata), and other non-giant toothed cetaceans.

“Analysis of other genes confirms the evolutionarily established groupings, meaning that the characteristics of minke whales and sperm whales are probably convergent adaptations – similar traits that evolved independently in separate groups via different routes,” Neary explains.

Although tumors would be expected in animals with a large number of cells, giant cetaceans show an exceptionally low incidence of cancer.

The researchers then analyzed the regulatory regions of four genes whose protein coding sequences had previously been studied. Non-coding sequences, which include regulatory elements such as promoters and enhancers, play a role in coordinating the timing and location of gene expression.

“It was important to analyze the coding and non-coding parts of these cetaceans’ genomes, as both proved important for these traits, which evolved very quickly in these animals, as the analysis also showed,” explains Silva.

The team speculated that these regulatory regions may not only have an impact on the size of cetaceans, but could affect their ability to suppress cancer.

“Humans also have these genes, so it will be interesting to learn more about how they inhibit tumorigenesis in these animals,” Neary says.

“Such knowledge could help develop future cancer treatments by activating or inhibiting specific regions of the genome, for example.”

The research was published in BMC ecology and evolution.

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