Scientists decoded the genome of the sturgeon Sterlet, a small species of sturgeon from Eurasia. An international team of researchers from the United States and Europe have designed the first high-quality genomic sequence for a small species of sturgeon (Euspner ruthenus) from Eurasia.
Sturgeons are among the oldest species on Earth in terms of evolutionary history. They are the ancestors of the more than 30,000 fish species that exist today, and therefore represent more than 96% of all living fish species and approximately half of all known vertebrate species.
Estrogens are distributed from subtropical to suburban rivers, lakes, and along the coast of Eurasia and North America. They live longer and reproduce late, usually not before they are ten years old. In many sturgeon species, adults repeatedly participate in fresh seawater.
Estrogens are famous among fish because of their pre-ovulation female gametes, called caviar. Despite its ancient lineage, its peculiar biological characteristics, and its economic value, the sturgeon genome remains largely unexplained.
“The sturgeon genome is an important part of the puzzle that helps us understand the lineage of vertebrates. And it’s still missing, “said co-lead author Professor Manfred Shertle, a researcher at Texas State University and the University of Wurzburg at Texas A&M University.
“His outward appearance has changed little since then and is also evident in his genetic material, DNA,” said first author Dr. Du Kang joined the University of Würzburg.
The team successfully assembled a high-quality chromosome-level reference genome for sterile sturgeon. Analysis revealed that the genome contains 1.8 billion base pairs, 120 chromosomes, and approximately 47,500 protein-coding genes.
It also detected very low protein growth rates that are at least as slow as other deep branches of the vertebrate tree, such as coelacanths. The rate of protein development of sterlet is similar to that of coelacanth or shark.
And two species of fish that roam the oceans have remained largely unchanged for more than 300 million years, with co-authors, Drs. Mathias Stoke is an evolutionary biologist at the Leibniz Institute for Freshwater Ecology and Inland Fisheries.
Scientists discovered that sturgeons reached their own development path sometime during the Upper Devonian or Carboniferous period, about 345 million years ago.
He also discovered that about 180 million years ago, Sterlet mimicked its genome, leaving species with four sets of chromosomes instead of the normal two, known as tetraplody. Such processes repeatedly have a major impact on the evolution of the vertebrate genome, Professor Shortall said.
Their ancestors have already crossed the ‘complete genome duplication’ twice in their evolutionary history. Some species have gone through this process about three or four times. The fact that the researchers were surprised that the long history of the sturgeon had occurred so far was repetitive.
“During this long interval of time, we would expect the genome to change more profoundly because gene segments in tetraploid organisms are often lost, gaining new function over time, silenced.”
Sturgeon’s exact genomic states have long been controversial among scientists. While some consider polyploids, meaning the genome was repeated multiple times, others interpreted Sturgeon as a functional bipolar.
This refers to a species that had previously replicated its genome to become tetraploid, but then reduces the content of the gene again when it develops. Although chromosomes are still present in two pairs, they share their functions with each other.
“We have come to know that steroids have not returned to diploid states. Instead, it has retained an unexpectedly high degree of structural and functional polyploids, “said Professor Shortall. This retention can be attributed to the slow rate of molecular evolution of most fractions of the esterlet genome.