February 9 (UPI) – When the first live African coelacanth fish, sometimes called the gombessa, was caught in 1938, researchers were caught. The fish were thought to be extinct for 65 million years.
It even surprised scientists that the species looked almost identical to its earliest relatives. They called the fish “living fossils.”
Fast forward more than 80 years, and scientists have now revealed the species, Latimeria chalumnae, have not spent the last 65 million years in evolutionary stasis.
According to a new paper, published Tuesday in the journal Molecular Biology and Evolution, the ocean predator discovered 62 new genes about 10 million years ago.
Follow-up data show that the novel genes were created by transposons, DNA sequences called autosomal genes. These traveling DNA sequences, also known as jump genes, can alter their position within the genome – moving, reproducing and rearranging themselves.
Scientists suspect that the African coelacanth fish obtained various transposons through interactions with other species. Autonomic genes routinely jump from one species to another.
“Our findings provide a very impressive example of this phenomenon of transposons contributing to the host genome,” lead study author Tim Hughes said in a press release.
“We don’t know what these 62 genes do, but many of them encode DNA-binding proteins and appear to have a place in gene regulation, where even small changes are important in micro- growth, “said Hughes, professor of molecular genetics at the University of Toronto.
Transposons boast a self-encoding enzyme that allows these traveling sequences to identify, copy, reassemble and fold DNA encoded into a new part of the genome. The process of cell division, when the genome is reproduced, ensures that these sequences are distributed throughout the genome.
Over time, jumping gene sequences break down and the ability to reproduce and reproduce is lost. However, if these autoimmune genes happen to offer a competitive advantage to the host organism, they can be cemented in sex.
Action genes derived from transposons have been found in several species, but it surprised scientists to find so many in a species that many scientists thought were frozen in evolutionary times.
“It was surprising to see coelacanths emerge among vertebrates as a large number of these transposon-derived genes because they have an undeserved reputation as a living fossil,” said a lead author the surveyor, Isaac Yellan.
“The coelacanth may have evolved a little slower but it is certainly not a fossil,” said Yellan, a graduate student at the University of Toronto.
Yellan discovered the collection of transposon-related genes in the African coelacanth fish while searching for passages of a human gene called CGGBP1.
The gene derived from transposons first originated in the common ancestor of mammals, birds and reptiles. Despite its original origins, Yellan found it difficult to find peers in other commonly studied species.
Using genomic databases, he found isolated specimens of CGGBP-related genes in a strange range of mammals, reptiles and birds. He also found examples of CGGBP-like genes in lamprey, primitive spine and rare fungi.
Eventually, his study led to Latimeria chalumnae. The genome of the African coelacanth fish, which was tracked and added to genomic databases for the first time in 2013, boasted 62 CGGBP-like genes.
The researchers concluded that all of these transposon-related genes did not appear to be descended from a single common ancestor. Instead, the CGGBP-like genes may follow different sequences, arriving at different times through horizontal gene transfer.
“Horizontal gene transfer goes up the picture of where the transposons came from but we know from other species that it can occur through parasites,” Yellan said. “The most likely explanation is that they have been introduced several times through the history of evolution.”
Test tube experiments and computer models suggest that the CGGBP-like genes found in the coelacanth genome secrete proteins that help link specific strands to DNA, which alter how rewrite and communicate genetic coding.
The research suggests that CGGBP-like genes in coelacanth fish appear to play a dynamic role in gene expression, similar to the role that CGGBP1 plays in the human genome.
because of Latimeria chalumnae and its relatives are so rare, scientists may never be able to trace the evolutionary origin of the 62 gene species derived from transposon, but the latest discovery has given scientists insights into the ways in which transposons can transfer from sex to sex.