There are only a few of them animals more bizarre than devils, a species that has so much trouble finding a partner that when males and females unite underwater, males actually unite their tissue with females for life. After merging, they both share a respiratory and digestive system.
Researchers have now found that anglerfish achieve this sexual parasitism because they have lost a key part of their immune system, which then allows the two bodies to become one without rejecting the tissue. (Remember symbiote Jadzia Daxová from Deep Space Nine?)
All vertebrates, including humans, have two types of immune systems. The first is an innate system that responds rapidly to attacks by microscopic invaders with various chemicals such as mucous membranes, physical barriers such as hair and skin, and cells affecting diseases called macrophages. The second line of defense is an adaptive system that produces “killer”; T cells to attack the pathogen and antibodies made to measure to fight specific bacteria or viruses. Both systems work together to fight infections and prevent disease.
But in a study published Thursday in a magazine science, researchers from the German Max Planck Institute and the University of Washington have found that many species of marine fish (there are more than 300) have evolved over time to lose the genes that control their adaptive immune systems, meaning they cannot produce antibodies and are absent. im T cells.
“Anglerfish traded on their immune abilities, which we consider essential for this reproductive behavior,” says Thomas Boehm, professor at the Institute of Immunobiology and Epigenetics in Freiburg, Germany, and lead author on paper.
To reach this conclusion, Boehm and his colleagues have spent the last six years genetically testing devilish tissue samples taken from around the world. They tried to catch them using deep-sea trawls, which collect specimens 1,000 feet below the surface, but because the devil is rare and elusive, they could not collect any live specimens. To obtain enough tissue for their genetic analysis, the researchers instead looked for museum collections and other laboratories in which the devil was stained with preservatives.
There are several reproductive methods in the Devil family. Females of some species mate with one male; others associate with more men; and another group has only a temporary merger. After crushing 31 tissue samples from 10 species, the team performed genetic tests and found that species that temporarily fuse with their comrades lacked the genes responsible for antibody maturation. Species that form a permanent association with their species have also lost a set of other genes that are responsible for the assembly of T cell receptors and antibody genes that underlie the innate immune system of all vertebrates.
“It was intuitive to think that there was a certain genetic tendency for this to happen,” Boehm says of the unusual immune systems of marine fish species. “This is the first evidence that these animals have this inability to reject part of themselves and allow these links to take place.”