Science: 100-year-old sex parasitic mystery finally solved! Sacrifice immune function in exchange for permanent male and female conjoinedness.

!--:page title"--/August 1, 2020 /PRNewswire/ -- --- deep-sea herring (anglerfish, also known as Ankangfish) has adopted an incredible breeding strategy.
dwarf males bind permanently with giant females, combining their tissues and creating common blood circulation.
so, the male fish is completely dependent on the nutritional supply of the female fish, just like the developing fetus in the mother's womb or the donor organ in the transplanted patient."
this unusual phenomenon, known as sexual parasiticism, is the reason for the breeding success of these animals living in vast spaces in the deep sea, otherwise females and males rarely meet.
the permanent union of males and females represents an anatomical form of bonding, a phenomenon unknown in nature, except for the rare presence of identical twins.
immune system represents a huge barrier.
it attacks foreign tissue, just as it destroys cells infected by pathogens.
see the difficulties of human organ transplantation, which requires careful cross-matching of donor and receptor tissue types, followed by immunosuppressive drugs to ensure the long-term survival of organ transplants.
But how can the catfish accept each other so easily when an organizational rejection reaction may occur? Photo from Science, 2020, doi: 10.1126/science.aaz9445.
Since 1920, when Iceland's fisheries biologists discovered the first conjoined male and female, the sex parasitic phenomenon has been a 100-year-old mystery.
now, in a new study, researchers from the Max Planck Institute for Immunobiology and Epigenetics in Germany and researchers at the University of Washington have solved the century-old puzzle and published their findings in the journal Science, titled "The Betagenetics of sexual lysitism."
key functions of the immune system were removed a few years ago, Dr. Thomas Boehm, an immunologist working at the Max Planck Institute for Immunobiology and Epigenetics, and Theodore W. Pietsch, a fish expert working at the University of Washington in Seattle, began studying the genomes of different species of catfish.
they first studied the structure of the main tissue compatibility (MHC) antigen.
these molecules are present on the surface of the body's cells, which alert the immune system when they are infected by viruses or bacteria.
to ensure that all pathogens are effectively identified, mHC molecules change so much that it is difficult to find the same or nearly the same form of MHC in any two individuals of a species.
this characteristic is the root cause of tissue matching problems that plague human organs and bone marrow transplants. Interestingly
, the researchers found thatfish using a permanent binding strategy largely removed the genes that encode the MHC molecules, as if they had eliminated immune recognition and opted for tissue fusion. "In addition to the removal of this unusual MHC gene, we found that the function of killer T cells that actively remove infected cells or attack foreign tissue during organ rejection is severely impaired, if not completely lost," said Jeremy Swann of the Max Planck Institute for Immunobiology and Epigenetics, the first author of the
paper.
these findings suggest that the herring's immune system is highly unusual among thousands of vertebrates.
survived these unexpected findings without acquired sexual immune function, the researchers speculated that the recombination of the herring's immune system may be more extensive than expected.
in fact, further research has shown that, as the second most powerful weapon in the immune defense arsenal, antibodies have also disappeared from some herring species. "For humans, the combined loss of important immune functions observed in mackerel can lead to fatal immunodeficiency," said
Boehm.
", however, it is clear that the herring can survive without the vital acquired immune function.
, the researchers concluded that the animals used a much-improved nate immune function to fight infection, an unexpected solution to all living things facing problems.
in fact, until now, it has been thought that once an evolutionary partnership between acquired and congenital immunity has been formed, it has not been possible to lift it without serious consequences.
immune systems influence reproductive strategies, the study shows that vertebrates can survive without adaptive immune functions previously considered irreplaceable, despite hundreds of millions of years of co-evolutionary co-evolution of congenital and acquired immune functions. "We hypothesize that the uncharted evolutionary forces first drive changes in the immune system and then use these changes to evolve sex parasites,"
Boehm said. "Interestingly, the researchers believe that among the fish they collected, they even caught fish that were producing sex parasites.
"We found that this unusual pattern of reproduction appeared independently several times in these fish, " said
Pietsch.
"Although details of the improvement in congenital immune function of the herring have yet to be found, the results of this study point to potential strategies for enhancing congenital immune function in patients with congenital immune function or acquired immune impairment."
thus, the scientific journey, which began with an unknown observation on a fishing boat in the mid-Atlantic, unexpectedly opened up new avenues for the treatment of human immunology.
(bioon.com) References: 1.Jeremy B. Swann et al. The immunogenetics of the sexual parasitism. Science, 2020, doi:10.1126/science.aaz9445.2. Immune functions traded in for success for the title"--!--/ewebeditor:page."