Sexual Parasitism: Deep-Sea Anglerfish Evolved a New Type of Immune System to Physically Fuse With Their Mates
Deep-sea anglerfishes have evolved a curious reproductive strategy. Tiny males attach themselves to gigantic females so tightly that the tissues of the two animals eventually fuse. The male esssentially turns into a sperm-producing parasite. This phenomenon is known as sexual parasitism which avoids rejection reaction that usually happens after organ transplantation. Researchers at the MPI of Immunobiology and Epigenetics in Freiburg, Germany and the University of Washington in Seattle, USA have now solved this enigma, and describe the mechanism by which the fusion of two individuals of the same species can so readily occur. They found that the unusual mode of reproduction is associated with changes in the genome that disable key functions of the acquired immune system and instead must rely on much improved innate facilities to deal with infections. The discovery of this unique immune system points to possible new ways of improving immune defence in patients who suffer from the consequences of a congenital or acquired immune disabilities.
A female specimen of the deep-sea anglerfish species Melanocetus johnsonii of about 75 mm in size with a 23.5 mm large male fused on her belly. Credit: Edith A. Widder
Deep-sea anglerfishes employ an incredible reproductive strategy. Tiny dwarfed males become permanently attached to relatively gigantic females, fuse their tissues and then establish a common blood circulation. In this way, the male becomes entirely dependent on the female for nutrient supply, like a developing fetus in the womb of her mother or a donor organ in a transplant patient. In anglerfishes, this unusual ...
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